Removal of Chromophoric Dissolved Organic Matter and Heavy Metals in a River-Sea System: Role of Aquatic Microgel Formation

NASA Astrophysics Data System (ADS)

Shiu, R. F.; Lee, C. L.

2016-12-01

Dissolved organic carbon (DOC) polymers are complex and poorly understood mixture of organic macromolecules in environment system. Portions of these polymers spontaneously form microgels that play key roles in many biogeochemical reactions, including mediating aggregation processes, element cycling, and pollutant mobility. However, the detailed interaction of microgels-heterogeneous materials in aquatic systems is still lacking. Insight into the interaction between surrounding materials and microgels from different types of aquatic DOC polymers are extremely important, as it is crucial in determining the fate and transport of these materials. Here, we use riverine and marine DOC polymers to examine their aggregation behavior, and to evaluate the roles of microgel formation in scavenging of chromophoric dissolved organic matter (CDOM) and heavy metals in a river-sea system. Our results indicate that riverine and marine microgels did not exhibit too much difference in size ( 3-5 μm) and self-assembly curve; however, the assembly effectiveness ([microgel]/DOC) of marine samples was much higher than riverine. Instead of concentration of DOC, other factors such as types and sources of DOC polymers may control the microgel abundance in aquatic environments. After filtering water samples (microgels removed), the CDOM and selected metals (Cu, Ni, Mn) in the filtrate were quantified. CDOM and metals were concurrently removed to an extent via DOC polymer re-aggregation, which also suggested that the microgels had the sequestering capability in CDOM and metals. This finding provides an alternative route for CDOM and heavy metals removal from the water column. As such the process of re-aggregation into microgels should then be considered besides traditional phase partitioning in the assessment of the ecological risk and fate of pollutant.

4D Printed Actuators with Soft-Robotic Functions.

PubMed

López-Valdeolivas, María; Liu, Danqing; Broer, Dick Jan; Sánchez-Somolinos, Carlos

2018-03-01

Soft matter elements undergoing programed, reversible shape change can contribute to fundamental advance in areas such as optics, medicine, microfluidics, and robotics. Crosslinked liquid crystalline polymers have demonstrated huge potential to implement soft responsive elements; however, the complexity and size of the actuators are limited by the current dominant thin-film geometry processing toolbox. Using 3D printing, stimuli-responsive liquid crystalline elastomeric structures are created here. The printing process prescribes a reversible shape-morphing behavior, offering a new paradigm for active polymer system preparation. The additive character of this technology also leads to unprecedented geometries, complex functions, and sizes beyond those of typical thin-films. The fundamental concepts and devices presented therefore overcome the current limitations of actuation energy available from thin-films, thereby narrowing the gap between materials and practical applications. © 2017 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An epistemology on the nature of polymers.

PubMed

Laridjani, Mortéza; Leboucher, Pierre

2014-01-01

Liquids have neither a periodic structure nor the completely random character of gases therefore the detailed study of their x-ray scattering diagram encounters many difficulties. The idea of periodic regularity in molecules of liquid polymers has been an attractive proposition for the simple interpretation of liquid polymer x-ray diagrams. The categorisation of polymer substances as being between a crystal phase with a perfect order and an amorphous disordered state is an over simplification of the complex reality. For obtaining structural information, during the early stages of the application of x-ray diffraction, a near crystalline model of the molecular arrangements in liquids was utilised. However, the results from these investigations led to just an approximation of the crystalline state. Our studies have analysed the real image of Fourier space of liquid polymers, for the first time, using anomalous diffractometry. The findings show the precise atomic structure of liquid polymers when transformed, by cooling, to solid polymers. We demonstrate that there is an intermediate ordered structure, characterised by the real full image of Fourier space. This prominent state of matter, an intermediate ordered structure, is defined by a regular unit cell with a five-fold symmetry. These structural atomic studies contribute to a more detailed understanding of the properties of polymers than the traditional studies of the degree of crystallinity.

An Epistemology on the Nature of Polymers

PubMed Central

Laridjani, Mortéza; Leboucher, Pierre

2014-01-01

Liquids have neither a periodic structure nor the completely random character of gases therefore the detailed study of their x-ray scattering diagram encounters many difficulties. The idea of periodic regularity in molecules of liquid polymers has been an attractive proposition for the simple interpretation of liquid polymer x-ray diagrams. The categorisation of polymer substances as being between a crystal phase with a perfect order and an amorphous disordered state is an over simplification of the complex reality. For obtaining structural information, during the early stages of the application of x-ray diffraction, a near crystalline model of the molecular arrangements in liquids was utilised. However, the results from these investigations led to just an approximation of the crystalline state. Our studies have analysed the real image of Fourier space of liquid polymers, for the first time, using anomalous diffractometry. The findings show the precise atomic structure of liquid polymers when transformed, by cooling, to solid polymers. We demonstrate that there is an intermediate ordered structure, characterised by the real full image of Fourier space. This prominent state of matter, an intermediate ordered structure, is defined by a regular unit cell with a five-fold symmetry. These structural atomic studies contribute to a more detailed understanding of the properties of polymers than the traditional studies of the degree of crystallinity. PMID:25329440

Nucleation in Polymers and Soft Matter

NASA Astrophysics Data System (ADS)

Xu, Xiaofei; Ting, Christina L.; Kusaka, Isamu; Wang, Zhen-Gang

2014-04-01

Nucleation is a ubiquitous phenomenon in many physical, chemical, and biological processes. In this review, we describe recent progress on the theoretical study of nucleation in polymeric fluids and soft matter, including binary mixtures (polymer blends, polymers in poor solvents, compressible polymer-small molecule mixtures), block copolymer melts, and lipid membranes. We discuss the methodological development for studying nucleation as well as novel insights and new physics obtained in the study of the nucleation behavior in these systems.

Equation of State and Shock-Driven Decomposition of 'Soft' Materials

DOE PAGES

Coe, Joshua Damon; Dattelbaum, Dana Mcgraw

2017-12-01

Equation of state (EOS) efforts at National Nuclear Security Administration (NNSA) national laboratories tend to focus heavily on metals, and rightly so given their obvious primacy in nuclear weapons. Our focus here, however, is on the EOS of 'soft' matter such as polymers and their derived foams, which present a number of challenges distinct from those of other material classes. This brief description will cover only one aspect of polymer EOS modeling: treatment of shock-driven decomposition. Here, these interesting (and sometimes neglected) materials exhibit a number of other challenging features— glass transitions, complex thermal behavior, response that is both viscousmore » and elastic—each warranting additional discussions of their own.« less

Equation of State and Shock-Driven Decomposition of 'Soft' Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coe, Joshua Damon; Dattelbaum, Dana Mcgraw

Equation of state (EOS) efforts at National Nuclear Security Administration (NNSA) national laboratories tend to focus heavily on metals, and rightly so given their obvious primacy in nuclear weapons. Our focus here, however, is on the EOS of 'soft' matter such as polymers and their derived foams, which present a number of challenges distinct from those of other material classes. This brief description will cover only one aspect of polymer EOS modeling: treatment of shock-driven decomposition. Here, these interesting (and sometimes neglected) materials exhibit a number of other challenging features— glass transitions, complex thermal behavior, response that is both viscousmore » and elastic—each warranting additional discussions of their own.« less

Computer Simulations and Theoretical Studies of Complex Systems: from complex fluids to frustrated magnets

NASA Astrophysics Data System (ADS)

Choi, Eunsong

Computer simulations are an integral part of research in modern condensed matter physics; they serve as a direct bridge between theory and experiment by systemactically applying a microscopic model to a collection of particles that effectively imitate a macroscopic system. In this thesis, we study two very differnt condensed systems, namely complex fluids and frustrated magnets, primarily by simulating classical dynamics of each system. In the first part of the thesis, we focus on ionic liquids (ILs) and polymers--the two complementary classes of materials that can be combined to provide various unique properties. The properties of polymers/ILs systems, such as conductivity, viscosity, and miscibility, can be fine tuned by choosing an appropriate combination of cations, anions, and polymers. However, designing a system that meets a specific need requires a concrete understanding of physics and chemistry that dictates a complex interplay between polymers and ionic liquids. In this regard, molecular dynamics (MD) simulation is an efficient tool that provides a molecular level picture of such complex systems. We study the behavior of Poly (ethylene oxide) (PEO) and the imidazolium based ionic liquids, using MD simulations and statistical mechanics. We also discuss our efforts to develop reliable and efficient classical force-fields for PEO and the ionic liquids. The second part is devoted to studies on geometrically frustrated magnets. In particular, a microscopic model, which gives rise to an incommensurate spiral magnetic ordering observed in a pyrochlore antiferromagnet is investigated. The validation of the model is made via a comparison of the spin-wave spectra with the neutron scattering data. Since the standard Holstein-Primakoff method is difficult to employ in such a complex ground state structure with a large unit cell, we carry out classical spin dynamics simulations to compute spin-wave spectra directly from the Fourier transform of spin trajectories. We conclude the study by showing an excellent agreement between the simulation and the experiment.

Bounds on the polymer scale from gamma ray bursts

NASA Astrophysics Data System (ADS)

Bonder, Yuri; Garcia-Chung, Angel; Rastgoo, Saeed

2017-11-01

The polymer representations, which are partially motivated by loop quantum gravity, have been suggested as alternative schemes to quantize the matter fields. Here we apply a version of the polymer representations to the free electromagnetic field, in a reduced phase space setting, and derive the corresponding effective (i.e., semiclassical) Hamiltonian. We study the propagation of an electromagnetic pulse, and we confront our theoretical results with gamma ray burst observations. This comparison reveals that the dimensionless polymer scale must be smaller than 4 ×10-35 , casting doubts on the possibility that the matter fields are quantized with the polymer representation we employed.

Straightforward and precise approach to replicate complex hierarchical structures from plant surfaces onto soft matter polymer

PubMed Central

Speck, Thomas; Bohn, Holger F.

2018-01-01

The surfaces of plant leaves are rarely smooth and often possess a species-specific micro- and/or nano-structuring. These structures usually influence the surface functionality of the leaves such as wettability, optical properties, friction and adhesion in insect–plant interactions. This work presents a simple, convenient, inexpensive and precise two-step micro-replication technique to transfer surface microstructures of plant leaves onto highly transparent soft polymer material. Leaves of three different plants with variable size (0.5–100 µm), shape and complexity (hierarchical levels) of their surface microstructures were selected as model bio-templates. A thermoset epoxy resin was used at ambient conditions to produce negative moulds directly from fresh plant leaves. An alkaline chemical treatment was established to remove the entirety of the leaf material from the cured negative epoxy mould when necessary, i.e. for highly complex hierarchical structures. Obtained moulds were filled up afterwards with low viscosity silicone elastomer (PDMS) to obtain positive surface replicas. Comparative scanning electron microscopy investigations (original plant leaves and replicated polymeric surfaces) reveal the high precision and versatility of this replication technique. This technique has promising future application for the development of bioinspired functional surfaces. Additionally, the fabricated polymer replicas provide a model to systematically investigate the structural key points of surface functionalities. PMID:29765666

Dynamical studies of confined fluids and polymers

NASA Astrophysics Data System (ADS)

Grabowski, Christopher A.

Soft matter, a class of materials including polymers, colloids, and surfactant molecules, are ubiquitous in our everyday lives. Plastics, soaps, foods and living organisms are mostly comprised of soft materials. Research conducted to understand soft matter behavior at the molecular level is essential to create new materials with unique properties. Self-healing plastics, targeted drug delivery, and nanowire assemblies have all been further advanced by soft matter research. The author of this dissertation investigates fundamental soft matter systems, including polymer solutions and melts, colloid dispersions in polymer melts, and interfacial fluids. The dynamics of polymers and confined fluids were studied using the single-molecule sensitive technique of fluorescence correlation spectroscopy (FCS). Here, fluorescent dyes are attached to polymer coils or by introducing free dyes directly into the solution/film. Complementary experiments were also performed, utilizing atomic force microscopy (AFM) and ellipsometry. FCS and AFM experiments demonstrated the significant difference in properties of thin fluid films of the nearly spherical, nonpolar molecule TEHOS (tetrakis(2-ethylhexoxy)silane) when compared to its bulk counterpart. AFM experiments confirmed TEHOS orders in layers near a solid substrate. FCS experiments show that free dyes introduced in these thin films do not have a single diffusion coefficient, indicating that these films have heterogeneity at the molecular level. FCS experiments have been applied to study the diffusion of gold colloids. The diffusion of gold colloids in polymer melts was found to dramatically depart from the Stokes-Einstein prediction when colloid size was smaller than the surrounding polymer mesh size. This effect is explained by noting the viscosity experienced by the colloid is not equivalent to the overall bulk viscosity of the polymer melt. The conformational change of polymers immersed in a binary solvent was measured via FCS. This experiment was conducted to test a theory proposed by Brochard and de Gennes, who postulated a polymer chain undergoes a collapse and a dramatic re-swelling as the critical point of the binary mixture is approached. Measuring polymer chain diffusion as a function of temperature, this theory was confirmed. To my knowledge, this was the first experimental evidence of contraction/re-swelling for polymers in critical binary solvents.

Statistical field theory description of inhomogeneous polarizable soft matter

NASA Astrophysics Data System (ADS)

Martin, Jonathan M.; Li, Wei; Delaney, Kris T.; Fredrickson, Glenn H.

2016-10-01

We present a new molecularly informed statistical field theory model of inhomogeneous polarizable soft matter. The model is based on fluid elements, referred to as beads, that can carry a net monopole of charge at their center of mass and a fixed or induced dipole through a Drude-type distributed charge approach. The beads are thus polarizable and naturally manifest attractive van der Waals interactions. Beyond electrostatic interactions, beads can be given soft repulsions to sustain fluid phases at arbitrary densities. Beads of different types can be mixed or linked into polymers with arbitrary chain models and sequences of charged and uncharged beads. By such an approach, it is possible to construct models suitable for describing a vast range of soft-matter systems including electrolyte and polyelectrolyte solutions, ionic liquids, polymerized ionic liquids, polymer blends, ionomers, and block copolymers, among others. These bead models can be constructed in virtually any ensemble and converted to complex-valued statistical field theories by Hubbard-Stratonovich transforms. One of the fields entering the resulting theories is a fluctuating electrostatic potential; other fields are necessary to decouple non-electrostatic interactions. We elucidate the structure of these field theories, their consistency with macroscopic electrostatic theory in the absence and presence of external electric fields, and the way in which they embed van der Waals interactions and non-uniform dielectric properties. Their suitability as a framework for computational studies of heterogeneous soft matter systems using field-theoretic simulation techniques is discussed.

Statistical field theory description of inhomogeneous polarizable soft matter.

PubMed

Martin, Jonathan M; Li, Wei; Delaney, Kris T; Fredrickson, Glenn H

2016-10-21

We present a new molecularly informed statistical field theory model of inhomogeneous polarizable soft matter. The model is based on fluid elements, referred to as beads, that can carry a net monopole of charge at their center of mass and a fixed or induced dipole through a Drude-type distributed charge approach. The beads are thus polarizable and naturally manifest attractive van der Waals interactions. Beyond electrostatic interactions, beads can be given soft repulsions to sustain fluid phases at arbitrary densities. Beads of different types can be mixed or linked into polymers with arbitrary chain models and sequences of charged and uncharged beads. By such an approach, it is possible to construct models suitable for describing a vast range of soft-matter systems including electrolyte and polyelectrolyte solutions, ionic liquids, polymerized ionic liquids, polymer blends, ionomers, and block copolymers, among others. These bead models can be constructed in virtually any ensemble and converted to complex-valued statistical field theories by Hubbard-Stratonovich transforms. One of the fields entering the resulting theories is a fluctuating electrostatic potential; other fields are necessary to decouple non-electrostatic interactions. We elucidate the structure of these field theories, their consistency with macroscopic electrostatic theory in the absence and presence of external electric fields, and the way in which they embed van der Waals interactions and non-uniform dielectric properties. Their suitability as a framework for computational studies of heterogeneous soft matter systems using field-theoretic simulation techniques is discussed.

Methods for removing contaminant matter from a porous material

DOEpatents

Fox, Robert V [Idaho Falls, ID; Avci, Recep [Bozeman, MT; Groenewold, Gary S [Idaho Falls, ID

2010-11-16

Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

A new synthesis route for Os-complex modified redox polymers for potential biofuel cell applications.

PubMed

Pöller, Sascha; Beyl, Yvonne; Vivekananthan, Jeevanthi; Guschin, Dmitrii A; Schuhmann, Wolfgang

2012-10-01

A new synthesis route for Os-complex modified redox polymers was developed. Instead of ligand exchange reactions for coordinative binding of suitable precursor Os-complexes at the polymer, Os-complexes already exhibiting the final ligand shell containing a suitable functional group were bound to the polymer via an epoxide opening reaction. By separation of the polymer synthesis from the ligand exchange reaction at the Os-complex, the modification of the same polymer backbone with different Os-complexes or the binding of the same Os-complex to a number of different polymer backbones becomes feasible. In addition, the Os-complex can be purified and characterized prior to its binding to the polymer. In order to further understand and optimize suitable enzyme/redox polymer systems concerning their potential application in biosensors or biofuel cells, a series of redox polymers was synthesized and used as immobilization matrix for Trametes hirsuta laccase. The properties of the obtained biofuel cell cathodes were compared with similar biocatalytic interfaces derived from redox polymers obtained via ligand exchange reaction of the parent Os-complex with a ligand integrated into the polymer backbone during the polymer synthesis. Copyright © 2011 Elsevier B.V. All rights reserved.

Stabilization of organic matter in soils: role of amorphous mineral phases

NASA Astrophysics Data System (ADS)

Zewde Tamrat, Wuhib; Rose, Jérôme; Levard, Clément; Chaurand, Perrine; Basile-Doelsch, Isabelle

2016-04-01

Soil organic matter (SOM) globally contributes the largest portion of continental carbon stock. One major issue concerning this large C pool includes its instability by mineralization and erosion due to land use. The main hypothesis of this work is that physicochemical stabilization of SOM is mainly driven by interactions of organic compounds, not with mineral surfaces as classically considered, but with amorphous polymers continuously formed by the alteration of soil minerals(1-3). Our objective is to understand how nano-organomineral complexes (nCOMx) are structured at the nanoscale, assess mechanisms of their formation, and quantify the effects of their occurrence on SOM turnovers. Due to inherent high complexity of natural samples, our methodology is based on the formation of nCOMx from both synthetic systems and natural mineral-weathered components. For the mineral component, biotite (from Bancroft, Canada) was selected. For the organic component, 3,4-Dihydroxy-L-phenylalanine, an amino acid with hydroxyl (pKa=9.95), carboxyl (pKa=2,58), amino (pKa=9,24) and an aromatic functions was chosen. The methodology aimed at developing conditions that generate biotite dissolution and nCOMx precipitation. The second step of the experiment consisted of the precipitation of nCOMx by slowly increasing pH over 3 to 12 hours of hydrolysis. Three final pH conditions were tested (4.2, 5 and 7) with Metal/Carbon ratios of 0.01, 0.1, 1, 10 and 'No Carbon'. The first results of dissolution rates and congruency, AFM imaging, ICPMS, HR-TEM and XRD as well as XAS characterizations (transmission and florescence mode at the Fe K-edge) of nCOMx will be presented. Experiments and analysis techniques were designed to study these synthetic phases with regard to Si, Al, Fe and OM proportions to increase the OM proportion (as in natural soil phases) and also increase the stability of the OM phase (as in increased residence time of OM in the soil). We will focus particularly on the Fe state probed by XAS as a proxy of nCOMx polymerization state. Results showed the Fe atomic structure within the nCOMx was strongly affected by the presence of carbon and the final pH state. Higher pH allowed Fe to polymerize even at a relatively higher carbon content. The increase in concentration of OM led to a decrease in the polymerisation level of Fe amorphous polymers. High carbon composition (M:C=0.1) totally hindered development of Fe-Fe polymers. Whereas, in relatively lower carbon concentrations (M:C=1) iron polymers were exhibited for only highest pH values of 7. For an even lower concentration (M:C=10) iron polymers started to form at lower pH values of 5 and also higher. These suggest the strong dependence of soil OM complexation to inorganic amorphous polymers on pH state and relative availability of these counter parts; and thus giving a better understanding of protection of the carbon from various forms of mineralization. 1-Basile-Doelsch, I., 2015 Environmental Science & Technology, 49(7). 2-Keiluweit, M. et al., 2015. Nature Clim. Change, 5(6). 3-Kleber, M. et al., 2015. In: Donald, L.S. (Ed.), Advances in Agronomy. Key words : soil organic matter (OM), organo-mineral interactions, amorphous minerals, pH

Optical characterizations of silver nanoprisms embedded in polymer thin film layers

NASA Astrophysics Data System (ADS)

Carlberg, Miriam; Pourcin, Florent; Margeat, Olivier; Le Rouzo, Judikael; Berginc, Gerard; Sauvage, Rose-Marie; Ackermann, Jorg; Escoubas, Ludovic

2017-10-01

The precise control of light-matter interaction has a wide range of applications and is currently driven by the use of nanoparticles (NPs) by the recent advances in nanotechnology. Taking advantage of the material, size, shape, and surrounding media dependence of the optical properties of plasmonic NPs, thin film layers with tunable optical properties are achieved. The NPs are synthesized by wet chemistry and embedded in a polyvinylpyrrolidone (PVP) polymer thin film layer. Spectrophotometer and spectroscopic ellipsometry measurements are coupled to finite-difference time domain numerical modeling to optically characterize the heterogeneous thin film layers. Silver nanoprisms of 10 to 50 nm edge size exhibit high absorption through the visible wavelength range. A simple optical model composed of a Cauchy law and a Lorentz law, accounting for the optical properties of the nonabsorbing polymer and the absorbing property of the nanoprisms, fits the spectroscopic ellipsometry measurements. Knowing the complex optical indices of heterogeneous thin film layers let us design layers of any optical properties.

BOOK REVIEW: Soft Condensed Matter

NASA Astrophysics Data System (ADS)

Jones, Richard A. L.

2002-11-01

The author states in the preface of the book that the aim is '...to give a unified overview of the various aspects of the physics of soft condensed matter'. The book succeeds in fulfilling this aim in many respects. i) The style is fluent and concise and gives the necessary explanations to make its content understandable to people with some knowledge of the basic principles of physics. ii) The content of the book is complete enough to give a panoramic view of the landscape of soft condensed matter. The first two chapters give, respectively, a short introduction and a presentation of forces, energies and timescales, giving a general overview and pointing out the particular importance of different aspects such as timescales, which are much more important in soft condensed matter than in traditional or 'hard' condensed matter. The next chapter, devoted to phase transition, recalls that the equilibrium between two phases is controlled by free energy considerations. Spinodal decomposition is presented as a counterpart of nucleation and growth. Again, characteristic length scales are considered and applied to a phase separation mixture of polymers in a common solvent. The following three chapters are devoted respectively to specific topics: colloidal dispersion, polymers and gelation. The stability and phase behaviour of colloids are related to the interaction between colloidal particles. Properties of colloidal crystals as well as colloidal dispersion are depicted in terms of stabilization of crystalline colloids. The flow properties of colloidal dispersion are presented in terms of free energy minimization and the structure of the dispersion. After a brief introduction to polymer chemistry and architecture, the coil-globule transition is discussed. Viscoelasticity of polymers is described and discussed by introducing the notion of entanglement. This leads to the introduction of the tube model and the theory of reptation. The sol-gel transition is presented phenomenologically and formulated through the current percolation model and the Flory-Stockmayer model. The next two chapters consider the molecular order in soft condensed matter. The rich complexity of liquid crystals is emphasized and the Frederiks transition is described in relation to liquid crystal displays. The crystallinity in polymers is discussed and its usual semi-crystallinity presented as a consequence of entanglement and timescales. The next chapter describes the self-assembly of phases and the great importance of the self-assembly phenomenon in solutions of amphiphilic molecules is largely discussed in several specific phenomena. The book ends with a chapter devoted to the description of soft matter realizations in nature. Special attention is paid to the components and structure of life: nucleic acids, proteins, polysaccharides and membranes. There are two appendixes recalling the basic concepts of thermodynamics and statistical mechanics. In each chapter, several problems are included, and solutions to a selection of them are given. The bibliography proposed is pertinent and each chapter gives details of further reading, mostly addressed to known books on the topic. iii) The presentation of the book is good. Throughout the book, the relevant, basic or new concepts of each topic are typed in bold characters and succinctly defined. The figures are abundant and adequately illustrate the text either by plots of experimental data or by computed predictions from models. Many schematic representations of structures, molecular distributions or arrangements are also included. In summary, the author has succeeded in producing a scientifically rigorous book of affordable size (around 200 pages) that is well illustrated (about 120 figures) and written in a fluent style that describes the many different physical phenomena involved in soft condensed matter. N Clavaguera

Aromatic/aliphatic diamine derivatives for advanced compositions and polymers

NASA Technical Reports Server (NTRS)

Delozier, Donovan M. (Inventor); Connell, John W. (Inventor); Smith, Jr., Joseph G. (Inventor); Watson, Kent A. (Inventor)

2010-01-01

Novel compositions of matter comprise certain derivatives of 9,9-dialkyl fluorene diamine (AFDA). The resultant compositions, whether compositions of matter or monomers that are subsequently incorporated into a polymer, are unique and useful in a variety of applications. Useful applications of AFDA-based material include heavy ion radiation shielding components and components of optical and electronic devices.

Polyphosphazine-based polymer materials

DOEpatents

Fox, Robert V.; Avci, Recep; Groenewold, Gary S.

2010-05-25

Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

Polymer Self-Assembled Nanostructures as Innovative Drug Nanocarrier Platforms.

PubMed

Pippa, Natassa; Pispas, Stergios; Demetzos, Costas

2016-01-01

Polymer self-assembled nanostructures are used in pharmaceutical sciences as bioactive molecules' delivery systems for therapeutic and diagnostic purposes. Micelles, polyelectrolyte complexes, polymersomes, polymeric nanoparticles, nanogels and polymer grafted liposomes represent delivery vehicles that are marketed and/or under clinical development, as drug formulations. In this mini-review, these, recently appeared in the literature, innovative polymer drug nanocarrier platforms are discussed, starting from their technological development in the laboratory to their potential clinical use, through studies of their biophysics, thermodynamics, physical behavior, morphology, bio-mimicry, therapeutic efficacy and safety. The properties of an ideal drug delivery system are the structural control over size and shape of drug or imaging agent cargo/domain, biocompatibility, nontoxic polymer/ pendant functionality and the precise, nanoscale container and/or scaffolding properties with high drug or imaging agent capacity features. Self-assembled polymer nanostructures exhibit all these properties and could be considered as ideal drug nanocarriers through control of their size, structure and morphology, with the aid of a large variety of parameters, in vitro and in vivo. These modern trends reside at the interface of soft matter self-assembly and pharmaceutical sciences and the technologies for health. Great advantages related to basic science and applications are expected by understanding the self-assembly behavior of these polymeric nanotechnological drug delivery systems, created through bio-inspiration and biomimicry and have potential utilization into clinical applications.

Modeling semiflexible polymer networks

NASA Astrophysics Data System (ADS)

Broedersz, C. P.; MacKintosh, F. C.

2014-07-01

This is an overview of theoretical approaches to semiflexible polymers and their networks. Such semiflexible polymers have large bending rigidities that can compete with the entropic tendency of a chain to crumple up into a random coil. Many studies on semiflexible polymers and their assemblies have been motivated by their importance in biology. Indeed, cross-linked networks of semiflexible polymers form a major structural component of tissue and living cells. Reconstituted networks of such biopolymers have emerged as a new class of biological soft matter systems with remarkable material properties, which have spurred many of the theoretical developments discussed here. Starting from the mechanics and dynamics of individual semiflexible polymers, the physics of semiflexible bundles, entangled solutions, and disordered cross-linked networks are reviewed. Finally, recent developments on marginally stable fibrous networks, which exhibit critical behavior similar to other marginal systems such as jammed soft matter, are discussed.

Preface

NASA Astrophysics Data System (ADS)

Mallamace, Francesco; Quintana, Jacqueline

2002-03-01

Complex systems represent one of the richest and more fascinating fields of current scientific research. The reason behind this is the important role that the properties of complex systems and materials play in a variety of different but overlapping areas in physics, chemistry, biology, mathematics, and social sciences, like medicine and economy. Such unusually broad research field is, therefore, of primary interest nowadays in pure science and technology. The role of statistical physics in this new field of complex systems has been present since its onset and it has been accelerating recently. Methods developed for studying ordering phenomena in simple systems have been generalized for application to more complex forms of matter (polymers, biological macromolecules, glasses, etc) and complex processes (e.g. chaos, turbulence, economy, jamming, biological processes). In particular, many different phenomena (considered in the past to belong to separate research fields) have now a common description. Pillars of such a description are the concepts of scaling and universality. The International Conference on `Scaling Concepts and Complex Systems' (a satellite meeting of STATPHYS21) was devoted to give an overview on recent developments around these two concepts. The Conference took place in Merida, Yucatan, Mexico, in July 9-14 2001. The meeting was held in the Gordon Conference style and was attended by about 100 scientists, it covered a large variety of theoretical and experimental research topics of current interest in complex systems and materials. The meeting consisted of a total number of about 40 invited and contributed talks and a poster session. The topics covered included: scaling behaviour, supra-molecular systems, aggregation, aggregation kinetics, growth mechanisms, disordered systems, soft condensed matter (polymers, biological polymers, bio-colloids, gels, colloids, membranes and interfacial phenomena), granular matter, phase separation and out-of-equilibrium dynamics, non-linear dynamics, chaos, turbulence and chaotic dynamics. The present issue contains a substantial number of the invited and contributed talks presented at the meeting. We made an effort to arrange these papers with an order similar to that of presentation during the meeting. It is our pleasure to thank the scientific committee, all the speakers, the session chairs and all participants who contributed to the success of the conference. We are grateful to the Bonino-Pulejo Foundation (Messina-Italy), and to the President On. Nino Calarco, for the Patronage and the enthusiastic support. Our thanks goes also for the Messina University, the INFM (Istituto Nazionale per la Fisica della Materia, Italy), the Consejo Nacional de Ciencia y Tecnología (CONACyT, Mexico) and the Universidad Nacional Autonoma de Mexico (UNAM). The Conference was sponsored by the INFM-Sec.C, CONACyT, UNAM, the Bonino-Pulejo Foundation which contributed financial support to participants and to the publication of the present issue. We are grateful to them for the support. Last, but not the least, we express our warmest gratitude to all the members of the local organizing committee for their assistance and for the work spent in organizing this meeting and especially to Professor~Alberto Robledo for his valuable advice.

Rheology of Soft Materials

NASA Astrophysics Data System (ADS)

Chen, Daniel T. N.; Wen, Qi; Janmey, Paul A.; Crocker, John C.; Yodh, Arjun G.

2010-04-01

Research on soft materials, including colloidal suspensions, glasses, pastes, emulsions, foams, polymer networks, liquid crystals, granular materials, and cells, has captured the interest of scientists and engineers in fields ranging from physics and chemical engineering to materials science and cell biology. Recent advances in rheological methods to probe mechanical responses of these complex media have been instrumental for producing new understanding of soft matter and for generating novel technological applications. This review surveys these technical developments and current work in the field, with partial aim to illustrate open questions for future research.

Redox electrodeposition polymers: adaptation of the redox potential of polymer-bound Os complexes for bioanalytical applications.

PubMed

Guschin, Dmitrii A; Castillo, John; Dimcheva, Nina; Schuhmann, Wolfgang

2010-10-01

The design of polymers carrying suitable ligands for coordinating Os complexes in ligand exchange reactions against labile chloro ligands is a strategy for the synthesis of redox polymers with bound Os centers which exhibit a wide variation in their redox potential. This strategy is applied to polymers with an additional variation of the properties of the polymer backbone with respect to pH-dependent solubility, monomer composition, hydrophilicity etc. A library of Os-complex-modified electrodeposition polymers was synthesized and initially tested with respect to their electron-transfer ability in combination with enzymes such as glucose oxidase, cellobiose dehydrogenase, and PQQ-dependent glucose dehydrogenase entrapped during the pH-induced deposition process. The different polymer-bound Os complexes in a library containing 50 different redox polymers allowed the statistical evaluation of the impact of an individual ligand to the overall redox potential of an Os complex. Using a simple linear regression algorithm prediction of the redox potential of Os complexes becomes feasible. Thus, a redox polymer can now be designed to optimally interact in electron-transfer reactions with a selected enzyme.

Multiple scales and phases in discrete chains with application to folded proteins

NASA Astrophysics Data System (ADS)

Sinelnikova, A.; Niemi, A. J.; Nilsson, Johan; Ulybyshev, M.

2018-05-01

Chiral heteropolymers such as large globular proteins can simultaneously support multiple length scales. The interplay between the different scales brings about conformational diversity, determines the phase properties of the polymer chain, and governs the structure of the energy landscape. Most importantly, multiple scales produce complex dynamics that enable proteins to sustain live matter. However, at the moment there is incomplete understanding of how to identify and distinguish the various scales that determine the structure and dynamics of a complex protein. Here we address this impending problem. We develop a methodology with the potential to systematically identify different length scales, in the general case of a linear polymer chain. For this we introduce and analyze the properties of an order parameter that can both reveal the presence of different length scales and can also probe the phase structure. We first develop our concepts in the case of chiral homopolymers. We introduce a variant of Kadanoff's block-spin transformation to coarse grain piecewise linear chains, such as the C α backbone of a protein. We derive analytically, and then verify numerically, a number of properties that the order parameter can display, in the case of a chiral polymer chain. In particular, we propose that in the case of a chiral heteropolymer the order parameter can reveal traits of several different phases, contingent on the length scale at which it is scrutinized. We confirm that this is the case with crystallographic protein structures in the Protein Data Bank. Thus our results suggest relations between the scales, the phases, and the complexity of folding pathways.

Rheological Design of Sustainable Block Copolymers

NASA Astrophysics Data System (ADS)

Mannion, Alexander M.

Block copolymers are extremely versatile materials that microphase separate to give rise to a rich array of complex behavior, making them the ideal platform for the development of rheologically sophisticated soft matter. In line with growing environmental concerns of conventional plastics from petroleum feedstocks, this work focuses on the rheological design of sustainable block copolymers--those derived from renewable sources and are degradable--based on poly(lactide). Although commercially viable, poly(lactide) has a number of inherent deficiencies that result in a host of challenges that require both creative and practical solutions that are cost-effective and amenable to large-scale production. Specifically, this dissertation looks at applications in which both shear and extensional rheology dictate performance attributes, namely chewing gum, pressure-sensitive adhesives, and polymers for blown film extrusion. Structure-property relationships in the context of block polymer architecture, polymer composition, morphology, and branching are explored in depth. The basic principles and fundamental findings presented in this thesis are applicable to a broader range of substances that incorporate block copolymers for which rheology plays a pivotal role.

Polymer Molecular Weight Analysis by [Superscript 1]H NMR Spectroscopy

ERIC Educational Resources Information Center

Izunobi, Josephat U.; Higginbotham, Clement L.

2011-01-01

The measurement and analysis of molecular weight and molecular weight distribution remain matters of fundamental importance for the characterization and physical properties of polymers. Gel permeation chromatography (GPC) is the most routinely used method for the molecular weight determination of polymers whereas matrix-assisted laser…

DNA/RNA binding and anticancer/antimicrobial activities of polymer-copper(II) complexes

NASA Astrophysics Data System (ADS)

Lakshmipraba, Jagadeesan; Arunachalam, Sankaralingam; Riyasdeen, Anvarbatcha; Dhivya, Rajakumar; Vignesh, Sivanandham; Akbarsha, Mohammad Abdulkader; James, Rathinam Arthur

2013-05-01

Water soluble polymer-copper(II) complexes with various degrees of coordination in the polymer chain were synthesized and characterized by elemental analysis, IR, UV-visible and EPR spectra. The DNA/RNA binding behavior of these polymer-copper(II) complexes was examined by UV-visible absorption, emission and circular dichroism spectroscopic methods, and cyclic voltammetry techniques. The binding of the polymer-copper(II) complexes with DNA/RNA was mainly through intercalation but some amount of electrostatic interaction was also observed. This binding capacity increased with the degree of coordination of the complexes. The polymer-copper(II) complex having the highest degree of coordination was subjected to analysis of cytotoxic and antimicrobial properties. The cytotoxicity study indicated that the polymer-copper(II) complexes affected the viability of MCF-7 mammary carcinoma cells, and the cells responded to the treatment with mostly through apoptosis although a few cells succumbed to necrosis. The antimicrobial screening showed activity against some human pathogens.

Bicarbonate Elution of Uranium from Amidoxime-Based Polymer Adsorbents for Sequestering Uranium from Seawater

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pan, Horng-Bin; Wai, Chien M.; Kuo, Li-Jung

Uranium adsorbed on amidoxime-based polyethylene fibers in simulated seawater can be quantitatively eluted using 3 M KHCO3 at 40°C. Thermodynamic calculations are in agreement with the experimental observation that at high bicarbonate concentrations (3 M) uranyl ions bound to amidoxime molecules are converted to uranyl tris-carbonato complex in the aqueous solution. The elution process is basically the reverse reaction of the uranium adsorption process which occurs at a very low bicarbonate concentration (~10-3 M) in seawater. In real seawater experiments, the bicarbonate elution is followed by a NaOH treatment to remove natural organic matter adsorbed on the polymer adsorbent. Usingmore » the sequential bicarbonate and NaOH elution, the adsorbent is reusable after rinsing with deionized water and the recycled adsorbent shows no loss of uranium loading capacity based on real seawater experiments.« less

Bicarbonate Elution of Uranium from Amidoxime-Based Polymer Adsorbents for Sequestering Uranium from Seawater

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pan, Horng-Bin; Wai, Chien M.; Kuo, Li-Jung

Uranium adsorbed on amidoxime-based polyethylene fibers in simulated seawater can be quantitatively eluted using 3 M KHCO 3 at 40°C. Thermodynamic calculations are in agreement with the experimental observation that at high bicarbonate concentrations (3 M) uranyl ions bound to amidoxime molecules are converted to uranyl tris-carbonato complex in the aqueous solution. The elution process is basically the reverse reaction of the uranium adsorption process which occurs at a very low bicarbonate concentration (~10 -3 M) in seawater. The bicarbonate elution is followed by a NaOH treatment to remove natural organic matter adsorbed on the polymer adsorbent, in real seawatermore » experiments. Furthermore, by using the sequential bicarbonate and NaOH elution, the adsorbent is reusable after rinsing with deionized water and the recycled adsorbent shows no loss of uranium loading capacity based on real seawater experiments.« less

Bicarbonate Elution of Uranium from Amidoxime-Based Polymer Adsorbents for Sequestering Uranium from Seawater

DOE PAGES

Pan, Horng-Bin; Wai, Chien M.; Kuo, Li-Jung; ...

2017-05-02

Uranium adsorbed on amidoxime-based polyethylene fibers in simulated seawater can be quantitatively eluted using 3 M KHCO 3 at 40°C. Thermodynamic calculations are in agreement with the experimental observation that at high bicarbonate concentrations (3 M) uranyl ions bound to amidoxime molecules are converted to uranyl tris-carbonato complex in the aqueous solution. The elution process is basically the reverse reaction of the uranium adsorption process which occurs at a very low bicarbonate concentration (~10 -3 M) in seawater. The bicarbonate elution is followed by a NaOH treatment to remove natural organic matter adsorbed on the polymer adsorbent, in real seawatermore » experiments. Furthermore, by using the sequential bicarbonate and NaOH elution, the adsorbent is reusable after rinsing with deionized water and the recycled adsorbent shows no loss of uranium loading capacity based on real seawater experiments.« less

New trends in the optical and electronic applications of polymers containing transition-metal complexes.

PubMed

Liu, Shu-Juan; Chen, Yang; Xu, Wen-Juan; Zhao, Qiang; Huang, Wei

2012-04-13

Polymers containing transition-metal complexes exhibit excellent optical and electronic properties, which are different from those of polymers with a pure organic skeleton and combine the advantages of both polymers and metal complexes. Hence, research about this class of polymers has attracted more and more interest in recent years. Up to now, a number of novel polymers containing transition-metal complexes have been exploited, and significant advances in their optical and electronic applications have been achieved. In this article, we summarize some new research trends in the applications of this important class of optoelectronic polymers, such as chemo/biosensors, electronic memory devices and photovoltaic devices. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

HCN Polymers: Toward Structure Comprehension Using High Resolution Mass Spectrometry

NASA Astrophysics Data System (ADS)

Bonnet, Jean-Yves; Thissen, Roland; Frisari, Ma; Vuitton, Veronique; Quirico, Eric; Le Roy, Léna; Fray, Nicolas; Cottin, Hervé; Horst, Sarah; Yelle, Roger

A lot of solar system materials, including cometary ices and Titan aerosols, contain dark matter that can be interpreted as complex nitrogen bearing organic matter [1]. In laboratory experi-ments, HCN polymers are thus analogs of great interest. In fact they may be present in Titan atmosphere and in comet nuclei and then reprocessed as a CN distributed source [2], when ices began to sublimate and ejects from the nucleus organic matter grains [3]. The presence of HCN polymers is suggested because HCN molecule has been directly observed in 1P/Halley comet [4] and others. HCN polymers are also of prebiotic interest [5] as it can form amino acid under hydrolysis conditions. Even if they have been studied during the last decades, their chemical composition and structure are still poorly understood, and a great analytical effort has to be continued. In this way we present a high resolution mass spectrometry (HRMS) and a high resolution tandem mass spectrometry (MS/HRMS) analysis of HCN polymers. It was shown [6] that this is a suitable technique to elucidate composition and structure of the soluble part of tholins analogs of Titan's atmosphere aerosols. HCN polymers have never been studied by HRMS, thus we used a LTQ-Orbitrap XL high resolution mass spectrometer to analyse the HCN polymers. These are produced at LISA by direct polymerisation of pure liquid HCN, catalyzed by ammonia. HCN polymers have been completely dissolved in methanol and then injected in the mass spectrometer by ElectroSpray Ionization (ESI). This atmospheric pressure ionization process produces protonated or deprotonated ions, but it does not fragment molecules. Thus HRMS, allows a direct access to the stoechiometry of all the ionizable molecules present in the samples. Fragmentation analyses (MS/MS) of selected ions have also been performed. Thess analysis provide information about the different chemical fonctionnalities present in HCN poly-mers and also about their structure. Thus we are able to derive quantitative and qualitative parameters, (H/C, N/C ratios for exemple). [1] D. P. Cruikshank, H. Imanaka, and C. M. Dalle Ore. Tholins as coloring agents on outer Solar System bodies. Advances in Space Research, 36:178-183, 2005. [2] H. Cottin and N. Fray. Distributed Sources in Comets. Space Science Reviews, 138:179-197, July 2008. [3] J. Kissel, R. Z. Sagdeev, J. L. Bertaux, V. N. Angarov, J. Audouze, J. E. Blamont, K. Buchler, E. N. Evlanov, H. Fechtig, M. N. Fomenkova, H. von Hoerner, N. A. Inogamov, V. N. Khromov, W. Knabe, F. R. Krueger, Y. Langevin, B. Leonasv, A. C. Levasseur-Regourd, G. G.Managadze, S. N. Podkolzin, V. D. Shapiro, S. R. Tabaldyev, and B. V. Zubkov. Com-position of comet Halley dust particles from VEGA observations. Nature, 321:280-282, May 1986. [4] D. Despois, J. Crovisier, D. Bockelee-Morvan, E. Gerard, and J. Schraml. Observations of hydrogen cyanide in comet halley. Astronomy and Astrophysics, 160:L11+, May 1986. [5] C. N. Matthews and R. D. Minard. Hydrogen cyanide polymers connect cosmochemistry and biochemistry. In IAU Symposium, volume 251 of IAU Symposium, pages 453-458, October 2008. [6] N. Sarker, A. Somogyi, J. I. Lunine, and M. A. Smith. Titan Aerosol Analogues: Analysis of the Nonvolatile Tholins. Astrobiology, 3:719-726, December 2003.

Systems and strippable coatings for decontaminating structures that include porous material

DOEpatents

Fox, Robert V [Idaho Falls, ID; Avci, Recep [Bozeman, MT; Groenewold, Gary S [Idaho Falls, ID

2011-12-06

Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

The effect of environmental and process parameters on flocculation treatment of high dry matter swine manure with polymers.

PubMed

Masse, Lucie; Massé, Daniel I

2010-08-01

This paper reports on the effects of environmental conditions and process parameters on flocculation of high dry matter (average DM of 7.3%) swine manure with cationic polymers with 10%, 35%, and 55% charge densities (CDs). Polymer solutions prepared with hard and distilled water allowed similar suspended solids (SS) reductions in the initial 24h. After 3-7 days at 20 degrees C, however, the efficiency of the hard water solutions started to decline, while the polymers made with distilled water maintained their performance for up to 10 days. The 10% CD polymer was considerably less affected than the 35% CD polymer by the age of the hard water solutions. During polymer injection, minimum velocity gradients (G) of 108 and 253 s(-1) were required to maximized efficiency of the 10% and 35% CD polymer, respectively. Flocculation mixing velocities up to 84 s(-1) and mixing times between 1 and 30 min had no effect on polymer efficiency. However, mixing at 22s(-1) for more than 30 min decreased SS reduction. Adding polymer in multiple injections did not improve the efficiency of medium and high CD polymers, and adversely affected that of the low CD polymer, maybe because of repeated rapid mixing cycles which ruptured the flocs. Polymer performance was not affected by operating temperature between 6 and 25 degrees C. These results were collected on a laboratory-scale apparatus and remain to be validated at larger scale. Crown Copyright 2010. Published by Elsevier Ltd. All rights reserved.

Volatile chemical reagent detector

DOEpatents

Chen, Liaohai; McBranch, Duncan; Wang, Rong; Whitten, David

2004-08-24

A device for detecting volatile chemical reagents based on fluorescence quenching analysis that is capable of detecting neutral electron acceptor molecules. The device includes a fluorescent material, a contact region, a light source, and an optical detector. The fluorescent material includes at least one polymer-surfactant complex. The polymer-surfactant complex is formed by combining a fluorescent ionic conjugated polymer with an oppositely charged surfactant. The polymer-surfactant complex may be formed in a polar solvent and included in the fluorescent material as a solution. Alternatively, the complex may be included in the fluorescent material as a thin film. The use of a polymer-surfactant complex in the fluorescent material allows the device to detect both neutral and ionic acceptor molecules. The use of a polymer-surfactant complex film allows the device and the fluorescent material to be reusable after exposing the fluorescent material to a vacuum for limited time.

Bipartite design of a self-fibrillating protein copolymer with nanopatterned peptide display capabilities.

PubMed

Bruning, Marc; Kreplak, Laurent; Leopoldseder, Sonja; Müller, Shirley A; Ringler, Philippe; Duchesne, Laurence; Fernig, David G; Engel, Andreas; Ucurum-Fotiadis, Zöhre; Mayans, Olga

2010-11-10

The development of biomatrices for technological and biomedical applications employs self-assembled scaffolds built from short peptidic motifs. However, biopolymers composed of protein domains would offer more varied molecular frames to introduce finer and more complex functionalities in bioreactive scaffolds using bottom-up approaches. Yet, the rules governing the three-dimensional organization of protein architectures in nature are complex and poorly understood. As a result, the synthetic fabrication of ordered protein association into polymers poses major challenges to bioengineering. We have now fabricated a self-assembling protein nanofiber with predictable morphologies and amenable to bottom-up customization, where features supporting function and assembly are spatially segregated. The design was inspired by the cross-linking of titin filaments by telethonin in the muscle sarcomere. The resulting fiber is a two-protein system that has nanopatterned peptide display capabilities as shown by the recruitment of functionalized gold nanoparticles at regular intervals of ∼ 5 nm, yielding a semiregular linear array over micrometers. This polymer promises the uncomplicated display of biologically active motifs to selectively bind and organize matter in the fine nanoscale. Further, its conceptual design has high potential for controlled plurifunctionalization.

Influence of confinement on polymer-electrolyte relaxational dynamics.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zanotti, J.-M.; Smith, L. J.; Price, D. L.

2004-01-01

Conception and industrial production of viable high specific energy/power batteries is a central issue for the development of non-polluting vehicles. In terms of stored energy and safety, solid-state devices using polymer electrolytes are highly desirable. One of the most studied systems is PEO (polyethylene oxide) complexed by Li salts. Polymer segmental motions and ionic conductivity are closely related. Bulk PEO is actually a biphasic system where an amorphous and a crystalline state (Tm 335 K) coexist. To improve ionic conduction in those systems requires a significant increase of the amorphous phase fraction where lithium conduction is known to mainly takemore » place. Confinement strongly affects properties of condensed matter and in particular the collective phenomena inducing crystallization. Confinement of the polymer matrix is therefore a possible alternative route to the unpractical use of high temperature. Results of a quasi-elastic incoherent neutron scattering study of the influence of confinement on polyethylene oxide (PEO) and (PEO)8Li+[(CF3SO2)2N]- (or (POE)8LiTFSI) dynamics are presented. The nano-confining media is Vycor, a silica based hydrophilic porous glass (characteristic size of the 3D pore network 50 {angstrom}). As expected, the presence of Li salt slows down the bulk polymer dynamics. The confinement also affects dramatically the apparent mean-square displacement of the polymer. Local relaxational PEO dynamics is described KWW model. We also present an alternate model and show how the detailed polymer dynamics (correlation times and local geometry of the motions) can be described without the use of such stretched exponentials so as to access a rheology-related meaningful physical quantity: the monomeric friction coefficient.« less

High performance shape memory polymer networks based on rigid nanoparticle cores

PubMed Central

Song, Jie

2010-01-01

Smart materials that can respond to external stimuli are of widespread interest in biomedical science. Thermal-responsive shape memory polymers, a class of intelligent materials that can be fixed at a temporary shape below their transition temperature (Ttrans) and thermally triggered to resume their original shapes on demand, hold great potential as minimally invasive self-fitting tissue scaffolds or implants. The intrinsic mechanism for shape memory behavior of polymers is the freezing and activation of the long-range motion of polymer chain segments below and above Ttrans, respectively. Both Ttrans and the extent of polymer chain participation in effective elastic deformation and recovery are determined by the network composition and structure, which are also defining factors for their mechanical properties, degradability, and bioactivities. Such complexity has made it extremely challenging to achieve the ideal combination of a Ttrans slightly above physiological temperature, rapid and complete recovery, and suitable mechanical and biological properties for clinical applications. Here we report a shape memory polymer network constructed from a polyhedral oligomeric silsesquioxane nanoparticle core functionalized with eight polyester arms. The cross-linked networks comprising this macromer possessed a gigapascal-storage modulus at body temperature and a Ttrans between 42 and 48 °C. The materials could stably hold their temporary shapes for > 1 year at room temperature and achieve full shape recovery ≤ 51 °C in a matter of seconds. Their versatile structures allowed for tunable biodegradability and biofunctionalizability. These materials have tremendous promise for tissue engineering applications. PMID:20375285

Biological and protein-binding studies of newly synthesized polymer-cobalt(III) complexes.

PubMed

Vignesh, G; Pradeep, I; Arunachalam, S; Vignesh, S; Arthur James, R; Arun, R; Premkumar, K

2016-03-01

The polymer-cobalt(III) complexes, [Co(bpy)(dien)BPEI]Cl3 · 4H2O (bpy = 2,2'-bipyridine, dien = diethylentriamine, BPEI = branched polyethyleneimine) were synthesized and characterized. The interaction of these complexes with human serum albumin (HSA) and bovine serum albumin (BSA) was investigated under physiological conditions using various physico-chemical techniques. The results reveal that the fluorescence quenching of serum albumins by polymer-cobalt(III) complexes took place through static quenching. The binding of these complexes changed the molecular conformation of the protein considerably. The polymer-cobalt(III) complex with x = 0.365 shows antimicrobial activity against several human pathogens. This complex also induces cytotoxicity against MCF-7 through apoptotic induction. However, further studies are needed to decipher the molecular mode of action of polymer-cobalt(III) complex and for its possible utilization in anticancer therapy. Copyright © 2015 John Wiley & Sons, Ltd.

3D Printing of Human Tissue Mimics via Layer-by-Layer Assembly of Polymer/Hydrogel Biopapers

NASA Astrophysics Data System (ADS)

Ringeisen, Bradley

2015-03-01

The foundations of tissue engineering were built on two fundamental areas of research: cells and scaffolds. Multipotent cells and their derivatives are traditionally randomly seeded into sophisticated polymer or hydrogel scaffolds, ultimately with the goal of forming a tissue-like material through cell differentiation and cell-material interactions. One problem with this approach is that no matter how complex or biomimetic the scaffold is, the cells are still homogeneously distributed throughout this three dimensional (3D) material. Natural tissue is inherently heterogeneous on both a microscopic and macroscopic level. It also contains different types of cells in close proximity, extracellular matrix, voids, and a complex vascularized network. Recently developed 3D cell and organ printers may be able to enhance traditional tissue engineering experiments by building scaffolds layer-by-layer that are crafted to mimic the microscopic and macroscopic structure of natural tissue or organs. Over the past decade, my laboratory has developed a capillary-free, live cell printer termed biological laser printing, or BioLP. We find that printed cells do not express heat shock protein and retain >99% viability. Printed cells also incur no DNA strand fracture and preserve their ability to differentiate. Recent work has used a layer-by-layer approach, stacking sheets of hybrid polymer/hydrogel biopapers in conjunction with live cell printing to create 3D tissue structures. Our specific work is now focused on the blood-brain-barrier and air-lung interface and will be described during the presentation.

Effective removal of effluent organic matter (EfOM) from bio-treated coking wastewater by a recyclable aminated hyper-cross-linked polymer.

PubMed

Yang, Wenlan; Li, Xuchun; Pan, Bingcai; Lv, Lu; Zhang, Weiming

2013-09-01

Effluent organic matter (EfOM) is a complex matrix of organic substance mainly from bio-treated sewage effluent and is considered as the main constraint to further advanced treatment. Here a recyclable aminated hyper-cross-linked polymeric adsorbent (NDA-802) featured with aminated functional groups, large specific surface area, and sufficient micropore region was synthesized for effective removal of EfOM from the bio-treated coking wastewater (BTCW), and its removal characteristics was investigated. It was found that hydrophobic fraction was the main constituent (64.8% of DOC) in EfOM of BTCW, and the hydrophobic-neutral fraction had the highest SUVA level (7.06 L mg(-1) m(-1)), which were significantly different from that in the domestic wastewater. Column adsorption experiments showed that NDA-802 exhibited much higher removal efficiency of EfOM than other polymeric adsorbents D-301, XAD-4, and XAD-7, and the efficiency could be readily sustained according to continuous 28-cycle batch adsorption-regeneration experiments. Moreover, dissolved organic matter (DOM) fractionation and excitation-emission matrix (EEM) fluorescence spectroscopy study indicated that NDA-802 showed attractive adsorption preference as well as high removal efficiency of hydrophobic and aromatic compounds. Possibly ascribed to the presence of functional aminated groups, relatively large specific surface area and micropore region of the unique polymer, NDA-802 possesses high and sustained efficiency for the removal of EfOM, and provides a potential alternative for the advanced treatment. Copyright © 2013 Elsevier Ltd. All rights reserved.

Removal of Cu(II) in water by polymer enhanced ultrafiltration: Influence of polymer nature and pH.

PubMed

Kochkodan, Olga D; Kochkodan, Viktor M; Sharma, Virender K

2018-01-02

This study presents an efficient removal of Cu(II) in water using the polymer enhanced ultrafiltration (PEUF) method. Polymer of different molecular weight (MW) (polyethyleneimine (PEI), sodium lignosulfonates (SLS) and dextrans) were investigated to evaluate efficiency in removal of Cu(II) in water by the PEUF method. The decomposition of Cu(II)-polymer complex was also evaluated in order to reuse polymers. Cu(II) complexation depends on the MW of chelating polymer and the pH of feed solution. It was found that the Cu(II) rejection increased with the polymer dosage with high removal of Cu(II) when using PEI and SLS at a 10:20 (mg/mg) ratio ([Cu(II)]:[polymer]). It was found that the maximum chelating capacity was 15 mg of Cu(II) per 20 mg of PEI. The Cu(II)-PEI complex could be decomposed by acid addition and the polymer could be efficiently reused with multiple complexation-decomplexation cycles. A conceptual flow chart of the integrated process of efficient removal of Cu(II) by PEUF method is suggested.

Momentum conserving Brownian dynamics propagator for complex soft matter fluids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Padding, J. T.; Briels, W. J.

2014-12-28

We present a Galilean invariant, momentum conserving first order Brownian dynamics scheme for coarse-grained simulations of highly frictional soft matter systems. Friction forces are taken to be with respect to moving background material. The motion of the background material is described by locally averaged velocities in the neighborhood of the dissolved coarse coordinates. The velocity variables are updated by a momentum conserving scheme. The properties of the stochastic updates are derived through the Chapman-Kolmogorov and Fokker-Planck equations for the evolution of the probability distribution of coarse-grained position and velocity variables, by requiring the equilibrium distribution to be a stationary solution.more » We test our new scheme on concentrated star polymer solutions and find that the transverse current and velocity time auto-correlation functions behave as expected from hydrodynamics. In particular, the velocity auto-correlation functions display a long time tail in complete agreement with hydrodynamics.« less

Removal of waterborne microorganisms by filtration using clay-polymer complexes.

PubMed

Undabeytia, Tomas; Posada, Rosa; Nir, Shlomo; Galindo, Irene; Laiz, Leonila; Saiz-Jimenez, Cesareo; Morillo, Esmeralda

2014-08-30

Clay-polymer composites were designed for use in filtration processes for disinfection during the course of water purification. The composites were formed by sorption of polymers based on starch modified with quaternary ammonium ethers onto the negatively charged clay mineral bentonite. The performance of the clay-polymer complexes in removal of bacteria was strongly dependent on the conformation adopted by the polycation on the clay surface, the charge density of the polycation itself and the ratio between the concentrations of clay and polymer used during the sorption process. The antimicrobial effect exerted by the clay-polymer system was due to the cationic monomers adsorbed on the clay surface, which resulted in a positive surface potential of the complexes and charge reversal. Clay-polymer complexes were more toxic to bacteria than the polymers alone. Filtration employing our optimal clay-polymer composite yielded 100% removal of bacteria after the passage of 3L, whereas an equivalent filter with granular activated carbon (GAC) hardly yielded removal of bacteria after 0.5L. Regeneration of clay-polymer complexes saturated with bacteria was demonstrated. Modeling of the filtration processes permitted to optimize the design of filters and estimation of experimental conditions for purifying large water volumes in short periods. Copyright © 2014 Elsevier B.V. All rights reserved.

New insights into the mechanism of interaction between CO2 and polymers from thermodynamic parameters obtained by in situ ATR-FTIR spectroscopy.

PubMed

Gabrienko, Anton A; Ewing, Andrew V; Chibiryaev, Andrey M; Agafontsev, Alexander M; Dubkov, Konstantin A; Kazarian, Sergei G

2016-03-07

This work reports new physical insights of the thermodynamic parameters and mechanisms of possible interactions occurring in polymers subjected to high-pressure CO2. ATR-FTIR spectroscopy has been used in situ to determine the thermodynamic parameters of the intermolecular interactions between CO2 and different functional groups of the polymers capable of specific interactions with sorbed CO2 molecules. Based on the measured ATR-FTIR spectra of the polymer samples subjected to high-pressure CO2 (30 bar) at different temperatures (300-340 K), it was possible to characterize polymer-polymer and CO2-polymer interactions. Particularly, the enthalpy and entropy of the formation of the specific non-covalent complexes between CO2 and the hydroxy (-OH), carbonyl (C[double bond, length as m-dash]O) and hydroxyimino ([double bond, length as m-dash]N-OH) functional groups of the polymer samples have been measured. Furthermore, the obtained spectroscopic results have provided an opportunity for the structure of these complexes to be proposed. An interesting phenomenon regarding the behavior of CO2/polymer systems has also been observed. It has been found that only for the polyketone, the value of enthalpy was negative indicating an exothermic process during the formation of the CO2-polymer non-covalent complexes. Conversely, for the polyoxime and polyalcohol samples there is a positive enthalpy determined. This is a result of the initial polymer-polymer interactions requiring more energy to break than is released during the formation of the CO2-polymer complex. The effect of increasing temperature to facilitate the breaking of the polymer-polymer interactions has also been observed. Hence, a mechanism for the formation of CO2-polymer complexes was suggested based on these results, which occurs via a two-step process: (1) the breaking of the existing polymer-polymer interactions followed by (2) the formation of new CO2-polymer non-covalent interactions.

Polymer complexes.. XXXX. Supramolecular assembly on coordination models of mixed-valence-ligand poly[1-acrylamido-2-(2-pyridyl)ethane] complexes

NASA Astrophysics Data System (ADS)

El-Sonbati, A. Z.; El-Bindary, A. A.; Diab, M. A.

2003-02-01

The build-up of polymer metallic supramolecules based on homopolymer (1-acrylamido-2-(2-pyridyl)ethane (AEPH)) and ruthenium, rhodium, palladium as well as platinum complexes has been pursued with great interest. The homopolymer shows three types of coordination behaviour. In the mixed valence paramagnetic trinuclear polymer complexes [( 11)+( 12)] in the paper and in mononuclear polymer complexes ( 1)-( 5) it acts as a neutral bidentate ligand coordinating through the N-pyridine and NH-imino atoms, while in the mixed ligand diamagnetic poly-chelates, which are obtained from the reaction of AEPH with PdX 2 and KPtCl 4 in the presence of N-heterocyclic base consisting of polymer complexes ( 9)+( 10), and in monouclear compounds ( 6)-( 8), it behaves as a monobasic bidentate ligand coordinating through the same donor atoms. In mononuclear compounds ( 13)+( 14) it acts as a monobasic and neutral bidentate ligand coordinating only through the same donor atoms. Monomeric distorted octahedral or trimeric chlorine-bridged, approximately octahedral structures are proposed for these polymer complexes. The poly-chelates are of 1:1, 1:2 and 3:2 (metal-homopolymer) stoichiometry and exhibit six coordination. The values of ligand field parameters were calculated. The homopolymer and their polymer complexes have been characterized physicochemically.

Polymer complexes. XXXX. Supramolecular assembly on coordination models of mixed-valence-ligand poly[1-acrylamido-2-(2-pyridyl)ethane] complexes.

PubMed

El-Sonbati, A Z; El-Bindary, A A; Diab, M A

2003-02-01

The build-up of polymer metallic supramolecules based on homopolymer (1-acrylamido-2-(2-pyridyl)ethane (AEPH)) and ruthenium, rhodium, palladium as well as platinum complexes has been pursued with great interest. The homopolymer shows three types of coordination behaviour. In the mixed valence paramagnetic trinuclear polymer complexes [(11)+(12)] in the paper and in mononuclear polymer complexes (1)-(5) it acts as a neutral bidentate ligand coordinating through the N-pyridine and NH-imino atoms, while in the mixed ligand diamagnetic poly-chelates, which are obtained from the reaction of AEPH with PdX2 and KPtCl4 in the presence of N-heterocyclic base consisting of polymer complexes (9)+(10), and in monouclear compounds (6)-(8), it behaves as a monobasic bidentate ligand coordinating through the same donor atoms. In mononuclear compounds (13)+(14) it acts as a monobasic and neutral bidentate ligand coordinating only through the same donor atoms. Monomeric distorted octahedral or trimeric chlorine-bridged, approximately octahedral structures are proposed for these polymer complexes. The poly-chelates are of 1:1, 1:2 and 3:2 (metal-homopolymer) stoichiometry and exhibit six coordination. The values of ligand field parameters were calculated. The homopolymer and their polymer complexes have been characterized physicochemically.

Carbon dioxide-soluble polymers and swellable polymers for carbon dioxide applications

DOEpatents

DeSimone, Joseph M.; Birnbaum, Eva; Carbonell, Ruben G.; Crette, Stephanie; McClain, James B.; McCleskey, T. Mark; Powell, Kimberly R.; Romack, Timothy J.; Tumas, William

2004-06-08

A method for carrying out a catalysis reaction in carbon dioxide comprising contacting a fluid mixture with a catalyst bound to a polymer, the fluid mixture comprising at least one reactant and carbon dioxide, wherein the reactant interacts with the catalyst to form a reaction product. A composition of matter comprises carbon dioxide and a polymer and a reactant present in the carbon dioxide. The polymer has bound thereto a catalyst at a plurality of chains along the length of the polymer, and wherein the reactant interacts with the catalyst to form a reaction product.

DNA binding and biological studies of some novel water-soluble polymer-copper(II)-phenanthroline complexes.

PubMed

Kumar, Rajendran Senthil; Arunachalam, Sankaralingam; Periasamy, Vaiyapuri Subbarayan; Preethy, Christo Paul; Riyasdeen, Anvarbatcha; Akbarsha, Mohammad Abdulkader

2008-10-01

Some novel water-soluble polymer-copper(II)-phenanthroline complex samples, [Cu(phen)2(BPEI)]Cl(2).4H2O (phen=1,10-phenanthroline, BPEI=branched polyethyleneimine), with different degrees of copper complex content in the polymer chain have been prepared by ligand substitution method in water-ethanol medium and characterized by infrared, UV-visible, EPR spectral and elemental analysis methods. The binding of these complex samples with DNA has been investigated by electronic absorption spectroscopy, emission spectroscopy and gel retardation assay. Electrostatic interactions between DNA molecule and polymer-copper(II) complex molecule containing many high positive charges have been observed. Besides these ionic interactions, van der Waals interactions, hydrogen bonding and other partial intercalation binding modes may also exist in this system. The polymer-copper(II) complex with higher degree of copper complex content was screened for its antimicrobial activity and antitumor activity.

Star polymers as unit cells for coarse-graining cross-linked networks

NASA Astrophysics Data System (ADS)

Molotilin, Taras Y.; Maduar, Salim R.; Vinogradova, Olga I.

2018-03-01

Reducing the complexity of cross-linked polymer networks by preserving their main macroscale properties is key to understanding them, and a crucial issue is to relate individual properties of the polymer constituents to those of the reduced network. Here we study polymer networks in a good solvent, by considering star polymers as their unit elements, and first quantify the interaction between their centers of masses. We then reduce the complexity of a network by replacing sets of its bridged star polymers by equivalent effective soft particles with dense cores. Our coarse graining allows us to approximate complex polymer networks by much simpler ones, keeping their relevant mechanical properties, as illustrated in computer experiments.

Molecular systems under shock compression into the dense plasma regime: carbon dioxide and hydrocarbon polymers

NASA Astrophysics Data System (ADS)

Mattsson, Thomas R.; Cochrane, Kyle R.; Root, Seth; Carpenter, John H.

2013-10-01

Density Functional Theory (DFT) has proven remarkably accurate in predicting properties of matter under shock compression into the dense plasma regime. Materials where chemistry plays a role are of interest for many applications, including planetary science and inertial confinement fusion (ICF). As examples of systems where chemical reactions are important, and demonstration of the high fidelity possible for these both structurally and chemically complex systems, we will discuss shock- and re-shock of liquid carbon dioxide (CO2) in the range 100 to 800 GPa and shock compression of hydrocarbon polymers, including GDP (glow discharge polymer) which is used as an ablator in laser ICF experiments. Experimental results from Sandia's Z machine validate the DFT simulations at extreme conditions and the combination of experiment and DFT provide reliable data for evaluating existing and constructing future wide-range equations of state models for molecular compounds. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Organimetallic Fluorescent Complex Polymers For Light Emitting Applications

DOEpatents

Shi, Song Q.; So, Franky

1997-10-28

A fluorescent complex polymer with fluorescent organometallic complexes connected by organic chain spacers is utilized in the fabrication of light emitting devices on a substantially transparent planar substrate by depositing a first conductive layer having p-type conductivity on the planar surface of the substrate, depositing a layer of a hole transporting and electron blocking material on the first conductive layer, depositing a layer of the fluorescent complex polymer on the layer of hole transporting and electron blocking material as an electron transporting emissive layer and depositing a second conductive layer having n-type conductivity on the layer of fluorescent complex polymer.

Brownian dynamics of a protein-polymer chain complex in a solid-state nanopore

NASA Astrophysics Data System (ADS)

Wells, Craig C.; Melnikov, Dmitriy V.; Gracheva, Maria E.

2017-08-01

We study the movement of a polymer attached to a large protein inside a nanopore in a thin silicon dioxide membrane submerged in an electrolyte solution. We use Brownian dynamics to describe the motion of a negatively charged polymer chain of varying lengths attached to a neutral protein modeled as a spherical bead with a radius larger than that of the nanopore, allowing the chain to thread the nanopore but preventing it from translocating. The motion of the protein-polymer complex within the pore is also compared to that of a freely translocating polymer. Our results show that the free polymer's standard deviations in the direction normal to the pore axis is greater than that of the protein-polymer complex. We find that restrictions imposed by the protein, bias, and neighboring chain segments aid in controlling the position of the chain in the pore. Understanding the behavior of the protein-polymer chain complex may lead to methods that improve molecule identification by increasing the resolution of ionic current measurements.

Brownian dynamics of a protein-polymer chain complex in a solid-state nanopore.

PubMed

Wells, Craig C; Melnikov, Dmitriy V; Gracheva, Maria E

2017-08-07

We study the movement of a polymer attached to a large protein inside a nanopore in a thin silicon dioxide membrane submerged in an electrolyte solution. We use Brownian dynamics to describe the motion of a negatively charged polymer chain of varying lengths attached to a neutral protein modeled as a spherical bead with a radius larger than that of the nanopore, allowing the chain to thread the nanopore but preventing it from translocating. The motion of the protein-polymer complex within the pore is also compared to that of a freely translocating polymer. Our results show that the free polymer's standard deviations in the direction normal to the pore axis is greater than that of the protein-polymer complex. We find that restrictions imposed by the protein, bias, and neighboring chain segments aid in controlling the position of the chain in the pore. Understanding the behavior of the protein-polymer chain complex may lead to methods that improve molecule identification by increasing the resolution of ionic current measurements.

Solid-state polymerisation via [2+2] cycloaddition reaction involving coordination polymers.

PubMed

Medishetty, Raghavender; Park, In-Hyeok; Lee, Shim Sung; Vittal, Jagadese J

2016-03-14

Highly crystalline metal ions containing organic polymers are potentially useful to manipulate the magnetic and optical properties to make advanced multifunctional materials. However, it is challenging to synthesise monocrystalline metal complexes of organic polymers and single-phase hybrid materials made up of both coordination and organic polymers by traditional solution crystallisation. This requires an entirely different approach in the solid-state by thermal or photo polymerisation of the ligands. Among the photochemical methods available, [2+2] cycloaddition reaction has been recently employed to generate cyclobutane based coordination polymers from the metal complexes. Cyclobutane polymers have also been integrated into coordination polymers in this way. Recent advancements in the construction of polymeric chains of cyclobutane rings through photo-dimerisation reaction in the monocrystalline solids containing metal complexes, coordination polymers and metal-organic framework structures are discussed here.

Polyphenylquinoxalines via Aromatic Nucleophilic Displacement

NASA Technical Reports Server (NTRS)

Hergenrother, Paul M.; Connell, John W.

1988-01-01

Polyphenylquinoxalines are produced by an aromatic nucleophilic displacement reaction involving an activated aromatic dihalide with an appropriate quinoxaline monomer. Polyphenylquinoxalines are high temperature thermoplastics used as adhesives, coatings, films and composite matrices. The novelty of this invention is threefold: (1) some of the quinoxaline monomers are new compositions of matter; (2) the phenylquinoxaline polymers which are the end products of the invention are new compositions of matter; and (3) the method of forming the polymers is novel, replacing a more costly prior art process, which is also limited in the kinds of products prepared therefrom.

Radiation preparation of drug carriers based polyacrylic acid (PAAc) using poly(vinyl pyrrolidone) (PVP) as a template polymer

NASA Astrophysics Data System (ADS)

Abd El-Rehim, H. A.; Hegazy, E. A.; Khalil, F. H.; Hamed, N. A.

2007-01-01

The present study deals with the radiation synthesis of stimuli response hydrophilic polymers from polyacrylic acid (PAAc). To maintain the property of PAAc and control the water swellibility for its application as a drug delivery system, radiation polymerization of AAc in the presence of poly(vinyl pyrrolidone) (PVP) as a template polymer was carried out. Characterization of the prepared PAA/PVP inter-polymer complex was investigated by determining gel content, swelling property, hydrogel microstructure and the release rate of caffeine as a model drug. The release rate of caffeine from the PAA/PVP inter-polymer complexes showed pH-dependency, and seemed to be mainly controlled by the dissolution rate of the complex above a p Ka of PAAc. The prepared inter-polymer complex could be used for application as drug carriers.

Accelerating materials discovery through the development of polymer databases

NASA Astrophysics Data System (ADS)

Audus, Debra

In our line of business we create chemical solutions for a wide range of applications, such as home and personal care, printing and packaging, automotive and structural coatings, and structural plastics and foams applications. In this environment, stable and highly automated workflows suitable to handle complex systems are a must. By satisfying these prerequisites, efficiency for the development of new materials can be significantly improved by combining modeling and experimental approaches. This is in fact in line with recent Materials Genome Initiative efforts sponsored by the US administration. From our experience, we know, that valuable contributions to product development are possible today by combining existing modeling techniques in an intelligent fashion, provided modeling and experiment work closely together. In my presentation I intend to review approaches to build and parameterize soft matter systems. As an example of our standard workflow, I will show a few applications, which include the design of a stabilizer molecule for dispersing polymer particles and the simulation of polystyrene dispersions.

Correlation between multiple stress creep recovery (MSCR) results and polymer modification of binder.

DOT National Transportation Integrated Search

2013-09-01

Nationwide traffic loads are increasing, pushing conventional asphalt to its limit. In New Jersey matters are made : worse by the heavy use of the Northeast Corridor. Polymer modification of asphalt, which can improve both low and high : performance,...

Amylose-Based Cationic Star Polymers for siRNA Delivery.

PubMed

Nishimura, Tomoki; Umezaki, Kaori; Mukai, Sada-atsu; Sawada, Shin-ichi; Akiyoshi, Kazunari

2015-01-01

A new siRNA delivery system using a cationic glyco-star polymer is described. Spermine-modified 8-arm amylose star polymer (with a degree of polymerization of approximately 60 per arm) was synthesized by chemoenzymatic methods. The cationic star polymer effectively bound to siRNA and formed spherical complexes with an average hydrodynamic diameter of 230 nm. The cationic 8-arm star polymer complexes showed superior cellular uptake characteristics and higher gene silencing effects than a cationic 1-arm polymer. These results suggest that amylose-based star polymers are a promising nanoplatform for glycobiomaterials.

Integration of motor proteins - towards an ATP fueled soft actuator.

PubMed

Kakugo, Akira; Shikinaka, Kazuhiro; Gong, Jian Ping

2008-09-01

We present a soft bio-machine constructed from biological motors (actin/myosin). We have found that chemically cross-linked polymer-actin complex gel filaments can move on myosin coated surfaces with a velocity as high as that of native F-actin, by coupling to ATP hydrolysis. Additionally, it is shown that the velocity of polymer-actin complex gel depends on the species of polycations binding to the F-actins. Since the design of functional actuators of well-defined size and morphology is important, the structural behavior of polymer-actin complexes has been investigated. Our results show that the morphology and growth size of polymer-actin complex can be controlled by changes in the electrostatic interactions between F-actins and polycations. Our results indicate that bio actuators with desired shapes can be created by using a polymer-actin complex.

Partitioning of dissolved organic matter-bound mercury between a hydrophobic surface and polysulfide-rubber polymer.

PubMed

Kim, Eun-Ah; Luthy, Richard G

2011-11-01

This study investigated the role of dissolved organic matter on mercury partitioning between a hydrophobic surface (polyethylene, PE) and a reduced sulfur-rich surface (polysulfide rubber, PSR). Comparative sorption studies employed polyethylene and polyethylene coated with PSR for reactions with DOM-bound mercuric ions. These studies revealed that PSR enhanced the Hg-DOM removal from water when DOM was Suwannee River natural organic matter (NOM), fulvic acid (FA), or humic acid (HA), while the same amount of 1,3-propanedithiol-bound mercuric ion was removed by both PE and PSR-PE. The differences for Hg-DOM removal efficiencies between PE and PSR-PE varied depending on which DOM was bound to mercuric ion as suggested by the PE/water and PSR-PE/water partition coefficients for mercury. The surface concentrations of mercury on PE and PSR-PE with the same DOM measured by x-ray photoelectron spectroscopy were similar, which indicated the comparable amounts of immobilized mercury on PE and PSR-PE being exposed to the aqueous phase. With these observations, two major pathways for the immobilization reactions between PSR-PE and Hg-DOM were examined: 1) adsorption of Hg-DOM on PE by hydrophobic interactions between DOM and PE, and 2) addition reaction of Hg-DOM onto PSR by a complexation reaction between Hg and PSR. The percent contribution of each pathway was derived from a mass balance and the ratios among aqueous mercury, PE-bound Hg-DOM, and PSR-bound Hg-DOM concentrations. The results indicate strong binding of mercuric ion with both dissolved organic matter and PSR polymer. The FT-IR examination of Hg-preloaded-PSR-PEs after the reaction with DOM corroborated a strong interaction between mercuric ion and 1,3-propanedithiol compared to Hg-HA, Hg-FA, or Hg-NOM interactions. Copyright © 2011 Elsevier Ltd. All rights reserved.

Partitioning of dissolved organic matter-bound mercury between a hydrophobic surface and polysulfide-rubber polymer

PubMed Central

Kim, Eun-Ah

2011-01-01

This study investigated the role of dissolved organic matter on mercury partitioning between a hydrophobic surface (polyethylene, PE) and a reduced sulfur-rich surface (polysulfide rubber, PSR). Comparative sorption studies employed polyethylene and polyethylene coated with PSR for reactions with DOM-bound mercuric ions. These studies revealed that PSR enhanced the Hg-DOM removal from water when DOM was Suwannee River natural organic matter (NOM), fulvic acid (FA), or humic acid (HA), while the same amount of 1,3-propanedithiol-bound mercuric ion was removed by both PE and PSR-PE. The differences for Hg-DOM removal efficiencies between PE and PSR-PE varied depending on which DOM was bound to mercuric ion as suggested by the PE/water and PSR-PE/water partition coefficients for mercury. The surface concentrations of mercury on PE and PSR-PE with the same DOM measured by x-ray – photoelectron spectroscopy were similar, which indicated the comparable amounts of immobilized mercury on PE and PSR-PE being exposed to the aqueous phase. With these observations, two major pathways for the immobilization reactions between PSR-PE and Hg- DOM were examined: 1) adsorption of Hg-DOM on PE by hydrophobic interactions between DOM and PE, and 2) addition reaction of Hg-DOM onto PSR by a complexation reaction between Hg and PSR. The percent contribution of each pathway was derived from a mass balance and the ratios among aqueous mercury, PE-bound Hg-DOM, and PSR-bound Hg-DOM concentrations. The results indicate strong binding of mercuric ion with both dissolved organic matter and PSR polymer. The FT-IR examination of Hg-preloaded-PSR-PEs after the reaction with DOM corroborated a strong interaction between mercuric ion and 1,3-propanedithiol compared to Hg-HA, Hg-FA, or Hg-NOM interactions. PMID:21872900

Smart Actuators and Adhesives for Reconfigurable Matter.

PubMed

Ko, Hyunhyub; Javey, Ali

2017-04-18

Biological systems found in nature provide excellent stimuli-responsive functions. The camouflage adaptation of cephalopods (octopus, cuttlefish), rapid stiffness change of sea cucumbers, opening of pine cones in response to humidity, and rapid closure of Venus flytraps upon insect touch are some examples of nature's smart systems. Although current technologies are still premature to mimic these sophisticated structures and functions in smart biological systems, recent work on stimuli-responsive programmable matter has shown great progress. Stimuli-responsive materials based on hydrogels, responsive nanocomposites, hybrid structures, shape memory polymers, and liquid crystal elastomers have demonstrated excellent responsivities to various stimuli such as temperature, light, pH, and electric field. However, the technologies in these stimuli-responsive materials are still not sophisticated enough to demonstrate the ultimate attributes of an ideal programmable matter: fast and reversible reconfiguration of programmable matter into complex and robust shapes. Recently, reconfigurable (or programmable) matter that reversibly changes its structure/shape or physical/chemical properties in response to external stimuli has attracted great interest for applications in sensors, actuators, robotics, and smart systems. In particular, key attributes of programmable matter including fast and reversible reconfiguration into complex and robust 2D and 3D shapes have been demonstrated by various approaches. In this Account, we review focused areas of smart materials with special emphasis on the material and device structure designs to enhance the response time, reversibility, multistimuli responsiveness, and smart adhesion for efficient shape transformation and functional actuations. First, the capability of fast reconfiguration of 2D and 3D structures in a reversible way is a critical requirement for programmable matter. For the fast and reversible reconfiguration, various approaches based on enhanced solvent diffusion rate through the porous or structured hydrogel materials, electrostatic repulsion between cofacial electrolyte nanosheets, and photothermal actuation are discussed. Second, the ability to reconfigure programmable matters into a variety of complex structures is beneficial for the use of reconfigurable matter in diverse applications. For the reconfiguration of planar 2D structures into complex 3D structures, asymmetric and multidirectional stress should be applied. In this regard, local hinges with stimuli-responsive stiffness, multilayer laminations with different responsiveness in individual layers, and origami and kirigami assembly approaches are reviewed. Third, multistimuli responsiveness will be required for the efficient reconfiguration of complex programmable matter in response to user-defined stimulus under different chemical and physical environments. In addition, with multistimuli responsiveness, the reconfigured shape can be temporarily affixed by one signal and disassembled by another signal at a user-defined location and time. Photoactuation depending on the chirality of carbon nanotubes and composite gels with different responsiveness will be discussed. Finally, the development of smart adhesives with on-demand adhesion strength is critically required to maintain the robust reconfigurable shapes and for the switching on/off of the binding between components or with target objects. Among various connectors and adhesives, thermoresponsive nanowire connectors, octopus-inspired smart adhesives, and elastomeric tiles with soft joints are described due to their potential applications in joints of deformable 3D structures and smart gripping systems.

Enhanced photophysics of conjugated polymers

DOEpatents

Chen, Liaohai [Argonne, IL; Xu, Su [Santa Clara, CA; McBranch, Duncan [Santa Fe, NM; Whitten, David [Santa Fe, NM

2003-05-27

The addition of oppositely charged surfactant to fluorescent ionic conjugated polymer forms a polymer-surfactant complex that exhibits at least one improved photophysical property. The conjugated polymer is a fluorescent ionic polymer that typically has at least one ionic side chain or moiety that interacts with the specific surfactant selected. The photophysical property improvements may include increased fluorescence quantum efficiency, wavelength-independent emission and absorption spectra, and more stable fluorescence decay kinetics. The complexation typically occurs in a solution of a polar solvent in which the polymer and surfactant are soluble, but it may also occur in a mixture of solvents. The solution is commonly prepared with a surfactant molecule:monomer repeat unit of polymer ratio ranging from about 1:100 to about 1:1. A polymer-surfactant complex precipitate is formed as the ratio approaches 1:1. This precipitate is recoverable and usable in many forms.

Controlling toughness and dynamics of polymer networks via mussel-inspired dynamical bonds

NASA Astrophysics Data System (ADS)

Filippidi, Emmanouela

For dry, thermoset, polymer systems increasing the degree of cross-linking increases the elastic modulus. However, it simultaneously compromises the elongation under tension, usually reducing the overall total energy dissipated before fracture (toughness). Dynamic reformable bonds and complex network topologies have been used to circumnavigate this issue with moderate success, mainly in hydrated network systems. Hydration, however, which swells these networks limits how far one could increase the modulus, while their chemistry prevents improvement of the mechanics upon drying. Employing the mussel byssus-inspired strategy of iron-catechol coordination bonds, we have synthesized and studied epoxy networks comprising covalently attached catechol moieties capable of forming additional iron-catechol complex cross-links that still function in dry conditions. In such a fashion, we create a high modulus, high elongation, high toughness material. The iron-catechol coordination bonds play multiple roles that enhance the mechanical performance of the system: at low strain and fast strain rates, they act like permanent cross-links with bonding strength similar to covalent bonds, but start disassociating at high elongation. They are also reformable, enabling material self-healing in a matter of minutes in the absence of load. Finally, the dissociative crosslink cleavage alters the local chain topology, creating length scales that unfold upon elongation. The elegance of this system lies on its general versatility. Both the polymer and metal ion can be used as control parameters to study the interplay of covalent and dynamical bonds as well as explore the limits of the design of elastomers with enhanced toughness. MRSEC of NSF Award No. DMR-1121053.

Viscoelastic and elastomeric active matter: linear instability and nonlinear dynamics

NASA Astrophysics Data System (ADS)

Hemingway, Ewan J.; Cates, M. E.; Marchetti, M. C.; Fielding, S. M.

We consider a continuum model of active viscoelastic matter, whereby a model of an active nematic liquid-crystal is coupled to a minimal model of polymer dynamics with a viscoelastic relaxation time τc. To explore the resulting interplay between active and polymeric dynamics, we first generalise a linear stability analysis (from earlier studies without polymer) to derive criteria for the onset of spontaneous flow. Perhaps surprisingly, our results show that the spontaneous flow instability persists even for divergent polymer relaxation times. We explore the novel dynamical states to which these instabilities lead by means of nonlinear numerical simulations. This reveals oscillatory shear-banded states in 1D, and activity-driven turbulence in 2D, even in the limit τc --> ∞ . Adding polymer can also have calming effects, increasing the net throughput of spontaneous flow along a channel in a new type of ''drag-reduction'', an effect that may have implications for cytoplasmic streaming processes within the cell.

Can organic matter hide from decomposers in the labyrinth of soil aggregates? Micro-engineered Soil Chips challenging foraging fungi

NASA Astrophysics Data System (ADS)

Hammer, Edith C.; Aleklett, Kristin; Arellano Caicedo, Carlos G.; Bengtsson, Martin; Micaela Mafla Endara, Paola; Ohlsson, Pelle

2017-04-01

From the point of view of microorganisms, the soil environment is an enormously complex labyrinth with paths and dead-end streets, where resources and shelters are unevenly distributed. We study foraging strategies of soil organisms, especially fungi, and the possibility of physio-spatial stabilization of organic matter by "hiding" in occluded soil spaces. We manipulate growth habitat microstructure with lab-on-a-chip techniques, where we designed complex environments with channels and obstacle at dimensions of the size of hyphae, and construct them in the transparent, gas-permeable polymer PDMS. We fill those with different nutrient solutions or combine with mineral nutrient gradients, and inoculate them with soil organisms. We analyze organisms and substrates with microscopy, fluorescence microscopy and analytical chemistry. We compared different soil litter decomposers and an arbuscular mycorrhizal fungus for their ability to forage through complex air-gap structures and attempt to classify them into functional traits concerning their mycelium directionality, space-exploring approach and ability to grow through acute angles and narrow constrictions. We identified structures which are very difficult to penetrate for most species, and compounds located behind such features may thus be spatially unavailable for decomposers. We discuss our approach in comparison to soil pore space tomographic analyses and findings we made in the pore space of colonized wood biochar.

Amylose-Based Cationic Star Polymers for siRNA Delivery

PubMed Central

Nishimura, Tomoki; Umezaki, Kaori; Mukai, Sada-atsu; Sawada, Shin-ichi; Akiyoshi, Kazunari

2015-01-01

A new siRNA delivery system using a cationic glyco-star polymer is described. Spermine-modified 8-arm amylose star polymer (with a degree of polymerization of approximately 60 per arm) was synthesized by chemoenzymatic methods. The cationic star polymer effectively bound to siRNA and formed spherical complexes with an average hydrodynamic diameter of 230 nm. The cationic 8-arm star polymer complexes showed superior cellular uptake characteristics and higher gene silencing effects than a cationic 1-arm polymer. These results suggest that amylose-based star polymers are a promising nanoplatform for glycobiomaterials. PMID:26539548

New rapid-curing, stable polyimide polymers with high-temperature strength and thermal stability

NASA Technical Reports Server (NTRS)

Burns, E. A.; Jones, J. F.; Kendrick, W. R.; Lubowitz, H. R.; Thorpe, R. S.; Wilson, E. R.

1969-01-01

Additive-type polymerization reaction forms thermally stable polyimide polymers, thereby eliminating the volatile matter attendant with the condensation reaction. It is based on the utilization of reactive alicyclic rings positioned on the ends of polyimide prepolymers having relatively low molecular weights.

Digital and analog chemical evolution.

PubMed

Goodwin, Jay T; Mehta, Anil K; Lynn, David G

2012-12-18

Living matter is the most elaborate, elegant, and complex hierarchical material known and is consequently the natural target for an ever-expanding scientific and technological effort to unlock and deconvolute its marvelous forms and functions. Our current understanding suggests that biological materials are derived from a bottom-up process, a spontaneous emergence of molecular networks in the course of chemical evolution. Polymer cooperation, so beautifully manifested in the ribosome, appeared in these dynamic networks, and the special physicochemical properties of the nucleic and amino acid polymers made possible the critical threshold for the emergence of extant cellular life. These properties include the precise and geometrically discrete hydrogen bonding patterns that dominate the complementary interactions of nucleic acid base-pairing that guide replication and ensure replication fidelity. In contrast, complex and highly context-dependent sets of intra- and intermolecular interactions guide protein folding. These diverse interactions allow the more analog environmental chemical potential fluctuations to dictate conformational template-directed propagation. When these two different strategies converged in the remarkable synergistic ribonucleoprotein that is the ribosome, this resulting molecular digital-to-analog converter achieved the capacity for both persistent information storage and adaptive responses to an ever-changing environment. The ancestral chemical networks that preceded the Central Dogma of Earth's biology must reflect the dynamic chemical evolutionary landscapes that allowed for selection, propagation, and diversification and ultimately the demarcation and specialization of function that modern biopolymers manifest. Not only should modern biopolymers contain molecular fossils of this earlier age, but it should be possible to use this information to reinvent these dynamic functional networks. In this Account, we review the first dynamic network created by modification of a nucleic acid backbone and show how it has exploited the digital-like base pairing for reversible polymer construction and information transfer. We further review how these lessons have been extended to the complex folding landscapes of templated peptide assembly. These insights have allowed for the construction of molecular hybrids of each biopolymer class and made possible the reimagining of chemical evolution. Such elaboration of biopolymer chimeras has already led to applications in therapeutics and diagnostics, to the construction of novel nanostructured materials, and toward orthogonal biochemical pathways that expand the evolution of existing biochemical systems. The ability to look beyond the primordial emergence of the ribosome may allow us to better define the origins of chemical evolution, to extend its horizons beyond the biology of today and ask whether evolution is an inherent property of matter unbounded by physical limitations imposed by our planet's diverse environments.

Process for the displacement of cyanide ions from metal-cyanide complexes

DOEpatents

Smith, Barbara F.; Robinson, Thomas W.

1997-01-01

The present invention relates to water-soluble polymers and the use of such water-soluble polymers in a process for the displacement of the cyanide ions from the metal ions within metal-cyanide complexes. The process waste streams can include metal-cyanide containing electroplating waste streams, mining leach waste streams, mineral processing waste streams, and related metal-cyanide containing waste streams. The metal ions of interest are metals that give very strong complexes with cyanide, mostly iron, nickel, and copper. The physical separation of the water-soluble polymer-metal complex from the cyanide ions can be accomplished through the use of ultrafiltration. Once the metal-cyanide complex is disrupted, the freed cyanide ions can be recovered for reuse or destroyed using available oxidative processes rendering the cyanide nonhazardous. The metal ions are released from the polymer, using dilute acid, metal ion oxidation state adjustment, or competing chelating agents, and collected and recovered or disposed of by appropriate waste management techniques. The water-soluble polymer can then be recycled. Preferred water-soluble polymers include polyethyleneimine and polyethyleneimine having a catechol or hydroxamate group.

Polymer architectures via mass spectrometry and hyphenated techniques: A review.

PubMed

Crotty, Sarah; Gerişlioğlu, Selim; Endres, Kevin J; Wesdemiotis, Chrys; Schubert, Ulrich S

2016-08-17

This review covers the application of mass spectrometry (MS) and its hyphenated techniques to synthetic polymers of varying architectural complexities. The synthetic polymers are discussed as according to their architectural complexity from linear homopolymers and copolymers to stars, dendrimers, cyclic copolymers and other polymers. MS and tandem MS (MS/MS) has been extensively used for the analysis of synthetic polymers. However, the increase in structural or architectural complexity can result in analytical challenges that MS or MS/MS cannot overcome alone. Hyphenation to MS with different chromatographic techniques (2D × LC, SEC, HPLC etc.), utilization of other ionization methods (APCI, DESI etc.) and various mass analyzers (FT-ICR, quadrupole, time-of-flight, ion trap etc.) are applied to overcome these challenges and achieve more detailed structural characterizations of complex polymeric systems. In addition, computational methods (software: MassChrom2D, COCONUT, 2D maps etc.) have also reached polymer science to facilitate and accelerate data interpretation. Developments in technology and the comprehension of different polymer classes with diverse architectures have significantly improved, which allow for smart polymer designs to be examined and advanced. We present specific examples covering diverse analytical aspects as well as forthcoming prospects in polymer science. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis and Study of Metallonitride Complexes and Polymers

DTIC Science & Technology

1992-03-02

heterobimetallic nitride-bridged complexes, examples of homobimetallic nitride-bridged complexes, and new linear chain metallonitride polymers. We...the Nitride Bridge. Synthesis and Reactivity of Early-Late Heterobimetallic Nitride-Bridged Complexes," C. M. Jones, D. M.-T. Chan, J. C. Calabrese

Applications of positron annihilation spectroscopy in materials research

NASA Technical Reports Server (NTRS)

Singh, Jag J.

1988-01-01

Positron Annihilation Spectroscopy (PAS) has emerged as a powerful technique for research in condensed matter. It has been used extensively in the study of metals, ionic crystals, glasses and polymers. The present review concentrates on applications of positron lifetime measurements for elucidation of the physicochemical structure of polymers.

Redox polymer electrodes for advanced batteries

DOEpatents

Gregg, Brian A.; Taylor, A. Michael

1998-01-01

Advanced batteries having a long cycle lifetime are provided. More specifically, the present invention relates to electrodes made from redox polymer films and batteries in which either the positive electrode, the negative electrode, or both, comprise redox polymers. Suitable redox polymers for this purpose include pyridyl or polypyridyl complexes of transition metals like iron, ruthenium, osmium, chromium, tungsten and nickel; porphyrins (either free base or metallo derivatives); phthalocyanines (either free base or metallo derivatives); metal complexes of cyclams, such as tetraazacyclotetradecane; metal complexes of crown ethers and metallocenes such as ferrocene, cobaltocene and ruthenocene.

Redox polymer electrodes for advanced batteries

DOEpatents

Gregg, B.A.; Taylor, A.M.

1998-11-24

Advanced batteries having a long cycle lifetime are provided. More specifically, the present invention relates to electrodes made from redox polymer films and batteries in which either the positive electrode, the negative electrode, or both, comprise redox polymers. Suitable redox polymers for this purpose include pyridyl or polypyridyl complexes of transition metals like iron, ruthenium, osmium, chromium, tungsten and nickel; porphyrins (either free base or metallo derivatives); phthalocyanines (either free base or metallo derivatives); metal complexes of cyclams, such as tetraazacyclotetradecane; metal complexes of crown ethers and metallocenes such as ferrocene, cobaltocene and ruthenocene. 2 figs.

Complexation of amyloid fibrils with charged conjugated polymers.

PubMed

Ghosh, Dhiman; Dutta, Paulami; Chakraborty, Chanchal; Singh, Pradeep K; Anoop, A; Jha, Narendra Nath; Jacob, Reeba S; Mondal, Mrityunjoy; Mankar, Shruti; Das, Subhadeep; Malik, Sudip; Maji, Samir K

2014-04-08

It has been suggested that conjugated charged polymers are amyloid imaging agents and promising therapeutic candidates for neurological disorders. However, very less is known about their efficacy in modulating the amyloid aggregation pathway. Here, we studied the modulation of Parkinson's disease associated α-synuclein (AS) amyloid assembly kinetics using conjugated polyfluorene polymers (PF, cationic; PFS, anionic). We also explored the complexation of these charged polymers with the various AS aggregated species including amyloid fibrils and oligomers using multidisciplinary biophysical techniques. Our data suggests that both polymers irrespective of their different charges in the side chains increase the fibrilization kinetics of AS and also remarkably change the morphology of the resultant amyloid fibrils. Both polymers were incorporated/aligned onto the AS amyloid fibrils as evident from electron microscopy (EM) and atomic force microscopy (AFM), and the resultant complexes were structurally distinct from their pristine form of both polymers and AS supported by FTIR study. Additionally, we observed that the mechanism of interactions between the polymers with different species of AS aggregates were markedly different.

Tunable Pickering Emulsions with Environmentally Responsive Hairy Silica Nanoparticles.

PubMed

Liu, Min; Chen, Xiaoli; Yang, Zongpeng; Xu, Zhou; Hong, Liangzhi; Ngai, To

2016-11-30

Surface modification of the nanoparticles using surface anchoring of amphiphilic polymers offers considerable scope for the design of a wide range of brush-coated hybrid nanoparticles with tunable surface wettability that may serve as new class of efficient Pickering emulsifiers. In the present study, we prepared mixed polymer brush-coated nanoparticles by grafting ABC miktoarm star terpolymers consisting of poly(ethylene glycol), polystyrene, and poly[(3-triisopropyloxysilyl)propyl methacrylate] (μ-PEG-b-PS-b-PIPSMA) on the surface of silica nanoparticles. The wettability of the as-prepared nanoparticles can be precisely tuned by a change of solvent or host-guest complexation. 1 H NMR result confirmed that such wettability change is due to the reorganization of the polymer chain at the grafted layer. We show that this behavior can be used for stabilization and switching between water-in-oil (W/O) and oil-in-water (O/W) emulsions. For hairy particles initially dispersed in oil, W/O emulsions were always obtained with collapsed PEG chains and mobile PS chains at the grafted layer. However, initially dispersing the hairy particles in water resulted in O/W emulsions with collapsed PS chains and mobile PEG chains. When a good solvent for both PS and PEG blocks such as toluene was used, W/O emulsions were always obtained no matter where the hairy particles were dispersed. The wettability of the mixed polymer brush-coated silica particles can also be tuned by host-guest complexation between PEG block and α-CD. More importantly, our result showed that surprisingly the resultant mixed brush-coated hairy nanoparticles can be employed for the one-step production of O/W/O multiple emulsions that are not attainable from conventional Pickering emulsifiers. The functionalized hairy silica nanoparticles at the oil-water interface can be further linked together utilizing poly(acrylic acid) as the reversible linker to form supramolecular colloidosomes, which show pH-dependent release of cargo.

New Platforms for Characterization of Biological Material Failure and Resilience Properties

NASA Astrophysics Data System (ADS)

Brown, Katherine; Butler, Benjamin J.; Nguyen, Thuy-Tien N.; Sorry, David; Williams, Alun; Proud, William G.

2017-06-01

Obtaining information about the material responses of viscoelastic soft matter, such as polymers and foams has, required adaptation of techniques traditionally used with hard condensed matter. More recently it has been recognized that understanding the strain-rate behavior of natural and synthetic soft biological materials poses even greater challenges for materials research due their heterogeneous composition and structural complexity. Expanding fundamental knowledge about how these classes of biomaterials function under different loading regimes is of considerable interest in both fundamental and applied research. A comparative overview of methods, developed in our laboratory or elsewhere, for determining material responses of cells and soft tissues over a wide range of strain rates (quasi-static to blast loading) will be presented. Examples will illustrate how data are obtained for studying material responses of cells and tissues. Strengths and weaknesses of current approaches will be discussed, with particular emphasis on challenges associated with the development of realistic experimental and computational models for trauma and other disease indications.

Life's Late Digital Revolution and Why It Matters for the Study of the Origins of Life.

PubMed

Baum, David A; Lehman, Niles

2017-08-25

The information contained in life exists in two forms, analog and digital. Analog information is manifest mainly in the differing concentrations of chemicals that get passed from generation to generation and can vary from cell to cell. Digital information is encoded in linear polymers such as DNA and RNA, whose side chains come in discrete chemical forms. Here, we argue that the analog form of information preceded the digital. Acceptance of this dichotomy, and this progression, can help direct future studies on how life originated and initially complexified on the primordial Earth, as well as expected trajectories for other, independent origins of complex life.

Properties of Shocked Polymers: Mbar experiments on Z and multi-scale simulations

NASA Astrophysics Data System (ADS)

Mattsson, Thomas R.

2010-03-01

Significant progress has been made over the last few years in understanding properties of matter subject to strong shocks and other extreme conditions. High-accuracy multi-Mbar experiments and first-principles theoretical studies together provide detailed insights into the physics and chemistry of high energy-density matter. While comprehensive advances have been made for pure elements like deuterium, helium, and carbon, progress has been slower for equally important, albeit more challenging, materials like molecular crystals, polymers, and foams. Hydrocarbon based polymer foams are common materials and in particular they are used in designing shock- and inertial confinement fusion experiments. Depending on their initial density, foams shock to relatively higher pressure and temperature compared to shocked dense polymers/plastics. As foams and polymers are shocked, they exhibit both structural and chemical transitions. We will present experimental and theoretical results for shocked polymers in the Mbar regime. By shock impact of magnetically launched flyer plates on poly(4-methyl-1-pentene) foams, we create multi-Mbar pressures in a dense plasma mixture of hydrogen, carbon, at temperatures of several eV. Concurrently with executing experiments, we analyze the system by multi-scale simulations, from density functional theory to continuum magneto-hydrodynamics simulations. In particular, density functional theory (DFT) molecular dynamics (MD) and classical MD simulations of the principal shock Hugoniot will be presented in detail for two hydrocarbon polymers: polyethylene (PE) and poly(4-methyl-1-pentene) (PMP).

Preparation and luminescent properties of the novel polymer-rare earth complexes composed of Poly(ethylene-co-acrylic acid) and Europium ions

NASA Astrophysics Data System (ADS)

Wu, Yuewen; Hao, Haixia; Wu, Qingyao; Gao, Zihan; Xie, Hongde

2018-06-01

A series of novel polymer-rare earth complexes with Eu3+ ions have been synthesized and investigated successfully, including the binary complexes containing the single ligand poly(ethylene-co-acrylic acid) (EAA) and the ternary complexes using 1,10-phenanthroline (phen), dibenzoylmethane (DBM) or thenoyltrifluoroacetone (TTA) as the second ligand. Their structures have been characterized by Fourier transform infrared spectroscopy (FT-IR), elemental analysis and X-ray diffraction (XRD), which confirm that both EAA and small molecules participate in the coordination reaction with rare earth ions, and they can disperse homogeneously in the polymer matrixes. Both ultraviolet-visible (UV-vis) absorption and photoluminescence tests for the complexes have been recorded. The relationship between fluorescence intensity of polymer-rare earth complexes and the quantity of ligand EAA has been studied and discussed. The films casted from the complexes solution can emit strong characteristic red light under UV light excitation. All these results suggest that the complexes possess potential application as luminescent materials.

Neighbor effect in complexation of a conjugated polymer.

PubMed

Sosorev, Andrey; Zapunidi, Sergey

2013-09-19

Charge-transfer complex (CTC) formation between a conjugated polymer and low-molecular-weight organic acceptor is proposed to be driven by the neighbor effect. Formation of a CTC on the polymer chain results in an increased probability of new CTC formation near the existing one. We present an analytical model for CTC distribution considering the neighbor effect, based on the principles of statistical mechanics. This model explains the experimentally observed threshold-like dependence of the CTC concentration on the acceptor content in a polymer:acceptor blend. It also allows us to evaluate binding energies of the complexes.

Water-soluble polymers for recovery of metal ions from aqueous streams

DOEpatents

Smith, Barbara F.; Robison, Thomas W.

1998-01-01

A process of selectively separating a target metal contained in an aqueous solution by contacting the aqueous solution containing a target metal with an aqueous solution including a water-soluble polymer capable of binding with the target metal for sufficient time whereby a water-soluble polymer-target metal complex is formed, and, separating the solution including the water-soluble polymer-target metal complex from the solution is disclosed.

Coordination Polymer: Synthesis, Spectral Characterization and Thermal Behaviour of Starch-Urea Based Biodegradable Polymer and Its Polymer Metal Complexes

PubMed Central

Malik, Ashraf; Parveen, Shadma; Ahamad, Tansir; Alshehri, Saad M.; Singh, Prabal Kumar; Nishat, Nahid

2010-01-01

A starch-urea-based biodegradable coordination polymer modified by transition metal Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) was prepared by polycondensation of starch and urea. All the synthesized polymeric compounds were characterized by Fourier transform-infrared spectroscopy (FT-IR), 1H-NMR spectroscopy, 13C-NMR spectroscopy, UV-visible spectra, magnetic moment measurements, differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA). The results of electronic spectra and magnetic moment measurements indicate that Mn(II), Co(II), and Ni(II) complexes show octahedral geometry, while Cu(II) and Zn(II) complexes show square planar and tetrahedral geometry, respectively. The thermogravimetric analysis revealed that all the polymeric metal complexes are more thermally stable than the parental ligand. In addition, biodegradable studies of all the polymeric compounds were also carried out through ASTM standards of biodegradable polymers by CO2 evolution method. PMID:20414461

Excited-State Complexes of Conjugated Polymers: Novel Photophysical Processes and Optoelectronic Materials.

DTIC Science & Technology

1995-03-20

corresponding excited-state complexes were only recently discovered. The results of our extensive studies of intermolecular excimers and exciplexes of many...the luminescence of conjugated polymers. The luminescence and charge photogeneration in exciplexes of conjugated polymers with donor triarylamines will also be presented. jg

Electronic polymers and soft-matter-like broken symmetries in underdoped cuprates.

PubMed

Capati, M; Caprara, S; Di Castro, C; Grilli, M; Seibold, G; Lorenzana, J

2015-07-06

Empirical evidence in heavy fermion, pnictide and other systems suggests that unconventional superconductivity appears associated to some form of real-space electronic order. For the cuprates, despite several proposals, the emergence of order in the phase diagram between the commensurate antiferromagnetic state and the superconducting state is not well understood. Here we show that in this regime doped holes assemble in 'electronic polymers'. Within a Monte Carlo study, we find that in clean systems by lowering the temperature the polymer melt condenses first in a smectic state and then in a Wigner crystal both with the addition of inversion symmetry breaking. Disorder blurs the positional order leaving a robust inversion symmetry breaking and a nematic order, accompanied by vector chiral spin order and with the persistence of a thermodynamic transition. Such electronic phases, whose properties are reminiscent of soft-matter physics, produce charge and spin responses in good accord with experiments.

Electrically contractile polymers augment right ventricular output in the heart.

PubMed

Ruhparwar, Arjang; Piontek, Patricia; Ungerer, Matthias; Ghodsizad, Ali; Partovi, Sasan; Foroughi, Javad; Szabo, Gabor; Farag, Mina; Karck, Matthias; Spinks, Geoffrey M; Kim, Seon Jeong

2014-12-01

Research into the development of artificial heart muscle has been limited to assembly of stem cell-derived cardiomyocytes seeded around a matrix, while nonbiological approaches to tissue engineering have rarely been explored. The aim of the study was to apply electrically contractile polymer-based actuators as cardiomyoplasty for positive inotropic support of the right ventricle. Complex trilayer polypyrrole (PPy) bending polymers for high-speed applications were generated. Bending motion occurred directly as a result of electrochemically driven charging and discharging of the PPy layers. In a rat model (n = 5), strips of polymers (3 × 20 mm) were attached and wrapped around the right ventricle (RV). RV pressure was continuously monitored invasively by direct RV cannulation. Electrical activation occurred simultaneously with either diastole (in order to evaluate the polymer's stand-alone contraction capacity; group 1) or systole (group 2). In group 1, the pressure generation capacity of the polymers was measured by determining the area under the pressure curve (area under curve, AUC). In group 2, the RV pressure AUC was measured in complexes directly preceding those with polymer contraction and compared to RV pressure complexes with simultaneous polymer contraction. In group 1, the AUC generated by polymer contraction was 2768 ± 875 U. In group 2, concomitant polymer contraction significantly increased AUC compared with complexes without polymer support (5987 ± 1334 U vs. 4318 ± 691 U, P ≤ 0.01). Electrically contractile polymers are able to significantly augment right ventricular contraction. This approach may open new perspectives for myocardial tissue engineering, possibly in combination with fetal or embryonic stem cell-derived cardiomyocytes. Copyright © 2014 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Platinated DNA oligonucleotides: new probes forming ultrastable conjugates with graphene oxide

NASA Astrophysics Data System (ADS)

Wang, Feng; Liu, Juewen

2014-05-01

Metal containing polymers have expanded the property of polymers by involving covalently associated metal complexes. DNA is a special block copolymer. While metal ions are known to influence DNA, little is explored on its polymer property when strong metal complexes are associated. In this work, we study cisplatin modified DNA as a new polymer and probe. Out of the complexes formed between cisplatin-A15, HAuCl4-A15, Hg2+-T15 and Ag+-C15, only the cisplatin adduct is stable under the denaturing gel electrophoresis condition. Each Pt-nucleobase bond gives a positive charge and thus makes DNA a zwitterionic polymer. This allows ultrafast adsorption of DNA by graphene oxide (GO) and the adsorbed complex is highly stable. Non-specific DNA, protein, surfactants and thiolated compounds cannot displace platinated DNA from GO, while non-modified DNA is easily displaced in most cases. The stable GO/DNA conjugate is further tested for surface hybridization. This is the first demonstration of using metallated DNA as a polymeric material for interfacing with nanoscale materials.Metal containing polymers have expanded the property of polymers by involving covalently associated metal complexes. DNA is a special block copolymer. While metal ions are known to influence DNA, little is explored on its polymer property when strong metal complexes are associated. In this work, we study cisplatin modified DNA as a new polymer and probe. Out of the complexes formed between cisplatin-A15, HAuCl4-A15, Hg2+-T15 and Ag+-C15, only the cisplatin adduct is stable under the denaturing gel electrophoresis condition. Each Pt-nucleobase bond gives a positive charge and thus makes DNA a zwitterionic polymer. This allows ultrafast adsorption of DNA by graphene oxide (GO) and the adsorbed complex is highly stable. Non-specific DNA, protein, surfactants and thiolated compounds cannot displace platinated DNA from GO, while non-modified DNA is easily displaced in most cases. The stable GO/DNA conjugate is further tested for surface hybridization. This is the first demonstration of using metallated DNA as a polymeric material for interfacing with nanoscale materials. Electronic supplementary information (ESI) available: Methods, additional gels, kinetics, mass spectrum. See DOI: 10.1039/c4nr00867g

EPR spin probe and spin label studies of some low molecular and polymer micelles

NASA Astrophysics Data System (ADS)

Wasserman, A. M.; Kasaikin, V. A.; Timofeev, V. P.

1998-12-01

The rotational mobility of spin probes of different shape and size in low molecular and polymer micelles has been studied. Several probes having nitroxide fragment localized either in the vicinity of micelle interface or in the hydrocarbon core have been used. Upon increasing the number of carbon atoms in hydrocarbon chain of detergent from 7 to 13 (sodium alkyl sulfate micelles) or from 12 to 16 (alkyltrimethylammonium bromide micelles) the rotational mobility of spin probes is decreased by the factor 1.5-2.0. The spin probe rotational mobility in polymer micelles (the complexes of alkyltrimethylammonium bromides and polymethacrylic or polyacrylic acids) is less than mobility in free micelles of the same surfactants. The study of EPR-spectra of spin labeled polymethacrylic acid (PMA) indicated that formation of water soluble complexes of polymer and alkyltrimethylammonium bromides in alkaline solutions (pH 9) does not affect the polymer segmental mobility. On the other hand, the polymer complexes formation in slightly acidic water solution (pH 6) breaks down the compact PMA conformation, thus increasing the polymer segmental mobility. Possible structures of polymer micelles are discussed.

Hierarchically Mesoporous o-Hydroxyazobenzene Polymers: Synthesis and Their Applications in CO2 Capture and Conversion.

PubMed

Ji, Guipeng; Yang, Zhenzhen; Zhang, Hongye; Zhao, Yanfei; Yu, Bo; Ma, Zhishuang; Liu, Zhimin

2016-08-08

The synthesis of hierarchically mesoporous polymers with multiple functionalities is challenging. Herein we reported a template-free strategy for synthesis of phenolic azo-polymers with hierarchical porous structures based on diazo-coupling reaction in aqueous solution under mild conditions. The resultant polymers have surface areas up to 593 m(2)  g(-1) with the mesopore ratio of >80 %, and a good ability to complex with metal ions, such as Cu(2+) , Zn(2+) ,Ni(2+) , achieving a metal loading up to 26.24 wt %. Moreover, the polymers complexed with Zn showed excellent performance for catalyzing the reaction of CO2 with epoxide, affording a TOF of 2570 h(-1) in the presence of tetrabutyl ammonium bromide (7.2 mol %). The polymer complexed with Cu could catalyze the oxidation of alcohol with high efficiency. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Viscoelastic and elastomeric active matter: Linear instability and nonlinear dynamics.

PubMed

Hemingway, E J; Cates, M E; Fielding, S M

2016-03-01

We consider a continuum model of active viscoelastic matter, whereby an active nematic liquid crystal is coupled to a minimal model of polymer dynamics with a viscoelastic relaxation time τ(C). To explore the resulting interplay between active and polymeric dynamics, we first generalize a linear stability analysis (from earlier studies without polymer) to derive criteria for the onset of spontaneous heterogeneous flows (strain rate) and/or deformations (strain). We find two modes of instability. The first is a viscous mode, associated with strain rate perturbations. It dominates for relatively small values of τ(C) and is a simple generalization of the instability known previously without polymer. The second is an elastomeric mode, associated with strain perturbations, which dominates at large τ(C) and persists even as τ(C)→∞. We explore the dynamical states to which these instabilities lead by means of direct numerical simulations. These reveal oscillatory shear-banded states in one dimension and activity-driven turbulence in two dimensions even in the elastomeric limit τ(C)→∞. Adding polymer can also have calming effects, increasing the net throughput of spontaneous flow along a channel in a type of drag reduction. The effect of including strong antagonistic coupling between the nematic and polymer is examined numerically, revealing a rich array of spontaneously flowing states.

Viscoelastic and elastomeric active matter: Linear instability and nonlinear dynamics

NASA Astrophysics Data System (ADS)

Hemingway, E. J.; Cates, M. E.; Fielding, S. M.

2016-03-01

We consider a continuum model of active viscoelastic matter, whereby an active nematic liquid crystal is coupled to a minimal model of polymer dynamics with a viscoelastic relaxation time τC. To explore the resulting interplay between active and polymeric dynamics, we first generalize a linear stability analysis (from earlier studies without polymer) to derive criteria for the onset of spontaneous heterogeneous flows (strain rate) and/or deformations (strain). We find two modes of instability. The first is a viscous mode, associated with strain rate perturbations. It dominates for relatively small values of τC and is a simple generalization of the instability known previously without polymer. The second is an elastomeric mode, associated with strain perturbations, which dominates at large τC and persists even as τC→∞ . We explore the dynamical states to which these instabilities lead by means of direct numerical simulations. These reveal oscillatory shear-banded states in one dimension and activity-driven turbulence in two dimensions even in the elastomeric limit τC→∞ . Adding polymer can also have calming effects, increasing the net throughput of spontaneous flow along a channel in a type of drag reduction. The effect of including strong antagonistic coupling between the nematic and polymer is examined numerically, revealing a rich array of spontaneously flowing states.

Synthesis and Exciton Dynamics of Triplet Sensitized Conjugated Polymers.

PubMed

Andernach, Rolf; Utzat, Hendrik; Dimitrov, Stoichko D; McCulloch, Iain; Heeney, Martin; Durrant, James R; Bronstein, Hugo

2015-08-19

We report the synthesis of a novel polythiophene-based host-guest copolymer incorporating a Pt-porphyrin complex (TTP-Pt) into the backbone for efficient singlet to triplet polymer exciton sensitization. We elucidated the exciton dynamics in thin films of the material by means of Transient Absorption Spectrosopcy (TAS) on multiple time scales and investigated the mechanism of triplet exciton formation. During sensitization, singlet exciton diffusion is followed by exciton transfer from the polymer backbone to the complex where it undergoes intersystem crossing to the triplet state of the complex. We directly monitored the triplet exciton back transfer from the Pt-porphyrin to the polymer and found that 60% of the complex triplet excitons were transferred with a time constant of 1087 ps. We propose an equilibrium between polymer and porphyrin triplet states as a result of the low triplet diffusion length in the polymer backbone and hence an increased local triplet population resulting in increased triplet-triplet annihilation. This novel system has significant implications for the design of novel materials for triplet sensitized solar cells and upconversion layers.

Functional Hybrid Biomaterials based on Peptide-Polymer Conjugates for Nanomedicine

NASA Astrophysics Data System (ADS)

Shu, Jessica Yo

The focus of this dissertation is the design, synthesis and characterization of hybrid functional biomaterials based on peptide-polymer conjugates for nanomedicine. Generating synthetic materials with properties comparable to or superior than those found in nature has been a "holy grail" for the materials community. Man-made materials are still rather simplistic when compared to the chemical and structural complexity of a cell. Peptide-polymer conjugates have the potential to combine the advantages of the biological and synthetic worlds---that is they can combine the precise chemical structure and diverse functionality of biomolecules with the stability and processibility of synthetic polymers. As a new family of soft matter, they may lead to materials with novel properties that have yet to be realized with either of the components alone. In order for peptide-polymer conjugates to reach their full potential as useful materials, the structure and function of the peptide should be maintained upon polymer conjugation. The success in achieving desirable, functional assemblies relies on fundamentally understanding the interactions between each building block and delicately balancing and manipulating these interactions to achieve targeted assemblies without interfering with designed structures and functionalities. Such fundamental studies of peptide-polymer interactions were investigated as the nature of the polymer (hydrophilic vs. hydrophobic) and the site of its conjugation (end-conjugation vs. side-conjugation) were varied. The fundamental knowledge gained was then applied to the design of amphiphiles that self-assemble to form stable functional micelles. The micelles exhibited exceptional monodispersity and long-term stability, which is atypical of self-assembled systems. Thus such micelles based on amphiphilic peptide-polymer conjugates may meet many current demands in nanomedicine, in particular for drug delivery of hydrophobic anti-cancer therapeutics. Lastly, biological evaluations were performed to investigate the potential of micelles as drug delivery vehicles. In vitro cell studies demonstrated that the micelles can be used as a delivery vehicle to tailor the cellular uptake, time release, and intracellular trafficking of drugs. In vivo biodistribution and pharmacokinetic experiments showed long blood circulation. This work demonstrates that peptide-polymer conjugates can be used as building blocks to generate hierarchical functional nanostructures with a wide range of applications, only one of which is drug delivery.

Nanocrystal/sol-gel nanocomposites

DOEpatents

Klimov, Victor L.; Petruska, Melissa A.

2010-05-25

The present invention is directed to a process for preparing a solid composite having colloidal nanocrystals dispersed within a sol-gel matrix, the process including admixing colloidal nanocrystals with an amphiphilic polymer including hydrophilic groups selected from the group consisting of --COOH, --OH, --SO.sub.3H, --NH.sub.2, and --PO.sub.3H.sub.2 within a solvent to form an alcohol-soluble colloidal nanocrystal-polymer complex, admixing the alcohol-soluble colloidal nanocrystal-polymer complex and a sol-gel precursor material, and, forming the solid composite from the admixture. The present invention is also directed to the resultant solid composites and to the alcohol-soluble colloidal nanocrystal-polymer complexes.

Fluorescent Polymer-Single-Walled Carbon Nanotube Complexes with Charged and Noncharged Dendronized Perylene Bisimides for Bioimaging Studies.

PubMed

Huth, Katharina; Glaeske, Mareen; Achazi, Katharina; Gordeev, Georgy; Kumar, Shiv; Arenal, Raúl; Sharma, Sunil K; Adeli, Mohsen; Setaro, Antonio; Reich, Stephanie; Haag, Rainer

2018-06-05

Fluorescent nanomaterials are expected to revolutionize medical diagnostic, imaging, and therapeutic tools due to their superior optical and structural properties. Their inefficient water solubility, cell permeability, biodistribution, and high toxicity, however, limit the full potential of their application. To overcome these obstacles, a water-soluble, fluorescent, cytocompatible polymer-single-walled carbon nanotube (SWNT) complex is introduced for bioimaging applications. The supramolecular complex consists of an alkylated polymer conjugated with neutral hydroxylated or charged sulfated dendronized perylene bisimides (PBIs) and SWNTs as a general immobilization platform. The polymer backbone solubilizes the SWNTs, decorates them with fluorescent PBIs, and strongly improves their cytocompatibility by wrapping around the SWNT scaffold. In photophysical measurements and biological in vitro studies, sulfated complexes exhibit superior optical properties, cellular uptake, and intracellular staining over their hydroxylated analogs. A toxicity assay confirms the highly improved cytocompatibility of the polymer-wrapped SWNTs toward surfactant-solubilized SWNTs. In microscopy studies the complexes allow for the direct imaging of the SWNTs' cellular uptake via the PBI and SWNT emission using the 1st and 2nd optical window for bioimaging. These findings render the polymer-SWNT complexes with nanometer size, dual fluorescence, multiple charges, and high cytocompatibility as valuable systems for a broad range of fluorescence bioimaging studies. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and supramolecular assembly of biomimetic polymers

NASA Astrophysics Data System (ADS)

Marciel, Amanda Brittany

A grand challenge in materials chemistry is the synthesis of macromolecules and polymers with precise shapes and architectures. Polymer microstructure and architecture strongly affect the resulting functionality of advanced materials, yet understanding the static and dynamic properties of these complex macromolecules in bulk has been difficult due to their inherit polydispersity. Single molecule studies have provided a wealth of information on linear flexible and semi-flexible polymers in dilute solutions. However, few investigations have focused on industrially relevant complex topologies (e.g., star, comb, hyperbranched polymers) in industrially relevant solution conditions (e.g., semi-dilute, concentrated). Therefore, from this perspective there is a strong need to synthesize precision complex architectures for bulk studies as well as complex architectures compatible with current single molecule techniques to study static and dynamic polymer properties. In this way, we developed a hybrid synthetic strategy to produce branched polymer architectures based on chemically modified DNA. Overall, this approach enables control of backbone length and flexibility, as well as branch grafting density and chemical identity. We utilized a two-step scheme based on enzymatic incorporation of non-natural nucleotides containing bioorthogonal dibenzocyclooctyne (DBCO) functional groups along the main polymer backbone, followed by copper-free "click" chemistry to graft synthetic polymer branches or oligonucleotide branches to the DNA backbone, thereby allowing for the synthesis of a variety of polymer architectures, including three-arm stars, H-polymers, graft block copolymers, and comb polymers for materials assembly and single molecule studies. Bulk materials properties are also affected by industrial processing conditions that alter polymer morphology. Therefore, in an alternative strategy we developed a microfluidic-based approach to assemble highly aligned synthetic oligopeptides nanostructures using microscale extensional flows. This strategy enabled reproducible, reliable fabrication of aligned hierarchical constructs that do not form spontaneously in solution. In this way, fluidic-directed assembly of supramolecular structures allows for unprecedented manipulation at the nano- and mesoscale, which has the potential to provide rapid and efficient control of functional materials properties.

Method for the preparation of thin-skinned asymmetric reverse osmosis membranes and products thereof

NASA Technical Reports Server (NTRS)

Wydeven, T. J. (Inventor); Katz, M. G.

1984-01-01

A method for preparing water insoluble asymmetric membranes from water soluble polymers is discussed. The process involves casting a film of the polymer, partially drying it, and then contacting it with a concentrated solution of a transition metal salt. The transition metal ions render the polymer insoluable and are believed to form a complex with it. Optionally, the polymer is crosslinked with heat or radiation. The most preferred polymer is poly(vinyl alcohol). The most preferred complexing salt is copper sulfate. The process and the metal ion linked membranes are discussed. The membranes are reverse osmosis membranes.

Architecture of Amylose Supramolecules in Form of Inclusion Complexes by Phosphorylase-Catalyzed Enzymatic Polymerization

PubMed Central

Kadokawa, Jun-ichi

2013-01-01

This paper reviews the architecture of amylose supramolecules in form of inclusion complexes with synthetic polymers by phosphorylase-catalyzed enzymatic polymerization. Amylose is known to be synthesized by enzymatic polymerization using α-d-glucose 1-phosphate as a monomer, by phosphorylase catalysis. When the phosphorylase-catalyzed enzymatic polymerization was conducted in the presence of various hydrophobic polymers, such as polyethers, polyesters, poly(ester-ether), and polycarbonates as a guest polymer, such inclusion supramolecules were formed by the hydrophobic interaction in the progress of polymerization. Because the representation of propagation in the polymerization is similar to the way that a vine of a plant grows, twining around a rod, this polymerization method for the formation of amylose-polymer inclusion complexes was proposed to be named “vine-twining polymerization”. To yield an inclusion complex from a strongly hydrophobic polyester, the parallel enzymatic polymerization system was extensively developed. The author found that amylose selectively included one side of the guest polymer from a mixture of two resemblant guest polymers, as well as a specific range in molecular weights of the guest polymers poly(tetrahydrofuran) (PTHF) in the vine-twining polymerization. Selective inclusion behavior of amylose toward stereoisomers of chiral polyesters, poly(lactide)s, also appeared in the vine-twining polymerization. PMID:24970172

Synthesis and photoluminescence properties of novel Schiff base type polymer-rare earth complexes containing furfural-based bidentate Schiff base ligands

NASA Astrophysics Data System (ADS)

Gao, Baojiao; Zhang, Dandan; Li, Yanbin

2018-03-01

Luminescent polymer-rare earth complexes are an important class of photoluminescence and electroluminescence materials. Via molecular design, two furfural-based bidentate Schiff base ligands, furfural-aniline (FA) type ligand and furfural-cyclohexylamine (FC) type ligand, were bonded on the side chains of polysulfone (PSF), respectively, forming two functionalized macromolecules, PSF-FA and PSF-FC. And then through respective coordination reactions of the two functionalized macromolecules with Eu(Ⅲ) ion and Tb(Ⅲ) ion, novel luminescent binary and ternary (with 1,10-phenanthroline as the second ligand) polymer-rare earth complexes were synthesized. For these complexes, on basis of the characterization of their chemical structures, they photoluminescence properties were main researched, and the relationship between their luminescent properties and structures was explored. The experimental results show that the complexes coming from PSF-FA and Eu(Ⅲ) ion including binary and ternary complexes emit strong red luminescence, indicating that the bonded bidentate Schiff base ligand FA can sensitize the fluorescence emission of Eu(III) ion. While the complexes coming from PSF-FC and Tb(Ⅲ) ion produce green luminescence, displaying that the bonded bidentate Schiff base ligand FC can sensitize the fluorescence emission of Tb(Ⅲ) ion. The fluorescence emission intensities of the ternary complexes were stronger than that of binary complexes, reflecting the important effect of the second ligand. The fluorescence emission of the solid film of complexes is much stronger than that of the solutions of complexes. Besides, by comparison, it is found that the furfural (as a heteroaromatic compound)-based Schiff base type polymer-rare earth complexes have stronger fluorescence emission and higher energy transfer efficiency than salicylaldehyde (as a common aromatic compound)-based Schiff base type polymer-rare earth complexes.

Multiscale Materials Modeling in an Industrial Environment.

PubMed

Weiß, Horst; Deglmann, Peter; In 't Veld, Pieter J; Cetinkaya, Murat; Schreiner, Eduard

2016-06-07

In this review, we sketch the materials modeling process in industry. We show that predictive and fast modeling is a prerequisite for successful participation in research and development processes in the chemical industry. Stable and highly automated workflows suitable for handling complex systems are a must. In particular, we review approaches to build and parameterize soft matter systems. By satisfying these prerequisites, efficiency for the development of new materials can be significantly improved, as exemplified here for formulation polymer development. This is in fact in line with recent Materials Genome Initiative efforts sponsored by the US government. Valuable contributions to product development are possible today by combining existing modeling techniques in an intelligent fashion, provided modeling and experiment work hand in hand.

Effect of introduction of chondroitin sulfate into polymer-peptide conjugate responding to intracellular signals

NASA Astrophysics Data System (ADS)

Tomiyama, Tetsuro; Toita, Riki; Kang, Jeong-Hun; Koga, Haruka; Shiosaki, Shujiro; Mori, Takeshi; Niidome, Takuro; Katayama, Yoshiki

2011-09-01

We recently developed a novel tumor-targeted gene delivery system responding to hyperactivated intracellular signals. Polymeric carrier for gene delivery consists of hydrophilic neutral polymer as main chains and cationic peptide substrate for target enzyme as side chains, and was named polymer-peptide conjugate (PPC). Introduction of chondroitin sulfate (CS), which induces receptor-medicated endocytosis, into polymers mainly with a high cationic charge density such as polyethylenimine can increase tumor-targeted gene delivery. In the present study, we examined whether introduction of CS into PPC containing five cationic amino acids can increase gene expression in tumor cells. Size and zeta potential of plasmid DNA (pDNA)/PPC/CS complex were <200 nm and between -10 and -15 mV, respectively. In tumor cell experiments, pDNA/PPC/CS complex showed lower stability and gene regulation, compared with that of pDNA/PPC. Moreover, no difference in gene expression was identified between positive and negative polymer. These results were caused by fast disintegration of pDNA/PPC/CS complexes in the presence of serum. Thus, we suggest that introduction of negatively charged CS into polymers with a low charge density may lead to low stability and gene regulation of complexes.

Erythrocyte interactions - Comparison of the aggregation power of polymer molecules used in medicine - Not only size does matter.

PubMed

Jovtchev, S; Alexandrov, S; Hristova-Avakumova, N; Miteva, S; Traikov, L; Gerasimova, D; Stoeff, S

2016-01-01

Different colloids are used as a part of solutions for fluid resuscitation and organ preservation: hydroxyethyl starches (HES), dextran (Dx), polyethylene glycols (PEG), polyvinyl pyrrolidone (PVP). Some of the problems associated with their application are addressed to alteration in erythrocyte (ERY) rheology. We intended to estimate in vitro and compare the aggregation power (AP) of these molecules related to ERY interactions. Washed human ERY are used during the study. The zeta sedimentation technique is used to quantify the cell aggregation. Zeta sedimentation ratio (ZSR) based indices (AI) are calculated. The hydrodynamic radius (Rh) of the polymer molecules is determined using viscometry. For all polymers tested a linear range in the relationship AI - concentration was found. The slope of the calculated line was interpreted as measure of the molecule's AP. The following ranking was obtained: PEG >PVP >DX >HES. Within the same chemical type of polymer, increasing Rh of the molecules leads to elevated AI. Comparison of the AP of molecules with similar Rh reveals a significant dependence on their chemical nature. Our results show that molecule's AP is significantly dependent on their chemical nature - i.e. not only molecular size does matter.

Influence of natural organic matter on transport and retention of polymer coated silver nanoparticles in porous media.

PubMed

Yang, Xinyao; Lin, Shihong; Wiesner, Mark R

2014-01-15

Interactions between organic matter (OM) and engineered polymer coatings as they affect the retention of polyvinylpyrrolidone (PVP) polymer-coated silver nanoparticles (AgNPs) were studied. Two distinct types of OM-cysteine representing low molecular weight multivalent functional groups, and Suwannee River Humic Acid (HA) representing high molecular weight polymers, were investigated with respect to their effects on particle stability in aggregation and deposition. Aggregation of the PVP coated AgNPs (PVP-AgNPs) was enhanced by cysteine addition at high ionic strengths, which was attributed to cysteine binding to the AgNPs and replacing the otherwise steric stabilizing agent PVP. In contrast the addition of HA did not increase aggregation rates and decreased PVP-AgNP deposition to the silica porous medium, consistent with enhanced electrosteric stabilization by the HA. Although cysteine also reduced deposition in the porous medium, the mechanisms of reduced deposition appear to be enhanced electric double layer (EDL) interaction at low ionic strengths. At higher ionic strengths, aggregation was favored leading to lower deposition due to smaller diffusion coefficients and single collector efficiencies despite the reduced EDL interactions. Copyright © 2013 Elsevier B.V. All rights reserved.

Cationic polymers for DNA origami coating - examining their binding efficiency and tuning the enzymatic reaction rates

NASA Astrophysics Data System (ADS)

Kiviaho, Jenny K.; Linko, Veikko; Ora, Ari; Tiainen, Tony; Järvihaavisto, Erika; Mikkilä, Joona; Tenhu, Heikki; Nonappa, Affc; Kostiainen, Mauri A.

2016-06-01

DNA origamis are fully tailored, programmable, biocompatible and readily functionalizable nanostructures that provide an excellent foundation for the development of sophisticated drug-delivery systems. However, the DNA origami objects suffer from certain drawbacks such as low cell-transfection rates and low stability. A great deal of studies on polymer-based transfection agents, mainly focusing on polyplex formation and toxicity, exists. In this study, the electrostatic binding between a brick-like DNA origami and cationic block-copolymers was explored. The effect of the polymer structure on the binding was investigated and the toxicity of the polymer-origami complexes evaluated. The study shows that all of the analyzed polymers had a suitable binding efficiency irrespective of the block structure. It was also observed that the toxicity of polymer-origami complexes was insignificant at the biologically relevant concentration levels. Besides brick-like DNA origamis, tubular origami carriers equipped with enzymes were also coated with the polymers. By adjusting the amount of cationic polymers that cover the DNA structures, we showed that it is possible to control the enzyme kinetics of the complexes. This work gives a starting point for further development of biocompatible and effective polycation-based block copolymers that can be used in coating different DNA origami nanostructures for various bioapplications.DNA origamis are fully tailored, programmable, biocompatible and readily functionalizable nanostructures that provide an excellent foundation for the development of sophisticated drug-delivery systems. However, the DNA origami objects suffer from certain drawbacks such as low cell-transfection rates and low stability. A great deal of studies on polymer-based transfection agents, mainly focusing on polyplex formation and toxicity, exists. In this study, the electrostatic binding between a brick-like DNA origami and cationic block-copolymers was explored. The effect of the polymer structure on the binding was investigated and the toxicity of the polymer-origami complexes evaluated. The study shows that all of the analyzed polymers had a suitable binding efficiency irrespective of the block structure. It was also observed that the toxicity of polymer-origami complexes was insignificant at the biologically relevant concentration levels. Besides brick-like DNA origamis, tubular origami carriers equipped with enzymes were also coated with the polymers. By adjusting the amount of cationic polymers that cover the DNA structures, we showed that it is possible to control the enzyme kinetics of the complexes. This work gives a starting point for further development of biocompatible and effective polycation-based block copolymers that can be used in coating different DNA origami nanostructures for various bioapplications. Electronic supplementary information (ESI) available: Details of materials, syntheses of the polymers, fabrication and purification of DNA origamis, luminescence decay assays, agarose gel electrophoresis, ethidium bromide displacement assay, MTT assay and TEM characterization. See DOI: 10.1039/c5nr08355a

Threshold-like complexation of conjugated polymers with small molecule acceptors in solution within the neighbor-effect model.

PubMed

Sosorev, Andrey Yu; Parashchuk, Olga D; Zapunidi, Sergey A; Kashtanov, Grigoriy S; Golovnin, Ilya V; Kommanaboyina, Srikanth; Perepichka, Igor F; Paraschuk, Dmitry Yu

2016-02-14

In some donor-acceptor blends based on conjugated polymers, a pronounced charge-transfer complex (CTC) forms in the electronic ground state. In contrast to small-molecule donor-acceptor blends, the CTC concentration in polymer:acceptor solution can increase with the acceptor content in a threshold-like way. This threshold-like behavior was earlier attributed to the neighbor effect (NE) in the polymer complexation, i.e., next CTCs are preferentially formed near the existing ones; however, the NE origin is unknown. To address the factors affecting the NE, we record the optical absorption data for blends of the most studied conjugated polymers, poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) and poly(3-hexylthiophene) (P3HT), with electron acceptors of fluorene series, 1,8-dinitro-9,10-antraquinone (), and 7,7,8,8-tetracyanoquinodimethane () in different solvents, and then analyze the data within the NE model. We have found that the NE depends on the polymer and acceptor molecular skeletons and solvent, while it does not depend on the acceptor electron affinity and polymer concentration. We conclude that the NE operates within a single macromolecule and stems from planarization of the polymer chain involved in the CTC with an acceptor molecule; as a result, the probability of further complexation with the next acceptor molecules at the adjacent repeat units increases. The steric and electronic microscopic mechanisms of NE are discussed.

Soft matter in hard confinement: phase transition thermodynamics, structure, texture, diffusion and flow in nanoporous media.

PubMed

Huber, Patrick

2015-03-18

Spatial confinement in nanoporous media affects the structure, thermodynamics and mobility of molecular soft matter often markedly. This article reviews thermodynamic equilibrium phenomena, such as physisorption, capillary condensation, crystallisation, self-diffusion, and structural phase transitions as well as selected aspects of the emerging field of spatially confined, non-equilibrium physics, i.e. the rheology of liquids, capillarity-driven flow phenomena, and imbibition front broadening in nanoporous materials. The observations in the nanoscale systems are related to the corresponding bulk phenomenologies. The complexity of the confined molecular species is varied from simple building blocks, like noble gas atoms, normal alkanes and alcohols to liquid crystals, polymers, ionic liquids, proteins and water. Mostly, experiments with mesoporous solids of alumina, gold, carbon, silica, and silicon with pore diameters ranging from a few up to 50 nm are presented. The observed peculiarities of nanopore-confined condensed matter are also discussed with regard to applications. A particular emphasis is put on texture formation upon crystallisation in nanoporous media, a topic both of high fundamental interest and of increasing nanotechnological importance, e.g. for the synthesis of organic/inorganic hybrid materials by melt infiltration, the usage of nanoporous solids in crystal nucleation or in template-assisted electrochemical deposition of nano structures.

Soft matter in hard confinement: phase transition thermodynamics, structure, texture, diffusion and flow in nanoporous media

NASA Astrophysics Data System (ADS)

Huber, Patrick

2015-03-01

Spatial confinement in nanoporous media affects the structure, thermodynamics and mobility of molecular soft matter often markedly. This article reviews thermodynamic equilibrium phenomena, such as physisorption, capillary condensation, crystallisation, self-diffusion, and structural phase transitions as well as selected aspects of the emerging field of spatially confined, non-equilibrium physics, i.e. the rheology of liquids, capillarity-driven flow phenomena, and imbibition front broadening in nanoporous materials. The observations in the nanoscale systems are related to the corresponding bulk phenomenologies. The complexity of the confined molecular species is varied from simple building blocks, like noble gas atoms, normal alkanes and alcohols to liquid crystals, polymers, ionic liquids, proteins and water. Mostly, experiments with mesoporous solids of alumina, gold, carbon, silica, and silicon with pore diameters ranging from a few up to 50 nm are presented. The observed peculiarities of nanopore-confined condensed matter are also discussed with regard to applications. A particular emphasis is put on texture formation upon crystallisation in nanoporous media, a topic both of high fundamental interest and of increasing nanotechnological importance, e.g. for the synthesis of organic/inorganic hybrid materials by melt infiltration, the usage of nanoporous solids in crystal nucleation or in template-assisted electrochemical deposition of nano structures.

Polymer therapeutics: concepts and applications.

PubMed

Haag, Rainer; Kratz, Felix

2006-02-13

Polymer therapeutics encompass polymer-protein conjugates, drug-polymer conjugates, and supramolecular drug-delivery systems. Numerous polymer-protein conjugates with improved stability and pharmacokinetic properties have been developed, for example, by anchoring enzymes or biologically relevant proteins to polyethylene glycol components (PEGylation). Several polymer-protein conjugates have received market approval, for example the PEGylated form of adenosine deaminase. Coupling low-molecular-weight anticancer drugs to high-molecular-weight polymers through a cleavable linker is an effective method for improving the therapeutic index of clinically established agents, and the first candidates have been evaluated in clinical trials, including, N-(2-hydroxypropyl)methacrylamide conjugates of doxorubicin, camptothecin, paclitaxel, and platinum(II) complexes. Another class of polymer therapeutics are drug-delivery systems based on well-defined multivalent and dendritic polymers. These include polyanionic polymers for the inhibition of virus attachment, polycationic complexes with DNA or RNA (polyplexes), and dendritic core-shell architectures for the encapsulation of drugs. In this Review an overview of polymer therapeutics is presented with a focus on concepts and examples that characterize the salient features of the drug-delivery systems.

Interactions between sodium dodecyl sulphate and non-ionic cellulose derivatives studied by size exclusion chromatography with online multi-angle light scattering and refractometric detection.

PubMed

Wittgren, Bengt; Stefansson, Morgan; Porsch, Bedrich

2005-08-05

The novel approach described allows to characterise the surfactant-polymer interaction under several sodium dodecyl sulphate (SDS) concentrations (0-20 mM) using size exclusion chromatography (SEC) with online multi-angle light scattering (MALS) and refractometric (RI) detection. Three different cellulose derivatives, hydroxypropyl cellulose (HPC), hydroxypropyl methyl cellulose (HPMC) and hydroxyethyl cellulose (HEC), have been studied in solution containing 10 mM NaCl and various concentrations of sodium dodecyl sulphate. It is shown that this approach is well suited for successful application of both Hummel-Dreyer and multi-component light scattering principles and yields reliable molecular masses of both the polymer complex and the polymer itself within the complex, the amount of surfactant bound into the complex as well as appropriate values of the refractive index increment (dn/dc)micro, of both the complex and the polymer in question. The more hydrophobic derivatives HPC and HPMC adsorbed significantly more SDS than HEC. The inter-chain interactions close to critical aggregation concentration (cac) were clearly seen for HPC and HPMC as an almost two-fold average increase in polymer molecular mass contained in the complex.

Tracing Single Electrons in a Disordered Polymer Film at Room Temperature.

PubMed

Wilma, Kevin; Issac, Abey; Chen, Zhijian; Würthner, Frank; Hildner, Richard; Köhler, Jürgen

2016-04-21

The transport of charges lies at the heart of essentially all modern (opto-) electronic devices. Although inorganic semiconductors built the basis for current technologies, organic materials have become increasingly important in recent years. However, organic matter is often highly disordered, which directly impacts the charge carrier dynamics. To understand and optimize device performance, detailed knowledge of the transport mechanisms of charge carriers in disordered matter is therefore of crucial importance. Here we report on the observation of the motion of single electrons within a disordered polymer film at room temperature, using single organic chromophores as probe molecules. The migration of a single electron gives rise to a varying electric field in its vicinity, which is registered via a shift of the emission spectra (Stark shift) of a chromophore. The spectral shifts allow us to determine the electron mobility and reveal for each nanoenvironment a distinct number of different possible electron-transfer pathways within the rugged energy landscape of the disordered polymer matrix.

Shear rheology and 1H TD-NMR combined to low-field RheoNMR: Set-up and application to quiescent and flow-induced crystallization of polymers

NASA Astrophysics Data System (ADS)

Räntzsch, Volker; Özen, Mürüvvet Begüm; Ratzsch, Karl-Friedrich; Guthausen, Gisela; Wilhelm, Manfred

2017-05-01

Rheology provides access to the flow properties of soft matter, while 1H TD-NMR is a useful technique for the characterization of molecular dynamics. To achieve greater insight into the interplay of these domains, especially under flow, it is desirable to combine these two methods in one set-up. We present a low-field RheoNMR set-up based on a portable 30 MHz 1H NMR unit that was integrated into a commercial strain-controlled shear rheometer. This unique combination can simultaneously conduct a full rheological characterization (G', G", |η*|, FT-Rheology: I3/1, Q0) while monitoring molecular dynamics in-situ via 1H TD-NMR for temperatures from -15 to +210 °C. Possible applications include the quantitative measurement of the composition in multiphase systems (fats, polymers, etc.) and soft matter during the application of flow, e.g. measurements on the flow-induced crystallization of polymers.

Synthesis and characterization of poly(phenylacetylene)s with Ru(II) bis-terpyridine complexes in the side-chain.

PubMed

Breul, Alexander M; Kübel, Joachim; Häupler, Bernhard; Friebe, Christian; Hager, Martin D; Winter, Andreas; Dietzek, Benjamin; Schubert, Ulrich S

2014-04-01

An alkyne-functionalized ruthenium(II) bis-terpyridine complex is directly copolymerized with phenylacetylene by alkyne polymerization. The polymer is characterized by size-exclusion chromatography (SEC), (1) H NMR spectroscopy, cyclic voltammetry (CV) measurements, and thermal analysis. The photophysical properties of the polymer are studied by UV-vis absorption spectroscopy. In addition, spectro-electrochemical measurements are carried out. Time-resolved luminescence lifetime decay curves show an enhanced lifetime of the metal complex attached to the conjugated polymer backbone compared with the Ru(tpy)2 (2+) model complex. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Robust Biomarker

NASA Technical Reports Server (NTRS)

Westall, F.; Steele, A.; Toporski, J.; Walsh, M. M.; Allen, C. C.; Guidry, S.; McKay, D. S.; Gibson, E. K.; Chafetz, H. S.

2000-01-01

Polymers of bacterial origin, either through cell secretion or the degraded product of cell lysis, form isolated mucoidal strands as well as well-developed biofilms on interfaces. Biofilms are structurally and compositionally complex and are readily distinguishable from abiogenic films. These structures range in size from micrometers to decimeters, the latter occurring as the well-known, mineralised biofilms called stromatolites. Compositionally bacterial polymers are greater than 90 % water, with while the majority of the macromolecules forming the framework of the polymers consisting of polysaccharides (with and some nucteic acids and proteins). These macromolecules contain a vaste amount of functional groups, such as carboxyls, hydroxyls, and phosphoryls which are implicated in cation-binding. It is the elevated metal- binding capacity which provides the bacterial polymer with structural support and also helps to preserves it for up to 3.5 b.y. in the terrestrial rock record. The macromolecules, thus, can become rapidly mineralised and trapped in a mineral matrix. Through early and late diagenesis (bacterial degradation, burial, heat, pressure and time) they break down, losing the functional groups and, gradually, their hydrogen atoms. The degraded product is known as "kerogen". With further diagenesis and metamorphism, all the hydrogen atoms are lost and the carbonaceous matter becomes graphite. until the remnant carbonaceous material become graphitised. This last sentence reads a bit as if ALL these macromolecules break down and end up as graphite., but since we find 441 this is not true for all of the macromolecules. We have traced fossilised polymer and biofilms in rocks from throughout Earth's history, to rocks as old as the oldest being 3.5 b.y.-old. Furthermore, Time of Flight Secondary Ion Mass Spectrometry has been able to identify individual macromolecules of bacterial origin, the identities of which are still being investigated, in all the samples containing fossil biofilm, including the 3.5 b.y..-old carbonaceous cherts from South Africa and Australia. As a result of the unique compositional, structural and "mineralisable" properties of bacterial polymer and biofilms, we conclude that bacterial polymers and biofilms constitute a robust and reliable biomarker for life on Earth and could be a potential biomarker for extraterrestrial life.

Chemical synthesis of water-soluble, chiral conducting-polymer complexes

DOEpatents

Wang, Hsing-Lin; McCarthy, Patrick A.; Yang, Sze Cheng

2003-01-01

The template-guided synthesis of water-soluble, chiral conducting polymer complexes is described. Synthesis of water-soluble polyaniline complexes is achieved by carefully controlling the experimental parameters such as; acid concentration, ionic strength, monomer/template ratio, total reagent concentration, and order of reagent addition. Chiral (helical) polyaniline complexes can be synthesized by addition of a chiral inducing agent (chiral acid) prior to polymerization, and the polyaniline helix can be controlled by the addition of the (+) or (-) form of the chiral acid. Moreover the quantity of chiral acid and the salt content has a significant impact on the degree of chirality in the final polymer complexes. The polyaniline and the template have been found to be mixed at the molecular level which results in chiral complexes that are robust through repeated doping and dedoping cycles.

Syntheses, structures and luminescence of three copper(I) cyanide coordination polymers based on trigonal 1,3,5-tris(1H-imidazol-1-yl)benzene ligand

NASA Astrophysics Data System (ADS)

Shao, Min; Li, Ming-Xing; Lu, Li-Ruo; Zhang, Heng-Hua

2016-09-01

Three Cu(I)-cyanide coordination polymers based on trigonal 1,3,5-tris(1H-imidazol-1-yl)benzene (tib) ligand, namely [Cu3(CN)3(tib)]n (1), [Cu4(CN)4(tib)]n (2), and [Cu2(CN)2(tib)]n (3), have been prepared and characterized by elemental analysis, IR, PXRD, thermogravimetry and single-crystal X-ray diffraction analysis. Complex 1 displays a 3D metal-organic framework with nanosized pores. Complex 2 is a 3D coordination polymer assembled by three μ2-cyanides and a μ3-cyanide with a very short Cu(I)···Cu(I) metal bond(2.5206 Å). Complex 3 is a 2D coordination polymer constructing from 1D Cu(I)-cyanide zigzag chain and bidentate tib spacer. Three Cu(I) complexes are thermally stable up to 250-350 °C. Complexes 1-3 show similar orange emission band at 602 nm originating from LMCT mechanism.

Chelate-modified polymers for atmospheric gas chromatography

NASA Technical Reports Server (NTRS)

Christensen, W. W.; Mayer, L. A.; Woeller, F. H. (Inventor)

1980-01-01

Chromatographic materials were developed to serve as the stationary phase of columns used in the separation of atmospheric gases. These materials consist of a crosslinked porous polymer matrix, e.g., a divinylbenzene polymer, into which has been embedded an inorganic complexed ion such as N,N'-ethylene-bis-(acetylacetoniminato)-cobalt (2). Organic nitrogenous bases, such as pyridine, may be incorporated into the chelate polymer complexes to increase their chromatographic utility. With such materials, the process of gas chromatography is greatly simplified, especially in terms of time and quantity of material needed for a gas separation.

Polymers containing nickel(II) complexes of Goedken's macrocycle: optimized synthesis and electrochemical characterization.

PubMed

Paquette, Joseph A; Sauvé, Ethan R; Gilroy, Joe B

2015-04-01

The synthesis and characterization of a new class of nickel-containing polymers is described. The optimized copolymerization of alkyne-bearing nickel(II) complexes of Goedken's macrocycle (4,11-dihydro-5,7,12,14-tetramethyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine) and brominated 9,9-dihexylfluorene produced polymers with potential application as functional redox-active materials. The title polymers exhibit electrochemically reversible, ligand-centered oxidation events at 0.24 and 0.73 V versus the ferrocene/ferrocenium redox couple. They also display exceptional thermal stability and interesting absorption properties due to the presence of the macrocyclic nickel(II) complexes and π-conjugated units incorporated in their backbones. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stable powders made from photosensitive polycrystalline complexes of heterocyclic monomers and their polymers

NASA Technical Reports Server (NTRS)

Murphy, Oliver J. (Inventor); Hitchens, G. Duncan (Inventor); Hodko, Dalibor (Inventor)

1999-01-01

The present invention relates to a low electronic conductivity polymer composition having well dispersed metal granules, a stable powder made from photosensitive polycrystalline complexes of pyrrole, or its substituted derivatives and silver cations for making the polymer composition, and methods of forming the stable powder and polymer composition, respectively. A polycrystalline complex of silver and a monomer, such as pyrrole, its substituted derivatives or combinations thereof, is precipitated in the form of a stable photosensitive powder upon addition of the monomer to a solvent solution, such as toluene containing an electron acceptor. The photosensitive powder can be stored in the dark until needed. The powder may be dissolved in a solvent, cast onto a substrate and photopolymerized.

Innovative NMR strategies for complex macromolecules

USDA-ARS?s Scientific Manuscript database

In recent years there has been an increasing research emphasis on complex macromolecular systems. These include polymers with precise control of structures, multicomponent systems with higher degrees of organization, polymers involved in micelles, interfaces, and confined environments, nanochemistr...

The guanidinium group as a key part of water-soluble polymer carriers for siRNA complexation and protection against degradation.

PubMed

Tabujew, Ilja; Freidel, Christoph; Krieg, Bettina; Helm, Mark; Koynov, Kaloian; Müllen, Klaus; Peneva, Kalina

2014-07-01

Here, the preparation of a novel block copolymer consisting of a statistical copolymer N-(2-hydroxypropyl) methacrylamide-s-N-(3-aminopropyl) methacrylamide and a short terminal 3-guanidinopropyl methacrylamide block is reported. This polymer structure forms neutral but water-soluble nanosized complexes with siRNA. The siRNA block copolymer complexes are first analyzed using agarose gel electrophoresis and their size is determined with fluorescence correlation spectroscopy. The protective properties of the polymer against RNA degradation are investigated by treating the siRNA block copolymer complexes with RNase V1. Heparin competition assays confirm the efficient release of the cargo in vitro. In addition, the utilization of microscale thermophoresis is demonstrated for the determination of the binding strength between a fluorescently labeled polyanion and a polymer molecule. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Active Polymers — Emergent Conformational and Dynamical Properties: A Brief Review

NASA Astrophysics Data System (ADS)

Winkler, Roland G.; Elgeti, Jens; Gompper, Gerhard

2017-10-01

Active matter exhibits a wealth of emerging nonequilibrium behaviours. A paradigmatic example is the interior of cells, where active components, such as the cytoskeleton, are responsible for its structural organization and the dynamics of the various components. Of particular interest are the properties of polymers and filaments. The intimate coupling of thermal and active noise, hydrodynamic interactions, and polymer conformations implies the emergence of novel structural and dynamical features. In this article, we review recent theoretical and simulation developments and results for the structural and dynamical properties of polymers exposed to activity. Two- and three-dimensional filaments are considered propelled by different mechanisms such as active Brownian particles or hydrodynamically-coupled force dipoles.

Morphological control of inter-penetrating polymer networks

NASA Technical Reports Server (NTRS)

Hansen, Marion

1989-01-01

Synthetic organic polymer chemistry has been successful in producing composition of matter with thermal oxidation stability and progressively higher glass transition temperatures. In part, this was done by increasing the steric-hindrance of moieties in the chain of a macromolecule. The resulting polymers are usually quite insoluble and produce molten polymers of very high viscosities. These types of polymers are not easily processed into graphite fiber prepregs by melt or solution impregnation methods. Hence, a technological need exists to produce new knowledge of how to produce polymer-fiber composites from this class of polymers. The concept of freeze drying amic-acid prepolymers with reactive thermoplastic was proposed as a research topic for the ASEE/NASA Summer Faculty Program of 1989 as a means of producing polymer-fiber composites. This process scheme has the thermodynamic attribute that the magnitude of phase separation due to differences in solubility of two organic constituents in solution will be greatly reduced by removing a solvent not by evaporation but by sublimation. Progress to date on evaluating this polymer processing concept is briefly outlined.

Fluorescence turn-on responses of anionic and cationic conjugated polymers toward proteins: effect of electrostatic and hydrophobic interactions.

PubMed

Pu, Kan-Yi; Liu, Bin

2010-03-11

Cationic and anionic poly(fluorenyleneethynylene-alt-benzothiadiazole)s (PFEBTs) are designed and synthesized via Sonagashira coupling reaction to show light-up signatures toward proteins. Due to the charge transfer character of the excited states, the fluorescence of PFEBTs is very weak in aqueous solution, while their yellow fluorescence can be enhanced by polymer aggregation. PFEBTs show fluorescence turn-on rather than fluorescence quenching upon complexation with proteins. Both electrostatic and hydrophobic interactions between PFEBTs and proteins are found to improve the polymer fluorescence, the extent of which is dependent on the nature of the polymer and the protein. Changes in solution pH adjust the net charges of proteins, providing an effective way to manipulate electrostatic interactions and in turn the increment in the polymer fluorescence. In addition, the effect of protein digestion on the fluorescence of polymer/protein complexes is probed. The results indicate that electrostatic interaction induced polymer fluorescence increase cannot be substantially reduced through cleaving protein into peptide fragments. In contrast, hydrophobic interactions, mainly determined by the hydrophobicity of proteins, can be minimized by digestion, imparting a light-off signature for the polymer/protein complexes. This study thus not only highlights the opportunities of exerting nonspecific interactions for protein sensing but also reveals significant implications for biosensor design.

Cationic polymers for DNA origami coating - examining their binding efficiency and tuning the enzymatic reaction rates.

PubMed

Kiviaho, Jenny K; Linko, Veikko; Ora, Ari; Tiainen, Tony; Järvihaavisto, Erika; Mikkilä, Joona; Tenhu, Heikki; Nonappa; Kostiainen, Mauri A

2016-06-02

DNA origamis are fully tailored, programmable, biocompatible and readily functionalizable nanostructures that provide an excellent foundation for the development of sophisticated drug-delivery systems. However, the DNA origami objects suffer from certain drawbacks such as low cell-transfection rates and low stability. A great deal of studies on polymer-based transfection agents, mainly focusing on polyplex formation and toxicity, exists. In this study, the electrostatic binding between a brick-like DNA origami and cationic block-copolymers was explored. The effect of the polymer structure on the binding was investigated and the toxicity of the polymer-origami complexes evaluated. The study shows that all of the analyzed polymers had a suitable binding efficiency irrespective of the block structure. It was also observed that the toxicity of polymer-origami complexes was insignificant at the biologically relevant concentration levels. Besides brick-like DNA origamis, tubular origami carriers equipped with enzymes were also coated with the polymers. By adjusting the amount of cationic polymers that cover the DNA structures, we showed that it is possible to control the enzyme kinetics of the complexes. This work gives a starting point for further development of biocompatible and effective polycation-based block copolymers that can be used in coating different DNA origami nanostructures for various bioapplications.

Polymeric Interventions for Microbial Infections: A Review.

PubMed

Hutnick, Melanie A; Pokorski, Jonathan K

2018-05-22

The world is facing a growing crisis of microbial infections, where resistant strains are rapidly outpacing the development of new therapeutics. In an effort to combat this, the polymer community is developing new ways to improve upon drug delivery, synthesizing novel antimicrobial polymers, and using polymer technology to harness combination therapies. This review focuses primarily on the use of polymers to treat both bacterial and fungal infections in recent years. A bevy of work has illustrated that polymer technologies can have a huge impact in treating bacterial infections. However, harnessing polymers to deliver antifungals or as stand-alone therapeutics lags far behind that of interventions for bacterial infections. Fungal infections can be crippling to both human health and the agricultural community, making this area ripe for drug delivery technologies. This review describes recent work and highlights opportunities for bacterial and fungal treatment using soft matter.

Polymer brushes infiltrated by nanoparticles and applications to the nuclear pore complex

NASA Astrophysics Data System (ADS)

Opferman, Michael G.

Systems of grafted polymers in the presence of additives are useful in a variety of contexts including industrial applications, solar cells, organic electronics, drug delivery, and nucleocytoplasmic transport. In this thesis, we will consider the morphologies that polymer brushes attain when exposed to a solution of additives (which we generically term "nanoparticles"), particularly when those nanparticles interact attractively with the polymers. We find that nanoparticles of this type can have a dramatic effect on the height of the polymer chains above the grafting surface, and they can induce highly non-uniform morphologies, including ones in which a dense layer of nanoparticles and monomers forms near the grafting surface. We consider especially the relevance of the system to several experiments performed on biopolymers in the nuclear pore complex when they interact attractively with transport factors that regulate nucleocytoplasmic transport. We find that, although these experiments appear to give inconsistent results, the inconsistencies can be reconciled through two simple models: the Alexander-de Gennes polymer brush, and the Milner-Witten-Cates polymer brush. Our findings should contribute to the understanding of the nuclear pore complex in that experiments can be better understood in the context of their relevant control parameters.

3D Printing of Biocompatible Supramolecular Polymers and their Composites.

PubMed

Hart, Lewis R; Li, Siwei; Sturgess, Craig; Wildman, Ricky; Jones, Julian R; Hayes, Wayne

2016-02-10

A series of polymers capable of self-assembling into infinite networks via supramolecular interactions have been designed, synthesized, and characterized for use in 3D printing applications. The biocompatible polymers and their composites with silica nanoparticles were successfully utilized to deposit both simple cubic structures, as well as a more complex twisted pyramidal feature. The polymers were found to be not toxic to a chondrogenic cell line, according to ISO 10993-5 and 10993-12 standard tests and the cells attached to the supramolecular polymers as demonstrated by confocal microscopy. Silica nanoparticles were then dispersed within the polymer matrix, yielding a composite material which was optimized for inkjet printing. The hybrid material showed promise in preliminary tests to facilitate the 3D deposition of a more complex structure.

High-rate wastewater treatment combining a moving bed biofilm reactor and enhanced particle separation.

PubMed

Helness, H; Melin, E; Ulgenes, Y; Järvinen, P; Rasmussen, V; Odegaard, H

2005-01-01

Many cities around the world are looking for compact wastewater treatment alternatives since space for treatment plants is becoming scarce. In this paper development of a new compact, high-rate treatment concept with results from experiments in lab-scale and pilot-scale are presented. The idea behind the treatment concept is that coagulation/floc separation may be used to separate suspended and colloidal matter (resulting in > 70% organic matter removal in normal wastewater) while a high-rate biofilm process (based on Moving Bed biofilm reactors) may be used for removing low molecular weight, easily biodegradable, soluble organic matter. By using flotation for floc/biomass separation, the total residence time for a plant according to this concept will normally be < 1 hour. A cationic polymer combined with iron is used as coagulant at low dosages (i.e. 1-2 mg polymer/l, 5-10 mg Fe/l) resulting in low sludge production (compared to conventional chemical treatment) and sufficient P-removal.

Physics of the gut: How polymers dynamically structure the gut environment

NASA Astrophysics Data System (ADS)

Preska Steinberg, Asher; Datta, Sujit; Bogatyrev, Said; Ismagilov, Rustem

While the gut microbiome and biological regulation of the gut environment is being exhaustively studied by the microbiology community, little is known about the rich physics that governs the macro- and microstructure of the gut environment. The mammalian gut abounds in soft materials; ranging from soluble polymers (e.g. dietary fibers, therapeutic polymers and mucins) to colloidal matter (e.g. bacteria, viruses and nanoparticles carrying drugs). We have found experimentally that soluble polymers can dynamically re-structure the colonic mucus hydrogel by modulating its degree of swelling. We implemented a mean-field Flory-Huggins model to reveal that these polymer-mucus interactions can be captured using a simple, first principles thermodynamics model. In this model, the amount of deswelling increases with polymer concentration and size. We then used these physical principles to make predictions about how different polymer solutions affect the structure of mucus. Lastly, we explore applying this framework and similar physical principles to a variety of biological problems in the gut.

Hollow porous ionic liquids composite polymers based solid phase extraction coupled online with high performance liquid chromatography for selective analysis of hydrophilic hydroxybenzoic acids from complex samples.

PubMed

Dai, Xingping; Wang, Dongsheng; Li, Hui; Chen, Yanyi; Gong, Zhicheng; Xiang, Haiyan; Shi, Shuyun; Chen, Xiaoqing

2017-02-10

Polar and hydrophilic properties of hydroxybenzoic acids usually made them coelute with interferences in high performance liquid chromatography (HPLC) analysis. Then selective analysis of them was necessary. Herein, hollow porous ionic liquids composite polymers (PILs) based solid phase extraction (SPE) was firstly fabricated and coupled online with HPLC for selective analysis of hydroxybenzoic acids from complex matrices. Hollow porous PILs were firstly synthesized using Mobil Composition of Matter No. 48 (MCM-48) spheres as sacrificial support, 1-vinyl-3-methylimidazolium chloride (VMIM + Cl - ) as monomer, and ethylene glycol dimethacrylate (EGDMA) as cross-linker. Various parameters affecting synthesis, adsorption and desorption behaviors were investigated and optimized. Steady-state adsorption studies showed the resulting hollow porous PILs exhibited high adsorption capacity, fast adsorption kinetics, and excellent specific adsorption. Subsequently, the application of online SPE system was studied by selective analysis of protocatechuic acid (PCA), 4-hydroxybenzoic acid (4-HBA), and vanillic acid (VA) from Pollen Typha angustifolia. The obtained limit of detection (LOD) varied from 0.002 to 0.01μg/mL, the linear range (0.05-5.0μg/mL) was wide with correlation coefficient (R) from 0.9982 to 0.9994, and the average recoveries at three spiking levels ranged from 82.7 to 102.4%, with column-to-column relative standard deviation (RSD) below 8.1%. The proposed online method showed good accuracy, precision, specificity and convenience, which opened up a universal and efficient route for selective analysis of hydroxybenzoic acids from complex samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthetic biology, inspired by synthetic chemistry.

PubMed

Malinova, V; Nallani, M; Meier, W P; Sinner, E K

2012-07-16

The topic synthetic biology appears still as an 'empty basket to be filled'. However, there is already plenty of claims and visions, as well as convincing research strategies about the theme of synthetic biology. First of all, synthetic biology seems to be about the engineering of biology - about bottom-up and top-down approaches, compromising complexity versus stability of artificial architectures, relevant in biology. Synthetic biology accounts for heterogeneous approaches towards minimal and even artificial life, the engineering of biochemical pathways on the organismic level, the modelling of molecular processes and finally, the combination of synthetic with nature-derived materials and architectural concepts, such as a cellular membrane. Still, synthetic biology is a discipline, which embraces interdisciplinary attempts in order to have a profound, scientific base to enable the re-design of nature and to compose architectures and processes with man-made matter. We like to give an overview about the developments in the field of synthetic biology, regarding polymer-based analogs of cellular membranes and what questions can be answered by applying synthetic polymer science towards the smallest unit in life, namely a cell. Copyright © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

On the computational modeling of the viscosity of colloidal dispersions and its relation with basic molecular interactions

NASA Astrophysics Data System (ADS)

Gama Goicochea, A.; Balderas Altamirano, M. A.; Lopez-Esparza, R.; Waldo-Mendoza, Miguel A.; Perez, E.

2015-09-01

The connection between fundamental interactions acting in molecules in a fluid and macroscopically measured properties, such as the viscosity between colloidal particles coated with polymers, is studied here. The role that hydrodynamic and Brownian forces play in colloidal dispersions is also discussed. It is argued that many-body systems in which all these interactions take place can be accurately solved using computational simulation tools. One of those modern tools is the technique known as dissipative particle dynamics, which incorporates Brownian and hydrodynamic forces, as well as basic conservative interactions. A case study is reported, as an example of the applications of this technique, which consists of the prediction of the viscosity and friction between two opposing parallel surfaces covered with polymer chains, under the influence of a steady flow. This work is intended to serve as an introduction to the subject of colloidal dispersions and computer simulations, for final-year undergraduate students and beginning graduate students who are interested in beginning research in soft matter systems. To that end, a computational code is included that students can use right away to study complex fluids in equilibrium.

Deformed soft matter under constraints

NASA Astrophysics Data System (ADS)

Bertrand, Martin

In the last few decades, an increasing number of physicists specialized in soft matter, including polymers, have turned their attention to biologically relevant materials. The properties of various molecules and fibres, such as DNA, RNA, proteins, and filaments of all sorts, are studied to better understand their behaviours and functions. Self-assembled biological membranes, or lipid bilayers, are also the focus of much attention as many life processes depend on these. Small lipid bilayers vesicles dubbed liposomes are also frequently used in the pharmaceutical and cosmetic industries. In this thesis, work is presented on both the elastic properties of polymers and the response of lipid bilayer vesicles to extrusion in narrow-channels. These two areas of research may seem disconnected but they both concern deformed soft materials. The thesis contains four articles: the first presenting a fundamental study of the entropic elasticity of circular chains; the second, a simple universal description of the effect of sequence on the elasticity of linear polymers such as DNA; the third, a model of the symmetric thermophoretic stretch of a nano-confined polymer; the fourth, a model that predicts the final sizes of vesicles obtained by pressure extrusion. These articles are preceded by an extensive introduction that covers all of the essential concepts and theories necessary to understand the work that has been done.

Self-healing antimicrobial polymer coating with efficacy in the presence of organic matter

NASA Astrophysics Data System (ADS)

Bastarrachea, Luis J.; Goddard, Julie M.

2016-08-01

A method to prepare a self-healing, antimicrobial polymer coating that retains efficacy against Escherichia coli O157:H7 in the presence of organic matter is reported. A coating composed of branched polyethyleneimine (PEI) and styrene maleic anhydride copolymer (SMA) was applied to a maleic anhydride functionalized polypropylene support. The chemistry of the polymer coating was designed to impart hydrophobicity due to the styrene subunits, intrinsic antimicrobial character (>99.9% reduction) from the cationic primary amine groups, and enhanced antimicrobial character (> 99.99% reduction) after chlorination of N-halamine forming groups. Antimicrobial effectiveness was demonstrated under conditions of increasing organic load. Up to 500 ppm horse serum, chlorinated coatings retained full antimicrobial character (>99.99% reduction). Even at 50,000 ppm of horse serum, the coating provided ∼90% reduction as prepared, and between ∼75% and ∼80% reduction in the form of N-halamines. Microscopy confirmed no evidence of bacterial adhesion on the coating surface. Finally, the coating exhibited self-healing properties after exposure to acid and alkaline solutions and restoration by heat, as confirmed through spectroscopy from the rebuilding of characteristic chemical bonds. Such robust antimicrobial polymer coatings with efficacy under conditions of increasing organic load may support reducing microbial cross-contamination in food and biomedical industries.

Recycling WEEE: Polymer characterization and pyrolysis study for waste of crystalline silicon photovoltaic modules.

PubMed

Dias, Pablo; Javimczik, Selene; Benevit, Mariana; Veit, Hugo

2017-02-01

Photovoltaic (PV) modules contain both valuable and hazardous materials, which makes its recycling meaningful economically and environmentally. In general, the recycling of PV modules starts with the removal of the polymeric ethylene-vinyl acetate (EVA) resin using pyrolysis, which assists in the recovery of materials such as silicon, copper and silver. The pyrolysis implementation, however, needs improvement given its importance. In this study, the polymers in the PV modules were characterized by Fourier transform infrared spectroscopy (FTIR) and the removal of the EVA resin using pyrolysis has been studied and optimized. The results revealed that 30min pyrolysis at 500°C removes >99% of the polymers present in photovoltaic modules. Moreover, the behavior of different particle size milled modules during the pyrolysis process was evaluated. It is shown that polymeric materials tend to remain at a larger particle size and thus, this fraction has the greatest mass loss during pyrolysis. A thermo gravimetric analysis (TGA) performed in all polymeric matter revealed the optimum pyrolysis temperature is around 500°C. Temperatures above 500°C continue to degrade matter, but mass loss rate is 6.25 times smaller. This study demonstrates the use of pyrolysis can remove >99% of the polymeric matter from PV modules, which assists the recycling of this hazardous waste and avoids its disposal. Copyright © 2016 Elsevier Ltd. All rights reserved.

Biochemical synthesis of water soluble conducting polymers

NASA Astrophysics Data System (ADS)

Bruno, Ferdinando F.; Bernabei, Manuele

2016-05-01

An efficient biomimetic route for the synthesis of conducting polymers/copolymers complexed with lignin sulfonate and sodium (polystyrenesulfonate) (SPS) will be presented. This polyelectrolyte assisted PEG-hematin or horseradish peroxidase catalyzed polymerization of pyrrole (PYR), 3,4 ethyldioxithiophene (EDOT) and aniline has provided a route to synthesize water-soluble conducting polymers/copolymers under acidic conditions. The UV-vis, FTIR, conductivity and cyclic voltammetry studies for the polymers/copolymer complex indicated the presence of a thermally stable and electroactive polymers. Moreover, the use of water-soluble templates, used as well as dopants, provided a unique combination of properties such as high electronic conductivity, and processability. These polymers/copolymers are nowadays tested/evaluated for antirust features on airplanes and helicopters. However, other electronic applications, such as photovoltaics, for transparent conductive polyaniline, actuators, for polypyrrole, and antistatic films, for polyEDOT, will be proposed.

A Functional Monomer Is Not Enough: Principal Component Analysis of the Influence of Template Complexation in Pre-Polymerization Mixtures on Imprinted Polymer Recognition and Morphology

PubMed Central

Golker, Kerstin; Karlsson, Björn C. G.; Rosengren, Annika M.; Nicholls, Ian A.

2014-01-01

In this report, principal component analysis (PCA) has been used to explore the influence of template complexation in the pre-polymerization phase on template molecularly imprinted polymer (MIP) recognition and polymer morphology. A series of 16 bupivacaine MIPs were studied. The ethylene glycol dimethacrylate (EGDMA)-crosslinked polymers had either methacrylic acid (MAA) or methyl methacrylate (MMA) as the functional monomer, and the stoichiometry between template, functional monomer and crosslinker was varied. The polymers were characterized using radioligand equilibrium binding experiments, gas sorption measurements, swelling studies and data extracted from molecular dynamics (MD) simulations of all-component pre-polymerization mixtures. The molar fraction of the functional monomer in the MAA-polymers contributed to describing both the binding, surface area and pore volume. Interestingly, weak positive correlations between the swelling behavior and the rebinding characteristics of the MAA-MIPs were exposed. Polymers prepared with MMA as a functional monomer and a polymer prepared with only EGDMA were found to share the same characteristics, such as poor rebinding capacities, as well as similar surface area and pore volume, independent of the molar fraction MMA used in synthesis. The use of PCA for interpreting relationships between MD-derived descriptions of events in the pre-polymerization mixture, recognition properties and morphologies of the corresponding polymers illustrates the potential of PCA as a tool for better understanding these complex materials and for their rational design. PMID:25391043

A functional monomer is not enough: principal component analysis of the influence of template complexation in pre-polymerization mixtures on imprinted polymer recognition and morphology.

PubMed

Golker, Kerstin; Karlsson, Björn C G; Rosengren, Annika M; Nicholls, Ian A

2014-11-10

In this report, principal component analysis (PCA) has been used to explore the influence of template complexation in the pre-polymerization phase on template molecularly imprinted polymer (MIP) recognition and polymer morphology. A series of 16 bupivacaine MIPs were studied. The ethylene glycol dimethacrylate (EGDMA)-crosslinked polymers had either methacrylic acid (MAA) or methyl methacrylate (MMA) as the functional monomer, and the stoichiometry between template, functional monomer and crosslinker was varied. The polymers were characterized using radioligand equilibrium binding experiments, gas sorption measurements, swelling studies and data extracted from molecular dynamics (MD) simulations of all-component pre-polymerization mixtures. The molar fraction of the functional monomer in the MAA-polymers contributed to describing both the binding, surface area and pore volume. Interestingly, weak positive correlations between the swelling behavior and the rebinding characteristics of the MAA-MIPs were exposed. Polymers prepared with MMA as a functional monomer and a polymer prepared with only EGDMA were found to share the same characteristics, such as poor rebinding capacities, as well as similar surface area and pore volume, independent of the molar fraction MMA used in synthesis. The use of PCA for interpreting relationships between MD-derived descriptions of events in the pre-polymerization mixture, recognition properties and morphologies of the corresponding polymers illustrates the potential of PCA as a tool for better understanding these complex materials and for their rational design.

Developments in the use of rare earth metal complexes as efficient catalysts for ring-opening polymerization of cyclic esters used in biomedical applications

NASA Astrophysics Data System (ADS)

Cota, Iuliana

2017-04-01

Biodegradable polymers represent a class of particularly useful materials for many biomedical and pharmaceutical applications. Among these types of polyesters, poly(ɛ-caprolactone) and polylactides are considered very promising for controlled drug delivery devices. These polymers are mainly produced by ring-opening polymerization of their respective cyclic esters, since this method allows a strict control of the molecular parameters (molecular weight and distribution) of the obtained polymers. The most widely used catalysts for ring-opening polymerization of cyclic esters are tin- and aluminium-based organometallic complexes; however since the contamination of the aliphatic polyesters by potentially toxic metallic residues is particularly of concern for biomedical applications, the possibility of replacing organometallic initiators by novel less toxic or more efficient organometallic complexes has been intensively studied. Thus, in the recent years, the use of highly reactive rare earth initiators/catalysts leading to lower polymer contamination has been developed. The use of rare earth complexes is considered a valuable strategy to decrease the polyester contamination by metallic residues and represents an attractive alternative to traditional organometallic complexes.

Topological analysis of long-chain branching patterns in polyolefins.

PubMed

Bonchev, D; Markel, E; Dekmezian, A

2001-01-01

Patterns in molecular topology and complexity for long-chain branching are quantitatively described. The Wiener number, the topological complexity index, and a new index of 3-starness are used to quantify polymer structure. General formulas for these indices were derived for the cases of 3-arm star, H-shaped, and B-arm comb polymers. The factors affecting complexity in monodisperse polymer systems are ranked as follows: number of arms > arm length > arm central position approximately equal to arm clustering > total molecular weight approximately equal to backbone molecular weight. Topological indices change rapidly and then plateau as the molecular weight of branches on a polyolefin backbone increases from 0 to 5 kD. Complexity calculations relate 2-arm or 3-arm comb structures to the corresponding 3-arm stars of equivalent complexity but much higher molecular weight. In a subsequent paper, we report the application of topological analysis for developing structure/property relationships for monodisperse polymers. While the focus of the present work is on the description of monodisperse, well-defined architectures, the methods may be extended to the description of polydisperse systems.

Polymer-Supported Optically Active fac(S)-Tris(thiotato)rhodium(III) Complex for Sulfur-Bridging Reaction With Precious Metal Ions.

PubMed

Aizawa, Sen-Ichi; Tsubosaka, Soshi

2016-01-01

The optically active mixed-ligand fac(S)-tris(thiolato)rhodium(III) complexes, ΔL -fac(S)-[Rh(aet)2 (L-cys-N,S)](-) (aet = 2-aminoethanethiolate, L-cys = L-cysteinate) () and ΔLL -fac(S)-[Rh(aet)(L-cys-N,S)2 ](2-) were newly prepared by the equatorial preference of the carboxyl group in the coordinated L-cys ligand. The amide formation reaction of with 1,10-diaminodecane and polyallylamine gave the diamine-bridged dinuclear Rh(III) complex and the single-chain polymer-supported Rh(III) complex with retention of the ΔL configuration of , respectively. These Rh(III) complexes reacted with Co(III) or Co(II) to give the linear-type trinuclear structure with the S-bridged Co(III) center and the two Δ-Rh(III) terminal moieties. The polymer-supported Rh(III) complex was applied not only to the CD spectropolarimetric detection and determination of a trace of precious metal ions such as Au(III), Pt(II), and Pd(II) but also to concentration and extraction of these metal ions into the solid polymer phase. Chirality 28:85-91, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Strategies for the Conversion of Lignin to High-Value Polymeric Materials: Review and Perspective.

PubMed

Upton, Brianna M; Kasko, Andrea M

2016-02-24

The majority of commodity plastics and materials are derived from petroleum-based chemicals, illustrating the strong dependence on products derived from non-renewable energy sources. As the most accessible, renewable form of carbon (in comparison to CO2), lignocellulosic biomass (defined as organic matter available on a renewable basis) has been acknowledged as the most logical carbon-based feedstock for a variety of materials such as biofuels and chemicals. This Review focuses on methods developed to synthesize polymers derived from lignin, monolignols, and lignin-derived chemicals. Major topics include the structure and processing of lignocellulosic biomass to lignin, polymers utilizing lignin as a macromonomer, synthesis of monomers and polymers from monolignols, and polymers from lignin-derived chemicals, such as vanillin.

Clustering effects in ionic polymers: Molecular dynamics simulations.

PubMed

Agrawal, Anupriya; Perahia, Dvora; Grest, Gary S

2015-08-01

Ionic clusters control the structure, dynamics, and transport in soft matter. Incorporating a small fraction of ionizable groups in polymers substantially reduces the mobility of the macromolecules in melts. These ionic groups often associate into random clusters in melts, where the distribution and morphology of the clusters impact the transport in these materials. Here, using molecular dynamic simulations we demonstrate a clear correlation between cluster size and morphology with the polymer mobility in melts of sulfonated polystyrene. We show that in low dielectric media ladderlike clusters that are lower in energy compared with spherical assemblies are formed. Reducing the electrostatic interactions by enhancing the dielectric constant leads to morphological transformation from ladderlike clusters to globular assemblies. Decrease in electrostatic interaction significantly enhances the mobility of the polymer.

Characterisation of the biodegradability of post-treated digestates via the chemical accessibility and complexity of organic matter.

PubMed

Maynaud, Géraldine; Druilhe, Céline; Daumoin, Mylène; Jimenez, Julie; Patureau, Dominique; Torrijos, Michel; Pourcher, Anne-Marie; Wéry, Nathalie

2017-05-01

The stability of digestate organic matter is a key parameter for its use in agriculture. Here, the organic matter stability was compared between 14 post-treated digestates and the relationship between organic matter complexity and biodegradability was highlighted. Respirometric activity and CH 4 yields in batch tests showed a positive linear correlation between both types of biodegradability (R 2 =0.8). The accessibility and complexity of organic matter were assessed using chemical extractions combined with fluorescence spectroscopy, and biodegradability was mostly anti-correlated with complexity of organic matter. Post-treatments presented a significant effect on the biodegradability and complexity of organic matter. Biodegradability was low for composted digestates which comprised slowly accessible complex molecules. Inversely, solid fractions obtained after phase separation contained a substantial part of remaining biodegradable organic matter with a significant easily accessible fraction comprising simpler molecules. Understanding the effect of post-treatment on the biodegradability of digestates should help to optimize their valorization. Copyright © 2017 Elsevier Ltd. All rights reserved.

High-aluminum-affinity silica is a nanoparticle that seeds secondary aluminosilicate formation.

PubMed

Jugdaohsingh, Ravin; Brown, Andy; Dietzel, Martin; Powell, Jonathan J

2013-01-01

Despite the importance and abundance of aluminosilicates throughout our natural surroundings, their formation at neutral pH is, surprisingly, a matter of considerable debate. From our experiments in dilute aluminum and silica containing solutions (pH ~ 7) we previously identified a silica polymer with an extraordinarily high affinity for aluminium ions (high-aluminum-affinity silica polymer, HSP). Here, further characterization shows that HSP is a colloid of approximately 2.4 nm in diameter with a mean specific surface area of about 1,000 m(2) g(-1) and it competes effectively with transferrin for Al(III) binding. Aluminum binding to HSP strongly inhibited its decomposition whilst the reaction rate constant for the formation of the β-silicomolybdic acid complex indicated a diameter between 3.6 and 4.1 nm for these aluminum-containing nanoparticles. Similarly, high resolution microscopic analysis of the air dried aluminum-containing silica colloid solution revealed 3.9 ± 1.3 nm sized crystalline Al-rich silica nanoparticles (ASP) with an estimated Al:Si ratio of between 2 and 3 which is close to the range of secondary aluminosilicates such as imogolite. Thus the high-aluminum-affinity silica polymer is a nanoparticle that seeds early aluminosilicate formation through highly competitive binding of Al(III) ions. In niche environments, especially in vivo, this may serve as an alternative mechanism to polyhydroxy Al(III) species binding monomeric silica to form early phase, non-toxic aluminosilicates.

High-Aluminum-Affinity Silica Is a Nanoparticle That Seeds Secondary Aluminosilicate Formation

PubMed Central

Jugdaohsingh, Ravin; Brown, Andy; Dietzel, Martin; Powell, Jonathan J.

2013-01-01

Despite the importance and abundance of aluminosilicates throughout our natural surroundings, their formation at neutral pH is, surprisingly, a matter of considerable debate. From our experiments in dilute aluminum and silica containing solutions (pH ~ 7) we previously identified a silica polymer with an extraordinarily high affinity for aluminium ions (high-aluminum-affinity silica polymer, HSP). Here, further characterization shows that HSP is a colloid of approximately 2.4 nm in diameter with a mean specific surface area of about 1,000 m2 g-1 and it competes effectively with transferrin for Al(III) binding. Aluminum binding to HSP strongly inhibited its decomposition whilst the reaction rate constant for the formation of the β-silicomolybdic acid complex indicated a diameter between 3.6 and 4.1 nm for these aluminum-containing nanoparticles. Similarly, high resolution microscopic analysis of the air dried aluminum-containing silica colloid solution revealed 3.9 ± 1.3 nm sized crystalline Al-rich silica nanoparticles (ASP) with an estimated Al:Si ratio of between 2 and 3 which is close to the range of secondary aluminosilicates such as imogolite. Thus the high-aluminum-affinity silica polymer is a nanoparticle that seeds early aluminosilicate formation through highly competitive binding of Al(III) ions. In niche environments, especially in vivo, this may serve as an alternative mechanism to polyhydroxy Al(III) species binding monomeric silica to form early phase, non-toxic aluminosilicates. PMID:24349573

Synthesis and Characterization of Electroresponsive Materials with Applications In: Part I. Second Harmonic Generation. Part II. Organic-Lanthanide Ion Complexes for Electroluminescence and Optical Amplifiers.

NASA Astrophysics Data System (ADS)

Claude, Charles

1995-01-01

Materials for optical waveguides were developed from two different approaches, inorganic-organic composites and soft gel polymers. Inorganic-organic composites were developed from alkoxysilane and organically modified silanes based on nonlinear optical chromophores. Organically modified silanes based on N-((3^' -trialkoxysilyl)propyl)-4-nitroaniline were synthesized and sol-gelled with trimethoxysilane. After a densification process at 190^circC with a corona discharge, the second harmonic of the film was measured with a Nd:YAG laser with a fundamental wavelength of 1064nm, d_{33} = 13pm/V. The decay of the second harmonic was expressed by a stretched bi-exponential equation. The decay time (tau _2) was equal to 3374 hours, and was comparable to nonlinear optical systems based on epoxy/Disperse Orange 1. The processing temperature of the organically modified silane was limited to 200^circC due to the decomposition of the organic chromophore. Soft gel polymers were synthesized and characterized for the development of optical waveguides with dc-electrical field assisted phase-matching. Polymers based on 4-nitroaniline terminated poly(ethylene oxide-co-propylene oxide) were shown to exhibit second harmonic generation that were optically phase-matched in an electrical field. The optical signals were stable and reproducible. Siloxane polymers modified with 1-mercapto-4-nitrobenzene and 1-mercapto-4-methylsulfonylstilbene nonlinear optical chromophores were synthesized. The physical and the linear and nonlinear optical properties of the polymers were characterized. Waveguides were developed from the polymers which were optically phase -matched and had an efficiency of 8.1%. The siloxane polymers exhibited optical phase-matching in an applied electrical field and can be used with a semiconductor laser. Organic lanthanide ion complexes for electroluminescence and optical amplifiers were synthesized and characterized. The complexes were characterized for their thermal and oxidative stability and for their optical properties. Organic-europium ion complexes based on derivatives of 2-benzoyl benzoate are stable to a temperature 70^circ C higher than the europium beta -diketonate complexes. The optical and fluorescence properties of the organic-europium ion complexes were characterized. The methoxy and the t-butyl derivatives of the europium 2-benzoylbenzoate complexes exhibited fluorescence quantum efficiencies that were comparable to europium tris(thenoyl trifluoroacetonate) in methylene chloride but the extinction coefficient was two-thirds of the europium thenoyltrifluoroacetonate complexes. The last complex characterized was the europium bis(diphenylphosphino)imine complex. The complex exhibited thermal stability to 550 ^circC under nitrogen.

Photovoltaic effect in organic polymer-iodine complex

NASA Technical Reports Server (NTRS)

Hermann, A. M.; Rembaum, A.

1967-01-01

Certain charge transfer complexes formed from organic polymers and iodine generate appreciable voltages at relatively low impedances upon exposure to light. These films show promise in applications requiring chemically and electrically stable films as detectors of optical radiation and as energy converters in photovoltaic cells.

Coarse-grained simulation of polymer-filler blends

NASA Astrophysics Data System (ADS)

Legters, Gregg; Kuppa, Vikram; Beaucage, Gregory; Univ of Dayton Collaboration; Univ of Cincinnati Collaboration

The practical use of polymers often relies on additives that improve the property of the mixture. Examples of such complex blends include tires, pigments, blowing agents and other reactive additives in thermoplastics, and recycled polymers. Such systems usually exhibit a complex partitioning of the components. Most prior work has either focused on fine-grained details such as molecular modeling of chains at interfaces, or on coarse, heuristic, trial-and-error approaches to compounding (eg: tire industry). Thus, there is a significant gap in our understanding of how complex hierarchical structure (across several decades in length) develops in these multicomponent systems. This research employs dissipative particle thermodynamics in conjunction with a pseudo-thermodynamic parameter derived from scattering experiments to represent polymer-filler interactions. DPD simulations will probe how filler dispersion and hierarchical morphology develops in these complex blends, and are validated against experimental (scattering) data. The outcome of our approach is a practical solution to compounding issues, based on a mutually validating experimental and simulation methodology. Support from the NSF (CMMI-1636036/1635865) is gratefully acknowledged.

Spectroscopic Evidence of Anthropogenic Compounds Extraction from Polymers by Fluorescent Dissolved Organic Matter in Natural Water

NASA Astrophysics Data System (ADS)

Miranda, M.; Trojzuck, A.; Voss, D.; Gassmann, S.; Zielinski, O.

2016-04-01

FDOM is one of the most important carriers of anthropogenic compounds in natural waters. It can combine with environmental contaminants and polymers to form diverse chemical structures. To this end, here a microfluidic chip was designed for the analysis of these changes in fluorescent dissolved organic matter (FDOM) fingerprints due to thermal treatment and varying time intervals of exposure. Excitation Emission Matrix Spectroscopy (EEMS) approach was utilized to detect and identify the inherent compounds in sampled FDOM. Strong direct correlations were founded, Spearman rank correlation values (ρ = 0.85 at α = 0.1, n = 4) and linear correlation R2 = 0.8359 were noted between thermal treatment pattern 2 and fluorescence intensity of samples. Materials, acrylic based glue and cyclic olefin copolymer (COC) polymer, used to design the microfluidic sensor were determined to possess unique spectral features in the ultraviolet to green spectrum using EEMS. The study therefore provides an insight on methods to identify contaminants in natural waters. This underlines the potential of optical sensors providing measurements at fast intervals, enabling environmental monitoring.

Biogeochemical Processes That Produce Dissolved Organic Matter From Wheat Straw

USGS Publications Warehouse

Wershaw, Robert L.; Rutherford, David W.; Leenheer, Jerry A.; Kennedy, Kay R.; Cox, Larry G.; Koci, Donald R.

2003-01-01

The chemical reactions that lead to the formation of dissolved organic matter (DOM) in natural waters are poorly understood. Studies on the formation of DOM generally are complicated because almost all DOM isolates have been derived from mixtures of plant species composed of a wide variety of different types of precursor compounds for DOM formation. This report describes a study of DOM derived mainly from bales of wheat straw that had been left in a field for several years. During this period of time, black water from the decomposing wheat straw accumulated in pools in the field. The nuclear magnetic resonance and infrared spectra of the black water DOM indicate that it is composed almost entirely of lignin and carbohydrate polymeric units. Analysis by high-performance size-exclusion chromatography with multi-angle laser-light scattering detection indicates that the number average molecular weight of the DOM is 124,000 daltons. The results presented in this report indicate that the black water DOM is composed of hemicellulose chains cross-linked to lignin oligomers. These types of structures have been shown to exist in the hemicellulose matrix of plant cell walls. The cross-linked lignin-hemicellulose complexes apparently were released from partially degraded wheat-straw cell walls with little alteration. In solution in the black water, these lignin-hemicellulose polymers fold into compact globular particles in which the nonpolar parts of the polymer form the interiors of the particles and the polar groups are on the exterior surfaces of the particles. The tightly folded, compact conformation of these particles probably renders them relatively resistant to microbial degradation. This should be especially the case for the aromatic lignin structures that will be buried in the interiors of the particles.

Effect of blending and nanoparticles on the ionic conductivity of solid polymer electrolyte systems

NASA Astrophysics Data System (ADS)

Manjunatha, H.; Damle, R.; Kumaraswamy, G. N.

2018-05-01

In the present work, a polymer electrolyte blend containing polymers Poly ethylene oxide (PEO) and Poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) was prepared. The polymer blend was complexed with potassium trifluoromethanesulfonate (KCF3SO3), and titanium oxide nanoparticles (TiO2) (10nm size) were dispersed in to the complex at different weight percentages. The conductivity due to ions in the blend is determined by Ac impedance measurements in the frequency range of 10Hz-1MHz. The nano composite polymer blend containing 5wt% of TiO2 shows a conductivity of 7.95×10-5Scm-1, which is almost 1.5 orders more than polymer electrolyte with PEO as a polymer. XRD studies show a decrease in the coherence length of XRD peaks on addition of nanoparticles, which is due to increase the amorphous phase in the systems. Temperature dependence conductivity studies of the systems shows that, activation energy decreases with increase in the percentage of nanoparticles in the blend.

Synthesis, characterization and anti-microbial activity of phenylurea-formaldehyde resin (PUF) and its polymer metal complexes (PUF-Mn(II)

NASA Astrophysics Data System (ADS)

Ahamad, Tansir; Alshehri, Saad M.

2012-10-01

Phenylurea-formaldehyde polymer (PUF) was synthesized via polycondensation of phenylurea and formaldehyde in basic medium, its polymer-metal complexes [PUF-M(II)] were prepared with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) ions. PUF and PUF-M(II) were characterized with magnetic moment measurements, elemental and spectral (UV-visible, FTIR, 1H-NMR, 13C-NMR and ESR) analysis. The thermal behaviors of all the synthesized polymers were carried out using thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The thermal data revealed that all of the PUF-M(II) showed higher thermal stabilities than the PUF and also ascribed that the PUF-Cu(II) showed better thermal stability than the other PUF-M(II). The kinetic parameters such as activation energy, pre-exponential factor etc., were evaluated for these polymer metal complexes using Coats-Redfern equation. In addition, the antimicrobial activity of the synthesized polymers was tested against several microorganisms using agar well diffusion methods. Among all of the PUF-M(II), the antimicrobial activity of the PUF-Cu(II) showed the highest zone of inhibition because of its higher stability constant and may be used in biomedical applications.

Control of hierarchical polymer mechanics with bioinspired metal-coordination dynamics

PubMed Central

Grindy, Scott C.; Learsch, Robert; Mozhdehi, Davoud; Cheng, Jing; Barrett, Devin G.; Guan, Zhibin; Messersmith, Phillip B.; Holten-Andersen, Niels

2015-01-01

In conventional polymer materials, mechanical performance is traditionally engineered via material structure, using motifs such as polymer molecular weight, polymer branching, or copolymer-block design1. Here, by means of a model system of 4-arm poly(ethylene glycol) hydrogels crosslinked with multiple, kinetically distinct dynamic metal-ligand coordinate complexes, we show that polymer materials with decoupled spatial structure and mechanical performance can be designed. By tuning the relative concentration of two types of metal-ligand crosslinks, we demonstrate control over the material’s mechanical hierarchy of energy-dissipating modes under dynamic mechanical loading, and therefore the ability to engineer a priori the viscoelastic properties of these materials by controlling the types of crosslinks rather than by modifying the polymer itself. This strategy to decouple material mechanics from structure may inform the design of soft materials for use in complex mechanical environments. PMID:26322715

Influence of carbon nanotubes on the optical properties of plasticized solid polymer electrolytes

NASA Astrophysics Data System (ADS)

Ibrahim, Suriani; Yasin, Siti Mariah Mohd; Johan, Mohd Rafie

2013-07-01

Polyethylene oxide (PEO) based solid polymer electrolyte films complexed with lithium hexafluorophosphate (LiPF6), ethylene carbonate (EC) and carbon nanotubes (CNTs) are prepared by solution-casting technique. The complexation of doping materials with polymer is confirmed by X-ray diffraction and infrared studies. The incorporation of LiPF6, EC and CNTs into the host polymer shows a significant increase in conductivity of 10-10 and 10-3 S cm-1. The optical properties such as direct and indirect band gaps are investigated for pure and doped polymer films within a wavelength range of 200-400 nm. It is found that the energy gaps and band edge values shift towards lower energies upon doping. It is shown that LiPF6, EC and CNTs are responsible for the formation of defects in polymer electrolytes, which increases the degree of disorder in the films.

Biochemical synthesis of water soluble conducting polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruno, Ferdinando F., E-mail: Ferdinando-Bruno@uml.edu; Bernabei, Manuele

2016-05-18

An efficient biomimetic route for the synthesis of conducting polymers/copolymers complexed with lignin sulfonate and sodium (polystyrenesulfonate) (SPS) will be presented. This polyelectrolyte assisted PEG-hematin or horseradish peroxidase catalyzed polymerization of pyrrole (PYR), 3,4 ethyldioxithiophene (EDOT) and aniline has provided a route to synthesize water-soluble conducting polymers/copolymers under acidic conditions. The UV-vis, FTIR, conductivity and cyclic voltammetry studies for the polymers/copolymer complex indicated the presence of a thermally stable and electroactive polymers. Moreover, the use of water-soluble templates, used as well as dopants, provided a unique combination of properties such as high electronic conductivity, and processability. These polymers/copolymers are nowadaysmore » tested/evaluated for antirust features on airplanes and helicopters. However, other electronic applications, such as photovoltaics, for transparent conductive polyaniline, actuators, for polypyrrole, and antistatic films, for polyEDOT, will be proposed.« less

Organic Chemistry in Two Dimensions: Surface-Functionalized Polymers and Self-Assembled Monolayer Films

DTIC Science & Technology

1988-09-01

surfaces as components of materials . In particular, we hope to develop the ability to rationalize and predict the macroscooic properties of surfaces...of much of the current research in areas such as materials science, condensed matter and device physics, and polymer physical chemistry. Surface...6 Underlying our program in surface chemistry is a broad interest in the prop- erties of organic surfaces as components of materials . In particular

Effective delivery of siRNA into cancer cells and tumors using well-defined biodegradable cationic star polymers.

PubMed

Boyer, Cyrille; Teo, Joann; Phillips, Phoebe; Erlich, Rafael B; Sagnella, Sharon; Sharbeen, George; Dwarte, Tanya; Duong, Hien T T; Goldstein, David; Davis, Thomas P; Kavallaris, Maria; McCarroll, Joshua

2013-06-03

Cancer is one of the most common causes of death worldwide. Two types of cancer that have high mortality rates are pancreatic and lung cancer. Despite improvements in treatment strategies, resistance to chemotherapy and the presence of metastases are common. Therefore, novel therapies which target and silence genes involved in regulating these processes are required. Short-interfering RNA (siRNA) holds great promise as a therapeutic to silence disease-causing genes. However, siRNA requires a delivery vehicle to enter the cell to allow it to silence its target gene. Herein, we report on the design and synthesis of cationic star polymers as novel delivery vehicles for siRNA to silence genes in pancreatic and lung cancer cells. Dimethylaminoethyl methacrylate (DMAEMA) was polymerized via reversible addition-fragmentation transfer polymerization (RAFT) and then chain extended in the presence of both cross-linkers N,N-bis(acryloyl)cistamine and DMAEMA, yielding biodegradable well-defined star polymers. The star polymers were characterized by transmission electron microscopy, dynamic light scattering, ζ potential, and gel permeation chromatography. Importantly, the star polymers were able to self-assemble with siRNA and form small uniform nanoparticle complexes. Moreover, the ratios of star polymer required to complex siRNA were nontoxic in both pancreatic and lung cancer cells. Treatment with star polymer-siRNA complexes resulted in uptake of siRNA into both cell lines and a significant decrease in target gene mRNA and protein levels. In addition, delivery of clinically relevant amounts of siRNA complexed to the star polymer were able to silence target gene expression by 50% in an in vivo tumor setting. Collectively, these results provide the first evidence of well-defined small cationic star polymers to deliver active siRNA to both pancreatic and lung cancer cells and may be a valuable tool to inhibit key genes involved in promoting chemotherapy drug resistance and metastases.

Physics through the 1990s: Condensed-matter physics

NASA Technical Reports Server (NTRS)

1986-01-01

The volume presents the current status of condensed-matter physics from developments since the 1970s to opportunities in the 1990s. Topics include electronic structure, vibrational properties, critical phenomena and phase transitions, magnetism, semiconductors, defects and diffusion, surfaces and interfaces, low-temperature physics, liquid-state physics, polymers, nonlinear dynamics, instabilities, and chaos. Appendices cover the connections between condensed-matter physics and applications of national interest, new experimental techniques and materials, laser spectroscopy, and national facilities for condensed-matter physics research. The needs of the research community regarding support for individual researchers and for national facilities are presented, as are recommendations for improved government-academic-industrial relations.

Molecular building blocks and their architecture in biologically/environmentally compatible soft matter chemical machinery.

PubMed

Toyota, Taro; Banno, Taisuke; Nitta, Sachiko; Takinoue, Masahiro; Nomoto, Tomonori; Natsume, Yuno; Matsumura, Shuichi; Fujinami, Masanori

2014-01-01

This review briefly summarizes recent developments in the construction of biologically/environmentally compatible chemical machinery composed of soft matter. Since environmental and living systems are open systems, chemical machinery must continuously fulfill its functions not only through the influx and generation of molecules but also via the degradation and dissipation of molecules. If the degradation or dissipation of soft matter molecular building blocks and biomaterial molecules/polymers can be achieved, soft matter particles composed of them can be used to realize chemical machinery such as selfpropelled droplets, drug delivery carriers, tissue regeneration scaffolds, protocell models, cell-/tissuemarkers, and molecular computing systems.

Origin of organic matter in the early solar system. VII - The organic polymer in carbonaceous chondrites

NASA Technical Reports Server (NTRS)

Hayatsu, R.; Matsuoka, S.; Anders, E.; Scott, R. G.; Studier, M. H.

1977-01-01

Degradation techniques, including pyrolysis, depolymerization, and oxidation, were used to study the insoluble polymer from the Murchison C2 chondrite. Oxidation with Cr2O7(2-) or O2/UV led to the identification of 15 aromatic ring systems. Of 11 aliphatic acids identified, three dicarboxylic acids presumably came from hydroaromatic portions of the polymer, whereas eight monocarboxylic acids probably derive from bridging groups or ring substituents. Depolymerization with CF3COO4 yielded some of the same ring systems, as well as alkanes (C1 through C8) and alkenes (C2 through C8), alkyl (C1 through C5) benzenes and naphthalenes, and methyl- or dimethyl -indene, -indane, -phenol, -pyrrole, and -pyridine. All these compounds were detected below 200 C, and are therefore probably indigenous constituents. The properties of the meteoritic polymer were compared with the properties of a synthetic polymer produced by the Fischer-Tropsch reaction. It is suggested that the meteoritic polymer was also produced by surface catalysis.

Proposed uses of laser light scattering instruments for polymerization studies

NASA Technical Reports Server (NTRS)

Mathias, Lon J.; Hoyle, Charles E.; Mclaughlin, Kevin; Mcmanus, Samuel P.; Caruthers, James M.; Runge, Michael L.

1989-01-01

Microgravity offers a unique environment for studying polymer diffusion and polymer polymerization reactions. The absence of convection currents, which are the major mode of mixing at the molecular level on Earth, are eliminated or reduced in the microgravity environment. More importantly, the prediction of unique copolymer composition development in microgravity allows controlled formation of new compositions of matter. The absence of mixing at the molecular level should produce unique short block copolymers available for the first time for comonomer compositions which normally lead to random or long block copolymer under good mixing. The investigation of fundamental polymer diffusion and polymer polymerization processes in microgravity is proposed. This effort will involve fundamental studies of monomer and polymer diffusion; their effects on initiation, propagation, and especially termination kinetics rate constant; and the accurate evaluation of copolymerization reactivity ratios in microgravity. The experimental design is presented for these studies along with an evaluation technique for in situ monitoring of polymer diffusion and polymerization kinetics.

Analysis of polymer/oxide interfaces under ambient conditions - An experimental perspective

NASA Astrophysics Data System (ADS)

González-Orive, A.; Giner, I.; de los Arcos, T.; Keller, A.; Grundmeier, G.

2018-06-01

In many different hybrid materials and materials composites polymers adhere to bulk oxides or oxide covered metal. The formed polymer/oxide interfaces are of crucial importance for the functionality and durability of such complex materials. Especially, under humid and corrosive conditions such interfaces tend to degrade due to permeability of polymers for water, the high adsorption energy of water on oxide surfaces and even corrosion processes of the metal. Different experimental studies considered such interfaces ranging from spectroscopy to electrochemical analysis. However, it is still a challenge to understand the complex interaction especially under non-ideal ambient conditions. The perspective article presents an overview on the existing experimental approaches and considers most recent experimental developments with regard to their potential applications in the area of polymer/oxide interfaces in the future.

In situ preparation of powder and the sorption behaviors of molecularly imprinted polymers through the complexation between polymer ion of methyl methacrylate/acrylic acid and Ca++ ion.

PubMed

Chough, Sung Hyo; Park, Kwang Ho; Cho, Seung Jin; Park, Hye Ryoung

2014-09-02

Molecularly imprinted polymer (MIP) powders were prepared using a simple complexation strategy between the polymer carboxylate groups and template molecule followed by metal cation cross-linking of residual polymer carboxylates. Polymer powders were formed in situ by templating carboxylic acid containing polymers with 4-ethylaniline (4-EA), followed by addition of an aqueous CaCl2 solution. The solution remained homogeneous. The powders were prepared by precipitation by slowly adding a non-solvent, H2O, to the mixture. The resulting particles were very porous with uptake capacity that approached the theoretical value. We suggest two types of complexes are formed between the template, 4-EA, and polymer. The isolated entry type forms well defined cavities for the template with high specific selectivity, while the adjacent entry type forms wider binding sites without specific sorption for isomeric molecules. To evaluate conditions for forming materials with high affinity and selectivity, three MIPs were prepared containing 0.5, 1.0, and 1.5 equivalents of template to the base polymer. The MIP containing 0.5 eq showed higher specific selectivity to 4-EA, but the MIP containing 1.5 eq had noticeably lower selectivity. The lower selectivity is attributed to poorly formed binding sites with little selective sorption to any isomer when the higher ratio of template was used. However at the lower ratio of template the isolated entry is preferably formed to produce well defined binding cavities with higher selectivity to template. Copyright © 2014 Elsevier B.V. All rights reserved.

Intracellular trafficking pathways for nuclear delivery of plasmid DNA complexed with highly efficient endosome escape polymers.

PubMed

Gillard, Marianne; Jia, Zhongfan; Hou, Jeff Jia Cheng; Song, Michael; Gray, Peter P; Munro, Trent P; Monteiro, Michael J

2014-10-13

Understanding the pathways for nuclear entry could see vast improvements in polymer design for the delivery of genetic materials to cells. Here, we use a novel diblock copolymer complexed with plasmid DNA (pDNA) to determine both its cellular entry and nuclear pathways. The diblock copolymer (A-C3) is specifically designed to bind and protect pDNA, release it at a specific time, but more importantly, rapidly escape the endosome. The copolymer was taken up by HEK293 cells preferentially via the clathrin-mediated endocytosis (CME) pathway, and the pDNA entered the nucleus to produce high gene expression levels in all cells after 48 h, a similar observation to the commercially available polymer transfection agent, PEI Max. This demonstrates that the polymers must first escape the endosome and then mediate transport of pDNA to the nucleus for occurrence of gene expression. The amount of pDNA within the nucleus was found to be higher for our A-C3 polymer than PEI Max, with our polymer delivering 7 times more pDNA than PEI Max after 24 h. We further found that entry into the nucleus was primarily through the small nuclear pores and did not occur during mitosis when the nuclear envelope becomes compromised. The observation that the polymers are also found in the nucleus supports the hypothesis that the large pDNA/polymer complex (size ~200 nm) must dissociate prior to nucleus entry and that cationic and hydrophobic monomer units on the polymer may facilitate active transport of the pDNA through the nuclear pore.

The removal of mercury from dental-operatory wastewater by polymer treatment.

PubMed Central

Pederson, E D; Stone, M E; Ovsey, V G

1999-01-01

The mercury (Hg) content of dental-operatory wastewater has become an issue in many localities, and Hg removal is rapidly becoming a matter of concern for all dental clinics. This preliminary study tested the efficacy of polymers for the removal of Hg contaminants from the dental-unit wastewater stream. Two commercially available polymers were used to treat dental-operatory wastewater. Used separately, each polymer removed from 74.9% to 88.4% of the Hg from dental-wastewater supernatant. The polymers used in combination, within the recommended pH range, removed up to 99.9% of the total Hg from dental-wastewater supernatant. The estimated optimal concentration of the two polymers is approximately 2.33 ml of each per liter of waste, and more than 90% of the Hg may be removed with 0.13 ml/l. Results indicate that a combination of the two polymers may sufficiently reduce Hg levels to allow discharge of clarified supernatants into public sewer systems. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 PMID:9872711

Nanostructured Ion-Exchange Membranes for Fuel Cells: Recent Advances and Perspectives.

PubMed

He, Guangwei; Li, Zhen; Zhao, Jing; Wang, Shaofei; Wu, Hong; Guiver, Michael D; Jiang, Zhongyi

2015-09-23

Polymer-based materials with tunable nanoscale structures and associated microenvironments hold great promise as next-generation ion-exchange membranes (IEMs) for acid or alkaline fuel cells. Understanding the relationships between nanostructure, physical and chemical microenvironment, and ion-transport properties are critical to the rational design and development of IEMs. These matters are addressed here by discussing representative and important advances since 2011, with particular emphasis on aromatic-polymer-based nanostructured IEMs, which are broadly divided into nanostructured polymer membranes and nanostructured polymer-filler composite membranes. For each category of membrane, the core factors that influence the physical and chemical microenvironments of the ion nanochannels are summarized. In addition, a brief perspective on the possible future directions of nanostructured IEMs is presented. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Clustering effects in ionic polymers: Molecular dynamics simulations

DOE PAGES

Agrawal, Anupriya; Perahia, Dvora; Grest, Gary S.

2015-08-18

Ionic clusters control the structure, dynamics, and transport in soft matter. Incorporating a small fraction of ionizable groups in polymers substantially reduces the mobility of the macromolecules in melts. Furthermore, these ionic groups often associate into random clusters in melts, where the distribution and morphology of the clusters impact the transport in these materials. Here, using molecular dynamic simulations we demonstrate a clear correlation between cluster size and morphology with the polymer mobility in melts of sulfonated polystyrene. We show that in low dielectric media ladderlike clusters that are lower in energy compared with spherical assemblies are formed. Reducing themore » electrostatic interactions by enhancing the dielectric constant leads to morphological transformation from ladderlike clusters to globular assemblies. Finally, decrease in electrostatic interaction significantly enhances the mobility of the polymer.« less

Structural stability of coprecipitated natural organic matter and ferric iron under reducing conditions

USGS Publications Warehouse

Henneberry, Yumiko K.; Kraus, Tamara E.C.; Nico, Peter S.; Horwath, William R.

2012-01-01

The objective was to assess the interaction of Fe coprecipitated with dissolved organic matter (DOM) and its effect on Fe (hydr)oxide crystallinity and DOM retention under abiotic reducing conditions. A Fe-based coagulant was reacted with DOM from an agricultural drain and the resulting precipitate (floc) was exposed to S(-II) and Fe(II). Solution concentrations of Fe(II/III) and DOM were monitored, floc crystallinity was determined using X-ray diffraction, and the composition and distribution of functional groups were assessed using scanning transmission X-ray microscopy (STXM) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Results indicate coprecipitation of Fe(III) with DOM forms a non-crystalline floc that withstands crystallization regardless of change in pH, Fe:DOM ratio and type of reductant added. There was no evidence that exposure to reducing conditions led to release of DOM from the floc, indicating that coprecipitation with complex natural DOM in aquatic environments may stabilize Fe (hydr)oxides against crystallization upon reaction with reduced species and lead to long term sequestration of the DOM. STXM analysis identified spatially distinct regions with remarkable functional group purity, contrary to the model of DOM as a relatively uniform complex polymer lacking identifiable organic compounds. Polysaccharide-like OM was strongly and directly correlated with the presence of Fe but showed different Fe binding strength depending on the presence of carboxylic acid functional groups, whereas amide and aromatic functional groups were inversely correlated with Fe content.

Conformation Control of a Conjugated Polymer through Complexation with Bile Acids Generates Its Novel Spectral and Morphological Properties.

PubMed

Tsuchiya, Youichi; Noguchi, Takao; Yoshihara, Daisuke; Roy, Bappaditya; Yamamoto, Tatsuhiro; Shinkai, Seiji

2016-11-29

Control of higher-order polymer structures attracts a great deal of interest for many researchers when they lead to the development of materials having various advanced functions. Among them, conjugated polymers that are useful as starting materials in the design of molecular wires are particularly attractive. However, an equilibrium existing between isolated chains and bundled aggregates is inevitable and has made their physical properties very complicated. As an attempt to simplify this situation, we previously reported that a polymer chain of a water-soluble polythiophene could be isolated through complexation with a helix-forming polysaccharide. More recently, a covalently self-threading polythiophene was reported, the main chain of which was physically protected from self-folding and chain-chain π-stacking. In this report, we wish to report a new strategy to isolate a water-soluble polythiophene and to control its higher-order structure by a supramolecular approach: that is, among a few bile acids, lithocholate can form stoichiometric complexes with cationic polythiophene to isolate the polymer chain, and the higher-order structure is changeable by the molar ratio. The optical and morphological studies have been thoroughly performed, and the resultant complex has been applied to the selective recognition of two AMP structural isomers.

Effect of polymer molecular weight on chitosan-protein interaction.

PubMed

Bekale, L; Agudelo, D; Tajmir-Riahi, H A

2015-01-01

We present a comprehensive study of the interactions between chitosan nanoparticles (15, 100 and 200 kDa with the same degree of deacetylation 90%) and two model proteins, i.e., bovine (BSA) and human serum albumins (HSA), with the aim of correlating chitosan molecular weight (Mw) and the binding affinity of these naturally occurring polymers to protein. The effect of chitosan on the protein secondary structure and the influence of protein complexation on the shape of chitosan nanoparticles are discussed. A combination of multiple spectroscopic methods, transmission electron microscopy (TEM) and thermodynamic analysis were used to assess the polymer-protein complex formation. Results revealed that the three chitosan nanoparticles interact with BSA to form chitosan-BSA complexes, mainly through hydrophobic contacts with the affinity order: 200>100>15 kDa. However, HSA-chitosan complexation is mainly via electrostatic interactions with the stability order: 100>200>15 kDa. Furthermore, the association between polymer and protein causes a partial protein conformational change by a major reduction of α-helix from 63% (free BSA) to 57% (chitosan-BSA) and 57% (free HSA) to 51% (chitosan-HSA). Finally, TEM micrographs clearly revealed that the binding of serum albumins with chitosan nanoparticles induces a significant change in protein morphology and the shape of the polymer. Copyright © 2014 Elsevier B.V. All rights reserved.

Dynamics in Complex Coacervates

NASA Astrophysics Data System (ADS)

Perry, Sarah

Understanding the dynamics of a material provides detailed information about the self-assembly, structure, and intermolecular interactions present in a material. While rheological methods have long been used for the characterization of complex coacervate-based materials, it remains a challenge to predict the dynamics for a new system of materials. Furthermore, most work reports only qualitative trends exist as to how parameters such as charge stoichiometry, ionic strength, and polymer chain length impact self-assembly and material dynamics, and there is little information on the effects of polymer architecture or the organization of charges within a polymer. We seek to link thermodynamic studies of coacervation phase behavior with material dynamics through a carefully-controlled, systematic study of coacervate linear viscoelasticity for different polymer chemistries. We couple various methods of characterizing the dynamics of polymer-based complex coacervates, including the time-salt superposition methods developed first by Spruijt and coworkers to establish a more mechanistic strategy for comparing the material dynamics and linear viscoelasticity of different systems. Acknowledgment is made to the Donors of the American Chemical Society Petroleum Research Fund for support of this research.

Method of preparation of removable syntactic foam

DOEpatents

Arnold, C. Jr.; Derzon, D.K.; Nelson, J.S.; Rand, P.B.

1995-07-11

Easily removable, environmentally safe, low-density, syntactic foams are disclosed which are prepared by mixing insoluble microballoons with a solution of water and/or alcohol-soluble polymer to produce a pourable slurry, optionally vacuum filtering the slurry in varying degrees to remove unwanted solvent and solute polymer, and drying to remove residual solvent. The properties of the foams can be controlled by the concentration and physical properties of the polymer, and by the size and properties of the microballoons. The suggested solute polymers are non-toxic and soluble in environmentally safe solvents such as water or low-molecular weight alcohols. The syntactic foams produced by this process are particularly useful in those applications where ease of removability is beneficial, and could find use in packaging recoverable electronic components, in drilling and mining applications, in building trades, in art works, in the entertainment industry for special effects, in manufacturing as temporary fixtures, in agriculture as temporary supports and containers and for delivery of fertilizer, in medicine as casts and splints, as temporary thermal barriers, as temporary protective covers for fragile objects, as filters for particulate matter, which matter may be easily recovered upon exposure to a solvent, as in-situ valves (for one-time use) which go from maximum to minimum impedance when solvent flows through, and for the automatic opening or closing of spring-loaded, mechanical switches upon exposure to a solvent, among other applications. 1 fig.

Method of preparation of removable syntactic foam

DOEpatents

Arnold, Jr., Charles; Derzon, Dora K.; Nelson, Jill S.; Rand, Peter B.

1995-01-01

Easily removable, environmentally safe, low-density, syntactic foams are disclosed which are prepared by mixing insoluble microballoons with a solution of water and/or alcohol-soluble polymer to produce a pourable slurry, optionally vacuum filtering the slurry in varying degrees to remove unwanted solvent and solute polymer, and drying to remove residual solvent. The properties of the foams can be controlled by the concentration and physical properties of the polymer, and by the size and properties of the microballoons. The suggested solute polymers are non-toxic and soluble in environmentally safe solvents such as water or low-molecular weight alcohols. The syntactic foams produced by this process are particularly useful in those applications where ease of removability is beneficial, and could find use in packaging recoverable electronic components, in drilling and mining applications, in building trades, in art works, in the entertainment industry for special effects, in manufacturing as temporary fixtures, in agriculture as temporary supports and containers and for delivery of fertilizer, in medicine as casts and splints, as temporary thermal barriers, as temporary protective covers for fragile objects, as filters for particulate matter, which matter may be easily recovered upon exposure to a solvent, as in-situ valves (for one-time use) which go from maximum to minimum impedance when solvent flows through, and for the automatic opening or closing of spring-loaded, mechanical switches upon exposure to a solvent, among other applications.

PREFACE: Fourh Workshop on Non-Equilibrium Phenomena in Supercooled Fluids, Glasses and Amorphous Materials

NASA Astrophysics Data System (ADS)

Andreozzi, Laura; Giordano, Marco; Leporini, Dino; Tosi, Mario

2007-04-01

This special issue of Journal of Physics: Condensed Matter presents the Proceedings of the Fourh Workshop on Non-Equilibrium Phenomena in Supercooled Fluids, Glasses and Amorphous Materials, held in Pisa from 17-22 September 2006. This was the fourth of a series of workshops on this theme started in 1995 as a joint initiative of the Università di Pisa and the Scuola Normale Superiore. The 2006 edition was attended by about 200 participants from Europe, Asia and the Americas. As for the earlier workshops, the main objective was to bring together scientists from different areas of science, technology and engineering, to comparatively discuss experimental facts and theoretical predictions on the dynamical processes that occur in supercooled fluids and other disordered materials in non-equilibrium states. The underlying conceptual unity of the field provides a common background for the scientific community working in its various areas. In this edition the number of sessions was increased to cover a wider range of topics of general and current interest, in a larger number of stimulating lectures. The core of the workshop was a set of general lectures followed by more specific presentations on current issues in the main areas of the field. The sessions were in sequence devoted to: non-equilibrium dynamics, aging and secondary relaxations, biomaterials, polyamorphism and water, polymer dynamics I, complex systems, pressure-temperature scaling, thin films, nanometre length-scale studies, folded states of proteins and polymer crystals, theoretical aspects and energy landscape approaches, relaxation and heterogeneous dynamics, rheology in fluids and entangled polymers, biopolymers, and polymer dynamics II. We thank the session chairmen and all speakers for the high quality of their contributions. The structure of this issue of the proceedings follows the sequence of the oral presentations in the workshop, complemented by some papers selected from the poster sessions. Two round-table discussion sessions were organized to discuss issues that have special impact on our current understanding (or lack of it) of the dynamics of glass transition: 'Low-energy excitations and relaxations in glasses' and 'An assessment of current theories: interconnections and relevance to experiments'. We are very grateful to M A Ramos and R Bömer, and to P G Debenedetti and H Z Cummins for organizing and leading these two activities. Two very active and profitable poster sessions collected contributions on the themes of relaxation processes, cooperativity in polymers and mixtures, polyamorphism and water, biomaterials, relaxation, aging phenomena in thin films, confined and complex systems, and theoretical aspect, energy landscape and molecular dynamics, low temperature, glass and PT procedures, tracer dynamics, heterogeneity and relaxation in glass formers We acknowledge the generous support given to the workshop by our institutions, and in particular by Scuola Normale Superiore. The organization of the events in its beautiful rooms and corridors, as well as the lunches and coffee breaks held in its courtyard, especially favoured meetings and discussions between the participants. Several public and private Institutions have also supported our efforts and we would like to thank them warmly: they are the 'Soft Matter' Center of Rome, the INFN Section in Pisa, the CNR/INFM Polylab, and Ital Scientifica, TA Instruments, Novocontrol Technologies, Up Group, Isole e Olena. Finally, we express our gratitude to all those individuals—we mention here in particular Dr Ciro Autiero, Dr Massimo Faetti, Dr Fabio Zulli, Ms Patrizia Pucci, and Ms Caterina D'Elia—who have given their work and time to the making and running of the Workshop.

Shape memory polymer network with thermally distinct elasticity and plasticity.

PubMed

Zhao, Qian; Zou, Weike; Luo, Yingwu; Xie, Tao

2016-01-01

Stimuli-responsive materials with sophisticated yet controllable shape-changing behaviors are highly desirable for real-world device applications. Among various shape-changing materials, the elastic nature of shape memory polymers allows fixation of temporary shapes that can recover on demand, whereas polymers with exchangeable bonds can undergo permanent shape change via plasticity. We integrate the elasticity and plasticity into a single polymer network. Rational molecular design allows these two opposite behaviors to be realized at different temperature ranges without any overlap. By exploring the cumulative nature of the plasticity, we demonstrate easy manipulation of highly complex shapes that is otherwise extremely challenging. The dynamic shape-changing behavior paves a new way for fabricating geometrically complex multifunctional devices.

Stability effect of cholesterol-poly(acrylic acid) in a stimuli-responsive polymer-liposome complex obtained from soybean lecithin for controlled drug delivery.

PubMed

Simões, M G; Alves, P; Carvalheiro, Manuela; Simões, P N

2017-04-01

The development of polymer-liposome complexes (PLCs), in particular for biomedical applications, has grown significantly in the last decades. The importance of these studies comes from the emerging need in finding intelligent controlled release systems, more predictable, effective and selective, for applications in several areas, such as treatment and/or diagnosis of cancer, neurological, dermatological, ophthalmic and orthopedic diseases, gene therapy, cosmetic treatments, and food engineering. This work reports the development and characterization of a pH sensitive system for controlled release based on PLCs. The selected hydrophilic polymer was poly(acrylic acid) (PAA) synthesized by atom transfer radical polymerization (ATRP) with a cholesterol (CHO) end-group to improve the anchoring of the polymer into the lipid bilayer. The polymer was incorporated into liposomes formulated from soybean lecithin and stearylamine, with different stearylamine/phospholipid and polymer/phospholipid ratios (5, 10 and 20%). The developed PLCs were characterized in terms of particle size, polydispersity, zeta potential, release profiles, and encapsulation efficiency. Cell viability studies were performed to assess the cytotoxic potential of PLCs. The results showed that the liposomal formulation with 5% of stearylamine and 10% of polymer positively contribute to the stabilization of the complexes. Afterwards, the carboxylic acid groups of the polymer present at the surface of the liposomes were crosslinked and the same parameters analyzed. The crosslinked complexes showed to be more stable at physiologic conditions. In addition, the release profiles at different pHs (2-12) revealed that the obtained complexes released all their content at acidic conditions. In summary, the main accomplishments of this work are: (i) innovative synthesis of cholesterol-poly(acrylic acid) (CHO-PAA) by ATRP; (ii) stabilization of the liposomal formulation by incorporation of stearylamine and CHO-PAA; (iii) new approach for CHO-PAA crosslinking, resulting in more stable PLCs at physiological conditions; (iv) destabilization of PLCs upon slight changes of pH, showing their pH sensitivity; and (v) the PLCs do not exhibit cellular toxicity. Copyright © 2017 Elsevier B.V. All rights reserved.

Self-assembly concepts for multicompartment nanostructures

NASA Astrophysics Data System (ADS)

Gröschel, André H.; Müller, Axel H. E.

2015-07-01

Compartmentalization is ubiquitous to many biological and artificial systems, be it for the separate storage of incompatible matter or to isolate transport processes. Advancements in the synthesis of sequential block copolymers offer a variety of tools to replicate natural design principles with tailor-made soft matter for the precise spatial separation of functionalities on multiple length scales. Here, we review recent trends in the self-assembly of amphiphilic block copolymers to multicompartment nanostructures (MCNs) under (semi-)dilute conditions, with special emphasis on ABC triblock terpolymers. The intrinsic immiscibility of connected blocks induces short-range repulsion into discrete nano-domains stabilized by a third, soluble block or molecular additive. Polymer blocks can be synthesized from an arsenal of functional monomers directing self-assembly through packing frustration or response to various fields. The mobility in solution further allows the manipulation of self-assembly processes into specific directions by clever choice of environmental conditions. This review focuses on practical concepts that direct self-assembly into predictable nanostructures, while narrowing particle dispersity with respect to size, shape and internal morphology. The growing understanding of underlying self-assembly mechanisms expands the number of experimental concepts providing the means to target and manipulate progressively complex superstructures.

Novel guanidinylated bioresponsive poly(amidoamine)s designed for short hairpin RNA delivery

PubMed Central

Yu, Jiankun; Zhang, Jinmin; Xing, Haonan; Sun, Yanping; Yang, Zhen; Yang, Tianzhi; Cai, Cuifang; Zhao, Xiaoyun; Yang, Li; Ding, Pingtian

2016-01-01

Two different disulfide (SS)-containing poly(amidoamine) (PAA) polymers were constructed using guanidino (Gua)-containing monomers (ie, arginine [Arg] and agmatine [Agm]) and N,N′-cystamine bisacrylamide (CBA) by Michael-addition polymerization. In order to characterize these two Gua-SS-PAA polymers and investigate their potentials as short hairpin RNA (shRNA)-delivery carriers, pSilencer 4.1-CMV FANCF shRNA was chosen as a model plasmid DNA to form complexes with these two polymers. The Gua-SS-PAAs and plasmid DNA complexes were determined with particle sizes less than 90 nm and positive ζ-potentials under 20 mV at nucleic acid:polymer weight ratios lower than 1:24. Bioresponsive release of plasmid DNA was observed from both newly constructed complexes. Significantly lower cytotoxicity was observed for both polymer complexes compared with polyethylenimine and Lipofectamine 2000, two widely used transfection reagents as reference carriers. Arg-CBA showed higher transfection efficiency and gene-silencing efficiency in MCF7 cells than Agm-CBA and the reference carriers. In addition, the cellular uptake of Arg-CBA in MCF7 cells was found to be higher and faster than Agm-CBA and the reference carriers. Similarly, plasmid DNA transport into the nucleus mediated by Arg-CBA was more than that by Agm-CBA and the reference carriers. The study suggested that guanidine and carboxyl introduced into Gua-SS-PAAs polymers resulted in a better nuclear localization effect, which played a key role in the observed enhancement of transfection efficiency and low cytotoxicity. Overall, two newly synthesized Gua-SS-PAAs polymers demonstrated great potential to be used as shRNA carriers for gene-therapy applications. PMID:27994462

Cyclodextrin based ternary system of modafinil: Effect of trimethyl chitosan and polyvinylpyrrolidone as complexing agents.

PubMed

Patel, Parth; Agrawal, Y K; Sarvaiya, Jayrajsinh

2016-03-01

Modafinil is an approved drug for the treatment of narcolepsy and have a strong market presence in many countries. The drug is widely consumed for off-label uses and currently listed as a restricted drug. Modafinil has very low water solubility. To enhance the aqueous solubility of modafinil by the formation of a ternary complex with Hydroxypropyl-β-cyclodextrin and two hydrophilic polymers was the main objective of the present study. Pyrrolidone (PVP K30) and a water soluble chitosan derivative, trimethyl chitosan (TMC) were studied by solution state and solid state characterization methods for their discriminatory efficiency in solubility enhancement of modafinil. Phase solubility study depicted the highest complexation efficiency (2.22) of cyclodextrin derivative in the presence of TMC compared to the same in the presence of PVP K30 (0.08) and in the absence of any polymer (0.92). FT-IR analysis of binary and ternary complex expressed comparable contribution of both polymers in formation of inclusion complex. The thermal behaviour of binary and ternary complex, involving individual polymers disclosed the influence of TMC on polymorphism of the drug. DSC study revealed efficiency of TMC to prevent conversion of metastable polymorphic form to stable polymorphic form. Ternary complex, involving TMC enhanced water solubility of the drug 1.5 times more compared to the binary complex of the drug whereas PVP K30 reduced the Solubility. Copyright © 2015 Elsevier B.V. All rights reserved.

Sphericity and symmetry breaking in the formation of Frank–Kasper phases from one component materials

DOE PAGES

Lee, Sangwoo; Leighton, Chris; Bates, Frank S.

2014-11-05

Frank–Kasper phases are tetrahedrally packed structures occurring in numerous materials, from elements to intermetallics to self-assembled soft materials. They exhibit complex manifolds of Wigner–Seitz cells with many-faceted polyhedra, forming an important bridge between the simple close-packed periodic and quasiperiodic crystals. The recent discovery of the Frank–Kasper σ-phase in diblock and tetrablock polymers stimulated the experiments reported here on a poly(isoprene- b-lactide) diblock copolymer melt. Thus, analysis of small-angle X-ray scattering and mechanical spectroscopy exposes an undiscovered competition between the tendency to form self-assembled particles with spherical symmetry, and the necessity to fill space at uniform density within the framework imposedmore » by the lattice. We thus deduce surprising analogies between the symmetry breaking at the body-centered cubic phase to σ-phase transition in diblock copolymers, mediated by exchange of mass, and the symmetry breaking in certain metals and alloys (such as the elements Mn and U), mediated by exchange of charge. Similar connections are made between the role of sphericity in real space for polymer systems, and the role of sphericity in reciprocal space for metallic systems such as intermetallic compounds and alloys. These findings establish new links between disparate materials classes, provide opportunities to improve the understanding of complex crystallization by building on synergies between hard and soft matter, and, perhaps most significantly, challenge the view that the symmetry breaking required to form reduced symmetry structures (possibly even quasiperiodic crystals) requires particles with multiple predetermined shapes and/or sizes.« less

Sphericity and symmetry breaking in the formation of Frank–Kasper phases from one component materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Sangwoo; Leighton, Chris; Bates, Frank S.

Frank–Kasper phases are tetrahedrally packed structures occurring in numerous materials, from elements to intermetallics to self-assembled soft materials. They exhibit complex manifolds of Wigner–Seitz cells with many-faceted polyhedra, forming an important bridge between the simple close-packed periodic and quasiperiodic crystals. The recent discovery of the Frank–Kasper σ-phase in diblock and tetrablock polymers stimulated the experiments reported here on a poly(isoprene- b-lactide) diblock copolymer melt. Thus, analysis of small-angle X-ray scattering and mechanical spectroscopy exposes an undiscovered competition between the tendency to form self-assembled particles with spherical symmetry, and the necessity to fill space at uniform density within the framework imposedmore » by the lattice. We thus deduce surprising analogies between the symmetry breaking at the body-centered cubic phase to σ-phase transition in diblock copolymers, mediated by exchange of mass, and the symmetry breaking in certain metals and alloys (such as the elements Mn and U), mediated by exchange of charge. Similar connections are made between the role of sphericity in real space for polymer systems, and the role of sphericity in reciprocal space for metallic systems such as intermetallic compounds and alloys. These findings establish new links between disparate materials classes, provide opportunities to improve the understanding of complex crystallization by building on synergies between hard and soft matter, and, perhaps most significantly, challenge the view that the symmetry breaking required to form reduced symmetry structures (possibly even quasiperiodic crystals) requires particles with multiple predetermined shapes and/or sizes.« less

Design and fabrication of uniquely shaped thiol-ene microfibers using a two-stage hydrodynamic focusing design.

PubMed

Boyd, Darryl A; Shields, Adam R; Howell, Peter B; Ligler, Frances S

2013-08-07

Microfluidic systems have advantages that are just starting to be realized for materials fabrication. In addition to the more common use for fabrication of particles, hydrodynamic focusing has been used to fabricate continuous polymer fibers. We have previously described such a microfluidics system which has the ability to generate fibers with controlled cross-sectional shapes locked in place by in situ photopolymerization. The previous fiber fabrication studies produced relatively simple round or ribbon shapes, demonstrated the use of a variety of polymers, and described the interaction between sheath-core flow-rate ratios used to control the fiber diameter and the impact on possible shapes. These papers documented the fact that no matter what the intended shape, higher flow-rate ratios produced rounder fibers, even in the absence of interfacial tension between the core and sheath fluids. This work describes how to fabricate the next generation of fibers predesigned to have a much more complex geometry, as exemplified by the "double anchor" shape. Critical to production of the pre-specified fibers with complex features was independent control over both the shape and the size of the fabricated microfibers using a two-stage hydrodynamic focusing system. Design and optimization of the channels was performed using finite element simulations and confocal imaging to characterize each of the two stages theoretically and experimentally. The resulting device design was then used to generate thiol-ene fibers with a unique double anchor shape. Finally, proof-of-principle functional experiments demonstrated the ability of the fibers to transport fluids and to interlock laterally.

Universal size properties of a star-ring polymer structure in disordered environments

NASA Astrophysics Data System (ADS)

Haydukivska, K.; Blavatska, V.

2018-03-01

We consider the complex polymer system, consisting of a ring polymer connected to the f1-branched starlike structure, in a good solvent in the presence of structural inhomogeneities. In particular cases f1=1 and f1=2 , such a system restores the synthesized tadpole-shaped polystyrenes [Doi et al., Macromolecules 46, 1075 (2013), 10.1021/ma302511j]. We assume that structural defects are correlated at large distances x according to a power law x-a. Applying the direct polymer renormalization approach, we evaluate the universal size characteristics such as the ratio of the radii of gyration of star-ring and star topologies, and compare the effective sizes of single arms in complex structures and isolated polymers of the same total molecular weight. The nontrivial impact of disorder on these quantities is analyzed.

Structural, microstructural and electrochemical properties of dispersed-type polymer nanocomposite films

NASA Astrophysics Data System (ADS)

Arya, Anil; Sharma, A. L.

2018-01-01

Free-standing solid polymer nanocomposite (PEO-PVC)  +  LiPF6-TiO2 films have been prepared through a standard solution-cast technique. The improvement in structural, microstructural and electrochemical properties has been observed on the dispersion of nanofiller in polymer salt complex. X-ray diffraction studies clearly reflect the formation of complex formation, as no corresponding salt peak appeared in the diffractograms. The Fourier transform infrared analysis suggested clear and convincing evidence of polymer-ion, ion-ion and polymer-ion-nanofiller interaction. The highest ionic conductivity of the prepared solid polymer electrolyte (SPE) films is ~5  ×  10-5 S cm-1 for 7 wt.% TiO2. The linear sweep voltammetry provides the electrochemical stability window of the prepared SPE films, about ~3.5 V. The ion transference number has been estimated, t ion  =  0.99 through the DC polarization technique. Dielectric spectroscopic studies were performed to understand the ion transport process in polymer electrolytes. All solid polymer electrolytes possess good thermal stability up to 300 °C. Differential scanning calorimetry analysis confirms the decrease of the melting temperature and signal of glass transition temperature with the addition of nanofiller, which indicates the decrease of crystallinity of the polymer matrix. An absolute correlation between diffusion coefficient (D), ion mobility (µ), number density (n), double-layer capacitance (C dl), glass transition temperature, melting temperature (T m), free ion area (%) and conductivity (σ) has been observed. A convincing model to study the role of nanofiller in a polymer salt complex has been proposed, which supports the experimental findings. The prepared polymer electrolyte system with significant ionic conductivity, high ionic transference number, and good thermal and voltage stability could be suggested as a potential candidate as electrolyte cum separator for the fabrication of a rechargeable lithium-ion battery system.

Synthesis, characterization and anti-microbial activity of phenylurea-formaldehyde resin (PUF) and its polymer metal complexes (PUF-Mn(II).

PubMed

Ahamad, Tansir; Alshehri, Saad M

2012-10-01

Phenylurea-formaldehyde polymer (PUF) was synthesized via polycondensation of phenylurea and formaldehyde in basic medium, its polymer-metal complexes [PUF-M(II)] were prepared with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) ions. PUF and PUF-M(II) were characterized with magnetic moment measurements, elemental and spectral (UV-visible, FTIR, 1H-NMR, 13C-NMR and ESR) analysis. The thermal behaviors of all the synthesized polymers were carried out using thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The thermal data revealed that all of the PUF-M(II) showed higher thermal stabilities than the PUF and also ascribed that the PUF-Cu(II) showed better thermal stability than the other PUF-M(II). The kinetic parameters such as activation energy, pre-exponential factor etc., were evaluated for these polymer metal complexes using Coats-Redfern equation. In addition, the antimicrobial activity of the synthesized polymers was tested against several microorganisms using agar well diffusion methods. Among all of the PUF-M(II), the antimicrobial activity of the PUF-Cu(II) showed the highest zone of inhibition because of its higher stability constant and may be used in biomedical applications. Copyright © 2012 Elsevier B.V. All rights reserved.

Bacterial Production and Enzymatic Activities in Deep-Sea Sediments of the Pacific Ocean: Biogeochemical Implications of Different Temperature Constraints

NASA Astrophysics Data System (ADS)

Danovaro, R.; Corinaldesi, C.; dell'Anno, A.

2002-12-01

The deep-sea bed, acting as the ultimate sink for organic material derived from the upper oceans primary production, is now assumed to play a key role in biogeochemical cycling of organic matter on global scale. Early diagenesis of organic matter in marine sediments is dependent upon biological processes (largely mediated by bacterial activity) and by molecular diffusion. Organic matter reaching the sea floor by sedimentation is subjected to complex biogeochemical transformations that make organic matter largely unsuitable for direct utilization by benthic heterotrophs. Extracellular enzymatic activities in the sediment is generally recognized as the key step in the degradation and utilization of organic polymers by bacteria and a key role in biopolymeric carbon mobilization is played by aminopeptidase, alkaline phosphatase and glucosidase activities. In the present study we investigated bacterial density, bacterial C production and exo-enzymatic activities (aminopeptidase, glucosidase and phosphatase activity) in deep-sea sediments of the Pacific Ocean in relation with the biochemical composition of sediment organic matter (proteins, carbohydrates and lipids), in order to gather information on organic matter cycling and diagenesis. Benthic viral abundance was also measured to investigate the potential role of viruses on microbial loop functioning. Sediment samples were collected at eight stations (depth ranging from 2070-3100 m) along two transects located at the opposite side (north and south) of ocean seismic ridge Juan Fernandez (along latitudes 33° 20' - 33° 40'), constituted by the submerged vulcanoes, which connects the Chilean coasts to Rapa Nui Island. Since the northern and southern sides of this ridge apparently displayed small but significant differences in deep-sea temperature (related to the general ocean circulation), this sampling strategy allowed also investigating the role of different temperature constraints on bacterial activity and biogeochemical processes and to define possible scenarios dealing with climate induced changes in deep-sea conditions.

On the influence of crosslinker on template complexation in molecularly imprinted polymers: a computational study of prepolymerization mixture events with correlations to template-polymer recognition behavior and NMR spectroscopic studies.

PubMed

Shoravi, Siamak; Olsson, Gustaf D; Karlsson, Björn C G; Nicholls, Ian A

2014-06-12

Aspects of the molecular-level basis for the function of ethylene glycol dimethacrylate and trimethylolproprane trimethacrylate crosslinked methacrylic acid copolymers molecularly imprinted with (S)-propranolol have been studied using a series of all-component and all-atom molecular dynamics studies of the corresponding prepolymerization systems. The crosslinking agents were observed to contribute to template complexation, and the results were contrasted with previously reported template-recognition behavior of the corresponding polymers. Differences in the extent to which the two crosslinkers interacted with the functional monomer were identified, and correlations were made to polymer-ligand recognition behavior and the results of nuclear magnetic resonance spectroscopic studies studies. This study demonstrates the importance of considering the functional monomer-crosslinker interaction when designing molecularly imprinted polymers, and highlights the often neglected general contribution of crosslinker to determining the nature of molecularly imprinted polymer-template selectivity.

Study on improving viscosity of polymer solution based on complex reaction

NASA Astrophysics Data System (ADS)

Sun, G.; Li, D.; Zhang, D.; Xu, T. H.

2018-05-01

The current status of polymer flooding Technology on high salinity oil reservoir is not ideal. A method for increasing the viscosity of polymer solutions is urgently needed. This paper systematically studied the effect of ions with different mass concentrations on the viscosity of polymer solutions. Based on the theory of complex reaction, a countermeasure of increasing viscosity of polymer solution under conditions of high salinity reservoir was proposed. The results show that Ca2+ and Mg2+ have greater influence on the solution viscosity than K+ and Na+. When the concentration of divalent ions increases from 0 mg/L to 80 mg/L, the viscosity of the polymer solution decreases from 210 mPa·s to 38.6 mPa·s. The viscosity of the polymer solution prepared from the sewage treated with the Na2C2O4 increased by 25.3%. Atomic force microscopy test results show that Na2C2O4 can effectively shield the divalent metal ions, so that the polymer molecules in the solution stretch more, thereby increasing the solution viscosity. Atomic force microscopy test results show that Na2C2O4 can effectively shield the divalent metal ions, so that the polymer molecules in the solution stretch more, thereby increasing the solution viscosity.

Relating structure and flow of soft colloids

NASA Astrophysics Data System (ADS)

Kundu, S. K.; Gupta, S.; Stellbrink, J.; Willner, L.; Richter, D.

2013-11-01

To relate the complex macroscopic flow of soft colloids to details of its microscopic equilibrium and non-equilibrium structure is still one big challenge in soft matter science. We investigated several well-defined colloidal model systems like star polymers or diblock copolymer micelles by linear/non-linear rheology, static/dynamic light scattering (SLS/DLS) and small angle neutron scattering (SANS). In addition, in-situ SANS experiments during shear (Rheo-SANS) revealed directly shear induced structural changes on a microscopic level. Varying the molecular architecture of the individual colloidal particle as well as particle-particle interactions and covering at the same time a broad concentration range from the very dilute to highly concentrated, glassy regime, we could separate contributions from intra- and inter-particle softness. Both can be precisely "tuned" by varying systematically the functionality, 6 ≤ f≤ 64, for star polymers or aggregation number, 30 ≤ N agg ≤ 1000 for diblock copolymer micelles, as well as the degree of polymerization of the individual polymer arm 100 ≤ D p ≤ 3000. In dilute solutions, the characteristic shear rate at which deformation of the soft colloid is observed can be related to the Zimm time of the polymeric corona. In concentrated solutions, we validated a generalized Stokes-Einstein approach to describe the increase in macroscopic viscosity and mesoscopic self diffusion coefficient on approaching the glassy regime. Both can be explained in terms of an ultra-soft interaction potential. Moreover, non-equilibrium structure factors are obtained by Rheo-SANS. All experimental results are in excellent quantitative agreement with recent theoretical predictions.

Localized Enzymatic Degradation of Polymers: Physics and Scaling Laws

NASA Astrophysics Data System (ADS)

Lalitha Sridhar, Shankar; Vernerey, Franck

2018-03-01

Biodegradable polymers are naturally abundant in living matter and have led to great advances in controlling environmental pollution due to synthetic polymer products, harnessing renewable energy from biofuels, and in the field of biomedicine. One of the most prevalent mechanisms of biodegradation involves enzyme-catalyzed depolymerization by biological agents. Despite numerous studies dedicated to understanding polymer biodegradation in different environments, a simple model that predicts the macroscopic behavior (mass and structural loss) in terms of microphysical processes (enzyme transport and reaction) is lacking. An interesting phenomenon occurs when an enzyme source (released by a biological agent) attacks a tight polymer mesh that restricts free diffusion. A fuzzy interface separating the intact and fully degraded polymer propagates away from the source and into the polymer as the enzymes diffuse and react in time. Understanding the characteristics of this interface will provide crucial insight into the biodegradation process and potential ways to precisely control it. In this work, we present a centrosymmetric model of biodegradation by characterizing the moving fuzzy interface in terms of its speed and width. The model predicts that the characteristics of this interface are governed by two time scales, namely the polymer degradation and enzyme transport times, which in turn depend on four main polymer and enzyme properties. A key finding of this work is simple scaling laws that can be used to guide biodegradation of polymers in different applications.

In Situ Stabilization of Persistent Organic Contaminants in Marine Sediments

DTIC Science & Technology

2004-04-01

dyes (25, 26), amino acids (27), and polymer additives (28, 29). In this study we extend the capabilities of µL2MS to detect PCBs. Using 212 nm...organic carbon followed by treatment with acid to remove inorganic carbon and analysis of the remaining carbon. The soot carbon material isolated by...aliphatic natural organic matter types (algae, cellulose, collagen, cuticle, lignin, kerogen, and humic acid ) and concluded that aliphatic organic matter

Synthesis and Characterization of Templated Ion Exchange Resins for the Selective Complexion of Actinide Ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murrray, George M.; Uy, O. Manuel

The purpose of this research is to develop polymeric extractants for the selective complexation of uranyl ions (and subsequently other actinyl and actinide ions) from aqueous solutions. Selectivity for a specific actinide ion is obtained by providing the polymers with cavities lined with complexing ligands so arranged as to match the charge, coordination number, coordination geometry, and size of the actinide ion. These cavity-containing polymers are produced by using a specific actinide ion (or surrogate) as a template around which monomeric complexing ligands are polymerized. The polymers provide useful sequestering agents for removing actinide ions from wastes and will formmore » the basis for a variety of analytical techniques for actinide determination.« less

Induced structural changes of humic acid by exposure of polystyrene microplastics: A spectroscopic insight.

PubMed

Chen, Wei; Ouyang, Zhen-Yu; Qian, Chen; Yu, Han-Qing

2018-02-01

The occurrence of microplastics (MPs) as emerging contaminants in the environment may cause changes in water or sediment characteristics, and further affect their biogeochemical cycles. Thus, insights into the interactions between dissolved organic matter (DOM) and MPs are essential for the assessment of environmental impacts of MPs in ecosystems. Integrating spectroscopic methods with chemometric analyses, this work explored the chemical and microstructural changes of DOM-MP complex to reveal the mechanism of DOM-MP interaction at a molecular level. MPs were found to interact with the aromatic structure of DOM via π-π conjugation, then be entrapped in the DOM polymers by the carboxyl groups and C=O bonds, constituting a highly conjugated co-polymer with increased electron density. This induced the fluorescence intensity increase in DOM. The interaction affinity of DOM-MP was highly dependent on the MP size and solution pH. This work offers a new insight into the impact of MP discharge on environment and may provide an analytical framework for evaluating MP hetero-aggregation and the roles of MPs in the transportation of other contaminants. Furthermore, the integrated methods used in this work exhibit potential applications in exploring the fragmentation processes of MPs and formation of secondary MPs under natural conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Elaboration, characterization and application of polysulfone and polyacrylic acid blends as ultrafiltration membranes for removal of some heavy metals from water.

PubMed

Mbareck, Chamekh; Nguyen, Quang Trong; Alaoui, Ouafa Tahiri; Barillier, Daniel

2009-11-15

Polysulfone (PSf)/polyacrylic acid ultrafiltration (PSf/PAA) membranes were prepared from a polymer blend in dimethylformamide by coagulation in water according to the wet phase inversion method. Immobilization of water-soluble PAA within the non-soluble PSf matrix was proven by the increase of ion exchange capacity and the intensity of the carboxyl groups' peak with the increase of PAA content as shown by Fourier transform infrared spectra. These results lead to consider that PSf and PAA form a semi-interpenetrating polymer networks. The obtained membranes showed a decrease of mean surface-pore sizes, the overall porosity and the hydraulic permeability with the increase in PAA content. Such results were imputed to the morphologic modifications of PSf film with the immobilization of increasing PAA amount. PSf/PAA membranes showed high lead, cadmium and chromium rejection which reaches 100% at pH superior to 5.7 and a low rejection at low pH. Moreover, the heavy metal rejection decreases with feed solution concentration and applied pressure increases. These behaviors were attributed to the role of carboxylic groups in ion exchange or complexation. As a matter of fact, the strong lead ion-PAA interactions were revealed by the scanning electron microscopy with energy dispersive X-rays (SEM-EDX).

Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete

DOEpatents

Sugama, Toshifumi; Kukacka, Lawrence E.; Horn, William H.

1985-01-01

Quick setting polymer concrete compositions with excellent structural properties are disclosed; these polymer concrete compositions are mixtures of unsaturated polyesters and crosslinking monomers together with appropriate initiators and promoters in association with aggregate, which may be wet, and with a source of bivalent metallic ions.

Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete

DOEpatents

Sugama, T.; Kukacka, L.E.; Horn, W.H.

1981-11-04

Quick setting polymer concrete compositions which are mixtures of unsaturated polyesters and crosslinking monomers together with appropriate initiators and promoters in association with aggregate which may be wet and a source of bivalent metallic ions which will set to polymer concrete with excellent structural properties.

DNA detection using water-soluble conjugated polymers and peptide nucleic acid probes

PubMed Central

Gaylord, Brent S.; Heeger, Alan J.; Bazan, Guillermo C.

2002-01-01

The light-harvesting properties of cationic conjugated polymers are used to sensitize the emission of a dye on a specific peptide nucleic acid (PNA) sequence for the purpose of homogeneous, “real-time” DNA detection. Signal transduction is controlled by hybridization of the neutral PNA probe and the negative DNA target. Electrostatic interactions bring the hybrid complex and cationic polymer within distances required for Förster energy transfer. Conjugated polymer excitation provides fluorescein emission >25 times higher than that obtained by exciting the dye, allowing detection of target DNA at concentrations of 10 pM with a standard fluorometer. A simple and highly sensitive assay with optical amplification that uses the improved hybridization behavior of PNA/DNA complexes is thus demonstrated. PMID:12167673

Shape memory polymer network with thermally distinct elasticity and plasticity

PubMed Central

Zhao, Qian; Zou, Weike; Luo, Yingwu; Xie, Tao

2016-01-01

Stimuli-responsive materials with sophisticated yet controllable shape-changing behaviors are highly desirable for real-world device applications. Among various shape-changing materials, the elastic nature of shape memory polymers allows fixation of temporary shapes that can recover on demand, whereas polymers with exchangeable bonds can undergo permanent shape change via plasticity. We integrate the elasticity and plasticity into a single polymer network. Rational molecular design allows these two opposite behaviors to be realized at different temperature ranges without any overlap. By exploring the cumulative nature of the plasticity, we demonstrate easy manipulation of highly complex shapes that is otherwise extremely challenging. The dynamic shape-changing behavior paves a new way for fabricating geometrically complex multifunctional devices. PMID:26824077

Efficient field-theoretic simulation of polymer solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Villet, Michael C.; Fredrickson, Glenn H., E-mail: ghf@mrl.ucsb.edu; Department of Materials, University of California, Santa Barbara, California 93106

2014-12-14

We present several developments that facilitate the efficient field-theoretic simulation of polymers by complex Langevin sampling. A regularization scheme using finite Gaussian excluded volume interactions is used to derive a polymer solution model that appears free of ultraviolet divergences and hence is well-suited for lattice-discretized field theoretic simulation. We show that such models can exhibit ultraviolet sensitivity, a numerical pathology that dramatically increases sampling error in the continuum lattice limit, and further show that this pathology can be eliminated by appropriate model reformulation by variable transformation. We present an exponential time differencing algorithm for integrating complex Langevin equations for fieldmore » theoretic simulation, and show that the algorithm exhibits excellent accuracy and stability properties for our regularized polymer model. These developments collectively enable substantially more efficient field-theoretic simulation of polymers, and illustrate the importance of simultaneously addressing analytical and numerical pathologies when implementing such computations.« less

Polymer complexes. LVII. Supramolecular assemblies of novel polymer complexes of dioxouranium(VI) with some substituted allyl azo dye compounds

NASA Astrophysics Data System (ADS)

Diab, M. A.; El-Sonbati, A. Z.; El-Bindary, A. A.; Balboula, M. Z.

2013-05-01

A novel method to synthesize some dioxouranium(VI) polymer complexes of the general formula [UO2(Ln)2(OAc)2] (where HLn = azo allyl rhodanine). The structure of the novel mononuclear dioxoutranium(VI) polymer complexes was characterized using elemental analysis, spectral (electronic, infrared, 1H &13C NMR) studies, magnetic susceptibility measurements and thermal analysis. The molar conductivities show that all the polymer complexes are non-electrolytes. The IR showed that the ligand HLn act as bidentate neutral through carbonyl group and imine group nitrogen atom forming thereby a six-membered chelating ring and concomitant formation of an intramolecular hydrogen bond. The υ3 frequency of UO2+2 has been shown to be an excellent molecular probe for studying the coordinating power of the ligands. The values of υ3 of the prepared complexes containing UO2+2 were successfully used to calculate the force constant, FUO (10-8 N/Å) and the bond length RUO (Å) of the Usbnd O bond. A strategy based upon both theoretical and experimental investigations has been adopted. The theoretical aspects are described in terms of the well-known theory of 5d-4f transitions. Wilson's, matrix method, Badger's formula, and Jones and El-Sonbati equations were used to calculate the Usbnd O bond distances from the values of the stretching and interaction force constants. The most probable correlation between Usbnd O force constant to Usbnd O bond distance were satisfactorily discussed in term of Badger's rule and the equations suggested by Jones and El-Sonbati. The effect of Hammet constant is also discussed.

Multi-Length Scale-Enriched Continuum-Level Material Model for Kevlar-Fiber-Reinforced Polymer-Matrix Composites

DTIC Science & Technology

2012-08-03

is unlimited. Multi-Length Scale-Enriched Continuum-Level Material Model for Kevlar ®-Fiber-Reinforced Polymer-Matrix Composites The views, opinions...12211 Research Triangle Park, NC 27709-2211 ballistics, composites, Kevlar , material models, microstructural defects REPORT DOCUMENTATION PAGE 11... Kevlar ®-Fiber-Reinforced Polymer-Matrix Composites Report Title Fiber-reinforced polymer matrix composite materials display quite complex deformation

Hemolytic activity of pH-responsive polymer-streptavidin bioconjugates.

PubMed

Lackey, C A; Murthy, N; Press, O W; Tirrell, D A; Hoffman, A S; Stayton, P S

1999-01-01

Drug delivery systems that increase the rate and/or quantity of drug release to the cytoplasm are needed to enhance cytosolic delivery and to circumvent nonproductive cell trafficking routes. We have previously demonstrated that poly(2-ethylacrylic acid) (PEAAc) has pH-dependent hemolytic properties, and more recently, we have found that poly(2-propylacrylic acid) (PPAAc) displays even greater pH-responsive hemolytic activity than PEAAc at the acidic pHs of the early endosome. Thus, these polymers could potentially serve as endosomal releasing agents in immunotoxin therapies. In this paper, we have investigated whether the pH-dependent membrane disruptive activity of PPAAc is retained after binding to a protein. We did this by measuring the hemolytic activity of PPAAc-streptavidin model complexes with different protein to polymer stoichiometries. Biotin was conjugated to amine-terminated PPAAc, which was subsequently bound to streptavidin by biotin complexation. The ability of these samples to disrupt red blood cell membranes was investigated for a range of polymer concentrations, a range of pH values, and two polymer-to-streptavidin ratios of 3:1 and 1:1. The results demonstrate that (a) the PPAAc-streptavidin complex retains the ability to lyse the RBC lipid bilayers at low pHs, such as those existing in endosomes, and (b) the hemolytic ability of the PPAAc-streptavidin complex is similar to that of the free PPAAc.

Zinc(II) and Cadmium(II) coordination polymers constructed from phenylenediacetate ligands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sezer, Güneş Günay; Department of Chemistry, Eskişehir Osmangazi University, Eskişehir; Yeşilel, Okan Zafer

ABSTRACT: A series of new coordination polymers {[Zn(μ-opda)(μ-bpa)]·2H_2O}{sub n} (1), [Zn(μ{sub 3}-ppda)(μ-bpa)]{sub n} (2), [Cd(μ{sub 3}-ppda)(μ-bpa)]{sub n} (3), [Cd(μ{sub 3}-mpda)(μ-bpa)]{sub n} (4) and [Cd(μ{sub 3}-mpda)(μ-bipy)]{sub n} (5), (o/m/ppda=1,2/1,3/1,4-phenylenediacetate, bpa=1,2-bi(4-pyridyl)ethane, bipy=4,4′-bipyridine) were synthesized. Their structures were characterized by elemental analysis, IR spectroscopy, single-crystal and powder X-ray diffraction. Furthermore, the effect of metal sources (zinc acetate and zinc oxide) and acidity of the solution on the structure of the coordination polymers was discussed for complexes 1 and 5, respectively. The single-crystal X-ray crystallographic studies revealed that complexes 1, 3, 4 and 5 are uninodal (4)-connected 2D frameworks and display sql topology withmore » the point symbol of (4{sup 4}.6{sup 2}). Complex 2 is 3D coordination polymer and exhibits pcu topology with the point symbol of (4{sup 12}.6{sup 3}). In addition, the luminescent properties and thermal behavior of all complexes were also investigated. - Graphical abstract: Scheme 1. Topologies of Coordination Polymers Reported in This Paper.« less

Microencapsulation of sulforaphane from broccoli seed extracts by gelatin/gum arabic and gelatin/pectin complexes.

PubMed

García-Saldaña, Jesús S; Campas-Baypoli, Olga N; López-Cervantes, Jaime; Sánchez-Machado, Dalia I; Cantú-Soto, Ernesto U; Rodríguez-Ramírez, Roberto

2016-06-15

Sulforaphane is a phytochemical that has received attention in recent years due to its chemopreventive properties. However, the uses and applications of this compound are very limited, because is an unstable molecule that is degraded mainly by changes in temperature and pH. In this research, the use of food grade polymers for microencapsulation of sulforaphane was studied by a complex coacervation method using the interaction of oppositely charged polymers as gelatin/gum arabic and gelatin/pectin. The polymers used were previously characterized in moisture content, ash and nitrogen. The encapsulation yield was over 80%. The gelatin/pectin complex had highest encapsulation efficiency with 17.91%. The presence of sulforaphane in the complexes was confirmed by FTIR and UV/visible spectroscopy. The materials used in this work could be a new and attractive option for the protection of sulforaphane. Copyright © 2016 Elsevier Ltd. All rights reserved.

Design guidelines for adapting scientific research articles: An example from an introductory level, interdisciplinary program on soft matter

NASA Astrophysics Data System (ADS)

Langbeheim, Elon; Safran, Samuel A.; Yerushalmi, Edit

2013-01-01

We present design guidelines for using Adapted Primary Literature (APL) as part of current interdisciplinary topics to introductory physics students. APL is a text genre that allows students to comprehend a scientific article, while maintaining the core features of the communication among scientists, thus representing an authentic scientific discourse. We describe the adaptation of a research paper by Nobel Laureate Paul Flory on phase equilibrium in polymer-solvent mixtures that was presented to high school students in a project-based unit on soft matter. The adaptation followed two design strategies: a) Making explicit the interplay between the theory and experiment. b) Re-structuring the text to map the theory onto the students' prior knowledge. Specifically, we map the theory of polymer-solvent systems onto a model for binary mixtures of small molecules of equal size that was already studied in class.

Fluorescence spectroscopy and molecular weight distribution of extracellular polymers from full-scale activated sludge biomass.

PubMed

Esparza-Soto, M; Westerhoff, P K

2001-01-01

Two fractions of extracellular polymer substances (EPSs), soluble and readily extractable (RE), were characterised in terms of their molecular weight distributions (MWD) and 3-D excitation-emission-matrix (EEM) fluorescence spectroscopy signatures. The EPS fractions were different: the soluble EPSs were composed mainly of high molecular weight compounds, while the RE EPSs were composed of small molecular weight compounds. Contrary to previous thought, EPS may not be considered only as macromolecular because most organic matter present in both fractions had low molecular weight. Three different fluorophore peaks were identified in the EEM fluorescence spectra. Two peaks were attributed to protein-like fluorophores, and the third to a humic-like fluorophore. Fluorescence signatures were different from other previously published signatures for marine and riverine environments. EEM spectroscopy proved to be a suitable method that may be used to characterise and trace organic matter of bacterial origin in wastewater treatment operations.

Phospholipid imprinted polymers as selective endotoxin scavengers

NASA Astrophysics Data System (ADS)

Sulc, Robert; Szekely, Gyorgy; Shinde, Sudhirkumar; Wierzbicka, Celina; Vilela, Filipe; Bauer, David; Sellergren, Börje

2017-03-01

Herein we explore phospholipid imprinting as a means to design receptors for complex glycolipids comprising the toxic lipopolysaccharide endotoxin. A series of polymerizable bis-imidazolium and urea hosts were evaluated as cationic and neutral hosts for phosphates and phosphonates, the latter used as mimics of the phospholipid head groups. The bis-imidazolium hosts interacted with the guests in a cooperative manner leading to the presence of tight and well defined 1:2 ternary complexes. Optimized monomer combinations were subsequently used for imprinting of phosphatidic acid as an endotoxin dummy template. Presence of the aforementioned ternary complexes during polymerization resulted in imprinting of lipid dimers - the latter believed to crudely mimic the endotoxin Lipid A motif. The polymers were characterized with respect to template rebinding, binding affinity, capacity and common structural properties, leading to the identification of polymers which were thereafter subjected to an industrially validated endotoxin removal test. Two of the polymers were capable of removing endotoxin down to levels well below the accepted threshold (0.005 EU/mg API) in pharmaceutical production.

Graphene Oxide-Polymer Composite Langmuir Films Constructed by Interfacial Thiol-Ene Photopolymerization

NASA Astrophysics Data System (ADS)

Luo, Xiaona; Ma, Kai; Jiao, Tifeng; Xing, Ruirui; Zhang, Lexin; Zhou, Jingxin; Li, Bingbing

2017-02-01

The effective synthesis and self-assembly of graphene oxide (GO) nanocomposites are of key importance for a broad range of nanomaterial applications. In this work, a one-step chemical strategy is presented to synthesize stable GO-polymer Langmuir composite films by interfacial thiol-ene photopolymerization at room temperature, without use of any crosslinking agents and stabilizing agents. It is discovered that photopolymerization reaction between thiol groups modified GO sheets and ene in polymer molecules is critically responsible for the formation of the composite Langmuir films. The film formed by Langmuir assembly of such GO-polymer composite films shows potential to improve the mechanical and chemical properties and promotes the design of various GO-based nanocomposites. Thus, the GO-polymer composite Langmuir films synthesized by interfacial thiol-ene photopolymerization with such a straightforward and clean manner, provide new alternatives for developing chemically modified GO-based hybrid self-assembled films and nanomaterials towards a range of soft matter and graphene applications.

Electropositive bivalent metallic ion unsaturated polyester complexed polymer concrete

DOEpatents

Sugama, T.; Kukacka, L.E.; Horn, W.H.

1983-05-13

Quick setting polymer concrete compositions are described which are mixtures of unsaturated polyesters and crosslinking monomers together with appropriate initiators and promoters in association with aggregate which may be wet and a source of bivalent metallic ions which will set to polymer concrete with excellent structural properties.

Synthesis, structure, luminescence and photocatalytic properties of an uranyl-2,5-pyridinedicarboxylate coordination polymer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Si, Zhen-Xiu; Xu, Wei, E-mail: xuwei@nbu.edu.cn; Zheng, Yue-Qing, E-mail: yqzhengmc@163.com

2016-07-15

An uranium coordination polymer, namely [(UO{sub 2}(pydc)(H{sub 2}O)]·H{sub 2}O (1) (H{sub 2}pydc=2,5-pyridinedicarboxylic acid), has been obtained by hydrothermal method and characterized by X-ray single crystal structure determination. Structural analysis reveals that complex 1 exhibits 1D chain coordination polymer, in which UO{sub 2}{sup 2+} ions are bridged by 2,5-pyridinedicarboxylate ligands and the chains are connected into a 3D supramolecular network by O–H···O hydrogen bond interactions and π–π stacking interactions. The photocatalytic properties of 1 for degradation of methylene blue (MB), Rhodamine B (RhB) and methyl orange (MO) under Hg-lamp irradiation have been performed, and the amount of the catalyst as wellmore » as Hg-lamp irradiation with different power on the photodegradation efficiency of MB have been investigated. Elemental analyses, infrared spectroscopy, TG-DTA analyses and luminescence properties were also discussed. - Graphical abstract: Complex 1 exhibits 1D chain coordination polymer in which UO{sub 2}{sup 2+} ions are bridged by 2,5-pyridinedicarboxylate ligand. Photoluminescence studies reveal that complex 1 exhibits characteristic emissions of uranyl centers. The compound is selective to degraded dye and displays good photocatalytic activities for the degradation of MB under Hg-lamp. Display Omitted - Highlights: • Complex 1 exhibits 1D chain coordination polymer. • Complex 1 could degrade methylene blue and Rhodamine B under Hg-lamp irradiation. • Luminescent property of 1 has been studied.« less

Responsive Guest Encapsulation of Dynamic Conjugated Microporous Polymers.

PubMed

Xu, Lai; Li, Youyong

2016-06-30

The host-guest complexes of conjugated microporous polymers encapsulating C60 and dye molecules have been investigated systematically. The orientation of guest molecules inside the cavities, have different terms: inside the open cavities of the polymer, or inside the cavities formed by packing different polymers. The host backbone shows responsive dynamic behavior in order to accommodate the size and shape of incoming guest molecule or guest aggregates. Simulations show that the host-guest binding of conjugated polymers is stronger than that of non-conjugated polymers. This detailed study could provide a clear picture for the host-guest interaction for dynamic conjugated microporous polymers. The mechanism obtained could guide designing new conjugated microporous polymers.

Measurement of the complex permittivity of low loss polymer powders in the millimeter-wave range.

PubMed

Kapilevich, Boris; Litvak, Boris; Wainstein, Vladimir; Moshe, Danny

2007-01-01

An improved measurement method of complex permittivity of low loss polymer powders is suggested. The measurements are done in the mm-wave range using a quasi optical resonator. The 2-D corrugated mode exciter is employed to improve suppression of undesirable higher modes. The model used for reconstructing complex permittivity takes into account ohm losses of metal mesh coupling that provide better accuracy of the reconstructing procedure. An example illustrating this method is reported.

Nanoparticles from renewable polymers

PubMed Central

Wurm, Frederik R.; Weiss, Clemens K.

2014-01-01

The use of polymers from natural resources can bring many benefits for novel polymeric nanoparticle systems. Such polymers have a variety of beneficial properties such as biodegradability and biocompatibility, they are readily available on large scale and at low cost. As the amount of fossil fuels decrease, their application becomes more interesting even if characterization is in many cases more challenging due to structural complexity, either by broad distribution of their molecular weights (polysaccharides, polyesters, lignin) or by complex structure (proteins, lignin). This review summarizes different sources and methods for the preparation of biopolymer-based nanoparticle systems for various applications. PMID:25101259

Complex and biofluids: From Maxwell to nowadays

NASA Astrophysics Data System (ADS)

Misbah, Chaouqi

2009-11-01

Complex fluids are the rule in biology and in many industrial applications. Typical examples are blood, cartilage, and polymer solutions. Unlike water (as well as domestic oils, soft clear drinks, and so on), the law(s) describing the behavior of complex fluids are not yet fully established. The complexity arises from strong coupling between microscopic scales (like the motion of a red blood cell in the case of blood, or a polymer molecule for a polymer solution) and the global scale of the flow (say at the scale of a blood artery, or a channel in laboratory experiments). In this issue entitled Complex and Biofluids a large panel of experimental and theoretical problems of complex fluids is exposed. The topics range from dilute polymer solutions, food products, to biology (blood flow, cell and tissue mechanics). One of the earliest model put forward as an attempt to describe a complex fluid was suggested a long time ago by James Clerk Maxwell (in 1867). Other famous scientists, like Einstein (in 1906), and Taylor (in 1932) have made important contributions to the field, but the topic of complex fluids still continues to pose a formidable challenge to science. This field has known during the past decade an unbelievable upsurge of interest in many branches of science (physics, mechanics, chemistry, biology, medical science, mathematics, and so on). Understanding complex fluids is viewed as one of the biggest challenge of the present century. This synthesis will provide a simple introduction to the topic, summarize the main contribution of this issue, and list major open questions in this field. To cite this article: C. Misbah, C. R. Physique 10 (2009).

Complexes of silver(I) ions and silver phosphate nanoparticles with hyaluronic acid and/or chitosan as promising antimicrobial agents for vascular grafts.

PubMed

Chudobova, Dagmar; Nejdl, Lukas; Gumulec, Jaromir; Krystofova, Olga; Rodrigo, Miguel Angel Merlos; Kynicky, Jindrich; Ruttkay-Nedecky, Branislav; Kopel, Pavel; Babula, Petr; Adam, Vojtech; Kizek, Rene

2013-06-28

Polymers are currently widely used to replace a variety of natural materials with respect to their favourable physical and chemical properties, and due to their economic advantage. One of the most important branches of application of polymers is the production of different products for medical use. In this case, it is necessary to face a significant disadvantage of polymer products due to possible and very common colonization of the surface by various microorganisms that can pose a potential danger to the patient. One of the possible solutions is to prepare polymer with antibacterial/antimicrobial properties that is resistant to bacterial colonization. The aim of this study was to contribute to the development of antimicrobial polymeric material ideal for covering vascular implants with subsequent use in transplant surgery. Therefore, the complexes of polymeric substances (hyaluronic acid and chitosan) with silver nitrate or silver phosphate nanoparticles were created, and their effects on gram-positive bacterial culture of Staphylococcus aureus were monitored. Stages of formation of complexes of silver nitrate and silver phosphate nanoparticles with polymeric compounds were characterized using electrochemical and spectrophotometric methods. Furthermore, the antimicrobial activity of complexes was determined using the methods of determination of growth curves and zones of inhibition. The results of this study revealed that the complex of chitosan, with silver phosphate nanoparticles, was the most suitable in order to have an antibacterial effect on bacterial culture of Staphylococcus aureus. Formation of this complex was under way at low concentrations of chitosan. The results of electrochemical determination corresponded with the results of spectrophotometric methods and verified good interaction and formation of the complex. The complex has an outstanding antibacterial effect and this effect was of several orders higher compared to other investigated complexes.

Complexes of Silver(I) Ions and Silver Phosphate Nanoparticles with Hyaluronic Acid and/or Chitosan as Promising Antimicrobial Agents for Vascular Grafts

PubMed Central

Chudobova, Dagmar; Nejdl, Lukas; Gumulec, Jaromir; Krystofova, Olga; Rodrigo, Miguel Angel Merlos; Kynicky, Jindrich; Ruttkay-Nedecky, Branislav; Kopel, Pavel; Babula, Petr; Adam, Vojtech; Kizek, Rene

2013-01-01

Polymers are currently widely used to replace a variety of natural materials with respect to their favourable physical and chemical properties, and due to their economic advantage. One of the most important branches of application of polymers is the production of different products for medical use. In this case, it is necessary to face a significant disadvantage of polymer products due to possible and very common colonization of the surface by various microorganisms that can pose a potential danger to the patient. One of the possible solutions is to prepare polymer with antibacterial/antimicrobial properties that is resistant to bacterial colonization. The aim of this study was to contribute to the development of antimicrobial polymeric material ideal for covering vascular implants with subsequent use in transplant surgery. Therefore, the complexes of polymeric substances (hyaluronic acid and chitosan) with silver nitrate or silver phosphate nanoparticles were created, and their effects on gram-positive bacterial culture of Staphylococcus aureus were monitored. Stages of formation of complexes of silver nitrate and silver phosphate nanoparticles with polymeric compounds were characterized using electrochemical and spectrophotometric methods. Furthermore, the antimicrobial activity of complexes was determined using the methods of determination of growth curves and zones of inhibition. The results of this study revealed that the complex of chitosan, with silver phosphate nanoparticles, was the most suitable in order to have an antibacterial effect on bacterial culture of Staphylococcus aureus. Formation of this complex was under way at low concentrations of chitosan. The results of electrochemical determination corresponded with the results of spectrophotometric methods and verified good interaction and formation of the complex. The complex has an outstanding antibacterial effect and this effect was of several orders higher compared to other investigated complexes. PMID:23812079

Rheological and tribological study of complex soft gels containing polymer, phospholipids, oil, and water

NASA Astrophysics Data System (ADS)

Farias, Barbara; Hsiao, Lilian; Khan, Saad

Oil-in-water emulsions with polymers are widely used for personal care products. Since the accumulation of traditional surfactants on the skin can promote irritation, an alternative is the use of hydrogenated phosphatidylcholine (HPC), a phospholipid that can form a lamellar structure similar to the skin barrier. This research aims to investigate the effect of composition on the rheological and tribological characteristics in complex systems containing HPC. For tribology experiments we used a soft model contacts made of polydimethylsiloxane (PDMS), while for bulk rheology studies we used dynamic and steady shear experiments. We examine how the addition of polymer, HPC and oil affects friction coefficients, lubrication regimes, viscoelasticity, yield stress, and gel formation. The bulk rheology shows that the studied systems are shear thinning and have gel-like behavior. The effect of each component was investigated by going from simple to more complex systems. The Stribeck curves obtained are related to the bulk rheology results to obtain physical insights into these complex systems. The results suggest that the polymer and phospholipids are being adsorbed onto the PDMS surface, reducing the friction coefficient at lower entrainment speeds.

PREFACE: International Symposium on Non-Equilibrium Soft Matter 2010 International Symposium on Non-Equilibrium Soft Matter 2010

NASA Astrophysics Data System (ADS)

Kawakatsu, T.; Matsuyama, A.; Ohta, T.; Tanaka, H.; Tanaka, S.

2011-07-01

Soft matter is a rapidly growing interdisciplinary research field covering a range of subject areas including physics, chemistry, biology, mathematics and engineering. Some of the important universal features of these materials are their mesoscopic structures and their dynamics. Due to the existence of such large-scale structures, which nevertheless exhibit interactions of the order of the thermal energy, soft matter can readily be taken out of equilibrium by imposing a weak external field such as an electric field, a mechanical stress or a shear flow. The importance of the coexistence of microscopic molecular dynamics and the mesoscopic/macroscopic structures and flows requires us to develop hierarchical approaches to understand the nonlinear and nonequilibrium phenomena, which is one of the central issues of current soft matter research. This special section presents selected contributions from the 'International Symposium on Non-Equilibrium Soft Matter 2010' held from 17-20 August 2010 in Nara, Japan, which aimed to describe recent advances in soft matter research focusing especially on its nonequilibrium aspects. The topics discussed cover statics and dynamics of a wide variety of materials ranging from traditional soft matter like polymers, gels, emulsions, liquid crystals and colloids to biomaterials such as biopolymers and biomembranes. Among these studies, we highlighted the physics of biomembranes and vesicles, which has attracted great attention during the last decade; we organized a special session for this active field. The work presented in this issue deals with (1) structure formation in biomembranes and vesicles, (2) rheology of polymers and gels, (3) mesophases in block copolymers, (4) mesoscopic structures in liquid crystals and ionic liquids, and (5) nonequilibrium dynamics. This symposium was organized as part of a research project supported by the Grant-in-Aid for the priority area 'Soft Matter Physics' (2006-2010) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan. We thank those who contributed to this symposium as well as members of the 'Soft Matter Physics' project for their valuable discussions and collaborations. Non-equilibrium soft matter contents Insights on raft behavior from minimal phenomenological models G Garbès Putzel and M Schick Dynamical membrane curvature instability controlled by intermonolayer friction Anne-Florence Bitbol, Jean-Baptiste Fournier, Miglena I Angelova and Nicolas Puff Numerical investigations of the dynamics of two-component vesicles Takashi Taniguchi, Miho Yanagisawa and Masayuki Imai Asymmetric distribution of cone-shaped lipids in a highly curved bilayer revealed by a small angle neutron scattering technique Y Sakuma, N Urakami, T Taniguchi and M Imai Hydration, phase separation and nonlinear rheology of temperature-sensitive water-soluble polymers Fumihiko Tanaka, Tsuyoshi Koga, Isamu Kaneda and Françoise M Winnik Morphology and rheology of an immiscible polymer blend subjected to a step electric field under shear flow H Orihara, Y Nishimoto, K Aida, Y H Na, T Nagaya and S Ujiie Surfactant-induced friction reduction for hydrogels in the boundary lubrication regime Kosuke Kamada, Hidemitsu Furukawa, Takayuki Kurokawa, Tomohiro Tada, Taiki Tominaga, Yukihiro Nakano and Jian Ping Gong Fabrication and structural analysis of polyrotaxane fibers and films Yasuhiro Sakai, Kentaro Ueda, Naoya Katsuyama, Koji Shimizu, Shunya Sato, Jun Kuroiwa, Jun Araki, Akira Teramoto, Koji Abe, Hideaki Yokoyama and Kohzo Ito Micellization kinetics of diblock copolymers in a homopolymer matrix: a self-consistent field study Raghuram Thiagarajan and David C Morse Hierarchical self-assembly of two-length-scale multiblock copolymers Gerrit ten Brinke, Katja Loos, Ivana Vukovic and Gerrit Gobius du Sart Kaleidoscopic morphologies from ABC star-shaped terpolymers Yushu Matsushita, Kenichi Hayashida, Tomonari Dotera and Atsushi Takano Direct and inverted nematic dispersions for soft matter photonics I Muševič, M Škarabot and M Humar Solvation effects in phase transitions in soft matter Akira Onuki, Takeaki Araki and Ryuichi Okamoto Non-equilibrium dynamics of 2D liquid crystals driven by transmembrane gas flow Kazuyoshi Seki, Ken Ueda, Yu-ichi Okumura and Yuka Tabe Roles of bond orientational ordering in glass transition and crystallization Hajime Tanaka Shear banding in thixotropic and normal emulsions José Paredes, Noushine Shahidzadeh-Bonn and Daniel Bonn Effects of hydrodynamic interactions in binary colloidal mixtures driven oppositely by oscillatory external fields Adam Wysocki and Hartmut Löwen Onsager's variational principle in soft matter Masao Doi

Method of preparation of removable syntactic foam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arnold, C. Jr.; Derzon, D.K.; Nelson, J.S.

1995-07-11

Easily removable, environmentally safe, low-density, syntactic foams are disclosed which are prepared by mixing insoluble microballoons with a solution of water and/or alcohol-soluble polymer to produce a pourable slurry, optionally vacuum filtering the slurry in varying degrees to remove unwanted solvent and solute polymer, and drying to remove residual solvent. The properties of the foams can be controlled by the concentration and physical properties of the polymer, and by the size and properties of the microballoons. The suggested solute polymers are non-toxic and soluble in environmentally safe solvents such as water or low-molecular weight alcohols. The syntactic foams produced bymore » this process are particularly useful in those applications where ease of removability is beneficial, and could find use in packaging recoverable electronic components, in drilling and mining applications, in building trades, in art works, in the entertainment industry for special effects, in manufacturing as temporary fixtures, in agriculture as temporary supports and containers and for delivery of fertilizer, in medicine as casts and splints, as temporary thermal barriers, as temporary protective covers for fragile objects, as filters for particulate matter, which matter may be easily recovered upon exposure to a solvent, as in-situ valves (for one-time use) which go from maximum to minimum impedance when solvent flows through, and for the automatic opening or closing of spring-loaded, mechanical switches upon exposure to a solvent, among other applications. 1 fig.« less

Self-consistent field theory of polymer-ionic molecule complexation.

PubMed

Nakamura, Issei; Shi, An-Chang

2010-05-21

A self-consistent field theory is developed for polymers that are capable of binding small ionic molecules (adsorbates). The polymer-ionic molecule association is described by Ising-like binding variables, C(i) ((a))(kDelta)(=0 or 1), whose average determines the number of adsorbed molecules, n(BI). Polymer gelation can occur through polymer-ionic molecule complexation in our model. For polymer-polymer cross-links through the ionic molecules, three types of solutions for n(BI) are obtained, depending on the equilibrium constant of single-ion binding. Spinodal lines calculated from the mean-field free energy exhibit closed-loop regions where the homogeneous phase becomes unstable. This phase instability is driven by the excluded-volume interaction due to the single occupancy of ion-binding sites on the polymers. Moreover, sol-gel transitions are examined using a critical degree of conversion. A gel phase is induced when the concentration of adsorbates is increased. At a higher concentration of the adsorbates, however, a re-entrance from a gel phase into a sol phase arises from the correlation between unoccupied and occupied ion-binding sites. The theory is applied to a model system, poly(vinyl alcohol) and borate ion in aqueous solution with sodium chloride. Good agreement between theory and experiment is obtained.

Manipulating Hydrophobic Interactions in Associative Polymer Solutions via Surfactant-Cyclodextrin Complexation

NASA Astrophysics Data System (ADS)

Talwar, Sachin; Harding, Jonathon; Khan, Saad A.

2008-07-01

Associative polymers in combination with cyclodextrin (CD) provide a potent tool to manipulate the solution rheology of aqueous solutions. In this study, we discuss the viability and scope of employing surfactants in such systems to facilitate a more versatile and effective tailoring of rheological properties. A model hydrophobically modified alkali-soluble emulsion (HASE) polymer is used which forms a transient physical network of intra- and inter-molecular hydrophobic junctions in solution arising from the interactions between hydrophobic groups grafted on the polymer backbone. The presence of these hydrophobic junctions significantly enhances the solution rheological properties with both the steady state viscosity and dynamic moduli exhibiting an increase by several orders of magnitude. The ability of nonionic surfactants to modulate and recover the hydrophobic interactions in these polymer solutions in the presence of cyclodextrin is examined. The presence of either a- or β-CD results in a dramatic decrease in viscosity and viscoelastic properties of the HASE polymer solution resulting from the encapsulation of polymer hydrophobes by CDs. Addition of nonionic surfactants to such systems promotes a competition between CDs and surfactant molecules to complex with polymer hydrophobes thereby altering the hydrophobic interactions. In this regard, nonylphenol ethoxylates (NPe) with different ethylene oxide (EO) chain lengths, which determine the surfactant hydrophilic-lipophilic balance (HLB), are used.

Drug Release Kinetics and Front Movement in Matrix Tablets Containing Diltiazem or Metoprolol/λ-Carrageenan Complexes

PubMed Central

Bonferoni, Maria Cristina; Colombo, Paolo; Zanelotti, Laura; Caramella, Carla

2014-01-01

In this work we investigated the moving boundaries and the associated drug release kinetics in matrix tablets prepared with two complexes between λ-carrageenan and two soluble model drugs, namely, diltiazem HCl and metoprolol tartrate aiming at clarifying the role played by drug/polymer interaction on the water uptake, swelling, drug dissolution, and drug release performance of the matrix. The two studied complexes released the drug with different mechanism indicating two different drug/polymer interaction strengths. The comparison between the drug release behaviour of the complexes and the relevant physical mixtures indicates that diltiazem gave rise to a less soluble and more stable complex with carrageenan than metoprolol. The less stable metoprolol complex afforded an erodible matrix, whereas the stronger interaction between diltiazem and carrageenan resulted in a poorly soluble, slowly dissolving matrix. It was concluded that the different stability of the studied complexes affords two distinct drug delivery systems: in the case of MTP, the dissociation of the complex, as a consequence of the interaction with water, affords a classical soluble matrix type delivery system; in the case of DTZ, the dissolving/diffusing species is the complex itself because of the very strong interaction between the drug and the polymer. PMID:25045689

Drug release kinetics and front movement in matrix tablets containing diltiazem or metoprolol/λ-carrageenan complexes.

PubMed

Bettini, Ruggero; Bonferoni, Maria Cristina; Colombo, Paolo; Zanelotti, Laura; Caramella, Carla

2014-01-01

In this work we investigated the moving boundaries and the associated drug release kinetics in matrix tablets prepared with two complexes between λ-carrageenan and two soluble model drugs, namely, diltiazem HCl and metoprolol tartrate aiming at clarifying the role played by drug/polymer interaction on the water uptake, swelling, drug dissolution, and drug release performance of the matrix. The two studied complexes released the drug with different mechanism indicating two different drug/polymer interaction strengths. The comparison between the drug release behaviour of the complexes and the relevant physical mixtures indicates that diltiazem gave rise to a less soluble and more stable complex with carrageenan than metoprolol. The less stable metoprolol complex afforded an erodible matrix, whereas the stronger interaction between diltiazem and carrageenan resulted in a poorly soluble, slowly dissolving matrix. It was concluded that the different stability of the studied complexes affords two distinct drug delivery systems: in the case of MTP, the dissociation of the complex, as a consequence of the interaction with water, affords a classical soluble matrix type delivery system; in the case of DTZ, the dissolving/diffusing species is the complex itself because of the very strong interaction between the drug and the polymer.

Polymer dynamics driven by a helical filament

NASA Astrophysics Data System (ADS)

Balin, Andrew; Shendruk, Tyler; Zoettl, Andreas; Yeomans, Julia

Microbial flagellates typically inhabit complex suspensions of extracellular polymeric material which can impact the swimming speed of motile microbes, filter-feeding of sessile cells, and the generation of biofilms. There is currently a need to better understand how the fundamental dynamics of polymers near active cells or flagella impacts these various phenomena. We study the hydrodynamic and steric influence of a rotating helical filament on suspended polymers using Stokesian Dynamics simulations. Our results show that as a stationary rotating helix pumps fluid along its long axis, nearby polymers migrate radially inwards and are elongated in the process. We observe that the actuation of the helix tends to increase the probability of finding polymeric material within its pervaded volume. At larger Weissenberg numbers, this accumulation of polymers within the vicinity of the helix is greater. Further, we have analysed the stochastic work performed by the helix on the polymers and we show that this quantity is positive on average and increases with polymer contour length. Our results provide a basis for understanding the microscopic interactions that govern cell dynamics in complex media. This work was supported through funding from the ERC Advanced Grant 291234 MiCE and we acknowledge EMBO funding to TNS (ALTF181-2013).

Novel polymer anchored Cr(III) Schiff base complexes: Synthesis, characterization and antimicrobial properties

NASA Astrophysics Data System (ADS)

Selvi, Canan; Nartop, Dilek

2012-09-01

New polymer-bound Schiff bases and Cr(III) complexes have been synthesized by the reaction of 4-benzyloxybenzaldehyde, polymer-bound with 2-aminophenol, 2-amino-4-chlorophenol and 2-amino-4-methylphenol. The structure of polymeric-Schiff bases and their Cr(III) complexes have been characterized by elemental analyses, magnetic measurements, IR, UV-Vis, TG-DTA and 1H-NMR. All these compounds have also been investigated for antibacterial activity by the well-diffusion method against Staphylococcus aureus (RSKK-07035), Shigella dysenteria type 10 (RSKK 1036), Listeria monocytogenes 4b(ATCC 19115, Escherichia coli (ATCC 1230), Salmonella typhi H (NCTC 901.8394), Staphylococcus epidermis (ATCC 12228), Brucella abortus (RSKK-03026), Micrococcs luteus (ATCC 93419, Bacillus cereus sp., Pseudomonas putida sp. and for antifungal activity against Candida albicans (Y-1200-NIH).

USING METHANOL-WATER SYSTEMS TO INVESTIGATE PHENANTHRENE SORPTION-DESORPTION ON SEDIMENT

EPA Science Inventory

Sorption isotherm nonlinearity, sorption-desorption hysteresis, slow desorption kinetics, and other nonideal phenomena have been attributed to the differing sorptive characteristics of the natural organic matter (NOM) polymers associated with soils and sediments. A conceptualizat...

Synthesis and study of conjugated polymers containing Di- or Triphenylamine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sukwattanasinitt, M.

1996-06-21

This thesis consists of two separate parts. The first part addresses the synthesis and study of conjugated polymers containing di- or triphenylamine. Two types of polymers: linear polymers and dendrimers, were synthesized. The polymers were characterized by NMR, IR, UV, GPC, TGA and DSC. Electronic and optical properties of the polymers were studied through the conductivity measurements and excitation- emission spectra. the second part of this thesis deals with a reaction of electron-rich acetylenes with TCNE. The discovery of the reaction from charge transfer complex studies and the investigation of this reaction on various electron-rich acetylenes are presented.

Simultaneous covalent and noncovalent hybrid polymerizations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Z.; Tantakitti, F.; Yu, T.

Covalent and supramolecular polymers are two distinct forms of soft matter, composed of long chains of covalently and noncovalently linked structural units, respectively. We report a hybrid system formed by simultaneous covalent and supramolecular polymerizations of monomers. The process yields cylindrical fibers of uniform diameter that contain covalent and supramolecular compartments, a morphology not observed when the two polymers are formed independently. The covalent polymer has a rigid aromatic imine backbone with helicoidal conformation, and its alkylated peptide side chains are structurally identical to the monomer molecules of supramolecular polymers. In the hybrid system, covalent chains grow to higher averagemore » molar mass relative to chains formed via the same polymerization in the absence of a supramolecular compartment. The supramolecular compartments can be reversibly removed and re-formed to reconstitute the hybrid structure, suggesting soft materials with novel delivery or repair functions.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tahir, Dahlang, E-mail: dtahir@fmipa.unhas.ac.id; Bakri, Fahrul; Liong, Syarifuddin

We have studied the molecular properties, structural properties, and chemical composition of composites by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, and X-ray fluorescence (XRF) spectroscopy, respectively. FTIR spectra shows absorption band of hydroxyl group (-OH), methyl group (-CH{sub 3}) and aromatic group (C-C). The absorption band for aromatic group (C-C) shows the formation of carbonaceous in composites. XRF shows chemical composition of composites, which the main chemicals are SO{sub 3}, Cl, and ZnO. The loss on ignition value (LOI) of activated charcoal indicates high carbonaceous matter. The crystallite size for diffraction pattern from hydrogel polymer is aboutmore » 17 nm and for activated charcoal are about 19 nm. The crystallite size of the polymer is lower than that of activated charcoal, which make possible of the particle from filler in contact with each other to form continuous conducting polymer through polymer matrix.« less

Comparison of nanoparticle diffusion using fluorescence correlation spectroscopy and differential dynamic microscopy within concentrated polymer solutions

NASA Astrophysics Data System (ADS)

Shokeen, Namita; Issa, Christopher; Mukhopadhyay, Ashis

2017-12-01

We studied the diffusion of nanoparticles (NPs) within aqueous entangled solutions of polyethylene oxide (PEO) by using two different optical techniques. Fluorescence correlation spectroscopy, a method widely used to investigate nanoparticle dynamics in polymer solution, was used to measure the long-time diffusion coefficient (D) of 25 nm radius particles within high molecular weight, Mw = 600 kg/mol PEO in water solutions. Differential dynamic microscopy (DDM) was used to determine the wave-vector dependent dynamics of NPs within the same polymer solutions. Our results showed good agreement between the two methods, including demonstration of normal diffusion and almost identical diffusion coefficients obtained by both techniques. The research extends the scope of DDM to study the dynamics and rheological properties of soft matter at a nanoscale. The measured diffusion coefficients followed a scaling theory, which can be explained by the coupling between polymer dynamics and NP motion.

Polymer-Based Protein Engineering: Synthesis and Characterization of Armored, High Graft Density Polymer-Protein Conjugates.

PubMed

Carmali, Sheiliza; Murata, Hironobu; Cummings, Chad; Matyjaszewski, Krzysztof; Russell, Alan J

2017-01-01

Atom transfer radical polymerization (ATRP) from the surface of a protein can generate remarkably dense polymer shells that serve as armor and rationally tune protein function. Using straightforward chemistry, it is possible to covalently couple or display multiple small molecule initiators onto a protein surface. The chemistry is fine-tuned to be sequence specific (if one desires a single targeted site) at controlled density. Once the initiator is anchored on the protein surface, ATRP is used to grow polymers on protein surface, in situ. The technique is so powerful that a single-protein polymer conjugate molecule can contain more than 90% polymer coating by weight. If desired, stimuli-responsive polymers can be "grown" from the initiated sites to prepare enzyme conjugates that respond to external triggers such as temperature or pH, while still maintaining enzyme activity and stability. Herein, we focus mainly on the synthesis of chymotrypsin-polymer conjugates. Control of the number of covalently coupled initiator sites by changing the stoichiometric ratio between enzyme and the initiator during the synthesis of protein-initiator complexes allowed fine-tuning of the grafting density. For example, very high grafting density chymotrypsin conjugates were prepared from protein-initiator complexes to grow the temperature-responsive polymers, poly(N-isopropylacrylamide), and poly[N,N'-dimethyl(methacryloyloxyethyl) ammonium propane sulfonate]. Controlled growth of polymers from protein surfaces enables one to predictably manipulate enzyme kinetics and stability without the need for molecular biology-dependent mutagenesis. © 2017 Elsevier Inc. All rights reserved.

House crickets can accumulate polybrominated diphenyl ethers (PBDEs) directly from polyurethane foam common in consumer products.

PubMed

Gaylor, Michael O; Harvey, Ellen; Hale, Robert C

2012-02-01

Polybrominated diphenyl ether (PBDE) flame retardants are added at percent levels to many polymers and textiles abundant in human spaces and vehicles, wherein they have been long assumed to be tightly sequestered. However, the mgkg(-1) burdens recently detected in indoor dust testify to substantial releases. The bulk of released PBDEs remain in the terrestrial environment, yet comparatively little research focuses on this compartment. There, insects/arthropods, such as crickets, are the most abundant invertebrate organisms and facilitate the trophic transfer of contaminants by breaking down complex organic matter (including discarded polymers) and serving as food for other organisms. Our experiments revealed that house crickets (Acheta domesticus) provided uncontaminated food and free access to PUF containing Penta-BDE (8.7%drywt) for 28 d accumulated substantial PBDE body burdens. Crickets allowed to depurate gut contents exhibited whole body burdens of up to 13.4 mg kg(-1) lipid ΣPenta-BDE, 1000-fold higher than typically reported in humans. Non-depurated crickets and molted exoskeletons incurred even higher ΣPenta-BDE, up to 80.6 and 63.3 mg kg(-1) lipid, respectively. Congener patterns of whole crickets and molts resembled those of PUF and the commercial Penta-BDE formulation, DE-71, indicative of minimal discrimination or biotransformation. Accumulation factor (AF) calculations were hampered by uncertainties in determining actual PUF ingestion. However, estimated AFs were low, in the range of 10(-4)-10(-3), suggesting that polymer-PBDE interactions limited uptake. Nonetheless, results indicate that substantial PBDE burdens may be incurred by insects in contact with current-use and derelict treated polymers within human spaces and solid waste disposal sites (e.g. landfills, automotive dumps, etc.). Once ingested, even burdens not absorbed across the gut wall may be dispersed within proximate terrestrial food webs via the insect's movements and/or predation. Copyright © 2011 Elsevier Ltd. All rights reserved.

Lignins : natural polymers from oxidative coupling of 4-hydroxyphenyl-propanoids

Treesearch

John Ralph; Knut Lundquist; Gosta Brunow; Fachuang Lu; Hoon Kim; Paul F. Schatz; Jane M. Marita; Ronald D. Hatfield; Sally A. Ralph; Jorgen Holst Christensen; Wout Boerjan

2004-01-01

Lignins are complex natural polymers resulting from oxidative coupling of, primarily, 4-hydroxyphenylpropanoids. An understanding of their nature is evolving as a result of detailed structural studies, recently aided by the availability of lignin-biosynthetic-pathway mutants and transgenics. The currently accepted theory is that the lignin polymer is formed by...

Heterobimetallic coordination polymers involving 3d metal complexes and heavier transition metals cyanometallates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peresypkina, Eugenia V.; Samsonenko, Denis G.; Novosibirsk State University, Novosibirsk 630090

The results of the first steps in the design of coordination polymers based on penta- and heptacyanometallates of heavier d transitions metals are presented. The 2D structure of the coordination polymers: [(Mn(acacen)){sub 2}Ru(NO)(CN){sub 5}]{sub n} and two complexes composed of different cyanorhenates, [Ni(cyclam)]{sub 2}[ReO(OH)(CN){sub 4}](ClO{sub 4}){sub 2}(H{sub 2}O){sub 1.25} and [Cu(cyclam)]{sub 2}[Re(CN){sub 7}](H{sub 2}O){sub 12}, was confirmed by single crystal XRD study, the rhenium oxidation state having been proved by the magnetic measurements. An amorphism of [M(cyclam)]{sub 3}[Re(CN){sub 7}]{sub 2} (M=Ni, Cu) polymers does not allow to define strictly their dimensionality and to model anisotropic magnetic behavior of the compounds.more » However, with high probability a honey-comb like layer structure could be expected for [M(cyclam)]{sub 3}[Re(CN){sub 7}]{sub 2} complexes, studied in this work, because such an arrangement is the most common among the bimetallic assemblies of hexa- and octacyanometallates with a ratio [M(cyclam)]/[M(CN){sub n}]=3/2. For the first time was prepared and fully characterized a precursor (n-Bu{sub 4}N){sub 2}[Ru(NO)(CN){sub 5}], soluble in organic media. - Graphical abstract: The very first results in the design of 2D coordination polymers based on penta- and heptacyanometallates of 4d and5d transitions metals are presented. - Highlights: • Design of coordination polymers based on penta- and heptacyanometallates. • New Ru and Re cyanide based heterobimetallic coordination complexes. • Hydrolysis and ox/red processes involving [Re(CN){sub 7}]{sup 3+} during crystallization. • High magnetic anisotropy of [M(cyclam)]{sub 3}[Re(CN){sub 7}]{sub 2}(H{sub 2}O){sub n}, M=Cu, Ni, complexes.« less

Multifunctional PHPMA-Derived Polymer for Ratiometric pH Sensing, Fluorescence Imaging, and Magnetic Resonance Imaging.

PubMed

Su, Fengyu; Agarwal, Shubhangi; Pan, Tingting; Qiao, Yuan; Zhang, Liqiang; Shi, Zhengwei; Kong, Xiangxing; Day, Kevin; Chen, Meiwan; Meldrum, Deirdre; Kodibagkar, Vikram D; Tian, Yanqing

2018-01-17

In this paper, we report synthesis and characterization of a novel multimodality (MRI/fluorescence) probe for pH sensing and imaging. A multifunctional polymer was derived from poly(N-(2-hydroxypropyl)methacrylamide) (PHPMA) and integrated with a naphthalimide-based-ratiometric fluorescence probe and a gadolinium-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid complex (Gd-DOTA complex). The polymer was characterized using UV-vis absorption spectrophotometry, fluorescence spectrofluorophotometry, magnetic resonance imaging (MRI), and confocal microscopy for optical and MRI-based pH sensing and cellular imaging. In vitro labeling of macrophage J774 and esophageal CP-A cell lines shows the polymer's ability to be internalized in the cells. The transverse relaxation time (T 2 ) of the polymer was observed to be pH-dependent, whereas the spin-lattice relaxation time (T 1 ) was not. The pH probe in the polymer shows a strong fluorescence-based ratiometric pH response with emission window changes, exhibiting blue emission under acidic conditions and green emission under basic conditions, respectively. This study provides new materials with multimodalities for pH sensing and imaging.

The interplay of ion crosslinking, free ion content, and polymer mobility in PEO-based single-ion conductors

NASA Astrophysics Data System (ADS)

Lin, Kan-Ju; Maranas, Janna

2010-03-01

We use molecular dynamics simulation to study ion clustering and dynamics in ion containing polymers. This PEO based single-ion conducting ionomer serves as a model system for understanding cation transport in solid state polymer electrolytes (SPEs). Although small-angle x-ray scattering does not show an ionomer peak, we observer various cation-anion complexes in the simulation, suggesting ionomer backbones are crosslinked through ion complexes. These crosslinks reduce the adjacent PEO mobility resulting in a symmetric mobility gradient along the PEO chain. We vary the cation-anion interaction in the simulation to observe the interplay of cation-anion association, polymer mobility and cation motion. Cation-anion association controls the number of free ions, which is important in ionic conductivity when these materials are used as SPEs. Polymer mobility controls how fast the free ions are able to move through the SPE. High conductivity requires both a high free ion content and fast polymer motion. To understand the connection between the two, we ``tune'' the force field in order to manipulate the free ion content and observe the influence on PEO dynamics.

Crowding, Entropic Forces, and Confinement: Crucial Factors for Structures and Functions in the Cell Nucleus.

PubMed

Hancock, R

2018-04-01

The view of the cell nucleus as a crowded system of colloid particles and that chromosomes are giant self-avoiding polymers is stimulating rapid advances in our understanding of its structure and activities, thanks to concepts and experimental methods from colloid, polymer, soft matter, and nano sciences and to increased computational power for simulating macromolecules and polymers. This review summarizes current understanding of some characteristics of the molecular environment in the nucleus, of how intranuclear compartments are formed, and of how the genome is highly but precisely compacted, and underlines the crucial, subtle, and sometimes unintuitive effects on structures and reactions of entropic forces caused by the high concentration of macromolecules in the nucleus.

Transmission electron microscopy of polymer blends and block copolymers

NASA Astrophysics Data System (ADS)

Gomez, Enrique Daniel

Transmission electron microscopy (TEM) of soft matter is a field that warrants further investigation. Developments in sample preparation, imaging and spectroscopic techniques could lead to novel experiments that may further our understanding of the structure and the role structure plays in the functionality of various organic materials. Unlike most hard materials, TEM of organic molecules is limited by the amount of radiation damage the material can withstand without changing its structure. Despite this limitation, TEM has been and will be a powerful tool to study polymeric materials and other soft matter. In this dissertation, an introduction of TEM for polymer scientists is presented. The fundamentals of interactions of electrons with matter are described using the Schrodinger wave equation and scattering cross-sections to fully encompass coherent and incoherent scattering. The intensity, which is the product of the wave function and its complex conjugate, shows no perceptible change due to the sample. Instead, contrast is generated through the optical system of the microscope by removing scattered electrons or by generating interference due to material-induced phase changes. Perhaps the most challenging aspect of taking TEM images, however, is sample preparation, because TEM experiments require materials with approximately 50 nm thickness. Although ultramicrotomy is a well-established powerful tool for preparing biological and polymeric sections for TEM, the development of cryogenic Focused Ion Beam may enable unprecedented cross-sectional TEM studies of polymer thin films on arbitrary substrates with nanometer precision. Two examples of TEM experiments of polymeric materials are presented. The first involves quantifying the composition profile across a lamellar phase obtained in a multicomponent blend of saturated poly(butadiene) and poly(isobutylene), stabilized by a saturated poly(butadiene) copolymer serving as a surfactant, using TEM and self-consistent field theory (SCFT). The liquid-like nature of this system at room temperature makes traditional staining methods for the enhancement of contrast ineffective. As an alternative, we take advantage of the large inelastic scattering cross-section of soft materials to generate contrast in zero-loss TEM images. Independent spatially resolved thickness measurements enable quantification of electron scattering. This enabled a comparison between the TEM data and predictions based on SCFT without any adjustable parameters. The second example involves the utilization of energy-filtered transmission electron microscopy (EFTEM) to compute elemental maps by taking advantage of ionization events. Elemental mapping of lithium is used to determine the distribution of salt in nanostructured poly(styrene-block-ethylene oxide) (SEO) copolymer/lithium salt electrolytes. Surprisingly, the concentration of lithium within a poly(ethylene oxide) (PEO) domain is found to be inhomogeneous; the salt is localized to the middle of the channels. Self-consistent field theory simulations suggest that localization of lithium is due to chain stretching at the interface, which increases with molecular weight. EFTEM and SCFT results show that the segregation of lithium salt to the middle of the PEO lamellae is greater for higher molecular weight polymers. This is correlated with the ionic conductivity of the copolymer electrolyte, which is found to show a higher conductivity for thinner lithium lamellae.

Dissolving microneedles for DNA vaccination: Improving functionality via polymer characterization and RALA complexation

PubMed Central

Cole, Grace; McCaffrey, Joanne; Ali, Ahlam A.; McBride, John W.; McCrudden, Cian M.; Vincente-Perez, Eva M.; Donnelly, Ryan F.; McCarthy, Helen O.

2017-01-01

ABSTRACT DNA vaccination holds the potential to treat or prevent nearly any immunogenic disease, including cancer. To date, these vaccines have demonstrated limited immunogenicity in vivo due to the absence of a suitable delivery system which can protect DNA from degradation and improve transfection efficiencies in vivo. Recently, microneedles have been described as a novel physical delivery technology to enhance DNA vaccine immunogenicity. Of these devices, dissolvable microneedles promise a safe, pain-free delivery system which may simultaneously improve DNA stability within a solid matrix and increase DNA delivery compared to solid arrays. However, to date little work has directly compared the suitability of different dissolvable matrices for formulation of DNA-loaded microneedles. Therefore, the current study examined the ability of 4 polymers to formulate mechanically robust, functional DNA loaded dissolvable microneedles. Additionally, complexation of DNA to a cationic delivery peptide, RALA, prior to incorporation into the dissolvable matrix was explored as a means to improve transfection efficacies following release from the polymer matrix. Our data demonstrates that DNA is degraded following incorporation into PVP, but not PVA matrices. The complexation of DNA to RALA prior to incorporation into polymers resulted in higher recovery from dissolvable matrices, and increased transfection efficiencies in vitro. Additionally, RALA/DNA nanoparticles released from dissolvable PVA matrices demonstrated up to 10-fold higher transfection efficiencies than the corresponding complexes released from PVP matrices, indicating that PVA is a superior polymer for this microneedle application. PMID:27846370

Incorporation and Effects of Nanoparticles in a Supramolecular Polymer

DTIC Science & Technology

2016-05-01

Oak Ridge, TN Robert H Lambeth and Frederick L Beyer Weapons and Materials Research Directorate, ARL Approved for...nanocomposites: phase diagram, rheology and structure using a combined small angle neutron scattering and reverse Monte Carlo approach. Soft Matter. 2010;6

Nuclear alkylated pyridine aldehyde polymers and conductive compositions thereof

NASA Technical Reports Server (NTRS)

Rembaum, A.; Singer, S. (Inventor)

1970-01-01

A thermally stable, relatively conductive polymer was disclosed. The polymer was synthesized by condensing in the presence of catalyst a 2, 4, or 6 nuclear alklylated 2, 3, or 4 pyridine aldehyde or quaternary derivatives thereof to form a polymer. The pyridine groups were liked by olefinic groups between 2-4, 2-6, 2-3, 3-4, 3-6 or 4-6 positions. Conductive compositions were prepared by dissolving the quaternary polymer and an organic charge transfer complexing agent such as TCNQ in a mutual solvent such as methanol.

Report on the NASA Soft and Complex Condensed Matter Workshop

NASA Technical Reports Server (NTRS)

Singh, Bhim (Technical Monitor); Chaikin, Paul; Nagel, Sidney

2003-01-01

During the past decade, NASA has been a leading U.S. supporter of soft and complex condensed matter research. Experiments in space shuttles, MIR, the International Space Station (ISS), as well as ground-based research have provided new insights into several areas including hard sphere colloids, crystal growth, phase ordering, and transport of complex fluids at the critical point. To help define the next generation of flight experiments needed to answer remaining important questions in the field of soft and complex condensed matter, NASA's Office of Biological and Physical Science sponsored a workshop on Soft and Complex Condensed Matter, March 6, 2003. This workshop asked leading members in the field of Soft and Complex Condensed Matter (at the APS March Meeting) to help identify exciting unanswered questions in the field, along with specific research topics for which the absence of gravity would enable significant results unobtainable by other means. The workshop was attended by 24 participants from universities across the U.S. and from five different countries (in addition to NASA GRC participants).

Tandem catalysis: a new approach to polymers.

PubMed

Robert, Carine; Thomas, Christophe M

2013-12-21

The creation of polymers by tandem catalysis represents an exciting frontier in materials science. Tandem catalysis is one of the strategies used by Nature for building macromolecules. Living organisms generally synthesize macromolecules by in vivo enzyme-catalyzed chain growth polymerization reactions using activated monomers that have been formed within cells during complex metabolic processes. However, these biological processes rely on highly complex biocatalysts, thus limiting their industrial applications. In order to obtain polymers by tandem catalysis, homogeneous and enzyme catalysts have played a leading role in the last two decades. In the following feature article, we will describe selected published efforts to achieve these research goals.

Dispersions of Carbon nanotubes in Polymer Matrices

NASA Technical Reports Server (NTRS)

Wise, Kristopher Eric (Inventor); Park, Cheol (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor); Lillehei, Peter T. (Inventor); Lowther, Sharon E. (Inventor)

2010-01-01

Dispersions of carbon nanotubes exhibiting long term stability are based on a polymer matrix having moieties therein which are capable of a donor-acceptor complexation with carbon nanotubes. The carbon nanotubes are introduced into the polymer matrix and separated therein by standard means. Nanocomposites produced from these dispersions are useful in the fabrication of structures, e.g., lightweight aerospace structures.

Polymer dual ring resonators for label-free optical biosensing using microfluidics.

PubMed

Salleh, Muhammad H M; Glidle, Andrew; Sorel, Marc; Reboud, Julien; Cooper, Jonathan M

2013-04-18

We demonstrate a polymer resonator microfluidic biosensor that overcomes the complex manufacturing procedures required to fabricate traditional devices. In this new format, we show that a gapless light coupling photonic configuration, fabricated in SU8 polymer, can achieve high sensitivity, label-free chemical sensing in solution and high sensitivity biological sensing, at visible wavelengths.

Cyclic Peptide-Polymer Nanotubes as Efficient and Highly Potent Drug Delivery Systems for Organometallic Anticancer Complexes.

PubMed

Larnaudie, Sophie C; Brendel, Johannes C; Romero-Canelón, Isolda; Sanchez-Cano, Carlos; Catrouillet, Sylvain; Sanchis, Joaquin; Coverdale, James P C; Song, Ji-Inn; Habtemariam, Abraha; Sadler, Peter J; Jolliffe, Katrina A; Perrier, Sébastien

2018-01-08

Functional drug carrier systems have potential for increasing solubility and potency of drugs while reducing side effects. Complex polymeric materials, particularly anisotropic structures, are especially attractive due to their long circulation times. Here, we have conjugated cyclic peptides to the biocompatible polymer poly(2-hydroxypropyl methacrylamide) (pHPMA). The resulting conjugates were functionalized with organoiridium anticancer complexes. Small angle neutron scattering and static light scattering confirmed their self-assembly and elongated cylindrical shape. Drug-loaded nanotubes exhibited more potent antiproliferative activity toward human cancer cells than either free drug or the drug-loaded polymers, while the nanotubes themselves were nontoxic. Cellular accumulation studies revealed that the increased potency of the conjugate appears to be related to a more efficient mode of action rather than a higher cellular accumulation of iridium.

Polymer Directed Self-Assembly of pH-Responsive Antioxidant Nanoparticles

PubMed Central

Tang, Christina; Amin, Devang; Messersmith, Phillip B.; Anthony, John E.; Prud’homme, Robert K.

2015-01-01

We have developed pH-responsive, multifunctional nanoparticles based on encapsulation of an antioxidant, tannic acid (TA), using Flash NanoPrecipitation, a polymer directed self-assembly method. Formation of insoluble coordination complexes of tannic acid and iron during mixing drives nanoparticle assembly. Tuning the core material to polymer ratio, the size of the nanoparticles can be readily tuned between 50 and 265 nm. The resulting nanoparticle is pH-responsive, i.e. stable at pH 7.4 and soluble under acidic conditions due to the nature of the coordination complex. Further, the coordination complex can be coprecipitated with other hydrophobic materials such as therapeutics or imaging agents. For example, coprecipitation with a hydrophobic fluorescent dye creates fluorescent nanoparticles. In vitro, the nanoparticles have low cytotoxicity show antioxidant activity. Therefore, these particles may facilitate intracellular delivery of antioxidants. PMID:25760226

Self-Assembly and Responsiveness of Polypeptide-Based Star and Triblock Copolymers

NASA Astrophysics Data System (ADS)

Savin, Daniel

This study involves the bottom-up design and tunability of responsive, peptide-based block polymers. The self-assembly of amphiphilic block polymers is dictated primarily by the balance between the hydrophobic core volume and the hydrophilic corona. In these studies, amphiphilic triblock and star copolymers containing poly(lysine) (PK), poly(leucine) (PL) and poly(glutamic acid) (PE) were synthesized and their solution properties studied using dynamic light scattering, circular dichroism spectroscopy and transmission electron microscopy. The peptide block in these structures can serve to introduce pH responsiveness (in the case of PK and PE), or can facilitate the formation of elongated or kinetically-trapped structures (in the case of PL.) This talk will present some recent studies in solution morphology transitions that occur in these materials under varying solution conditions. As the topological complexity of the polymers increases from diblock to linear triblock or star polymers, the solution morphology and response becomes much more complex. We present a systematic series of structures, with increasing complexity, that have applications as passive and active delivery vehicles, hydrogels, and responsive viscosity modifiers. NSF CHE-1539347.

Role of microgel formation in scavenging of chromophoric dissolved organic matter and heavy metals in a river-sea system.

PubMed

Shiu, Ruei-Feng; Lee, Chon-Lin

2017-04-15

We use riverine and marine dissolved organic carbon (DOC) polymers to examine their aggregation behavior, and to evaluate the roles of microgel formation in scavenging of chromophoric dissolved organic matter (CDOM) and heavy metals in a river-sea system. Our results indicate that riverine and marine microgels did not exhibit very much difference in size and self-assembly curve; however, the assembly effectiveness ([microgel]/DOC) of marine samples was much higher than riverine. Instead of concentration of DOC, other factors such as types and sources of DOC polymers may control the microgel abundance in aquatic environments. After filtering water samples (microgels removed), the CDOM and selected metals (Cu, Ni, Mn) in the filtrate were quantified. CDOM and metals were concurrently removed to an extent via DOC polymer re-aggregation, which also suggested that the microgels had sequestering capability in CDOM and metals. This finding provides an alternative route for CDOM and heavy metals removal from the water column. As such the process of re-aggregation into microgels should then be considered besides traditional phase partitioning in the assessment of the ecological risk and fate of hazardous materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Liquid scintillators with near infrared emission based on organoboron conjugated polymers.

PubMed

Tanaka, Kazuo; Yanagida, Takayuki; Yamane, Honami; Hirose, Amane; Yoshii, Ryousuke; Chujo, Yoshiki

2015-11-15

The organic liquid scintillators based on the emissive polymers are reported. A series of conjugated polymers containing organoboron complexes which show the luminescence in the near infrared (NIR) region were synthesized. The polymers showed good solubility in common organic solvents. From the comparison of the luminescent properties of the synthesized polymers between optical and radiation excitation, similar emission bands were detected. In addition, less significant degradation was observed. These data propose that the organoboron conjugated polymers are attractive platforms to work as an organic liquid scintillator with the emission in the NIR region. Copyright © 2015 Elsevier Ltd. All rights reserved.

Control of Electron Flow Direction in Photoexcited Cycloplatinated Complex Containing Conjugated Polymer-Single Walled Carbon Nanotube Hybrids.

PubMed

Xiong, Wenjuan; Du, Lili; Lo, Kin Cheung; Shi, Haiting; Takaya, Tomohisa; Iwata, Koichi; Chan, Wai Kin; Phillips, David Lee

2018-06-25

Conjugated polymers incorporated with cycloplatinated complexes (P1-Pt and P2-Pt) were used as dispersants for single walled carbon nanotubes (SWCNTs). Significant changes in the UV-vis absorption spectra were observed after the formation of the polymer/SWCNT hybrids. Molecular dynamics (MD) simulations revealed the presence of a strong interaction between the cycloplatinated complex moieties and the SWCNT surface. The photoinduced electron transfer processes in these hybrids were strongly dependent on the type of the comonomer unit. Upon photoexcitation, the excited P1-Pt donates electrons to the SWCNT, while P2-Pt accepts electrons from the photoexcited SWCNT. These observations were supported by results from Raman and femtosecond time-resolved transient absorption spectroscopy experiments. The strong electronic interaction between the Pt complexes and the SWCNT gives rise to a new hybrid system that has a controllable photo-induced electron transfer flow, which are important in regulating the charge transport processes SWCNT-based optoelectronic devices.

Recognition-Mediated Hydrogel Swelling Controlled by Interaction with a Negative Thermoresponsive LCST Polymer.

PubMed

Belal, Khaled; Stoffelbach, François; Lyskawa, Joël; Fumagalli, Matthieu; Hourdet, Dominique; Marcellan, Alba; Smet, Lieselot De; de la Rosa, Victor R; Cooke, Graeme; Hoogenboom, Richard; Woisel, Patrice

2016-11-02

Most polymeric thermoresponsive hydrogels contract upon heating beyond the lower critical solution temperature (LCST) of the polymers used. Herein, we report a supramolecular hydrogel system that shows the opposite temperature dependence. When the non-thermosesponsive hydrogel NaphtGel, containing dialkoxynaphthalene guest molecules, becomes complexed with the tetra cationic macrocyclic host CBPQT 4+ , swelling occurred as a result of host-guest complex formation leading to charge repulsion between the host units, as well as an osmotic contribution of chloride counter-ions embedded in the network. The immersion of NaphtGel in a solution of poly(N-isopropylacrylamide) with tetrathiafulvalene (TTF) end groups complexed with CBPQT 4+ induced positive thermoresponsive behaviour. The LCST-induced dethreading of the polymer-based pseudorotaxane upon heating led to transfer of the CBPQT 4+ host and a concomitant swelling of NaphtGel. Subsequent cooling led to reformation of the TTF-based host-guest complexes in solution and contraction of the hydrogel. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Experimental and theoretical studies on the gas/solid/gas transformation cycle in extraterrestrial environments

NASA Astrophysics Data System (ADS)

Cottin, Hervé; Gazeau, Marie-Claire; Chaquin, Patrick; Raulin, François; Bénilan, Yves

2001-12-01

The ubiquity of molecular material in the universe, from hydrogen to complex organic matter, is the result of intermixed physicochemical processes that have occurred throughout history. In particular, the gas/solid/gas phase transformation cycle plays a key role in chemical evolution of organic matter from the interstellar medium to planetary systems. This paper focuses on two examples that are representative of the diversity of environments where such transformations occur in the Solar System: (1) the photolytic evolution from gaseous to solid material in methane containing planetary atmospheres and (2) the degradation of high molecular weight compounds into gas phase molecules in comets. We are currently developing two programs which couple experimental and theoretical studies. The aim of this research is to provide data necessary to build models in order to better understand (1) the photochemical evolution of Titan's atmosphere, through a laboratory program to determine quantitative spectroscopic data on long carbon chain molecules (polyynes) obtained in the SCOOP program (French acronym for Spectroscopy of Organic Compounds Oriented for Planetology), and (2) the extended sources in comets, through a laboratory program of quantitative studies of photochemical and thermal degradation processes on relevant polymers (e.g., Polyoxymethylene) by the SEMAPhOrE Cometaire program (French acronym for Experimental Simulation and Modeling Applied to Organic Chemistry in Cometary Environment).

Quantifying the adhesion and interaction forces between Pseudomonas aeruginosa and natural organic matter.

PubMed

Abu-Lail, Laila I; Liu, Yatao; Atabek, Arzu; Camesano, Terri A

2007-12-01

Atomic force microscopy (AFM) was used to characterize interactions between natural organic matter (NOM), and glass or bacteria. Poly(methacrylic acid) (PMA), soil humic Acid (SHA), and Suwannee River humic Acid (SRHA), were adsorbed to silica AFM probes. Adhesion forces (Fadh) for the interaction of organic-probes and glass slides correlated with organic molecular weight (MW), but not with radius of the organic aggregate (R), charge density (Q), or zeta potential (zeta). Two Pseudomonas aeruginosa strains with different lipopolysaccharides (LPS) were chosen: PAO1 (A+B+), whose LPS have common antigen (A-band) + O-antigen (B-band); and mutant AK1401 (A+B-). Fadh between bacteria and organics correlated with organic MW, R, and Q, but not zeta. PAO1 had lower Fadh with silica than NOM, which was attributed to negative charges from the B-band polymers causing electrostatic repulsion. AK1401 adhered stronger to silica than to the organics, perhaps because the absence of the B-band exposed underlying positively charged proteins. DLVO calculations could not explain the differences in the two bacteria or predict qualitative or quantitative trends in interaction forces in these systems. Molecular-level information from AFM studies can bring us closer to understanding the complex nature of bacterial-NOM interactions.

How do natural, uncultivated microbes interact with organic matter? Insights from single cell genomics and metagenomics

NASA Astrophysics Data System (ADS)

Lloyd, K. G.; Bird, J.; Schreiber, L.; Petersen, D.; Kjeldsen, K.; Schramm, A.; Stepanauskas, R.; Jørgensen, B. B.

2013-12-01

Since most of the microbes in marine sediments remain uncultured, little is known about the mechanisms by which these natural communities degrade organic matter (OM). Likewise, little is known about the make-up of labile OM in marine sediments beyond general functional classes such as proteins, carbohydrates, and lipids, measured as monomers. However, microbes have complex interactions with specific polymers within these functional classes, which can be indicated by a microbe's enzymatic toolkit. We found that four single cell genomes of archaea have very different peptidase compositions than four single cells of bacteria, suggesting that archaea and bacteria may play different roles in OM degradation. We also found that predicted extracellular cysteine peptidases, which require chemically reducing conditions, were common in IMG database metagenomes from marine sediments, and absent in those from seawater. This suggests that the pathways, and not just the rates, of OM degradation may differ between seawater and sediments. By comparing enzyme classes in different organisms, or in different types of marine environments, we present an emerging view of the microbial potential for specific carbon remineralization pathways in marine sediments. In addition, the methods we present hold promise for characterizing OM degradation in any environment where genomic information is available.

Mechanistic Representation of Soil C Dynamics: for Arctic Ecosystem

NASA Astrophysics Data System (ADS)

Dwivedi, D.; Riley, W. J.; Bisht, G.

2013-12-01

Arctic and sub-Arctic soils store vast amounts of carbon, approximately 1700 billion metric tones of frozen organic carbon. This carbon is susceptible to release to the atmosphere due to environmental changes (e.g., rapidly evolving landscape, warming); however, the mechanisms responsible for this susceptibility of soil organic matter (SOM) are not well understood, and uncertainties exist in terms of their representation in Earth System models. The representation of SOM dynamics in Earth System Models is critical for future climate prediction. To investigate the impacts of various physical (e.g., multi-phase transport, sorption, desorption, temperature), chemical (e.g., pH), and biological (e.g., microbial activity, enzyme dynamics) factors on SOM stability, we have developed CENTURY-like (describing labile and recalcitrant pools) and complex (describing multiple archetypal polymers and monomers C substrate groups) reaction networks. These reaction networks are integrated in a three-dimensional, multi-phase reactive transport solver (PFLOTRAN) and include representations of bacterial and fungal activity as well as population dynamics, gaseous and aqueous advection, and adsorption and desorption. We test and compare these reaction networks in PFLOTRAN to accurately predict depth-resolved soil organic matter (SOM) in the subsurface. We present results showing impacts of abiotic controls (e.g., surface interactions and temperature) on the long-term stabilization of SOM under permafrost conditions.

DFT modeling of chemistry on the Z machine

NASA Astrophysics Data System (ADS)

Mattsson, Thomas

2013-06-01

Density Functional Theory (DFT) has proven remarkably accurate in predicting properties of matter under shock compression for a wide-range of elements and compounds: from hydrogen to xenon via water. Materials where chemistry plays a role are of particular interest for many applications. For example the deep interiors of Neptune, Uranus, and hundreds of similar exoplanets are composed of molecular ices of carbon, hydrogen, oxygen, and nitrogen at pressures of several hundred GPa and temperatures of many thousand Kelvin. High-quality thermophysical experimental data and high-fidelity simulations including chemical reaction are necessary to constrain planetary models over a large range of conditions. As examples of where chemical reactions are important, and demonstration of the high fidelity possible for these both structurally and chemically complex systems, we will discuss shock- and re-shock of liquid carbon dioxide (CO2) in the range 100 to 800 GPa, shock compression of the hydrocarbon polymers polyethylene (PE) and poly(4-methyl-1-pentene) (PMP), and finally simulations of shock compression of glow discharge polymer (GDP) including the effects of doping with germanium. Experimental results from Sandia's Z machine have time and again validated the DFT simulations at extreme conditions and the combination of experiment and DFT provide reliable data for evaluating existing and constructing future wide-range equations of state models for molecular compounds like CO2 and polymers like PE, PMP, and GDP. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Programmable Matter

DTIC Science & Technology

2012-01-03

over it (Fig. 3d). The hydrogel prepolymer is then photopolymerized using a mask to align the electrical array with the polymer shape’s design. In...order to sandwich the electronic mesh into the receiving hydrogel, a second hydrogel prepolymer solution is then added and polymerized in registry

Multifunctional triblock co-polymer mP3/4HB-b-PEG-b-lPEI for efficient intracellular siRNA delivery and gene silencing.

PubMed

Zhou, Li; Chen, Zhifei; Wang, Feifei; Yang, Xiuqun; Zhang, Biliang

2013-04-01

A non-viral siRNA carrier composed of mono-methoxy-poly (3-hydroxybutyrate-co-4-hydroxybutyrate)-block-polyethylene glycol-block-linear polyethyleneimine (mP3/4HB-b-PEG-b-lPEI) was synthesized using 1800 Da linear polyethyleneimine and evaluated for siRNA delivery. Our study demonstrated that siRNA could be efficiently combined with mP3/4HB-b-PEG-b-lPEI (mAG) co-polymer and was protected from nuclease degradation. The combined siRNA were released from the complexes easily under heparin competition. The particle size of the mAG/siRNA complexes was 158 nm, with a ζ-potential of around 28 mV. Atomic force microscopy images displayed spherical and homogeneously distributed complexes. The mAG block co-polymer displayed low cytotoxicity and efficient cellular uptake of Cy3-siRNA in A549 cells by flow cytometry and confocal microscopy. In vitro transfection efficiency of the block co-polymer was assessed using siRNA against luciferase in cultured A549-Luc, HeLa-Luc, HLF-Luc, A375-Luc and MCF-7-Luc cells. A higher transfection efficiency and lower cytotoxicity was obtained by mAG block co-polymer in five cell lines. Furthermore, a remarkable improvement in luciferase gene silencing efficiency of the mAG complex (up to 90-95%) over that of Lipofectamine™ 2000 (70-82%) was observed in HLF-Luc and A375-Luc cells. Additionally, a mAG/p65-siRNA complex also showed a better capability than Lipofectamine™ 2000/p65-siRNA complex to drastically reduce the p65 mRNA level down to 10-16% in HeLa, U251 and HUVEC cells at an N/P ratio of 70. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Salen complexes with dianionic counterions

DOEpatents

Job, Gabriel E.; Farmer, Jay J.; Cherian, Anna E.

2016-08-02

The present invention describes metal salen complexes having dianionic counterions. Such complexes can be readily precipitated and provide an economical method for the purification and isolation of the complexes, and are useful to prepare novel polymer compositions.

Influence of Chemical Extraction on Rheological Behavior, Viscoelastic Properties and Functional Characteristics of Natural Heteropolysaccharide/Protein Polymer from Durio zibethinus Seed

PubMed Central

Amid, Bahareh Tabatabaee; Mirhosseini, Hamed

2012-01-01

In recent years, the demand for a natural plant-based polymer with potential functions from plant sources has increased considerably. The main objective of the current study was to study the effect of chemical extraction conditions on the rheological and functional properties of the heteropolysaccharide/protein biopolymer from durian (Durio zibethinus) seed. The efficiency of different extraction conditions was determined by assessing the extraction yield, protein content, solubility, rheological properties and viscoelastic behavior of the natural polymer from durian seed. The present study revealed that the soaking process had a more significant (p < 0.05) effect than the decolorizing process on the rheological and functional properties of the natural polymer. The considerable changes in the rheological and functional properties of the natural polymer could be due to the significant (p < 0.05) effect of the chemical extraction variables on the protein fraction present in the molecular structure of the natural polymer from durian seed. The natural polymer from durian seed had a more elastic (or gel like) behavior compared to the viscous (liquid like) behavior at low frequency. The present study revealed that the natural heteropolysaccharide/protein polymer from durian seed had a relatively low solubility ranging from 9.1% to 36.0%. This might be due to the presence of impurities, insoluble matter and large particles present in the chemical structure of the natural polymer from durian seed. PMID:23203099

The Lowe-Andersen thermostat as an alternative to the dissipative particle dynamics in the mesoscopic simulation of entangled polymers.

PubMed

Khani, Shaghayegh; Yamanoi, Mikio; Maia, Joao

2013-05-07

Dissipative Particle Dynamics (DPD) has shown a great potential in studying the dynamics and rheological properties of soft matter; however, it is associated with deficiencies in describing the characteristics of entangled polymer melts. DPD deficiencies are usually correlated to the time integrating method and the unphysical bond crossings due to utilization of soft potentials. One shortcoming of DPD thermostat is the inability to produce real values of Schmidt number for fluids. In order to overcome this, an alternative Lowe-Anderson (LA) method, which successfully stabilizes the temperature, is used in the present work. Additionally, a segmental repulsive potential was introduced to avoid unphysical bond crossings. The performance of the method in simulating polymer systems is discussed by monitoring the static and dynamic characteristics of polymer chains and the results from the LA method are compared to standard DPD simulations. The performance of the model is evaluated on capturing the main shear flow properties of entangled polymer systems. Finally the linear and nonlinear viscoelastic properties of such systems are discussed.

Evaluation of conceptual models of natural organic matter (humus) from a consideration of the chemical and biochemical processes of humification

USGS Publications Warehouse

Wershaw, Robert L.

2004-01-01

Natural organic matter (NOM) has been studied for more than 200 years because of its importance in enhancing soil fertility, soil structure, and water-holding capacity and as a carbon sink in the global carbon cycle. Two different types of models have been proposed for NOM: (1) the humic polymer models and (2) the molecular aggregate models. In the humic polymer models, NOM molecules are depicted as large (humic) polymers that have unique chemical structures that are different from those of the precursor plant degradation products. In the molecular aggregate models, NOM is depicted as being composed of molecular aggregates (supramolecular aggregates) of plant degradation products held together by non-covalent bonds. The preponderance of evidence favors the supramolecular aggregate models. These models were developed by studying the properties of NOM extracted from soils and natural waters, and as such, they provide only a very generalized picture of the structure of NOM aggregates in soils and natural waters prior to extraction. A compartmental model, in which the structure of the NOM in each of the compartments is treated separately, should provide a more accurate representation of NOM in soil and sediment systems. The proposed NOM compartments are: (1) partially degraded plant tissue, (2) biomass from microorganisms, (3) organic coatings on mineral grains, (4) pyrolytic carbon, (5) organic precipitates, and (6) dissolved organic matter (DOM) in interstitial water. Within each of these compartments there are NOM supramolecular aggregates that will be dissolved by the solvent systems that are used by researchers for extraction of NOM from soils and sediments. In natural water systems DOM may be considered as existing in two subcompartments: (1) truly dissolved DOM and (2) colloidal DOM.

PREFACE: The Eighth Liquid Matter Conference The Eighth Liquid Matter Conference

NASA Astrophysics Data System (ADS)

Dellago, Christoph; Kahl, Gerhard; Likos, Christos N.

2012-07-01

The Eighth Liquid Matter Conference (LMC8) was held at the Universität Wien from 6-10 September 2011. Initiated in 1990, the conferences of this series cover a broad range of highly interdisciplinary topics, ranging from simple liquids to soft matter and biophysical systems. The vast spectrum of scientific subjects presented and discussed at the LMC8 is reflected in the themes of the ten symposia: Ionic and quantum liquids, liquid metals Water, solutions and reaction dynamics Liquid crystals Polymers, polyelectrolytes, biopolymers Colloids Films, foams, surfactants, emulsions, aerosols Confined fluids, interfacial phenomena Supercooled liquids, glasses, gels Non-equilibrium systems, rheology, nanofluids Biofluids, active matter This special issue contains scientific papers, authored by participants of the LMC8, which provide a cross-section of the scientific activities in current liquid matter science, as discussed at the conference, and demonstrate the scientific as well as methodological progress made in this field over the past couple of years. The Eighth Liquid Matter Conference contents The Eighth Liquid Matter ConferenceChristoph Dellago, Gerhard Kahl and Christos N Likos Comparing light-induced colloidal quasicrystals with different rotational symmetriesMichael Schmiedeberg and Holger Stark Hydrogen bond network relaxation in aqueous polyelectrolyte solutions: the effect of temperatureS Sarti, D Truzzolillo and F Bordi Equilibrium concentration profiles and sedimentation kinetics of colloidal gels under gravitational stressS Buzzaccaro, E Secchi, G Brambilla, R Piazza and L Cipelletti The capillary interaction between two vertical cylindersHimantha Cooray, Pietro Cicuta and Dominic Vella Hydrodynamic and viscoelastic effects in polymer diffusionJ Farago, H Meyer, J Baschnagel and A N Semenov A density-functional theory study of microphase formation in binary Gaussian mixturesM Carta, D Pini, A Parola and L Reatto Microcanonical determination of the interface tension of flat and curved interfaces from Monte Carlo simulationsA Tröster and K Binder Phase diagrams of particles with dissimilar patches: X-junctions and Y-junctionsJ M Tavares and P I C Teixeira The unbearable heaviness of colloids: facts, surprises, and puzzles in sedimentationRoberto Piazza, Stefano Buzzaccaro and Eleonora Secchi Exploring water and other liquids at negative pressureFrédéric Caupin, Arnaud Arvengas, Kristina Davitt, Mouna El Mekki Azouzi, Kirill I Shmulovich, Claire Ramboz, David A Sessoms and Abraham D Stroock The configurational space of colloidal patchy polymers with heterogeneous sequencesIvan Coluzza and Christoph Dellago Repeated sorption of water in SBA-15 investigated by means of in situ small-angle x-ray scatteringM Erko, D Wallacher, G H Findenegg and O Paris Transition of the hydration state of a surfactant accompanying structural transitions of self-assembled aggregatesM Hishida and K Tanaka The effects of topology on the structural, dynamic and mechanical properties of network-forming materialsMark Wilson Surface tension of an electrolyte-air interface: a Monte Carlo studyAlexandre Diehl, Alexandre P dos Santos and Yan Levin Water and other tetrahedral liquids: order, anomalies and solvationB Shadrack Jabes, Divya Nayar, Debdas Dhabal, Valeria Molinero and Charusita Chakravarty Diffusion coefficient and shear viscosity of rigid water modelsSami Tazi, Alexandru Boţan, Mathieu Salanne, Virginie Marry, Pierre Turq and Benjamin Rotenberg Phase behaviour of colloidal assemblies on 2D corrugated substratesSamir El Shawish, Emmanuel Trizac and Jure Dobnikar Structural properties of dendrimer-colloid mixturesDominic A Lenz, Ronald Blaak and Christos N Likos Fluid-fluid demixing of off-critical colloid-polymer systems confined between parallel platesE A G Jamie, R P A Dullens and D G A L Aarts Simulations of nematic homopolymer melts using particle-based models with interactions expressed through collective variablesKostas Ch Daoulas, Victor Rühle and Kurt Kremer Smectic shellsTeresa Lopez-Leon, Alberto Fernandez-Nieves, Maurizio Nobili and Christophe Blanc Intrinsic profiles and the structure of liquid surfacesP Tarazona, E Chacón and F Bresme Competing ordered structures formed by particles with a regular tetrahedral patch decorationGünther Doppelbauer, Eva G Noya, Emanuela Bianchi and Gerhard Kahl Heterogeneous crystallization in colloids and complex plasmas: the role of binary mobilitiesH Löwen, E Allahyarov, A Ivlev and G E Morfill Isotope effects in water as investigated by neutron diffraction and path integral molecular dynamicsAnita Zeidler, Philip S Salmon, Henry E Fischer, Jörg C Neuefeind, J Mike Simonson and Thomas E Markland Confined cubic blue phases under shearO Henrich, K Stratford, D Marenduzzo, P V Coveney and M E Cates Depletion-induced biaxial nematic states of boardlike particlesS Belli, M Dijkstra and R van Roij Active Brownian motion tunable by lightIvo Buttinoni, Giovanni Volpe, Felix Kümmel, Giorgio Volpe and Clemens Bechinger Structure and stability of charged clustersMark A Miller, David A Bonhommeau, Christopher J Heard, Yuyoung Shin, Riccardo Spezia and Marie-Pierre Gaigeot Non-equilibrium relaxation and tumbling times of polymers in semidilute solutionChien-Cheng Huang, Gerhard Gompper and Roland G Winkler Thermophoresis of colloids by mesoscale simulationsDaniel Lüsebrink, Mingcheng Yang and Marisol Ripoll Computing the local pressure in molecular dynamics simulationsThomas W Lion and Rosalind J Allen Gradient-driven fluctuations in microgravityA Vailati, R Cerbino, S Mazzoni, M Giglio, C J Takacs and D S Cannell

Theoretical Studies of Nonuniform Orientational Order in Liquid Crystals and Active Particles

NASA Astrophysics Data System (ADS)

Duzgun, Ayhan

I investigate three systems that exhibit complex patterns in orientational order, which are controlled by geometry interacting with the dynamics of phase transitions, metastability, and activity. 1. Liquid Crystal Elastomers: Liquid-crystal elastomers are remarkable materials that combine the elastic properties of cross-linked polymer networks with the anisotropy of liquid crystals. Any distortion of the polymer network affects the nematic order of the liquid crystal, and, likewise, any change in the magnitude or direction of the nematic order influences the shape of the elastomer. When elastomers are prepared without any alignment, they develop disordered polydomain structures as they are cooled into the nematic phase. To model these polydomain structures, I develop a dynamic theory for the isotropic-nematic transition in elastomers. 2. Active Brownian Particles: Unlike equilibrium systems, active matter is not governed by the conventional laws of thermodynamics. I perform Langevin dynamics simulations and analytic calculations to explore how systems cross over from equilibrium to active behavior as the activity is increased. Based on these results, I calculate how the pressure depends on wall curvature, and hence make analytic predictions for the motion of curved tracers and other effects of confinement in active matter systems. 3. Skyrmions in Liquid Crystals: Skyrmions are localized topological defects in the orientation of an order parameter field, without a singularity in the magnitude of the field. For many years, such defects have been studied in the context of chiral liquid crystals--for example, as bubbles in a confined cholesteric phase or as double-twist tubes in a blue phase. More recently, skyrmions have been investigated extensively in the context of chiral magnets. In this project, I compare skyrmions in chiral liquid crystals with the analogous magnetic defects. Through simulations based on the nematic order tensor, I model both isolated skyrmions and periodic defect lattices.

A novel gene delivery composite system based on biodegradable folate-poly (ester amine) polymer and thermosensitive hydrogel for sustained gene release

PubMed Central

Yang, Yi; Zhao, Hang; Jia, YanPeng; Guo, QingFa; Qu, Ying; Su, Jing; Lu, XiaoLing; Zhao, YongXiang; Qian, ZhiYong

2016-01-01

Local anti-oncogene delivery providing high local concentration of gene, increasing antitumor effect and decreasing systemic side effects is currently attracting interest in cancer therapy. In this paper, a novel local sustained anti-oncogene delivery system, PECE thermoresponsive hydrogel containing folate-poly (ester amine) (FA-PEA) polymer/DNA (tumor suppressor) complexes, is demonstrated. First, a tumor-targeted biodegradable folate-poly (ester amine) (FA-PEA) polymer based on low-molecular-weight polyethyleneimine (PEI) was synthesized and characterized, and the application for targeted gene delivery was investigated. The polymer had slight cytotoxicity and high transfection efficiency in vitro compared with PEI 25k, which indicated that FA-PEA was a potential vector for targeted gene delivery. Meanwhile, we successfully prepared a thermoresponsive PECE hydrogel composite containing FA-PEA/DNA complexes which could contain the genes and slowly release the genes into cells. We concluded the folate-poly (ester amine) (FA-PEA) polymer would be useful for targeted gene delivery, and the novel gene delivery composite based on biodegradable folate-poly (ester amine) polymer and thermosensitive PECE hydrogel showed potential for sustained gene release. PMID:26883682

Polymer gel electrolytes for application in aluminum deposition and rechargeable aluminum ion batteries

DOE PAGES

Sun, Xiao -Guang; Fang, Youxing; Jiang, Xueguang; ...

2015-10-22

Polymer gel electrolyte using AlCl3 complexed acrylamide as functional monomer and ionic liquids based on acidic mixture of 1-ethyl-3-methylimidazolium chloride (EMImCl) and AlCl 3 as plasticizer has been successfully prepared for the first time by free radical polymerization. Aluminum deposition is successfully obtained with a polymer gel membrane contianing 80 wt% ionic liquid. As a result, the polymer gel membranes are also good candidates for rechargeable aluminum ion batteries.

Active turnover regulates pattern formation and stress transmission in disordered acto-myosin networks

NASA Astrophysics Data System (ADS)

McCall, Patrick; Stam, Samantha; Kovar, David; Gardel, Margaret

The shape and mechanics of animal cells are controlled by a dynamic, thin network of semiflexible actin filaments and myosin-II motor proteins called the actomyosin cortex. Motor-generated stresses in the cortex drive changes in cell shape during cell division and morphogenesis, while dynamic turnover of actin filaments dissipates stress. The relative effects that force generation, force dissipation, and disassembly and reassembly of material have on motion in these networks are unknown. We find that cross-linked actin networks in vitro contract under myosin-generated stresses, resulting in partial filament disassembly, the formation of asters, and clustering of myosin motors. We observe a rapid restoration of uniform polymer density in the presence of the assembly factors which catalyze network turnover through elongation of severed actin filaments. When severing is accelerated further by the addition of a severing protein, network contraction and motor clustering are dramatically suppressed. We test the relative effects of material regeneration and force transmission using image analysis, and conclude that the dominant mechanism for this effect is relatively short-lived stresses that do not propagate over considerable distance or push network deformation into the nonlinear contractile regime we have previously characterized. Our results present a framework to understand cytoskeletal active matter that are influenced by a complex interplay between stress generation, network reorganization, and polymer turnover.

Luminescence properties and molecular mechanics calculation of bis-β-diketonate Eu3+ complex/polymer hybrid fibers

NASA Astrophysics Data System (ADS)

Bai, Jinyuan; Gu, Huiquan; Hou, Yanjun; Wang, Shuhong

2018-05-01

Two series of bis-β-diketonate Eu3+ complex/polymer hybrid fibers, namely, Eu2(BTP)3(H2O)4/PMMA (Eu/PMMA) and Eu2(BTP)3(H2O)4/PVP (Eu/PVP) have been prepared by electrospinning technology (BTP = 1,3-bis(4,4,4-trifluoro-1,3-dioxobutyl)phenyl, PVP = poly (vinyl pyrrolidone) and PMMA = poly (methyl methacrylate)). The effect of complex Eu2(BTP)3(H2O)4 on the luminescence, thermal stability and morphology of composite fibers were studied by characterization techniques. The Judd-Ofelt theory was applied to this study for explaining the effect of the distribution of Eu2(BTP)3(H2O)4 and the mutual effect of the Eu2(BTP)3(H2O)4 coordination compound and neighboring chain segments of PMMA and PVP polymer matrix.

Gel Phase Formation in Dilute Triblock Copolyelectrolyte Complexes

NASA Astrophysics Data System (ADS)

Srivastava, Samanvaya; Andreev, Marat; Prabhu, Vivek; de Pablo, Juan; Tirrell, Matthew

Assembly of oppositely charged triblock copolyelectrolytes into phase-separated gels at extremely low polymer concentrations (<1 % by mass) has been observed in scattering experiments and molecular dynamics simulations. In contrast to uncharged, amphiphilic block copolymers that form discrete micelles at low concentrations and enter a phase of strongly interacting micelles in a gradual manner with increasing polymer concentrations, the formation of a dilute phase of individual micelles is prevented in polyelectrolyte complexation-driven assemblies of triblock copolyelectrolytes. Gel phases form and phase separate almost instantaneously upon solvation of the copolymers. Furthermore, molecular models of self-assembly demonstrate the presence of oligo-chain aggregates in early stages of triblock copolyelectrolyte assembly, at experimentally unobservable polymer concentrations. Our discoveries not only contribute to our fundamental understanding of the structure and pathways of complexation driven assemblies, but also raise intriguing prospects for formation of gel structures at extraordinarily low concentrations, with applications in tissue engineering, agriculture, water purification and theranostics.

Ligand extraction of rare earth elements from aquifer sediments: Implications for rare earth element complexation with organic matter in natural waters

NASA Astrophysics Data System (ADS)

Tang, Jianwu; Johannesson, Karen H.

2010-12-01

The ability of organic matter as well as carbonate ions to extract rare earth elements (REEs) from sandy sediments of a Coastal Plain aquifer was investigated for unpurified organic matter from different sources (i.e., Mississippi River natural organic matter, Aldrich humic acid, Nordic aquatic fulvic acid, Suwannee River fulvic acid, and Suwannee River natural organic matter) and for extraction solutions containing weak (i.e., CH 3COO -) or strong (i.e., CO32-) ligands. The experimental results indicate that, in the absence of strong REE complexing ligands in solution, the amount of REEs released from the sand is small and the fractionation pattern of the released REEs appears to be controlled by the surface stability constants for REE sorption with Fe(III) oxides/oxyhydroxides. In the presence of strong solution complexing ligands, however, the amount and the fractionation pattern of the released REEs reflect the strength and variation of the stability constants of the dominant aqueous REE species across the REE series. The varying amount of REEs extracted by the different organic matter employed in the experiments indicates that organic matter from different sources has different complexing capacity for REEs. However, the fractionation pattern of REEs extracted by the various organic matter used in our experiments is remarkable consistent, being independent of the source and the concentration of organic matter used, as well as solution pH. Because natural aquifer sand and unpurified organic matter were used in our experiments, our experimental conditions are more broadly similar to natural systems than many previous laboratory experiments of REE-humic complexation that employed purified humic substances. Our results suggest that the REE loading effect on REE-humic complexation is negligible in natural waters as more abundant metal cations (e.g., Fe, Al) out-compete REEs for strong binding sites on organic matter. More specifically, our results indicate that REE complexation with organic matter in natural waters is dominated by REE binding to weak sites on dissolved organic matter, which subsequently leads to a middle REE (MREE: Sm-Ho)-enriched fractionation pattern. The experiments also indicate that carbonate ions may effectively compete with fulvic acid in binding with dissolved REEs, but cannot out compete humic acids for REEs. Therefore, in natural waters where low molecular weight (LMW) dissolved organic carbon (DOC) is the predominant form of DOC (e.g., lower Mississippi River water), REEs occur as "truly" dissolved species by complexing with carbonate ions as well as FA, resulting in heavy REE (HREE: Er-Lu)-enriched shale-normalized fractionation patterns. Whereas, in natural terrestrial waters where REE speciation is dominated by organic complexes with high molecular weight DOC (e.g., "colloidal" HA), only MREE-enriched fractionation patterns will be observed because the more abundant, weak sites preferentially complex MREEs relative to HREEs and light REEs (LREEs: La-Nd).

Design and its limitations in the construction of bi- and poly-nuclear coordination complexes and coordination polymers (aka MOFs): a personal view.

PubMed

Robson, R

2008-10-14

This article, presented from a personal point of view, is concerned with the design of ligands intended to give specifically either binuclear or tetranuclear metal complexes or coordination polymers. No attempt is made to provide a comprehensive coverage of these topics, the focus being mainly upon results from our laboratory. Some emphasis is placed upon aspects of the historical development of the deliberate construction of coordination polymers (aka MOFs)--materials promising useful applications, the study of which continues to expand exponentially. Some of our recent research is described in which the carbonate ion and the tetracyanoquinodimethane dianion are used as bridging ligands to generate targeted coordination polymers. It is intended that Dalton Perspectives be easily comprehensible to non-specialists in the field; an average second year university chemistry student should be easily able to understand the present contribution.

Polymer-assisted deposition of films and preparation of carbon nanotube arrays using the films

DOEpatents

Luo, Hongmei; Li, Qingwen; Bauer, Eve; Burrell, Anthony Keiran; McCleskey, Thomas Mark; Jia, Quanxi

2013-07-16

Carbon nanotubes were prepared by coating a substrate with a coating solution including a suitable solvent, a soluble polymer, a metal precursor having a first metal selected from iron, nickel, cobalt, and molybdenum, and optionally a second metal selected from aluminum and magnesium, and also a binding agent that forms a complex with the first metal and a complex with the second metal. The coated substrate was exposed to a reducing atmosphere at elevated temperature, and then to a hydrocarbon in the reducing atmosphere. The result was decomposition of the polymer and formation of carbon nanotubes on the substrate. The carbon nanotubes were often in the form of an array on the substrate.

1. Catalytic asymmetric hydroformylation. 2. Hydroformylation with polymer-supported platinum complexes. 3. The reaction between dicobalt octacarbonyl and alcohols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bortinger, A.

1977-01-01

Chiral polymer-supported metal complexes were catalytically active in the hydroformylation of prochiral olefins, but they induced only small optical activity. All the optical rotations in 2-phenylpropanal, obtained by the hydroformylation of styrene, were positive. In studies of asymmetric hydroformylation with homogeneous catalysts, no correlation was found between the optical inductions and ligand structure. Polymer-supported platinum catalysts having similar structure to their homogeneous counterparts showed the same high selectivity toward the formation of straight-chain aldehyde (89-95%) as the homogeneous catalysts in the hydroformylation of 1-hexene. Aldehyde yields were low (up to 45%); no reduction to alcohol occurred.

The ability of the Coincidence Doppler Broadening Spectroscopy to characterize polymers containing different chemical elements

NASA Astrophysics Data System (ADS)

Yang, J.; Zhang, T.; Han, L. A.; Cao, X. Z.; Yu, R. S.; Wang, B. Y.

2017-04-01

Hydrocarbon polymers, O-containing, F-containing and Cl-containing polymers are comprehensively studied by Coincidence Doppler Broadening Spectroscopy (CDBS). It is shown that for polymers with different chemical structure, CDBS results can effectively distinguish polar groups C dbnd O, Csbnd Cl, and Csbnd F. For polymers with similar chemical structure, the intensity of the element-specific peak in the CDBS ratio curve is dependent not only on the fraction of free positrons, but also on the content of characteristic atom in polymer repeated unit, and the polarity of the polymer molecule. For polymers containing several different polar groups, such as PCTFE (Csbnd F & Csbnd Cl) and PFA (Csbnd F & C dbnd O), whether the element-specific peak appears or not depends on the amount of the polar groups and its positron capture ability. This work may provide insights into potential applications of CDBS for studying complex polymer systems.

Slippery self-lubricating polymer surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aizenberg, Joanna; Aizenberg, Michael; Cui, Jiaxi

The present disclosure describes a strategy to create self-healing, slippery self-lubricating polymers. Lubricating liquids with affinities to polymers can be utilized to get absorbed within the polymer and form a lubricant layer (of the lubricating liquid) on the polymer. The lubricant layer can repel a wide range of materials, including simple and complex fluids (water, hydrocarbons, crude oil and bodily fluids), restore liquid-repellency after physical damage, and resist ice, microorganisms and insects adhesion. Some exemplary applications where self-lubricating polymers will be useful include energy-efficient, friction-reduction fluid handling and transportation, medical devices, anti-icing, optical sensing, and as self-cleaning, and anti-fouling materialsmore » operating in extreme environments.« less

Pedogenic formation of montmorillonite from a 2:1-2:2 intergrade clay mineral

USGS Publications Warehouse

Malcolm, R.L.; Nettleton, W.D.; McCracken, R.J.

1968-01-01

Montmorillonite was found to be the dominant clay mineral in surface horizons of certain soils of the North Carolina Coastal Plain whereas a 2:1-2:2 intergrade clay mineral was dominant in subjacent horizons. In all soils where this clay mineral sequence was found, the surface horizon was low in pH (below 4⋅5) and high in organic matter content. In contrast, data from studies of other soils of this region (Weed and Nelson, 1962) show that: (1) montmorillonite occurs infrequently; (2) maximum accumulation of the 2:1-2:2 intergrade normally occurs in the surface horizon and decreases with depth in the profile; (3) organic matter contents are low; and (4) pH values are only moderately acid (pH 5-6).It is theorized that the montmorillonite in the surface horizon of the soils studied originated by pedogenic weathering of the 2:1-2:2 intergrade clay mineral. The combined effects of low pH (below 4⋅5) and high organic matter content in surface horizons are believed to be the agents responsible for this mineral transformation. The protonation and solubilization (reverse of hydrolysis) of Al-polymers in the interlayer of expansible clay minerals will occur at or below pH 4⋅5 depending on the charge and steric effects of the interlayer. A low pH alone may cause this solubilization and thus mineral transformation, but in the soils studied the organic matter is believed to facilitate and accelerage the transformation. The intermediates of organic matter decomposition provide an acid environment, a source of protons, and a source of watersoluble mobile organic substances (principally fulvic acids) which have the ability to complex the solubilized aluminum and move it down the profile. This continuous removal of solubilized aluminum would provide for a favorable gradient for aluminum solubilization.The drainage class or position in a catena is believed to be less important than the chemical factors in formation of montmorillonite from 2:1-2:2 intergrade, because montmorillonite is present in all drainage classes if the surface horizon is low in pH and high in organic matter.

ToF-SIMS and Laser-SNMS Imaging of Heterogeneous Topographically Complex Polymer Systems.

PubMed

Pelster, Andreas; Körsgen, Martin; Kurosawa, Takako; Morita, Hiromi; Arlinghaus, Heinrich F

2016-10-04

Heterogeneous polymer coatings, such as those used in organic electronics and medical devices, are of increasing industrial importance. In order to advance the development of these types of systems, analytical techniques are required which are able to determine the elemental and molecular spatial distributions, on a nanometer scale, with very high detection efficiency and sensitivity. The goal of this study was to investigate the suitability of laser postionization secondary neutral mass spectrometry (Laser-SNMS) with a 157 nm postionization laser beam to image structured polymer mixtures and compare the results with time-of-flight secondary ion mass spectrometry (ToF-SIMS) measurements using Bi 3 + primary ions. The results showed that Laser-SNMS is better suited than ToF-SIMS for unambiguous detection and submicrometer imaging of the wide range of polymers investigated. The data also showed that Laser-SNMS has the advantage of being much more sensitive (in general higher by more than an order of magnitude and peaking at up to 3 orders of magnitude) than ToF-SIMS while also showing superior performance on topographically complex structured insulating surfaces, due to significantly reduced field effects and a higher dynamic range as compared to ToF-SIMS. It is concluded that Laser-SNMS is a powerful complementary technique to ToF-SIMS for the analysis of heterogeneous polymers and other complex structured organic mixtures, providing submicrometer resolution and high sensitivity.

Real-time single-molecule electronic DNA sequencing by synthesis using polymer-tagged nucleotides on a nanopore array

PubMed Central

Fuller, Carl W.; Kumar, Shiv; Porel, Mintu; Chien, Minchen; Bibillo, Arek; Stranges, P. Benjamin; Dorwart, Michael; Tao, Chuanjuan; Li, Zengmin; Guo, Wenjing; Shi, Shundi; Korenblum, Daniel; Trans, Andrew; Aguirre, Anne; Liu, Edward; Harada, Eric T.; Pollard, James; Bhat, Ashwini; Cech, Cynthia; Yang, Alexander; Arnold, Cleoma; Palla, Mirkó; Hovis, Jennifer; Chen, Roger; Morozova, Irina; Kalachikov, Sergey; Russo, James J.; Kasianowicz, John J.; Davis, Randy; Roever, Stefan; Church, George M.; Ju, Jingyue

2016-01-01

DNA sequencing by synthesis (SBS) offers a robust platform to decipher nucleic acid sequences. Recently, we reported a single-molecule nanopore-based SBS strategy that accurately distinguishes four bases by electronically detecting and differentiating four different polymer tags attached to the 5′-phosphate of the nucleotides during their incorporation into a growing DNA strand catalyzed by DNA polymerase. Further developing this approach, we report here the use of nucleotides tagged at the terminal phosphate with oligonucleotide-based polymers to perform nanopore SBS on an α-hemolysin nanopore array platform. We designed and synthesized several polymer-tagged nucleotides using tags that produce different electrical current blockade levels and verified they are active substrates for DNA polymerase. A highly processive DNA polymerase was conjugated to the nanopore, and the conjugates were complexed with primer/template DNA and inserted into lipid bilayers over individually addressable electrodes of the nanopore chip. When an incoming complementary-tagged nucleotide forms a tight ternary complex with the primer/template and polymerase, the tag enters the pore, and the current blockade level is measured. The levels displayed by the four nucleotides tagged with four different polymers captured in the nanopore in such ternary complexes were clearly distinguishable and sequence-specific, enabling continuous sequence determination during the polymerase reaction. Thus, real-time single-molecule electronic DNA sequencing data with single-base resolution were obtained. The use of these polymer-tagged nucleotides, combined with polymerase tethering to nanopores and multiplexed nanopore sensors, should lead to new high-throughput sequencing methods. PMID:27091962

Insight into the nature and formation of the organic matter observed on Ceres

NASA Astrophysics Data System (ADS)

Ammannito, E.; Vinogradoff, V.; De Sanctis, M. C.; De Angelis, S.; Ferrari, M.; Ciarniello, M.; Raponi, A.; Raymond, C. A.; Russell, C. T.

2017-12-01

Observed by the Dawn spacecraft since March 2015, Ceres is a fascinating world [1]. Its surface, covered by phyllosilicates, carbonates, ammoniated-bearing hydrated minerals, water ice, salts and opaque materials indicates a complex chemical environment [1,2,3]. VIR, the Visible and InfraRed mapping spectrometer onboard the Dawn mission, has revealed the presence of aliphatic carbons with the 3.3-3.5 µm bands, near the Ernutet crater [4]. The origin of this OM is likely related to an endogenous source [4] and new issues are raised: what is the origin formation and the true nature of the OM hidden behind these aliphatic signatures? We used the spectral imaging (SPIM) facility in use at the laboratory of IAPS-INAF (spare of the VIR instrument onboard Dawn) to measure organic materials in the range 0.2-5.1 µm. These materials, such as insoluble organic matter (IOM) of chondrites, synthetic polymers, asphaltite, as well as spectra from literature data have been compared to VIR data. The Ceres aliphatic bands might match with an aliphatic branched polymer structure, i.e. with a 1.3 < CH2/CH3 ratio < 1.7, may contain some amine groups and likely some aromatic carbons such as chondritic IOM. Two hypotheses, which could be complementary, arise for the origin and formation of this OM: i) from internal processes only: due to past hydrothermal activity on Ceres [2], the circulation of H2-rich fluids during serpentinization processes with the presence of carbon dioxide might have led to Fischer-Tropsch-type reactions (methane and hydrocarbons formation [5]), subsequently processed during the pervasive hydrothermal alteration; ii) from interstellar heritage and internal processes: a part of the OM might have interstellar or protoplanetary precursors, coming from icy-grains, which were accreted into Ceres and undergone hydrothermal alteration with minerals. In either case, the partial differentiation of Ceres, might have driven the volatiles (i.e. the organic matter) near the surface. The second hypothesis, might also explain the high concentration of nitrogen. [1] Russell et al., (2016) Science, 353 (6303) 1008-1010. [2] De Sanctis et al., (2015) Nature 528, 241-244. [3] De Sanctis et al., (2016) Nature 536, 54- 57. [4] De Sanctis et al., (2017) Science, 355, 719-722. [5] Holm et al., (2015), Astrobiology, 15, 587-600.

Molecular Engineering of Azobenzene-Functionalized Polyimides to Enhance Both Photomechanical Work and Motion (POSTPRINT)

DTIC Science & Technology

2014-09-01

8520−8524. (14) Jiang, Z.; Xu, M.; Li, F.; Yu, Y. J. Am. Chem. Soc. 2013, 135, 16446−16453. (15) White, T. J.; Tabiryan, N. V .; Serak, S. V .; Hrozhyk, U...A.; Tondiglia, V . P.; Koerner, H.; Vaia, R. A.; Bunning, T. J. Soft Matter 2008, 4, 1796−1798. (16) Lee, K. M.; Wang, D. H.; Koerner, H.; Vaia, R. A...Bershtein, V . A.; Egorov, V . M.; Podolsky, A. F.; Stepanov, V . A. J. Polym. Sci., Polym. Lett. Ed. 1985, 23, 371−377. (34) Bershtein, V . A.; Rydjov

Non-affine deformations in polymer hydrogels

PubMed Central

Wen, Qi; Basu, Anindita; Janmey, Paul A.; Yodh, A. G.

2012-01-01

Most theories of soft matter elasticity assume that the local strain in a sample after deformation is identical everywhere and equal to the macroscopic strain, or equivalently that the deformation is affine. We discuss the elasticity of hydrogels of crosslinked polymers with special attention to affine and non-affine theories of elasticity. Experimental procedures to measure non-affine deformations are also described. Entropic theories, which account for gel elasticity based on stretching out individual polymer chains, predict affine deformations. In contrast, simulations of network deformation that result in bending of the stiff constituent filaments generally predict non-affine behavior. Results from experiments show significant non-affine deformation in hydrogels even when they are formed by flexible polymers for which bending would appear to be negligible compared to stretching. However, this finding is not necessarily an experimental proof of the non-affine model for elasticity. We emphasize the insights gained from experiments using confocal rheoscope and show that, in addition to filament bending, sample micro-inhomogeneity can be a significant alternative source of non-affine deformation. PMID:23002395

N-nitrosodimethylamine (NDMA) formation during ozonation of wastewater and water treatment polymers.

PubMed

Sgroi, Massimiliano; Roccaro, Paolo; Oelker, Gregg; Snyder, Shane A

2016-02-01

N-Nitrosodimethylamine (NDMA) formation by ozonation was investigated in the effluents of four different wastewater treatment plants destined for alternative reuse. Very high levels of NDMA formation were observed in wastewaters from treatment plants non operating with biological nitrogen removal. Selected experiments showed that hydroxyl radical did not have a significant role in NDMA formation during ozonation of wastewater. Furthermore, ozonation of three different polymers used for water treatment, including polyDADMAC, anionic polyacrylamide, and cationic polyacrylamide, spiked in wastewater did not increase the NDMA formation. Effluent organic matter (EfOM) likely reduced the availability of ozone in water able to react with polymers and quenched the produced ·OH radicals which limited polymer degradation and subsequent NDMA production. Excellent correlations were observed between NDMA formation, UV absorbance at 254 nm, and total fluorescence reduction. These data provide evidence that UV and fluorescence surrogates could be used for monitoring and/or controlling NDMA formation during ozonation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Tunable Infrared Metasurface on a Soft Polymer Scaffold.

PubMed

Reeves, Jeremy B; Jayne, Rachael K; Stark, Thomas J; Barrett, Lawrence K; White, Alice E; Bishop, David J

2018-05-09

The fabrication of metallic electromagnetic meta-atoms on a soft microstructured polymer scaffold using a MEMS-based stencil lithography technique is demonstrated. Using this technique, complex metasurfaces that are generally impossible to fabricate with traditional photolithographic techniques are created. By engineering the mechanical deformation of the polymer scaffold, the metasurface reflectivity in the mid-infrared can be tuned by the application of moderate strains.

Polyplex formation between four-arm poly(ethylene oxide)-b-poly(2-(diethylamino)ethyl methacrylate) and plasmid DNA in gene delivery.

PubMed

He, E; Yue, C Y; Simeon, F; Zhou, L H; Too, H P; Tam, K C

2009-12-01

Amphiphilic polyelectrolytes comprising cationic and uncharged hydrophilic segments condensed negatively charged DNA to form a core-shell structure stabilized by a layer of hydrophilic corona chains. At physiological pH, four-arm star-shaped poly(ethylene oxide)-b-poly(2-(diethylamino)ethyl methacrylate) (four-arm PEO-b-PDEAEMA) block copolymer possessed positively charged amine groups that interacted with negatively charged plasmid DNA to form polymer/DNA complexes. The mechanism and physicochemical properties of the complex formation were investigated at varying molar ratio of amine groups on polymer chains and phosphate group on plasmid DNA segments (N/P ratio). The capability of the star block copolymer to condense DNA was demonstrated through gel electrophoresis and ethidium bromide exclusion assay. In the absence of salt, the hydrodynamic radius of polyplexes was about 94 nm at low polymer/DNA ratio, and it decreased to about 34 nm at large N/P ratios, forming a compact spherical structure with a weighted average molecular weight of 4.39 +/- 0.22 x 10(6) g/mol. Approximately 15 polymeric chains were required to condense a plasmid DNA. The addition of monovalent salt to the polyplexes significantly altered the size of the complexes, which would have an impact on cell transfection. Because of the electrostatic interaction induced by the diffusion of small ions, the polyplex increased in size to about 53 nm with a less compact structure. In vitro cytotoxicty of polymer and polymer/pDNA complexes were evaluated, and the polyplexes exhibited low toxicity at low N/P ratios. At N/P ratio of 4.5, the four-arm PEO-b-PDEAEMA showed the highest level of transfection in Neuro-2A cells. These observations showed that the star-shaped multi-arm polymers offers interesting properties in self-association and condensation ability for plasmid DNA and can serve as a nonviral DNA delivery system. Copyright 2008 Wiley Periodicals, Inc.

Gas adsorption/separation properties of metal directed self-assembly of two coordination polymers with 5-nitroisophthalate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arıcı, Mürsel; Yeşilel, Okan Zafer, E-mail: yesilel@ogu.edu.tr; Keskin, Seda

2014-02-15

Two new coordination polymers, namely, [Co(µ-nip)(µ-bpe)]{sub n} (1) and [Zn(µ-nip)(µ-bpe)]{sub n} (2) (nip: 5-nitroisophthalate, bpe: 1,2-bis(4-pyridyl)ethane) were hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction, IR spectroscopy, elemental analysis and thermal analysis. Moreover, atomically detailed simulation studies of complex 2 for CO{sub 2}/CH{sub 4} adsorption and separation were performed. Complex 1 consists of two dimensional (2D) (4,4) grid networks with the point symbol of 4{sup 4}.6{sup 2}. Complex 2 exhibits a 3-fold interpenetrating 3D framework with 6{sup 5}.8-dmp topology. Thermal properties of the complexes showed that both complexes were stable over 320 °C. Simulation studies demonstrated that complexmore » 2 can separate CO{sub 2} from CH{sub 4} at low pressures at 273 K. - Graphical abstract: In this study, two new coordination polymers, namely, [Co(µ-nip)(µ-bpe)]{sub n} (1) and [Zn(µ-nip)(µ-bpe)]{sub n} (2) (nip: 5-nitroisophthalate, bpe: 1,2-bis(4-pyridyl)ethane) were hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction, IR spectroscopy, elemental analysis and thermal analysis. Moreover, atomically detailed simulation studies of complex 2 for CO{sub 2}/CH{sub 4} adsorption and separation were performed. Complex 1 consists of two dimensional (2D) (4,4) grid networks with the point symbol of 4{sup 4}.6{sup 2}. Complex 2 exhibits a 3-fold interpenetrating 3D framework with 6{sup 5}.8-dmp topology. Simulation studies demonstrated that complex 2 can separate CO{sub 2} from CH{sub 4} at low pressures at 273 K. Display Omitted - Highlights: • Two new coordination polymers with 5-nitroisophthalate and 1,2-bis(4-pyridyl)ethane. • Atomically detailed simulation studies of the complexes. • Complex 2 can be proposed as molecular sieve to separate CO{sub 2} from CH{sub 4} at low pressures.« less

Bioerodible System for Sequential Release of Multiple Drugs

PubMed Central

Sundararaj, Sharath C.; Thomas, Mark V.; Dziubla, Thomas D.; Puleo, David A.

2013-01-01

Because many complex physiological processes are controlled by multiple biomolecules, comprehensive treatment of certain disease conditions may be more effectively achieved by administration of more than one type of drug. Thus, the objective of the present research was to develop a multilayered, polymer-based system for sequential delivery of multiple drugs. The polymers used were cellulose acetate phthalate (CAP) complexed with Pluronic F-127 (P). After evaluating morphology of the resulting CAPP system, in vitro release of small molecule drugs and a model protein was studied from both single and multilayered devices. Drug release from single-layered CAPP films followed zero-order kinetics related to surface erosion of the association polymer. Release studies from multilayered CAPP devices showed the possibility of achieving intermittent release of one type of drug as well as sequential release of more than one type of drug. Mathematical modeling accurately predicted the release profiles for both single layer and multilayered devices. The present CAPP association polymer-based multilayer devices can be used for localized, sequential delivery of multiple drugs for the possible treatment of complex disease conditions, and perhaps for tissue engineering applications, that require delivery of more than one type of biomolecule. PMID:24096151

Heterobimetallic coordination polymers involving 3d metal complexes and heavier transition metals cyanometallates

NASA Astrophysics Data System (ADS)

Peresypkina, Eugenia V.; Samsonenko, Denis G.; Vostrikova, Kira E.

2015-04-01

The results of the first steps in the design of coordination polymers based on penta- and heptacyanometallates of heavier d transitions metals are presented. The 2D structure of the coordination polymers: [{Mn(acacen)}2Ru(NO)(CN)5]n and two complexes composed of different cyanorhenates, [Ni(cyclam)]2[ReO(OH)(CN)4](ClO4)2(H2O)1.25 and [Cu(cyclam)]2[Re(CN)7](H2O)12, was confirmed by single crystal XRD study, the rhenium oxidation state having been proved by the magnetic measurements. An amorphism of [M(cyclam)]3[Re(CN)7]2 (M=Ni, Cu) polymers does not allow to define strictly their dimensionality and to model anisotropic magnetic behavior of the compounds. However, with high probability a honey-comb like layer structure could be expected for [M(cyclam)]3[Re(CN)7]2 complexes, studied in this work, because such an arrangement is the most common among the bimetallic assemblies of hexa- and octacyanometallates with a ratio [M(cyclam)]/[M(CN)n]=3/2. For the first time was prepared and fully characterized a precursor (n-Bu4N)2[Ru(NO)(CN)5], soluble in organic media.

GDP-tubulin incorporation into growing microtubules modulates polymer stability.

PubMed

Valiron, Odile; Arnal, Isabelle; Caudron, Nicolas; Job, Didier

2010-06-04

Microtubule growth proceeds through the endwise addition of nucleotide-bound tubulin dimers. The microtubule wall is composed of GDP-tubulin subunits, which are thought to come exclusively from the incorporation of GTP-tubulin complexes at microtubule ends followed by GTP hydrolysis within the polymer. The possibility of a direct GDP-tubulin incorporation into growing polymers is regarded as hardly compatible with recent structural data. Here, we have examined GTP-tubulin and GDP-tubulin incorporation into polymerizing microtubules using a minimal assembly system comprised of nucleotide-bound tubulin dimers, in the absence of free nucleotide. We find that GDP-tubulin complexes can efficiently co-polymerize with GTP-tubulin complexes during microtubule assembly. GDP-tubulin incorporation into microtubules occurs with similar efficiency during bulk microtubule assembly as during microtubule growth from seeds or centrosomes. Microtubules formed from GTP-tubulin/GDP-tubulin mixtures display altered microtubule dynamics, in particular a decreased shrinkage rate, apparently due to intrinsic modifications of the polymer disassembly properties. Thus, although microtubules polymerized from GTP-tubulin/GDP-tubulin mixtures or from homogeneous GTP-tubulin solutions are both composed of GDP-tubulin subunits, they have different dynamic properties, and this may reveal a novel form of microtubule "structural plasticity."

Mucopolysaccharide complexes in the fibrous tissue surrounding hydrophilic polymers in subcutaneous implantation.

PubMed

Sprincl, L; Terescenko, T L; Kálal, J; Lipatova, T E; Kopecek, J; Pchakadze, G A

1976-01-01

The biocompatibility of three types of hydrophilic poly-(glycol methacrylate) gels--homogeneous, microporous and macroporous--was investigated in an experimental subcutaneous implantation. The occurrence of mucopolysaccharide complexes formed by both hyaluronic acid and chondroitine sulphates was examined in the fibrous tissue which surrounds the implant and penetrates into it in the case of a macroporous polymer. In an early stage of investigation hyaluronic acid prevails, but with proceeding collagenization the chondroitine sulphate part becomes predominant.

Comparison of sensitivity and resolution load sensor at various configuration polymer optical fiber

NASA Astrophysics Data System (ADS)

Arifin, A.; Yusran, Miftahuddin, Abdullah, Bualkar; Tahir, Dahlang

2017-01-01

This study uses a load sensor with a macro-bending on polymer optical fiber loop model which is placed between two plates with a buffer spring. The load sensor with light intensity modulation principle is an infrared LED emits light through the polymer optical fiber then received by the phototransistor and amplifier. Output voltage from the amplifier continued to arduino sequence and displayed on the computer. Load augment on the sensor resulted in an increase of curvature on polymer optical fibers that can cause power losses gets bigger too. This matter will result in the intensity of light that received by phototransistor getting smaller, so that the output voltage that ligable on computer will be getting smaller too. The sensitivity and resolution load sensors analyzed based on configuration with various amount of loops, imperfection on the jacket, and imperfection at the cladding and core of polymer optical fiber. The results showed that the augment on the amount of load, imperfection on the jacket and imperfection on the sheath and core polymer optical fiber can improve the sensitivity and resolution of the load sensor. The best sensors resolution obtained on the number of loops 4 with imperfection 8 on the core and cladding polymer optical fiber that is 0.037 V/N and 0,026 N. The advantages of the load sensor based on polymers optical fiber are easy to make, low cost and simple to use measurement methods.

SPRUCE Advanced Molecular Techniques Provide a Rigorous Method for Characterizing Organic Matter Quality in Complex Systems: Supporting Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilson, Rachel M; Tfaily, Malak M

These data are provided in support of the Commentary, Advanced molecular techniques provide a rigorous method for characterizing organic matter quality in complex systems, Wilson and Tfaily (2018). Measurement results demonstrate that optical characterization of peatland dissolved organic matter (DOM) may not fully capture classically identified chemical characteristics and may, therefore, not be the best measure of organic matter quality.

Photonic polymer-blend structures and method for making

DOEpatents

Barnes, Michael D.

2004-06-29

The present invention comprises the formation of photonic polymer-blend structures having tunable optical and mechanical properties. The photonic polymer-blend structures comprise monomer units of spherical microparticles of a polymer-blend material wherein the spherical microparticles have surfaces partially merged with one another in a robust inter-particle bond having a tunable inter-particle separation or bond length sequentially attached in a desired and programmable architecture. The photonic polymer-blend structures of the present invention can be linked by several hundred individual particles sequentially linked to form complex three-dimensional structures or highly ordered two-dimensional arrays of 3D columns with 2D spacing.

Large photorefractive effect in a thermally decomposed polymer compared with that in molecularly doped systems

NASA Astrophysics Data System (ADS)

Yokoyama, Kenji; Arishima, Koichi; Sukegawa, Ken

1994-07-01

Photorefractive polymers with the same electro-optic effect were fabricated to investigate the photorefractive effects in different photoconductive systems. The photoconduction in the polymers was varied by the addition of squarylium dye to diethylaminobenzaldehyde-diphenylhydrazone (DEH), by the formation of a charge-transfer complex between tetracyanoquinodimethane and DEH, and by the thermal decomposition of DEH. The largest photorefractive effect was observed in the thermally decomposed polymer among these polymers. A diffraction efficiency of 1.1% and a beam-coupling gain coefficient of 10 cm-1 were achieved in a 34.9 V/μm dc electric field.

A multiple-shape memory polymer-metal composite actuator capable of programmable control, creating complex 3D motion of bending, twisting, and oscillation

NASA Astrophysics Data System (ADS)

Shen, Qi; Trabia, Sarah; Stalbaum, Tyler; Palmre, Viljar; Kim, Kwang; Oh, Il-Kwon

2016-04-01

Development of biomimetic actuators has been an essential motivation in the study of smart materials. However, few materials are capable of controlling complex twisting and bending deformations simultaneously or separately using a dynamic control system. Here, we report an ionic polymer-metal composite actuator having multiple-shape memory effect, and is able to perform complex motion by two external inputs, electrical and thermal. Prior to the development of this type of actuator, this capability only could be realized with existing actuator technologies by using multiple actuators or another robotic system. This paper introduces a soft multiple-shape-memory polymer-metal composite (MSMPMC) actuator having multiple degrees-of-freedom that demonstrates high maneuverability when controlled by two external inputs, electrical and thermal. These multiple inputs allow for complex motions that are routine in nature, but that would be otherwise difficult to obtain with a single actuator. To the best of the authors’ knowledge, this MSMPMC actuator is the first solitary actuator capable of multiple-input control and the resulting deformability and maneuverability.

A multiple-shape memory polymer-metal composite actuator capable of programmable control, creating complex 3D motion of bending, twisting, and oscillation

PubMed Central

Shen, Qi; Trabia, Sarah; Stalbaum, Tyler; Palmre, Viljar; Kim, Kwang; Oh, Il-Kwon

2016-01-01

Development of biomimetic actuators has been an essential motivation in the study of smart materials. However, few materials are capable of controlling complex twisting and bending deformations simultaneously or separately using a dynamic control system. Here, we report an ionic polymer-metal composite actuator having multiple-shape memory effect, and is able to perform complex motion by two external inputs, electrical and thermal. Prior to the development of this type of actuator, this capability only could be realized with existing actuator technologies by using multiple actuators or another robotic system. This paper introduces a soft multiple-shape-memory polymer-metal composite (MSMPMC) actuator having multiple degrees-of-freedom that demonstrates high maneuverability when controlled by two external inputs, electrical and thermal. These multiple inputs allow for complex motions that are routine in nature, but that would be otherwise difficult to obtain with a single actuator. To the best of the authors’ knowledge, this MSMPMC actuator is the first solitary actuator capable of multiple-input control and the resulting deformability and maneuverability. PMID:27080134

A multiple-shape memory polymer-metal composite actuator capable of programmable control, creating complex 3D motion of bending, twisting, and oscillation.

PubMed

Shen, Qi; Trabia, Sarah; Stalbaum, Tyler; Palmre, Viljar; Kim, Kwang; Oh, Il-Kwon

2016-04-15

Development of biomimetic actuators has been an essential motivation in the study of smart materials. However, few materials are capable of controlling complex twisting and bending deformations simultaneously or separately using a dynamic control system. Here, we report an ionic polymer-metal composite actuator having multiple-shape memory effect, and is able to perform complex motion by two external inputs, electrical and thermal. Prior to the development of this type of actuator, this capability only could be realized with existing actuator technologies by using multiple actuators or another robotic system. This paper introduces a soft multiple-shape-memory polymer-metal composite (MSMPMC) actuator having multiple degrees-of-freedom that demonstrates high maneuverability when controlled by two external inputs, electrical and thermal. These multiple inputs allow for complex motions that are routine in nature, but that would be otherwise difficult to obtain with a single actuator. To the best of the authors' knowledge, this MSMPMC actuator is the first solitary actuator capable of multiple-input control and the resulting deformability and maneuverability.

Quantifying Contributions to Transport in Ionic Polymers Across Multiple Length Scales

NASA Astrophysics Data System (ADS)

Madsen, Louis

Self-organized polymer membranes conduct mobile species (ions, water, alcohols, etc.) according to a hierarchy of structural motifs that span sub-nm to >10 μm in length scale. In order to comprehensively understand such materials, our group combines multiple types of NMR dynamics and transport measurements (spectroscopy, diffusometry, relaxometry, imaging) with structural information from scattering and microscopy as well as with theories of porous media,1 electrolytic transport, and oriented matter.2 In this presentation, I will discuss quantitative separation of the phenomena that govern transport in polymer membranes, from intermolecular interactions (<= 2 nm),3 to locally ordered polymer nanochannels (a few to 10s of nm),2 to larger polymer domain structures (10s of nm and larger).1 Using this multi-scale information, we seek to give informed feedback on the design of polymer membranes for use in, e . g . , efficient batteries, fuel cells, and mechanical actuators. References: [1] J. Hou, J. Li, D. Mountz, M. Hull, and L. A. Madsen. Journal of Membrane Science448, 292-298 (2013). [2] J. Li, J. K. Park, R. B. Moore, and L. A. Madsen. Nature Materials 10, 507-511 (2011). [3] M. D. Lingwood, Z. Zhang, B. E. Kidd, K. B. McCreary, J. Hou, and L. A. Madsen. Chemical Communications 49, 4283 - 4285 (2013).

Folding Behaviors of Protein (Lysozyme) Confined in Polyelectrolyte Complex Micelle.

PubMed

Wu, Fu-Gen; Jiang, Yao-Wen; Chen, Zhan; Yu, Zhi-Wu

2016-04-19

The folding/unfolding behavior of proteins (enzymes) in confined space is important for their properties and functions, but such a behavior remains largely unexplored. In this article, we reported our finding that lysozyme and a double hydrophilic block copolymer, methoxypoly(ethylene glycol)5K-block-poly(l-aspartic acid sodium salt)10 (mPEG(5K)-b-PLD10), can form a polyelectrolyte complex micelle with a particle size of ∼30 nm, as verified by dynamic light scattering and transmission electron microscopy. The unfolding and refolding behaviors of lysozyme molecules in the presence of the copolymer were studied by microcalorimetry and circular dichroism spectroscopy. Upon complex formation with mPEG(5K)-b-PLD10, lysozyme changed from its initial native state to a new partially unfolded state. Compared with its native state, this copolymer-complexed new folding state of lysozyme has different secondary and tertiary structures, a decreased thermostability, and significantly altered unfolding/refolding behaviors. It was found that the native lysozyme exhibited reversible unfolding and refolding upon heating and subsequent cooling, while lysozyme in the new folding state (complexed with the oppositely charged PLD segments of the polymer) could unfold upon heating but could not refold upon subsequent cooling. By employing the heating-cooling-reheating procedure, the prevention of complex formation between lysozyme and polymer due to the salt screening effect was observed, and the resulting uncomplexed lysozyme regained its proper unfolding and refolding abilities upon heating and subsequent cooling. Besides, we also pointed out the important role the length of the PLD segment played during the formation of micelles and the monodispersity of the formed micelles. Furthermore, the lysozyme-mPEG(5K)-b-PLD10 mixtures prepared in this work were all transparent, without the formation of large aggregates or precipitates in solution as frequently observed in other protein-polyelectrolyte systems. Hence, the present protein-PEGylated poly(amino acid) mixture provides an ideal water-soluble model system to study the important role of electrostatic interaction in the complexation between proteins and polymers, leading to important new knowledge on the protein-polymer interactions. Moreover, the polyelectrolyte complex micelle formed between protein and PEGylated polymer may provide a good drug delivery vehicle for therapeutic proteins.

Parallel Synthesis of photoluminescent π-conjugated polymers by polymer reactions of an organotitanium polymer with a titanacyclopentadiene unit.

PubMed

Matsumura, Yoshimasa; Fukuda, Katsura; Inagi, Shinsuke; Tomita, Ikuyoshi

2015-04-01

A regioregular organometallic polymer with titanacyclopentadiene unit, obtained by the reaction of a 2,7-diethynylfluorene derivative and a low-valent titanium complex, is subjected to the reaction with three kinds of electrophiles (i.e., sulfur monochloride, hydrochloric acid, and dichlorophenylphosphine) to give π-conjugated polymers possessing both fluorene and building blocks originated from the transformation of the titanacycles in the main chain. For example, a phosphole-containing polymer whose number-average molecular weight is estimated as 5000 is obtained in 50% yield. The obtained thiophene, butadiene, and phosphole-containing polymers exhibit efficient photoluminescence (PL) with emission colors of blue, green, and yellow, respectively. For example, the phosphole-containing polymer exhibits yellow PL with an emission maximum (Emax ) of 533 nm and a quantum yield (Φ) of 0.37. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Semi-permeable coatings fabricated from comb-polymers efficiently protect proteins in vivo

NASA Astrophysics Data System (ADS)

Liu, Mi; Johansen, Pål; Zabel, Franziska; Leroux, Jean-Christophe; Gauthier, Marc A.

2014-11-01

In comparison to neutral linear polymers, functional and architecturally complex (that is, non-linear) polymers offer distinct opportunities for enhancing the properties and performance of therapeutic proteins. However, understanding how to harness these parameters is challenging, and studies that capitalize on them in vivo are scarce. Here we present an in vivo demonstration that modification of a protein with a polymer of appropriate architecture can impart low immunogenicity, with a commensurably low loss of therapeutic activity. These combined properties are inaccessible by conventional strategies using linear polymers. For the model protein L-asparaginase, a comb-polymer bio-conjugate significantly outperformed the linear polymer control in terms of lower immune response and more sustained bioactivity. The semi-permeability characteristics of the coatings are consistent with the phase diagram of the polymer, which will facilitate the application of this strategy to other proteins and with other therapeutic models.

Fabrication of multilayered conductive polymer structures via selective visible light photopolymerization

NASA Astrophysics Data System (ADS)

Cullen, Andrew T.; Price, Aaron D.

2017-04-01

Electropolymerization of pyrrole is commonly employed to fabricate intrinsically conductive polymer films that exhibit desirable electromechanical properties. Due to their monolithic nature, electroactive polypyrrole films produced via this process are typically limited to simple linear or bending actuation modes, which has hindered their application in complex actuation tasks. This initiative aims to develop the specialized fabrication methods and polymer formulations required to realize three-dimensional conductive polymer structures capable of more elaborate actuation modes. Our group has previously reported the application of the digital light processing additive manufacturing process for the fabrication of three-dimensional conductive polymer structures using ultraviolet radiation. In this investigation, we further expand upon this initial work and present an improved polymer formulation designed for digital light processing additive manufacturing using visible light. This technology enables the design of novel electroactive polymer sensors and actuators with enhanced capabilities and brings us one step closer to realizing more advanced electroactive polymer enabled devices.

Adsorption of finite semiflexible polymers and their loop and tail distributions

NASA Astrophysics Data System (ADS)

Kampmann, Tobias A.; Kierfeld, Jan

2017-07-01

We discuss the adsorption of semiflexible polymers to a planar attractive wall and focus on the questions of the adsorption threshold for polymers of finite length and their loop and tail distributions using both Monte Carlo simulations and analytical arguments. For the adsorption threshold, we find three regimes: (i) a flexible or Gaussian regime if the persistence length is smaller than the adsorption potential range, (ii) a semiflexible regime if the persistence length is larger than the potential range, and (iii) for finite polymers, a novel crossover to a rigid rod regime if the deflection length exceeds the contour length. In the flexible and semiflexible regimes, finite size corrections arise because the correlation length exceeds the contour length. In the rigid rod regime, however, it is essential how the global orientational or translational degrees of freedom are restricted by grafting or confinement. We discuss finite size corrections for polymers grafted to the adsorbing surface and for polymers confined by a second (parallel) hard wall. Based on these results, we obtain a method to analyze adsorption data for finite semiflexible polymers such as filamentous actin. For the loop and tail distributions, we find power laws with an exponential decay on length scales exceeding the correlation length. We derive and confirm the loop and tail power law exponents for flexible and semiflexible polymers. This allows us to explain that, close to the transition, semiflexible polymers have significantly smaller loops and both flexible and semiflexible polymers desorb by expanding their tail length. The tail distribution allows us to extract the free energy per length of adsorption for actin filaments from experimental data [D. Welch et al., Soft Matter 11, 7507 (2015)].

Lanthanide coordination polymers: Synthesis, diverse structure and luminescence properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Xue-Qin, E-mail: songxq@mail.lzjtu.cn; Lei, Yao-Kun; Wang, Xiao-Run

2014-10-15

The new semirigid exo-bidentate ligand incorporating furfurysalicylamide terminal groups, namely, 1,4-bis([(2′-furfurylaminoformyl)phenoxyl]methyl)-2,5-bismethylbenzene (L) was synthesized and used as building blocks for constructing lanthanide coordination polymers with luminescent properties. The series of lanthanide nitrate complexes have been characterized by elemental analysis, IR spectroscopy, and X-ray diffraction analysis. The semirigid ligand L, as a bridging ligand, reacts with lanthanide nitrates forming three distinct structure types: chiral noninterpenetrated two-dimensional (2D) honeycomblike (6,3) (hcb, Schläfli symbol 6{sup 3}, vertex symbol 6 6 6) topological network as type I, 1D zigzag chain as type II and 1D trapezoid ladder-like chain as type III. The structural diversitiesmore » indicate that lanthanide contraction effect played significant roles in the structural self-assembled process. The luminescent properties of Eu{sup III}, Tb{sup III} and Dy{sup III} complexes are discussed in detail. Due to the good match between the lowest triplet state of the ligand and the resonant energy level of the lanthanide ion, the lanthanide ions in Eu{sup III}, Tb{sup III} and Dy{sup III} complexes can be efficiently sensitized by the ligand. - Graphical abstract: We present herein six lanthanide coordination polymers of a new semirigid exo-bidentate ligand which not only display diverse structures but also possess strong luminescence properties. - Highlights: • We present lanthanide coordination polymers of a new semirigid exo-bidentate ligand. • The lanthanide coordination polymers exhibit diverse structures. • The luminescent properties of Tb{sup III}, Eu{sup III} and Dy{sup III} complexes are discussed in detail.« less

Elaboration of thermoresponsive supramolecular diblock copolymers in water from complementary CBPQT4+ and TTF end-functionalized polymers.

PubMed

Sambe, Léna; Stoffelbach, François; Poltorak, Katarzyna; Lyskawa, Joël; Malfait, Aurélie; Bria, Marc; Cooke, Graeme; Woisel, Patrice

2014-02-01

A well-defined poly(N-isopropyl acrylamide) 1 incorporating at one termini a cyclobis(paraquat-p-phenylene) (CBPQT(4+)) recognition unit is prepared via a RAFT polymerization followed by a copper-catalyzed azide-alkyne cycloaddition (CuAAC). (1)H NMR (1D, DOSY), UV-vis and ITC experiments reveal that polymer 1 is able of forming effective host-guest complexes with tetrathiafulvalene (TTF) end-functionalized polymers in water, thereby leading to the formation of non-covalently-linked double-hydrophilic block copolymers. The effect of the temperature on both the LCST phase transition of 1 and its complexes and on CBPQT(4+)/TTF host-guest interactions is investigated. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The growth of Scenedesmus quadricauda in RO concentrate and the impacts on refractory organic matter, Escherichia coli, and trace organic compounds

EPA Science Inventory

This study achieves a better operational simplicity for the phycoremediation of reverse osmosis (RO) concentrate using Scenedesmus quadricauda microalgae. Under continuous illumination with CO2 supplementation, algal growth in the RO concentrate resulted in a conversion of polyme...

Diffusion of Sites versus Polymers in Polyelectrolyte Complexes and Multilayers.

PubMed

Fares, Hadi M; Schlenoff, Joseph B

2017-10-18

It has long been assumed that the spontaneous formation of materials such as complexes and multilayers from charged polymers depends on (inter)diffusion of these polyelectrolytes. Here, we separately examine the mass transport of polymer molecules and extrinsic sites-charged polyelectrolyte repeat units balanced by counterions-within thin films of polyelectrolyte complex, PEC, using sensitive isotopic labeling techniques. The apparent diffusion coefficients of these sites within PEC films of poly(diallyldimethylammonium), PDADMA, and poly(styrenesulfonate), PSS, are at least 2 orders of magnitude faster than the diffusion of polyelectrolytes themselves. This is because site diffusion requires only local rearrangements of polyelectrolyte repeat units, placing far fewer kinetic limitations on the assembly of polyelectrolyte complexes in all of their forms. Site diffusion strongly depends on the salt concentration (ionic strength) of the environment, and diffusion of PDADMA sites is faster than that of PSS sites, accounting for the asymmetric nature of multilayer growth. Site diffusion is responsible for multilayer growth in the linear and into the exponential regimes, which explains how PDADMA can mysteriously "pass through" layers of PSS. Using quantitative relationships between site diffusion coefficient and salt concentration, conditions were identified that allowed the diffusion length to always exceed the film thickness, leading to full exponential growth over 3 orders of magnitude thickness. Both site and polymer diffusion were independent of molecular weight, suggesting that ion pairing density is a limiting factor. Polyelectrolyte complexes are examples of a broader class of dynamic bulk polymeric materials that (self-) assemble via the transport of cross-links or defects rather than actual molecules.

Decreased solubilization of Pu(IV) polymers by humic acids under anoxic conditions

NASA Astrophysics Data System (ADS)

Xie, Jinchuan; Lin, Jianfeng; Liang, Wei; Li, Mei; Zhou, Xiaohua

2016-11-01

Pu(IV) polymer has a very low solubility (log[Pu(IV)aq]total = -10.4 at pH 7.2 and I = 0). However, some aspects of their environmental fate remain unclear. Humic acids are able to complex with Pu4+ ions and their dissolved species (<10 kD) in the groundwater (neutral to alkaline pH) may cause solubilization of the polymers. Also, humic acids have the native reducing capacity and potentially reduce the polymeric Pu(IV) to Pu(III)aq (log[Pu(III)aq]total = -5.3 at pH 7.2 and I = 0). Solubilization and reduction of the polymers can enhance their mobility in subsurface environments. Nevertheless, humic acids readily coat the surfaces of metal oxides via electrostatic interaction and ligand exchange mechanisms. The humic coatings are expected to prevent both solubilization and reduction of the polymers. Experiments were conducted under anoxic and slightly alkaline (pH 7.2) conditions in order to study whether humic acids have effects on stability of the polymers. The results show that the polymeric Pu(IV) was almost completely transformed into aqueous Pu(IV) in the presence of EDTA ligands. In contrast, the dissolved humic acids did not solubilize the polymers but in fact decreased their solubility by one order of magnitude. The humic coatings were responsible for the decreased solubilization. Such coatings limited the contact between the polymers and EDTA ligands, especially at the relatively high concentrations of humic acids (>0.57 mg/L). Solubilization of the humic-coated polymers was thus inhibited to a significant extent although EDTA, having the great complexation ability, was present in the humic solutions. Reduction of Pu(IV) polymers by the humic acids was also not observed in the absence of EDTA. In the presence of EDTA, the polymers were partially reduced to Pu(III)aq by the humic acids of 0.57 mg/L and the percentage of Pu(III)aq accounted for 51.7% of the total aqueous Pu. This demonstrates that the humic acids were able to reduce the aqueous Pu(IV), instead of the polymeric Pu(IV). Such a demonstration is supported by the very positive redox potential of aqueous Pu(IV)-EDTA complex: Eho ‧ (PuL24-/PuL25-) = 154.3 mV >>Eh (PuO2 (am) /Pu3+) = -182.7 mV calculated at 10-10 mol/L Pu3+ and pH 7.2. At the higher humic concentrations (>0.57 mg/L), the polymers were reduced to a lesser extent because the much denser humic coatings resulted in lower concentrations of the aqueous Pu(IV). Consequently, humic acids make Pu(IV) polymers pretty stable unless the artificial ligands such as EDTA are present in the groundwater.

Artificially Engineered Protein Polymers.

PubMed

Yang, Yun Jung; Holmberg, Angela L; Olsen, Bradley D

2017-06-07

Modern polymer science increasingly requires precise control over macromolecular structure and properties for engineering advanced materials and biomedical systems. The application of biological processes to design and synthesize artificial protein polymers offers a means for furthering macromolecular tunability, enabling polymers with dispersities of ∼1.0 and monomer-level sequence control. Taking inspiration from materials evolved in nature, scientists have created modular building blocks with simplified monomer sequences that replicate the function of natural systems. The corresponding protein engineering toolbox has enabled the systematic development of complex functional polymeric materials across areas as diverse as adhesives, responsive polymers, and medical materials. This review discusses the natural proteins that have inspired the development of key building blocks for protein polymer engineering and the function of these elements in material design. The prospects and progress for scalable commercialization of protein polymers are reviewed, discussing both technology needs and opportunities.

Quenching of fluorescence of conjugated poly(p-phenylene) polymers by benzil and dimethylaminobenzil molecules

NASA Astrophysics Data System (ADS)

Bagnich, S. A.; Knyukshto, V. N.

2006-11-01

We have studied the mechanisms for quenching of the fluorescence of conjugated poly(p-phenylene) polymers by benzil and dimethylaminobenzil molecules. We have shown that molecules in the diketone series are quenching agents for the fluorescence of the indicated polymers, and can serve as singlet-triplet converters capable of populating the triplet state of the polymer. We have observed that the efficiency of quenching of the fluorescence of the studied polymers depends considerably on the presence of bulky side groups in the polymer or in the activator molecules. Based on analysis of the data obtained, we conclude that in the case of a rigid planar structure for the polymer, a significant contribution to quenching of its fluorescence comes from not only singlet-singlet energy transfer but also charge transfer, leading to formation of intermolecular complexes (exciplexes).

SVP-like MADS-box protein from Carya cathayensis forms higher-order complexes.

PubMed

Wang, Jingjing; Hou, Chuanming; Huang, Jianqin; Wang, Zhengjia; Xu, Yingwu

2015-03-01

To properly regulate plant flowering time and construct floral pattern, MADS-domain containing transcription factors must form multimers including homo- and hetero-dimers. They are also active in forming hetero-higher-order complexes with three to five different molecules. However, it is not well known if a MADS-box protein can also form homo-higher-order complex. In this study a biochemical approach is utilized to provide insight into the complex formation for an SVP-like MADS-box protein cloned from hickory. The results indicated that the protein is a heterogeneous higher-order complex with the peak population containing over 20 monomers. Y2H verified the protein to form homo-complex in yeast cells. Western blot of the hickory floral bud sample revealed that the protein exists in higher-order polymers in native. Deletion assays indicated that the flexible C-terminal residues are mainly responsible for the higher-order polymer formation and the heterogeneity. Current results provide direct biochemical evidences for an active MADS-box protein to be a high order complex, much higher than a quartermeric polymer. Analysis suggests that a MADS-box subset may be able to self-assemble into large complexes, and thereby differentiate one subfamily from the other in a higher-order structural manner. Present result is a valuable supplement to the action of mechanism for MADS-box proteins in plant development. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Mystery of the Hidden Cosmos [Complex Dark Matter

DOE PAGES

Dobrescu, Bogdan A.; Lincoln, Don

2015-06-16

Scientists know there must be more matter in the universe than what is visible. Searches for this dark matter have focused on a single unseen particle, but decades of experiments have been unsuccessful at finding it. Exotic possibilities for dark matter are looking increasingly plausible. Rather than just one particle, dark matter could contain an entire world of particles and forces that barely interact with normal matter. Complex dark matter could form dark atoms and molecules and even clump together to make hidden galactic disks that overlap with the spiral arms of the Milky Way and other galaxies. Experiments aremore » under way to search for evidence of such a dark sector.« less

Enhanced photophysics of conjugated polymers

DOEpatents

Chen, Liaohai [Darien, IL

2007-06-12

A particulate fluorescent conjugated polymer surfactant complex and method of making and using same. The particles are between about 15 and about 50 nm and when formed from a lipsome surfactant have a charge density similar to DNA and are strongly absorbed by cancer cells.

Four unexpected lanthanide coordination polymers involving in situ reaction of solvent N, N-Dimethylformamide

NASA Astrophysics Data System (ADS)

Jin, Jun-Cheng; Tong, Wen-Quan; Fu, Ai-Yun; Xie, Cheng-Gen; Chang, Wen-Gui; Wu, Ju; Xu, Guang-Nian; Zhang, Ya-Nan; Li, Jun; Li, Yong; Yang, Peng-Qi

2015-05-01

Four unexpected 2D lanthanide coordination polymers have been synthesized through in situ reactions of DMF solvent under solvothermal conditions. The isostructural complexes 1-3 contain four types of 21 helical chains. While the Nd(III) ions are bridged through μ2-HIDC2- and oxalate to form a 2D sheet along the bc plane without helical character in 4. Therefore, complex 1 exhibits bright red solid-state phosphorescence upon exposure to UV radiation at room temperature.

Frustration of resonant preheating by exotic kinetic terms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rahmati, Shohreh; Seahra, Sanjeev S., E-mail: srahmati@unb.ca, E-mail: sseahra@unb.ca

2014-10-01

We study the effects of exotic kinetic terms on parametric resonance during the preheating epoch of the early universe. Specifically, we consider modifications to the action of ordinary matter fields motivated by generalized uncertainty principles, polymer quantization, as well as Dirac-Born-Infeld and k-essence models. To leading order in an ''exotic physics'' scale, the equations of motion derived from each of these models have the same algebraic form involving a nonlinear self-interaction in the matter sector. Neglecting spatial dependence, we show that the nonlinearity effectively shuts down the parametric resonance after a finite time period. We find numeric evidence that themore » frustration of parametric resonance persists to spatially inhomogenous matter in (1+1)-dimensions.« less

Long conducting polymer nanonecklaces with a `beads-on-a-string' morphology: DNA nanotube-template synthesis and electrical properties

NASA Astrophysics Data System (ADS)

Chen, Guofang; Mao, Chengde

2016-05-01

Complex and functional nanostructures are always desired. Herein, we present the synthesis of novel long conducting polymer nanonecklaces with a `beads-on-a-string' morphology by the DNA nanotube-template approach and in situ oxidative polymerization of the 3-methylthiophene monomer with FeCl3 as the oxidant/catalyst. The length of the nanonecklaces is up to 60 μm, and the polymer beads of around 20-25 nm in diameter are closely packed along the axis of the DNA nanotube template with a density of ca. 45 particles per μm. The formation of porous DNA nanotubes impregnated with FeCl3 was also demonstrated as intermediate nanostructures. The mechanisms for the formation of both the porous DNA nanotubes and the conducting polymer nanonecklaces are discussed in detail. The as-synthesized polymer/DNA nanonecklaces exhibit good electrical properties.Complex and functional nanostructures are always desired. Herein, we present the synthesis of novel long conducting polymer nanonecklaces with a `beads-on-a-string' morphology by the DNA nanotube-template approach and in situ oxidative polymerization of the 3-methylthiophene monomer with FeCl3 as the oxidant/catalyst. The length of the nanonecklaces is up to 60 μm, and the polymer beads of around 20-25 nm in diameter are closely packed along the axis of the DNA nanotube template with a density of ca. 45 particles per μm. The formation of porous DNA nanotubes impregnated with FeCl3 was also demonstrated as intermediate nanostructures. The mechanisms for the formation of both the porous DNA nanotubes and the conducting polymer nanonecklaces are discussed in detail. The as-synthesized polymer/DNA nanonecklaces exhibit good electrical properties. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01603k

Lower Critical Solution Temperature (LCST) and drug conjugation of polyacetal

NASA Astrophysics Data System (ADS)

de Silva, Chathuranga; Samanta, Sanjoy; Leophairatana, Porakrit; Koberstein, Jeffrey

There has been an increasing focus in polymer research for materials that can efficiently deliver therapeutics to a pre-identified solid tumor target. Due to their unique properties, stimuli responsive polymers (SRPs) have been of particular interest. One such novel SRP is a polyacetal-based copolymer (PAC). PAC shows a remarkable temperature response (LCST) that is linearly dependent on composition. Here, we discuss the fundamental physical origins of this LCST behavior, exhibited by this polymer. Our results indicate that the observed LCST scales linearly with the number of carbon and oxygen atoms in the polymer repeat units, allowing for precise control over the LCST. We design PAC to include cancer therapeutics in its polymer-backbone, utilizing strategies to modify step-growth polymerization to obtain, for the first time, temperature-responsive main-chain drug conjugates. The temperature response in these main-chain drug conjugates allow for effective delivery of therapeutics to the tumor site, followed by acid-hydrolysis in acidic local tumor environments, to release pristine therapeutics directly at the tumor site. Due to these reasons, we foresee PAC to be in the forefront of soft-matter SRP drug-delivery systems.

Quaternization enhances the transgene expression efficacy of aminoglycoside-derived polymers.

PubMed

Miryala, Bhavani; Feng, Yunpeng; Omer, Ala; Potta, Thrimoorthy; Rege, Kaushal

2015-07-15

The objective of the present study was to synthesize and investigate the transgene expression efficacy of quaternized derivatives of aminoglycoside polymers in different cancer cell lines. A series of glycidyltrimethylammonium chloride (GTMAC) derivatives of aminoglycoside polymers (GTMAC-AM polymers), containing varying degrees of quaternization (13-45%), were synthesized. The structures and properties of GTMAC-AM polymers were investigated using FT-IR and (1)H NMR spectroscopy. Physicochemical factors that influence transgene expression efficacy including DNA binding, hydrodynamic size, zeta potential and cytotoxicity, were determined. Formation of polymer-plasmid DNA complexes was also visualized using atomic force microscopy. GTMAC-AM polymers demonstrated higher transgene expression efficacies compared to their parent polymers, 25 kDa poly(ethyleneimine), as well as Lipofectamine-3000. Our results indicate that quaternization enhances the transgene expression efficacy and reduces the cytotoxicity of aminoglycoside-derived polymers, making it an attractive strategy for nucleic acid delivery with these new materials. Copyright © 2015 Elsevier B.V. All rights reserved.

BSA binding and antimicrobial studies of branched polyethyleneimine-copper(II)bipyridine/phenanthroline complexes

NASA Astrophysics Data System (ADS)

Vignesh, Gopalaswamy; Arunachalam, Sankaralingam; Vignesh, Sivanandham; James, Rathinam Arthur

2012-10-01

The interaction of two water soluble branched polyethyleneimine-copper(II) complexes containing bipyridine/phenanthroline with bovine serum albumin (BSA) was studied by, UV-Visible absorption, fluorescence, lifetime measurements and circular dichroism spectroscopic techniques. The polymer-copper(II) complexes strongly quench the intrinsic fluorescence of BSA is the static quenching mechanism through hydrogen bonds and van der Waal's attraction. The distance r, between the BSA and the complexes seems to be less than 2 nm indicating that the energy transfer between the donor and acceptor occurs with high probability. Synchronous fluorescence studies indicate the binding of polymer-copper(II) complexes with BSA mostly changes the polarity around tryptophan residues rather than tyrosine residues. The circular dichroism studies indicate that the binding has induced considerable amount of conformational changes in the protein. The complexes also show some antibacterial and antifungal properties.

A look at the effect of sequence complexity on pressure destabilisation of DNA polymers.

PubMed

Rayan, Gamal; Macgregor, Robert B

2015-04-01

Our previous studies on the helix-coil transition of double-stranded DNA polymers have demonstrated that molar volume change (ΔV) accompanying the thermally-induced transition can be positive or negative depending on the experimental conditions, that the pressure-induced transition is more cooperative than the heat-induced transition [Rayan and Macgregor, J Phys Chem B2005, 109, 15558-15565], and that the pressure-induced transition does not occur in the absence of water [Rayan and Macgregor, Biophys Chem, 2009, 144, 62-66]. Additionally, we have shown that ΔV values obtained by pressure-dependent techniques differ from those obtained by ambient pressure techniques such as PPC [Rayan et al. J Phys Chem B2009, 113, 1738-1742] thus shedding light on the effects of pressure on DNA polymers. Herein, we examine the effect of sequence complexity, and hence cooperativity on pressure destabilisation of DNA polymers. Working with Clostridium perfringes DNA under conditions such that the estimated ΔV of the helix-coil transition corresponds to -1.78 mL/mol (base pair) at atmospheric pressure, we do not observe the pressure-induced helix-coil transition of this DNA polymer, whereas synthetic copolymers poly[d(A-T)] and poly[d(I-C)] undergo cooperative pressure-induced transitions at similar ΔV values. We hypothesise that the reason for the lack of pressure-induced helix-coil transition of C. perfringens DNA under these experimental conditions lies in its sequence complexity. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of PEG and mPEG-anthracene on tRNA aggregation and particle formation.

PubMed

Froehlich, E; Mandeville, J S; Arnold, D; Kreplak, L; Tajmir-Riahi, H A

2012-01-09

Poly(ethylene glycol) (PEG) and its derivatives are synthetic polymers with major applications in gene and drug delivery systems. Synthetic polymers are also used to transport miRNA and siRNA in vitro. We studied the interaction of tRNA with several PEGs of different compositions, such as PEG 3350, PEG 6000, and mPEG-anthracene under physiological conditions. FTIR, UV-visible, CD, and fluorescence spectroscopic methods as well as atomic force microscopy (AFM) were used to analyze the PEG binding mode, the binding constant, and the effects of polymer complexation on tRNA stability, aggregation, and particle formation. Structural analysis showed that PEG-tRNA interaction occurs via RNA bases and the backbone phosphate group with both hydrophilic and hydrophobic contacts. The overall binding constants of K(PEG 3350-tRNA)= 1.9 (±0.5) × 10(4) M(-1), K(PEG 6000-tRNA) = 8.9 (±1) × 10(4) M(-1), and K(mPEG-anthracene)= 1.2 (±0.40) × 10(3) M(-1) show stronger polymer-RNA complexation by PEG 6000 and by PEG 3350 than the mPEG-anthracene. AFM imaging showed that PEG complexes contain on average one tRNA with PEG 3350, five tRNA with PEG 6000, and ten tRNA molecules with mPEG-anthracene. tRNA aggregation and particle formation occurred at high polymer concentrations, whereas it remains in A-family structure.

Polymer-grafted QCM chemical sensor and application to heavy metalions real time detection.

PubMed

Sartore, Luciana; Barbaglio, Marzia; Borgese, Laura; Bontempi, Elza

2011-07-20

A flow type quartz crystal microbalance (QCM) chemical sensor was developed for monitoring of heavy metal ions in aqueous solutions (that is suitable for environmental monitoring). The sensor is based upon surface chelation of the metal ions at multifunctional polymer modified gold electrodes on 9 MHz AT-cut quartz resonators, functioning as a QCM. New processes have been developed which enable to obtain surface-modified gold electrodes with high heavy metal ions complexing ability. These polymer grafted QCM sensors can selectively adsorb heavy metal ions, such as copper lead chrome and cadmium, from solution over a wide range from 0.01 to 1000 ppm concentration by complexation with functional groups in the polymers. Cations typically present in natural water did not interfere with the detection of heavy metals. X-Ray Reflectivity (XRR) and Total Reflection X-ray Fluorescence (TXRF) were carried out to characterise the unmodified and modified gold surfaces as well as to verify the possibility to selectively bond and remove metal ions.

Studies on guanidinated N-3-aminopropyl methacrylamide-N-2-hydroxypropyl methacrylamide co-polymers as gene delivery carrier.

PubMed

Qin, Zhu; Liu, Wei; Guo, Liang; Li, Xinsong

2012-01-01

Guanidinated N-3-aminopropyl methacrylamide (APMA)-N-2-hydroxypropyl methacrylamide (HPMA) co-polymers were prepared and evaluated to develop novel non-viral gene transfection carriers. The co-polymers were synthesized via radical co-polymerization of APMA and HPMA followed by total guanidination of amino groups, which employed guanidinated APMA (GPMA) for increasing cell-penetrating and HPMA as the positive shielding content. The molecular weight of guanidinated APMA-HPMA co-polymers (GPMA-HPMA) was determined by static light scattering. Furthermore, cytotoxicity and transfection experiments of GPMA-HPMA/pDNA complexes were conducted. A significant decrease of their parent cytotoxicity and an efficient transfection at relative low charge ratios were observed. The cellular distribution of most GPMA-HPMA/pDNA complexes was partially localized in the nucleus, as indicated by confocal laser scanning microscopy. The guanidination strategy employed may lead to non-viral gene delivery carriers that combine satisfactory transfection efficiency and cytotoxicity, which contribute to their cell-penetrating ability.

Chaperonin polymers in archaea: The cytoskeleton of prokaryotes?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trent, J.D.; Kagawa, H.K.; Zaluzec, N.J.

Chaperonins are protein complexes that play a critical role in folding nascent polypeptides under normal conditions and refolding damaged proteins under stress conditions. In all organisms these complexes are composed of evolutionarily conserved 60-kDa proteins arranged in double-ring structures with between 7 and 9 protein subunits per ring. These double ring structures are assumed to be the functional units in vivo, although they have never been observed inside cells. Here the authors show that the purified chaperonin from the hyperthermophilic archaeon Sulfolobus shibatae, which is closely related to chaperonins in eukaryotes, has a double ring structure at low concentrations (0.1more » mg/ml), but at more physiological concentrations, the rings stack end to end to form polymers. The polymers are stable at physiological temperatures (75 C) and closely resemble structures observed inside unfixed S. shibatae cells. The authors suggest that in vivo chaperonin activity may be regulated by polymerization and that chaperonin polymers may act as a cytoskeleton-like structure in archaea and bacteria.« less

Chaperonin Polymers in Archaea: The Cytoskeleton of Prokaryotes?

DOE R&D Accomplishments Database

Trent, J. D.; Kagawa, H. K.; Zaluzec, N. J.

1997-07-01

Chaperonins are protein complexes that play a critical role in folding nascent polypeptides under normal conditions and refolding damaged proteins under stress conditions. In all organisms these complexes are composed of evolutionarily conserved 60-kDa proteins arranged in double-ring structures with between 7 and 9 protein subunits per ring. These double ring structures are assumed to be the functional units in vivo, although they have never been observed inside cells. Here the authors show that the purified chaperonin from the hyperthermophilic archaeon Sulfolobus shibatae, which is closely related to chaperonins in eukaryotes, has a double ring structure at low concentrations (0.1 mg/ml), but at more physiological concentrations, the rings stack end to end to form polymers. The polymers are stable at physiological temperatures (75 C) and closely resemble structures observed inside unfixed S. shibatae cells. The authors suggest that in vivo chaperonin activity may be regulated by polymerization and that chaperonin polymers may act as a cytoskeleton-like structure in archaea and bacteria.

Dynamically Tunable Cell Culture Platforms for Tissue Engineering and Mechanobiology

PubMed Central

Uto, Koichiro; Tsui, Jonathan H.; DeForest, Cole A.; Kim, Deok-Ho

2016-01-01

Human tissues are sophisticated ensembles of many distinct cell types embedded in the complex, but well-defined, structures of the extracellular matrix (ECM). Dynamic biochemical, physicochemical, and mechano-structural changes in the ECM define and regulate tissue-specific cell behaviors. To recapitulate this complex environment in vitro, dynamic polymer-based biomaterials have emerged as powerful tools to probe and direct active changes in cell function. The rapid evolution of polymerization chemistries, structural modulation, and processing technologies, as well as the incorporation of stimuli-responsiveness, now permit synthetic microenvironments to capture much of the dynamic complexity of native tissue. These platforms are comprised not only of natural polymers chemically and molecularly similar to ECM, but those fully synthetic in origin. Here, we review recent in vitro efforts to mimic the dynamic microenvironment comprising native tissue ECM from the viewpoint of material design. We also discuss how these dynamic polymer-based biomaterials are being used in fundamental cell mechanobiology studies, as well as towards efforts in tissue engineering and regenerative medicine. PMID:28522885

Hybrid Nanomaterial Complexes for Advanced Phage-guided Gene Delivery

PubMed Central

Yata, Teerapong; Lee, Koon-Yang; Dharakul, Tararaj; Songsivilai, Sirirurg; Bismarck, Alexander; Mintz, Paul J; Hajitou, Amin

2014-01-01

Developing nanomaterials that are effective, safe, and selective for gene transfer applications is challenging. Bacteriophages (phage), viruses that infect bacteria only, have shown promise for targeted gene transfer applications. Unfortunately, limited progress has been achieved in improving their potential to overcome mammalian cellular barriers. We hypothesized that chemical modification of the bacteriophage capsid could be applied to improve targeted gene delivery by phage vectors into mammalian cells. Here, we introduce a novel hybrid system consisting of two classes of nanomaterial systems, cationic polymers and M13 bacteriophage virus particles genetically engineered to display a tumor-targeting ligand and carry a transgene cassette. We demonstrate that the phage complex with cationic polymers generates positively charged phage and large aggregates that show enhanced cell surface attachment, buffering capacity, and improved transgene expression while retaining cell type specificity. Moreover, phage/polymer complexes carrying a therapeutic gene achieve greater cancer cell killing than phage alone. This new class of hybrid nanomaterial platform can advance targeted gene delivery applications by bacteriophage. PMID:25118171

Preparation of Lanthanide-Polymer Composite Material via Click Chemistry.

PubMed

Chen, Bin; Wen, Guian; Wu, Jiajie; Feng, Jiachun

2015-10-01

Covalently attaching lanthanide complexes to the polymer backbone can effectively reduce the clustering of lanthanides and thus become an important strategy to fully unleash their potential. In this Communication, a metal-free click reaction is used for the first time to link a lanthanide complex to the polymer matrix. A diene-bearing copolymer with anthracenylmethyl methacrylate as a monomer and a dienophile-bearing lanthanide complex with 5-maleimido-1,10-phenanthroline as the second ligand are synthesized and coupled together through a Diels-Alder cycloaddition (DA). A comparative investigation demonstrates that the composite material prepared by DA click reaction shows the highest quantum yields in the same lanthanide concentration as compared to materials prepared by widely used "directly doping" and "in situ coordinating lanthanide ions with macromolecular ligand" approaches. This work suggests that the "metal-free" DA click reaction can be a promising tool in the synthesis of high efficient lanthanide functionalized polymeric materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Complex rheological properties of a water-soluble extract from the fronds of the black tree fern, Cyathea medullaris.

PubMed

Goh, Kelvin K T; Matia-Merino, Lara; Hall, Christopher E; Moughan, Paul J; Singh, Harjinder

2007-11-01

A water-soluble extract was obtained from the fronds of a New Zealand native black tree fern (Cyathea medullaris or Mamaku in Māori). The extract exhibited complex rheological behavior. Newtonian, shear-thinning, shear-thickening, thixotropic, antithixotropic, and viscoelastic behaviors were observed depending on polymer concentration, shear rate, and shear history. The extract also displayed rod-climbing and self-siphoning properties typical of viscoelastic fluids. Such complex rheological properties have been reported in synthetic or chemically modified polymers but are less frequent in unmodified biopolymers. Although Mamaku extract obtained from the pith of the fern has been traditionally used by the Māori in New Zealand for treating wounds and diarrhea among other ailments, this material has never been characterized before. This study reports on the chemical composition of the extract and on its viscoelastic properties through rotational and oscillatory rheological measurements. Explanations of the mechanism behind the rheological properties were based on transient network models for associating polymers.

Bio-inspired metal-coordinate hydrogels with programmable viscoelastic material functions controlled by longwave UV light.

PubMed

Grindy, Scott C; Holten-Andersen, Niels

2017-06-07

Control over the viscoelastic mechanical properties of hydrogels intended for use as biomedical materials has long been a goal of soft matter scientists. Recent research has shown that materials made from polymers with reversibly associating transient crosslinks are a promising strategy for controlling viscoelasticity in hydrogels, for example leading to systems with precisely tunable mechanical energy-dissipation. We and others have shown that bio-inspired histidine:transition metal ion complexes allow highly precise and tunable control over the viscoelastic properties of transient network hydrogels. In this paper, we extend the design of these hydrogels such that their viscoelastic properties respond to longwave UV radiation. We show that careful selection of the histidine:transition metal ion crosslink mixtures allows unique control over pre- and post-UV viscoelastic properties. We anticipate that our strategy for controlling stimuli-responsive viscoelastic properties will aid biomedical materials scientists in the development of soft materials with specific stress-relaxing or energy-dissipating properties.

Transformation of regioregular organotitanium polymers into group 16 heterole-containing π-conjugated materials.

PubMed

Nishiyama, Hiroki; Kino, Tomoko; Tomita, Ikuyoshi

2012-04-13

Regioregular organometallic polymers with titanacyclopentadiene units, obtained from terminal diynes and a low-valent titanium complex, were subjected to reactions with disulfur dichloride and selenium (I) chloride to give π-conjugated polymers with thiophene and selenophene units in the main chain in 63% and 86% yields. Their number-average molecular weights were estimated as 4300 and 5700, respectively. Both polymers were found to be fully π-conjugated and their HOMO energy levels were remarkably high (-5.3 eV and -5.0 eV for thiophene- and selenophene-containing polymers, respectively) as supported by their UV-vis absorption spectra and CV analyses. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multilevel Investigation of Charge Transport in Conjugated Polymers.

PubMed

Dong, Huanli; Hu, Wenping

2016-11-15

Conjugated polymers have attracted the world's attentions since their discovery due to their great promise for optoelectronic devices. However, the fundamental understanding of charge transport in conjugated polymers remains far from clear. The origin of this challenge is the natural disorder of polymers with complex molecular structures in the solid state. Moreover, an effective way to examine the intrinsic properties of conjugated polymers is absent. Optoelectronic devices are always based on spin-coated films. In films, polymers tend to form highly disordered structures at nanometer to micrometer length scales due to the high degree of conformational freedom of macromolecular chains and the irregular interchain entanglement, thus typically resulting in much lower charge transport properties than their intrinsic performance. Furthermore, a subtle change of processing conditions may dramatically affect the film formation-inducing large variations in the morphology, crystallinity, microstructure, molecular packing, and alignment, and finally varying the effective charge transport significantly and leading to great inconsistency over an order of magnitude even for devices based on the same polymer semiconductor. Meanwhile, the charge transport mechanism in conjugated polymers is still unclear and its investigation is challenging based on such complex microstructures of polymers in films. Therefore, how to objectively evaluate the charge transport and probe the charge transport mechanism of conjugated polymers has confronted the world for decades. In this Account, we present our recent progress on multilevel charge transport in conjugated polymers, from disordered films, uniaxially aligned thin films, and single crystalline micro- or nanowires to molecular scale, where a derivative of poly(para-phenylene ethynylene) with thioacetyl end groups (TA-PPE) is selected as the candidate for investigation, which could also be extended to other conjugated polymer systems. Our systematic investigations demonstrated that 3-4 orders higher charge transport properties could be achieved with the improvement of polymer chain order and confirmed efficient charge transport along the conjugated polymer backbones. Moreover, with downscaling to molecular scale, many novel phenomena were observed such as the largely quantized electronic structure for an 18 nm-long TA-PPE and the modulation of the redox center of tetrathiafulvalene (TTF) units on tunneling charge transport, which opens the door for conjugated polymers used in nanometer quantum devices. We hope the understanding of charge transport in PPE and its related conjugated polymer at multilevel scale in this Account will provide a new method to sketch the charge transport properties of conjugated polymers, and new insights into the combination of more conjugated polymer materials in the multilevel optoelectronic and other related functional devices, which will offer great promise for the next generation of electronic devices.

Use of Li.sub.2[B.sub.12H.sub.12] salt to absorb water into polymers

DOEpatents

Eastwood, Eric A.; Bowen, III, Daniel E.

2016-08-30

Methods of adjusting the properties of a composition are provided. The compositions comprise a polymer-containing matrix and a filler comprising a hygroscopic salt. Preferred such salts comprise a cage compound selected from the group consisting of borane cage compounds, carborane cage compounds, metal complexes thereof, residues thereof, mixtures thereof, and/or agglomerations thereof, where the cage compound is not covalently bound to the matrix polymer.

Polymer-free nanofibers from vanillin/cyclodextrin inclusion complexes: high thermal stability, enhanced solubility and antioxidant property.

PubMed

Celebioglu, Asli; Kayaci-Senirmak, Fatma; İpek, Semran; Durgun, Engin; Uyar, Tamer

2016-07-13

Vanillin/cyclodextrin inclusion complex nanofibers (vanillin/CD-IC NFs) were successfully obtained from three modified CD types (HPβCD, HPγCD and MβCD) in three different solvent systems (water, DMF and DMAc) via an electrospinning technique without using a carrier polymeric matrix. Vanillin/CD-IC NFs with uniform and bead-free fiber morphology were successfully produced and their free-standing nanofibrous webs were obtained. The polymer-free CD/vanillin-IC-NFs allow us to accomplish a much higher vanillin loading (∼12%, w/w) when compared to electrospun polymeric nanofibers containing CD/vanillin-IC (∼5%, w/w). Vanillin has a volatile nature yet, after electrospinning, a significant amount of vanillin was preserved due to complex formation depending on the CD types. Maximum preservation of vanillin was observed for vanillin/MβCD-IC NFs which is up to ∼85% w/w, besides, a considerable amount of vanillin (∼75% w/w) was also preserved for vanillin/HPβCD-IC NFs and vanillin/HPγCD-IC NFs. Phase solubility studies suggested a 1 : 1 molar complexation tendency between guest vanillin and host CD molecules. Molecular modelling studies and experimental findings revealed that vanillin : CD complexation was strongest for MβCD when compared to HPβCD and HPγCD in vanillin/CD-IC NFs. For vanillin/CD-IC NFs, water solubility and the antioxidant property of vanillin was improved significantly owing to inclusion complexation. In brief, polymer-free vanillin/CD-IC NFs are capable of incorporating a much higher loading of vanillin and effectively preserve volatile vanillin. Hence, encapsulation of volatile active agents such as flavor, fragrance and essential oils in electrospun polymer-free CD-IC NFs may have potential for food related applications by integrating the particularly large surface area of NFs with the non-toxic nature of CD and inclusion complexation benefits, such as high temperature stability, improved water solubility and an enhanced antioxidant property, etc.

A supramolecular miktoarm star polymer based on porphyrin metal complexation in water.

PubMed

Hou, Zhanyao; Dehaen, Wim; Lyskawa, Joël; Woisel, Patrice; Hoogenboom, Richard

2017-07-25

A novel supramolecular miktoarm star polymer was successfully constructed in water from a pyridine end-decorated polymer (Py-PmDEGA) and a metalloporphyrin based star polymer (ZnTPP-(PEG) 4 ) via metal-ligand coordination. The Py-PmDEGA moiety was prepared via a combination of reversible addition-fragmentation chain transfer polymerization (RAFT) and subsequent aminolysis and Michael addition reactions to introduce the pyridine end-group. The ZnTPP(PEG) 4 star-polymer was synthesized by the reaction between tetrakis(p-hydroxyphenyl)porphyrin and toluenesulfonyl-PEG, followed by insertion of a zinc ion into the porphyrin core. The formation of a well-defined supramolecular AB 4 -type miktoarm star polymer was unambiguously demonstrated via UV-Vis spectroscopic titration, isothermal titration calorimetry (ITC) and diffusion ordered NMR spectroscopy (DOSY).

Exact Calculation of the Thermodynamics of Biomacromolecules on Cubic Recursive Lattice.

NASA Astrophysics Data System (ADS)

Huang, Ran

The thermodynamics of biomacromolecules featured as foldable polymer with inner-linkage of hydrogen bonds, e. g. protein, RNA and DNA, play an impressive role in either physical, biological, and polymer sciences. By treating the foldable chains to be the two-tolerate self-avoiding trails (2T polymer), abstract lattice modeling of these complex polymer systems to approach their thermodynamics and subsequent bio-functional properties have been developed for decades. Among these works, the calculations modeled on Bethe and Husimi lattice have shown the excellence of being exactly solvable. Our project extended this effort into the 3D situation, i.e. the cubic recursive lattice. The preliminary exploration basically confirmed others' previous findings on the planar structure, that we have three phases in the grand-canonical phase diagram, with a 1st order transition between non-polymerized and polymer phases, and a 2nd order transition between two distinguishable polymer phases. However the hydrogen bond energy J, stacking energy ɛ, and chain rigidity energy H play more vigorous effects on the thermal behaviors, and this is hypothesized to be due to the larger number of possible configurations provided by the complicated 3D model. By the so far progress, the calculation of biomacromolecules may be applied onto more complex recursive lattices, such as the inhomogeneous lattice to describe the cross-dimensional situations, and beside the thermal properties of the 2T polymers, we may infer some interesting insights of the mysterious folding problem itself. National Natural Science Foundation of China.

Molecular modeling the microstructure and phase behavior of bulk and inhomogeneous complex fluids

NASA Astrophysics Data System (ADS)

Bymaster, Adam

Accurate prediction of the thermodynamics and microstructure of complex fluids is contingent upon a model's ability to capture the molecular architecture and the specific intermolecular and intramolecular interactions that govern fluid behavior. This dissertation makes key contributions to improving the understanding and molecular modeling of complex bulk and inhomogeneous fluids, with an emphasis on associating and macromolecular molecules (water, hydrocarbons, polymers, surfactants, and colloids). Such developments apply broadly to fields ranging from biology and medicine, to high performance soft materials and energy. In the bulk, the perturbed-chain statistical associating fluid theory (PC-SAFT), an equation of state based on Wertheim's thermodynamic perturbation theory (TPT1), is extended to include a crossover correction that significantly improves the predicted phase behavior in the critical region. In addition, PC-SAFT is used to investigate the vapor-liquid equilibrium of sour gas mixtures, to improve the understanding of mercaptan/sulfide removal via gas treating. For inhomogeneous fluids, a density functional theory (DFT) based on TPT1 is extended to problems that exhibit radially symmetric inhomogeneities. First, the influence of model solutes on the structure and interfacial properties of water are investigated. The DFT successfully describes the hydrophobic phenomena on microscopic and macroscopic length scales, capturing structural changes as a function of solute size and temperature. The DFT is used to investigate the structure and effective forces in nonadsorbing polymer-colloid mixtures. A comprehensive study is conducted characterizing the role of polymer concentration and particle/polymer size ratio on the structure, polymer induced depletion forces, and tendency towards colloidal aggregation. The inhomogeneous form of the association functional is used, for the first time, to extend the DFT to associating polymer systems, applicable to any association scheme. Theoretical results elucidate how reversible bonding governs the structure of a fluid near a surface and in confined environments, the molecular connectivity (formation of supramolecules, star polymers, etc.) and the phase behavior of the system. Finally, the DFT is extended to predict the inter- and intramolecular correlation functions of polymeric fluids. A theory capable of providing such local structure is important to understanding how local chemistry, branching, and bond flexibility affect the thermodynamic properties of polymers.

Molecular rheology of branched polymers: decoding and exploring the role of architectural dispersity through a synergy of anionic synthesis, interaction chromatography, rheometry and modeling.

PubMed

van Ruymbeke, E; Lee, H; Chang, T; Nikopoulou, A; Hadjichristidis, N; Snijkers, F; Vlassopoulos, D

2014-07-21

An emerging challenge in polymer physics is the quantitative understanding of the influence of a macromolecular architecture (i.e., branching) on the rheological response of entangled complex polymers. Recent investigations of the rheology of well-defined architecturally complex polymers have determined the composition in the molecular structure and identified the role of side-products in the measured samples. The combination of different characterization techniques, experimental and/or theoretical, represents the current state-of-the-art. Here we review this interdisciplinary approach to molecular rheology of complex polymers, and show the importance of confronting these different tools for ensuring an accurate characterization of a given polymeric sample. We use statistical tools in order to relate the information available from the synthesis protocols of a sample and its experimental molar mass distribution (typically obtained from size exclusion chromatography), and hence obtain precise information about its structural composition, i.e. enhance the existing sensitivity limit. We critically discuss the use of linear rheology as a reliable quantitative characterization tool, along with the recently developed temperature gradient interaction chromatography. The latter, which has emerged as an indispensable characterization tool for branched architectures, offers unprecedented sensitivity in detecting the presence of different molecular structures in a sample. Combining these techniques is imperative in order to quantify the molecular composition of a polymer and its consequences on the macroscopic properties. We validate this approach by means of a new model asymmetric comb polymer which was synthesized anionically. It was thoroughly characterized and its rheology was carefully analyzed. The main result is that the rheological signal reveals fine molecular details, which must be taken into account to fully elucidate the viscoelastic response of entangled branched polymers. It is important to appreciate that, even optimal model systems, i.e., those synthesized with high-vacuum anionic methods, need thorough characterization via a combination of techniques. Besides helping to improve synthetic techniques, this methodology will be significant in fine-tuning mesoscopic tube-based models and addressing outstanding issues such as the quantitative description of the constraint release mechanism.

Star Polymers.

PubMed

Ren, Jing M; McKenzie, Thomas G; Fu, Qiang; Wong, Edgar H H; Xu, Jiangtao; An, Zesheng; Shanmugam, Sivaprakash; Davis, Thomas P; Boyer, Cyrille; Qiao, Greg G

2016-06-22

Recent advances in controlled/living polymerization techniques and highly efficient coupling chemistries have enabled the facile synthesis of complex polymer architectures with controlled dimensions and functionality. As an example, star polymers consist of many linear polymers fused at a central point with a large number of chain end functionalities. Owing to this exclusive structure, star polymers exhibit some remarkable characteristics and properties unattainable by simple linear polymers. Hence, they constitute a unique class of technologically important nanomaterials that have been utilized or are currently under audition for many applications in life sciences and nanotechnologies. This article first provides a comprehensive summary of synthetic strategies towards star polymers, then reviews the latest developments in the synthesis and characterization methods of star macromolecules, and lastly outlines emerging applications and current commercial use of star-shaped polymers. The aim of this work is to promote star polymer research, generate new avenues of scientific investigation, and provide contemporary perspectives on chemical innovation that may expedite the commercialization of new star nanomaterials. We envision in the not-too-distant future star polymers will play an increasingly important role in materials science and nanotechnology in both academic and industrial settings.

Polymers in Fluid Flows

NASA Astrophysics Data System (ADS)

Benzi, Roberto; Ching, Emily S. C.

2018-03-01

The interaction of flexible polymers with fluid flows leads to a number of intriguing phenomena observed in laboratory experiments, namely drag reduction, elastic turbulence, and heat transport modification in natural convection, and is one of the most challenging subjects in soft matter physics. In this review, we examine our present knowledge on the subject. Our present knowledge is mostly based on direct numerical simulations performed in the last twenty years, which have successfully explained, at least qualitatively, most of the experimental results. Our goal is to disentangle as much as possible the basic mechanisms acting in the system in order to capture the basic features underlying different theoretical approaches and explanations.

Imaging and controlling intracellular reactions: Lysosome transport as a function of diameter and the intracellular synthesis of conducting polymers

NASA Astrophysics Data System (ADS)

Payne, Christine

2014-03-01

Eukaryotic cells are the ultimate complex environment with intracellular chemical reactions regulated by the local cellular environment. For example, reactants are sequestered into specific organelles to control local concentration and pH, motor proteins transport reactants within the cell, and intracellular vesicles undergo fusion to bring reactants together. Current research in the Payne Lab in the School of Chemistry and Biochemistry at Georgia Tech is aimed at understanding and utilizing this complex environment to control intracellular chemical reactions. This will be illustrated using two examples, intracellular transport as a function of organelle diameter and the intracellular synthesis of conducting polymers. Using single particle tracking fluorescence microscopy, we measured the intracellular transport of lysosomes, membrane-bound organelles, as a function of diameter as they underwent transport in living cells. Both ATP-dependent active transport and diffusion were examined. As expected, diffusion scales with the diameter of the lysosome. However, active transport is unaffected suggesting that motor proteins are insensitive to cytosolic drag. In a second example, we utilize intracellular complexity, specifically the distinct micro-environments of different organelles, to carry out chemical reactions. We show that catalase, found in the peroxisomes of cells, can be used to catalyze the polymerization of the conducting polymer PEDOT:PSS. More importantly, we have found that a range of iron-containing biomolecules are suitable catalysts with different iron-containing biomolecules leading to different polymer properties. These experiments illustrate the advantage of intracellular complexity for the synthesis of novel materials.

Ultrafast Transient Absorption Spectroscopy of Polymer-Based Organophotoredox Catalysts Mimicking Transition-Metal Complexes

NASA Astrophysics Data System (ADS)

Jamhawi, Abdelqader; Paul, Anam C.; Smith, Justin D.; Handa, Sachin; Liu, Jinjun

2017-06-01

Transition-metal complexes of rare earth metals including ruthenium and iridium are most commonly employed as visible-light photocatalysts. Despite their highly important and broad applications, they have many disadvantages including high cost associated with low abundance in earth crust, potential toxicity, requirement of specialized ligands for desired activity, and difficulty in recycling of metal contents as well as associated ligands. Polymer-based organophotoredox catalysts are promising alternatives and possess unique advantages such as easier synthesis from inexpensive starting material, longer excited state life time, broad range of activity, sustainability, and recyclability. In this research talk, time-resolved photoluminescence and femtosecond transient absorption (TA) spectroscopy measurements of three novel polymer-based organophotoredox catalysts will be presented. By our synthetic team, their catalytic activity has been proven in some highly valuable chemical transformations, that otherwise require transition metal complexes. Time-resolved spectroscopic investigations have demonstrated that photoinduced processes in these catalysts are similar to the transition metal complexes. Especially, intramolecular vibrational relaxation, internal conversion, and intersystem crossing from the S1 state to the T1 state all occur on a sub-picosecond timescale. The long lifetime of the T1 state ( 2-3 microsecond) renders these polymers potent oxidizing and reducing agents. A spectroscopic and kinetic model has been developed for global fitting of TA spectra in both the frequency and time domains. Implication of the current ultrafast spectroscopy studies of these novel molecules to their roles in photocatalysis will be discussed.

Effect of Charge Patterning on the Phase Behavior of Polymer Coacervates for Charge Driven Self Assembly

NASA Astrophysics Data System (ADS)

Radhakrishna, Mithun; Sing, Charles E.

Oppositely charged polymers can undergo associative liquid-liquid phase separation when mixed under suitable conditions of ionic strength, temperature and pH to form what are known as `polymeric complex coacervates'. Polymer coacervates find use in diverse array of applications like microencapsulation, drug delivery, membrane filtration and underwater adhesives. The similarity between complex coacervate environments and those in biological systems has also found relevance in areas of bio-mimicry. Our previous works have demonstrated how local charge correlations and molecular connectivity can drastically affect the phase behavior of coacervates. The precise location of charges along the chain therefore dramatically influences the local charge correlations, which consequently influences the phase behavior of coacervates. We investigate the effect of charge patterning along the polymer chain on the phase behavior of coacervates in the framework of the Restricted Primitive Model using Gibbs Ensemble Monte Carlo simulations. Our results show that charge patterning dramatically changes the phase behavior of polymer coacervates, which contrasts with the predictions of the classical Voorn-Overbeek theory. This provides the basis for designing new materials through charge driven self assembly by controlling the positioning of the charged monomers along the chain.

Design and synthesis of heterobimetallic Ru(II)-Ln(III) complexes as chemodosimetric ensembles for the detection of biogenic amine odorants.

PubMed

Chow, Cheuk-Fai; Lam, Michael H W; Wong, Wai-Yeung

2013-09-03

The detection of neutral biogenic amines plays a crucial role in food safety. Three new heterobimetallic Ru(II)-Ln(III) donor-acceptor complexes, KPrRu, KNdRu, and KSmRu, K{[Ru((II))((t)Bubpy)(CN)4]2-Ln((III))(H2O)4} (where (t)Bubpy = 4,4'-di-tert-butyl-2,2'-bipyridine), have been synthesized and characterized. Their photophysical and X-ray crystallographic data were reported in this study. These complexes were found to be selective for biogenic amine vapors, such as histamine, putrescine, and spermidine, with a detection limit down to the ppb level. The sensitivities of these complexes to the amines were recorded as ~log K = 3.6-5.0. Submicron rods of the complexes, with a nanoscale diameter and microscale length, were obtained through a simple precipitation process. Free-standing polymeric films with different degrees of porosity were fabricated by blending the submicron rods with polystyrene polymer. The polymer with the highest level of porosity exhibited the strongest luminescence enhancement after amine exposure. Real time monitoring of gaseous biogenic amines was applied to real fish samples (Atlantic mackerel) by studying the spectrofluorimetric responses of the Ru(II)-Ln(III) blended polymer film.

Complex Dark Matter

ScienceCinema

Lincoln, Don

2018-01-16

After a century of study, scientists have come to the realization that the ordinary matter made of atoms is a minority in the universe. In order to explain observations, it appears that there exists a new and undiscovered kind of matter, called dark matter, that is five times more prevalent than ordinary matter. The evidence for this new matter’s existence is very strong, but scientists know only a little about its nature. In today’s video, Fermilab’s Dr. Don Lincoln talks about an exciting and unconventional idea, specifically that dark matter might have a very complex set of structures and interactions. While this idea is entirely speculative, it is an interesting hypothesis and one that scientists are investigating.

Biopolymer dynamics driven by helical flagella

NASA Astrophysics Data System (ADS)

Balin, Andrew K.; Zöttl, Andreas; Yeomans, Julia M.; Shendruk, Tyler N.

2017-11-01

Microbial flagellates typically inhabit complex suspensions of polymeric material which can impact the swimming speed of motile microbes, filter feeding of sessile cells, and the generation of biofilms. There is currently a need to better understand how the fundamental dynamics of polymers near active cells or flagella impacts these various phenomena, in particular, the hydrodynamic and steric influence of a rotating helical filament on suspended polymers. Our Stokesian dynamics simulations show that as a stationary rotating helix pumps fluid along its long axis, polymers migrate radially inward while being elongated. We observe that the actuation of the helix tends to increase the probability of finding polymeric material within its pervaded volume. This accumulation of polymers within the vicinity of the helix is stronger for longer polymers. We further analyze the stochastic work performed by the helix on the polymers and show that this quantity is positive on average and increases with polymer contour length.

Solid Rocket Fuel Constitutive Theory and Polymer Cure

NASA Technical Reports Server (NTRS)

Ream, Robert

2006-01-01

Solid Rocket Fuel is a complex composite material for which no general constitutive theory, based on first principles, has been developed. One of the principles such a relation would depend on is the morphology of the binder. A theory of polymer curing is required to determine this morphology. During work on such a theory an algorithm was developed for counting the number of ways a polymer chain could assemble. The methods used to develop and check this algorithm led to an analytic solution to the problem. This solution is used in a probability distribution function which characterizes the morphology of the polymer.

Solid electrolytes

DOEpatents

Abraham, Kuzhikalail M.; Alamgir, Mohamed

1993-06-15

This invention pertains to Li ion (Li.sup.+) conductive solid polymer electrolytes composed of solvates of Li salts immobilized (encapsulated) in a solid organic polymer matrix. In particular, this invention relates to solid polymer electrolytes derived by immobilizing complexes (solvates) formed between a Li salt such as LiAsF.sub.6, LiCF.sub.3 SO.sub.3 or LiClO.sub.4 and a mixture of aprotic organic solvents having high dielectric constants such as ethylene carbonate (EC) (dielectric constant=89.6) and propylene carbonate (PC) (dielectric constant=64.4) in a polymer matrix such as polyacrylonitrile, poly(tetraethylene glycol diacrylate), or poly(vinyl pyrrolidinone).

Optical, thermal and morphological study of ZnS doped PVA polymer nano composites

NASA Astrophysics Data System (ADS)

Guruswamy, B.; Ravindrachary, V.; Shruthi, C.; Sagar, Rohan N.; Hegde, Shreedatta

2018-05-01

The effect of ZnS nano particle doping on optical, thermal properties and morphological study of the PVA polymer has been investigated using FTIR, UV-Visible and TGA, FESEM techniques. Nano sized ZnS particles were synthesized by a simple wet chemical route. Pure and ZnS/PVA nano composites were prepared using solution casting technique. The FTIR study confirms that the ZnS nano particles interacts with the OH group of PVA polymer and forms the complex. The formation of these complexes affects the optical and thermal properties of the composite. The changes in optical properties were studied using UV-Vis absorption method. The variation in thermal property was analysed using TGA results. The modified surface morphology analysis was carried out using FESEM.

Production of alpha-amylase from Aspergillus oryzae for several industrial applications in a single step.

PubMed

Porfirif, María C; Milatich, Esteban J; Farruggia, Beatriz M; Romanini, Diana

2016-06-01

A one-step method as a strategy of alpha-amylase concentration and purification was developed in this work. This methodology requires the use of a very low concentration of biodegradable polyelectrolyte (Eudragit(®) E-PO) and represents a low cost, fast, easy to scale up and non-polluting technology. Besides, this methodology allows recycling the polymer after precipitation. The formation of reversible soluble/insoluble complexes between alpha-amylase and the polymer Eudragit(®) E-PO was studied, and their precipitation in selected conditions was applied with bioseparation purposes. Turbidimetric assays allowed to determine the pH range where the complexes are insoluble (4.50-7.00); pH 5.50 yielded the highest turbidity of the system. The presence of NaCl (0.05M) in the medium totally dissociates the protein-polymer complexes. When the adequate concentration of polymer was added under these conditions to a liquid culture of Aspergillus oryzae, purification factors of alpha-amylase up to 7.43 and recoveries of 88% were obtained in a simple step without previous clarification. These results demonstrate that this methodology is suitable for the concentration and production of alpha-amylase from this source and could be applied at the beginning of downstream processing. Copyright © 2016 Elsevier B.V. All rights reserved.

Measurement of complex terahertz dielectric properties of polymers using an improved free-space technique

NASA Astrophysics Data System (ADS)

Chang, Tianying; Zhang, Xiansheng; Yang, Chuanfa; Sun, Zhonglin; Cui, Hong-Liang

2017-04-01

The complex dielectric properties of non-polar solid polymer materials were measured in the terahertz (THz) band by a free-space technique employing a frequency-extended vector network analyzer (VNA), and by THz time-domain spectroscopy (TDS). Mindful of THz wave’s unique characteristics, the free-space method for measurement of material dielectric properties in the microwave band was expanded and improved for application in the THz frequency region. To ascertain the soundness and utility of the proposed method, measurements of the complex dielectric properties of a variety of polymers were carried out, including polytetrafluoroethylene (PTFE, known also by the brand name Teflon), polypropylene (PP), polyethylene (PE), and glass fiber resin (Composite Stone). The free-space method relies on the determination of electromagnetic scattering parameters (S-parameters) of the sample, with the gated-reflect-line (GRL) calibration technique commonly employed using a VNA. Subsequently, based on the S-parameters, the dielectric constant and loss characteristic of the sample were calculated by using a Newtonian iterative algorithm. To verify the calculated results, THz TDS technique, which produced Fresnel parameters such as reflection and transmission coefficients, was also used to independently determine the dielectric properties of these polymer samples, with results satisfactorily corroborating those obtained by the free-space extended microwave technique.

Binary Polymer Brushes of Strongly Immiscible Polymers.

PubMed

Chu, Elza; Babar, Tashnia; Bruist, Michael F; Sidorenko, Alexander

2015-06-17

The phenomenon of microphase separation is an example of self-assembly in soft matter and has been observed in block copolymers (BCPs) and similar materials (i.e., supramolecular assemblies (SMAs) and homo/block copolymer blends (HBCs)). In this study, we use microphase separation to construct responsive polymer brushes that collapse to generate periodic surfaces. This is achieved by a chemical reaction between the minor block (10%, poly(4-vinylpyridine)) of the block copolymer and a substrate. The major block of polystyrene (PS) forms mosaic-like arrays of grafted patches that are 10-20 nm in size. Depending on the nature of the assembly (SMA, HBC, or neat BCP) and annealing method (exposure to vapors of different solvents or heating above the glass transition temperature), a range of "mosaic" brushes with different parameters can be obtained. Successive grafting of a secondary polymer (polyacrylamide, PAAm) results in the fabrication of binary polymer brushes (BPBs). Upon being exposed to specific selective solvents, BPBs may adopt different conformations. The surface tension and adhesion of the binary brush are governed by the polymer occupying the top stratum. The "mosaic" brush approach allows for a combination of strongly immiscible polymers in one brush. This facilitates substantial contrast in the surface properties upon switching, previously only possible for substrates composed of predetermined nanostructures. We also demonstrate a possible application of such PS/PAAm brushes in a tunable bioadhesion-bioadhesive (PS on top) or nonbioadhesive (PAAm on top) surface as revealed by Escherichia coli bacterial seeding.

Molecular complexation of curcumin with pH sensitive cationic copolymer enhances the aqueous solubility, stability and bioavailability of curcumin.

PubMed

Kumar, Sunny; Kesharwani, Siddharth S; Mathur, Himanshi; Tyagi, Mohit; Bhat, G Jayarama; Tummala, Hemachand

2016-01-20

Curcumin is a natural dietary compound with demonstrated potential in preventing/treating several chronic diseases in animal models. However, this success is yet to be translated to humans mainly because of its poor oral bioavailability caused by extremely low water solubility. This manuscript demonstrates that water insoluble curcumin (~1μg/ml) forms highly aqueous soluble complexes (>2mg/ml) with a safe pH sensitive polymer, poly(butyl-methacrylate-co-(2-dimethylaminoethyl) methacrylate-co-methyl-methacrylate) when precipitated together in water. The complexation process was optimized to enhance curcumin loading by varying several formulation factors. Acetone as a solvent and polyvinyl alcohol as a stabilizer with 1:2 ratio of drug to polymer yielded complexes with relatively high loading (~280μg/ml) and enhanced solubility (>2mg/ml). The complexes were amorphous in solid and were soluble only in buffers with pHs less than 5.0. Hydrogen bond formation and hydrophobic interactions between curcumin and the polymer were recorded by infrared spectroscopy and nuclear magnetic resonance spectroscopy, respectively. Molecular complexes of curcumin were more stable at various pHs compared to unformulated curcumin. In mice, these complexes increased peak plasma concentration of curcumin by 6 times and oral bioavailability by ~20 times. This is a simple, economic and safer strategy of enhancing the oral bioavailability of curcumin. Copyright © 2015 Elsevier B.V. All rights reserved.

Emerging Materials Technologies That Matter to Manufacturers

NASA Technical Reports Server (NTRS)

Misra, Ajay K.

2015-01-01

A brief overview of emerging materials technologies. Exploring the weight reduction benefit of replacing Carbon Fiber with Carbon Nanotube (CNT) in Polymer Composites. Review of the benign purification method developed for CNT sheets. The future of manufacturing will include the integration of computational material design and big data analytics, along with Nanomaterials as building blocks.

Molecular simulation of simple fluids and polymers in nanoconfinement

NASA Astrophysics Data System (ADS)

Rasmussen, Christopher John

Prediction of phase behavior and transport properties of simple fluids and polymers confined to nanoscale pores is important to a wide range of chemical and biochemical engineering processes. A practical approach to investigate nanoscale systems is molecular simulation, specifically Monte Carlo (MC) methods. One of the most challenging problems is the need to calculate chemical potentials in simulated phases. Through the seminal work of Widom, practitioners have a powerful method for calculating chemical potentials. Yet, this method fails for dense and inhomogeneous systems, as well as for complex molecules such as polymers. In this dissertation, the gauge cell MC method, which had previously been successfully applied to confined simple fluids, was employed and extended to investigate nanoscale fluids in several key areas. Firstly, the process of cavitation (the formation and growth of bubbles) during desorption of fluids from nanopores was investigated. The dependence of cavitation pressure on pore size was determined with gauge cell MC calculations of the nucleation barriers correlated with experimental data. Additional computational studies elucidated the role of surface defects and pore connectivity in the formation of cavitation bubbles. Secondly, the gauge cell method was extended to polymers. The method was verified against the literature results and found significantly more efficient. It was used to examine adsorption of polymers in nanopores. These results were applied to model the dynamics of translocation, the act of a polymer threading through a small opening, which is implicated in drug packaging and delivery, and DNA sequencing. Translocation dynamics was studied as diffusion along the free energy landscape. Thirdly, we show how computer simulation of polymer adsorption could shed light on the specifics of polymer chromatography, which is a key tool for the analysis and purification of polymers. The quality of separation depends on the physico-chemical mechanisms of polymer/pore interaction. We considered liquid chromatography at critical conditions, and calculated the dependence of the partition coefficient on chain length. Finally, solvent-gradient chromatography was modeled using a statistical model of polymer adsorption. A model for predicting separation of complex polymers (with functional groups or copolymers) was developed for practical use in chromatographic separations.

Modular "Click" Preparation of Bifunctional Polymeric Heterometallic Catalysts.

PubMed

Wang, Wenlong; Zhao, Liyuan; Lv, Hui; Zhang, Guodong; Xia, Chungu; Hahn, F Ekkehardt; Li, Fuwei

2016-06-27

Heterobimetallic molecular complexes or strictly alternating metallated polymers are obtained by a click reaction between mononuclear metal complexes (secondary building units, SBUs) bearing NHCs functionalized with either p-azidophenyl or p-ethynylphenyl wingtips. With a copper-NHC complex as SBU the formation of molecular or polymeric compounds did not require any additives as the copper complex catalyzes the click reaction. Transmetallation from heterobimetallic Cu/Ag derivatives to Cu/Pd derivatives was achieved. The linker between the SBUs (flexible or rigid) influences the catalytic activity of the heterobimetallic compounds. The polymer with alternating copper-NHC and silver-NHC units and a flexible methylene-triazole bridge between them shows the highest activity in the catalytic alkynylation of trifluoromethyl ketones to give fluorinated propargylic alcohols. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Water-soluble polymers bearing phosphorylcholine group and other zwitterionic groups for carrying DNA derivatives.

PubMed

Lin, Xiaojie; Ishihara, Kazuhiko

2014-01-01

Water-soluble polymers with equal positive and negative charges in the same monomer unit, such as the phosphorylcholine group and other zwitterionic groups, exhibit promising potential in gene delivery with appreciable transfection efficiency, compared with the traditional poly(ethylene glycol)-based polycation-gene complexes. These zwitterionic polymers with various architectural structures and properties have been synthesized by various polymerization methods, such as conventional radical polymerization, atom-transfer radical-polymerization, reversible addition-fragmentation chain-transfer polymerization, and nitroxide-mediated radical polymerization. These techniques have been used to efficiently facilitate gene therapy by fabrication of non-viral vectors with high cytocompatibility, large gene-carrying capacity, effective cell-membrane permeability, and in vivo gene-loading/releasing functionality. Zwitterionic polymer-based gene delivery vectors systems can be categorized into soluble-polymer/gene mixing, molecular self-assembly, and polymer-gene conjugation systems. This review describes the preparation and characterization of various zwitterionic polymer-based gene delivery vectors, specifically water-soluble phospholipid polymers for carrying gene derivatives.

Method for separating water soluble organics from a process stream by aqueous biphasic extraction

DOEpatents

Chaiko, David J.; Mego, William A.

1999-01-01

A method for separating water-miscible organic species from a process stream by aqueous biphasic extraction is provided. An aqueous biphase system is generated by contacting a process stream comprised of water, salt, and organic species with an aqueous polymer solution. The organic species transfer from the salt-rich phase to the polymer-rich phase, and the phases are separated. Next, the polymer is recovered from the loaded polymer phase by selectively extracting the polymer into an organic phase at an elevated temperature, while the organic species remain in a substantially salt-free aqueous solution. Alternatively, the polymer is recovered from the loaded polymer by a temperature induced phase separation (cloud point extraction), whereby the polymer and the organic species separate into two distinct solutions. The method for separating water-miscible organic species is applicable to the treatment of industrial wastewater streams, including the extraction and recovery of complexed metal ions from salt solutions, organic contaminants from mineral processing streams, and colorants from spent dye baths.

Synthesis and characterization of new ion-imprinted polymer for separation and preconcentration of uranyl (UO2(2+)) ions.

PubMed

Ahmadi, Seyed Javad; Noori-Kalkhoran, Omid; Shirvani-Arani, Simindokht

2010-03-15

UO(2)(2+) ion-imprinted polymer materials used for solid-phase extraction were prepared by copolymerization of a ternary complex of uranyl ions with styrene and divinyl benzene in the presence of 2,2'-azobisisobutyronitrile. The imprinted particles were leached by HCl 6M. Various parameters in polymerization steps such as DVB/STY ratio, time of polymerization and temperature of polymerization were varied to achieve the most efficient uranyl-imprinted polymer. X-ray diffraction (XRD), infra-red spectroscopy (IR), thermo gravimetric analysis (TGA), UV-vis and nitrogen sorption were used to characterize the polymer particles. The XRD results showed that uranyl ions were completely removed from the polymer after leaching process. IR Analysis indicated that the N,N'-ethylenebis(pyridoxylideneiminato) remained intact in the polymer even after leaching. Some parameters such as pH, weight of the polymer, elution time, eluent volume and aqueous phase volume which affects the efficiency of the polymer were studied. (c) 2009 Elsevier B.V. All rights reserved.

Development of PVA based micro-porous polymer electrolyte by a novel preferential polymer dissolution process

NASA Astrophysics Data System (ADS)

Subramania, A.; Kalyana Sundaram, N. T.; Sukumar, N.

A micro-porous polymer electrolyte based on PVA was obtained from PVA-PVC based polymer blend film by a novel preferential polymer dissolution technique. The ionic conductivity of micro-porous polymer electrolyte increases with increase in the removal of PVC content. Finally, the effect of variation of lithium salt concentration is studied for micro-porous polymer electrolyte of high ionic conductivity composition. The ionic conductivity of the micro-porous polymer electrolyte is measured in the temperature range of 301-351 K. It is observed that a 2 M LiClO 4 solution of micro-porous polymer electrolyte has high ionic conductivity of 1.5055 × 10 -3 S cm -1 at ambient temperature. Complexation and surface morphology of the micro-porous polymer electrolytes are studied by X-ray diffraction and SEM analysis. TG/DTA analysis informs that the micro-porous polymer electrolyte is thermally stable upto 277.9 °C. Chronoamperommetry and linear sweep voltammetry studies were made to find out lithium transference number and stability of micro-porous polymer electrolyte membrane, respectively. Cyclic voltammetry study was performed for carbon/micro-porous polymer electrolyte/LiMn 2O 4 cell to reveal the compatibility and electrochemical stability between electrode materials.

Frustration in Biomolecules

PubMed Central

Ferreiro, Diego U.; Komives, Elizabeth A.; Wolynes, Peter G.

2014-01-01

Biomolecules are the prime information processing elements of living matter. Most of these inanimate systems are polymers that compute their own structures and dynamics using as input seemingly random character strings of their sequence, following which they coalesce and perform integrated cellular functions. In large computational systems with a finite interaction-codes, the appearance of conflicting goals is inevitable. Simple conflicting forces can lead to quite complex structures and behaviors, leading to the concept of frustration in condensed matter. We present here some basic ideas about frustration in biomolecules and how the frustration concept leads to a better appreciation of many aspects of the architecture of biomolecules, and how biomolecular structure connects to function. These ideas are simultaneously both seductively simple and perilously subtle to grasp completely. The energy landscape theory of protein folding provides a framework for quantifying frustration in large systems and has been implemented at many levels of description. We first review the notion of frustration from the areas of abstract logic and its uses in simple condensed matter systems. We discuss then how the frustration concept applies specifically to heteropolymers, testing folding landscape theory in computer simulations of protein models and in experimentally accessible systems. Studying the aspects of frustration averaged over many proteins provides ways to infer energy functions useful for reliable structure prediction. We discuss how frustration affects folding mechanisms. We review here how a large part of the biological functions of proteins are related to subtle local physical frustration effects and how frustration influences the appearance of metastable states, the nature of binding processes, catalysis and allosteric transitions. We hope to illustrate how Frustration is a fundamental concept in relating function to structural biology. PMID:25225856

Clarification of olive mill and winery wastewater by means of clay-polymer nanocomposites.

PubMed

Rytwo, Giora; Lavi, Roy; Rytwo, Yuval; Monchase, Hila; Dultz, Stefan; König, Tom N

2013-01-01

Highly polluted effluents from olive mills and wineries, among others, are unsuitable for discharge into standard sewage-treatment plants due to the large amounts of organic and suspended matter. Efficiency of all management practices for such effluents depends on an effective pretreatment that lowers the amount of suspended solids. Such pretreatments are usually based on three separate stages, taking a total of 2 to 6h: coagulation-neutralizing the colloids, flocculation-aggregating the colloids into larger particles, and separation via filtration or decanting. Previous studies have presented the concept of coagoflocculation based on the use of clay-polymer nanocomposites. This process adds a higher density clay particle to the flocs, accelerating the process to between 15 and 60 min. This study examined suitable nanocomposites based on different clays and polymers. The charge of the compounds increased proportionally to the polymer-to-clay ratio. X-ray diffraction (XRD) measurements indicated that in sepiolite-based nanocomposites there is no change in the structure of the mineral, whereas in smectite-based nanocomposites, the polymer intercalates between the clay layers and increases the spacing depending on the polymer-to-clay ratio. Efficiency of the coagoflocculation process was studied with a dispersion analyzer. Sequential addition of olive mill or winery effluents with a boosting dose of nanocomposites may yield a very efficient and rapid clarification pretreatment. Copyright © 2012 Elsevier B.V. All rights reserved.

Topological Constraints in Directed Polymer Melts

NASA Astrophysics Data System (ADS)

Serna, Pablo; Bunin, Guy; Nahum, Adam

2015-11-01

Polymers in a melt may be subject to topological constraints, as in the example of unlinked polymer rings. How to do statistical mechanics in the presence of such constraints remains a fundamental open problem. We study the effect of topological constraints on a melt of directed polymers, using simulations of a simple quasi-2D model. We find that fixing the global topology of the melt to be trivial changes the polymer conformations drastically. Polymers of length L wander in the transverse direction only by a distance of order (ln L )ζ with ζ ≃1.5 . This is strongly suppressed in comparison with the Brownian L1 /2 scaling which holds in the absence of the topological constraint. It is also much smaller than the predictions of standard heuristic approaches—in particular the L1 /4 of a mean-field-like "array of obstacles" model—so our results present a sharp challenge to theory. Dynamics are also strongly affected by the constraints, and a tagged monomer in an infinite system performs logarithmically slow subdiffusion in the transverse direction. To cast light on the suppression of the strands' wandering, we analyze the topological complexity of subregions of the melt: the complexity is also logarithmically small, and is related to the wandering by a power law. We comment on insights the results give for 3D melts, directed and nondirected.

Topological Constraints in Directed Polymer Melts.

PubMed

Serna, Pablo; Bunin, Guy; Nahum, Adam

2015-11-27

Polymers in a melt may be subject to topological constraints, as in the example of unlinked polymer rings. How to do statistical mechanics in the presence of such constraints remains a fundamental open problem. We study the effect of topological constraints on a melt of directed polymers, using simulations of a simple quasi-2D model. We find that fixing the global topology of the melt to be trivial changes the polymer conformations drastically. Polymers of length L wander in the transverse direction only by a distance of order (lnL)^{ζ} with ζ≃1.5. This is strongly suppressed in comparison with the Brownian L^{1/2} scaling which holds in the absence of the topological constraint. It is also much smaller than the predictions of standard heuristic approaches-in particular the L^{1/4} of a mean-field-like "array of obstacles" model-so our results present a sharp challenge to theory. Dynamics are also strongly affected by the constraints, and a tagged monomer in an infinite system performs logarithmically slow subdiffusion in the transverse direction. To cast light on the suppression of the strands' wandering, we analyze the topological complexity of subregions of the melt: the complexity is also logarithmically small, and is related to the wandering by a power law. We comment on insights the results give for 3D melts, directed and nondirected.

Insights into the nature of cometary organic matter from terrestrial analogues

NASA Astrophysics Data System (ADS)

Court, Richard W.; Sephton, Mark A.

2012-04-01

The nature of cometary organic matter is of great interest to investigations involving the formation and distribution of organic matter relevant to the origin of life. We have used pyrolysis-Fourier transform infrared (FTIR) spectroscopy to investigate the chemical effects of the irradiation of naturally occurring bitumens, and to relate their products of pyrolysis to their parent assemblages. The information acquired has then been applied to the complex organic matter present in cometary nuclei and comae. Amalgamating the FTIR data presented here with data from published studies enables the inference of other comprehensive trends within hydrocarbon mixtures as they are progressively irradiated in a cometary environment, namely the polymerization of lower molecular weight compounds; an increased abundance of polycyclic aromatic hydrocarbon structures; enrichment in 13C; reduction in atomic H/C ratio; elevation of atomic O/C ratio and increase in the temperature required for thermal degradation. The dark carbonaceous surface of a cometary nucleus will display extreme levels of these features, relative to the nucleus interior, while material in the coma will reflect the degree of irradiation experienced by its source location in the nucleus. Cometary comae with high methane/water ratios indicate a nucleus enriched in methane, favouring the formation of complex organic matter via radiation-induced polymerization of simple precursors. In contrast, production of complex organic matter is hindered in a nucleus possessing a low methane/water ration, with the complex organic matter that does form possessing more oxygen-containing species, such as alcohol, carbonyl and carboxylic acid functional groups, resulting from reactions with hydroxyl radicals formed by the radiolysis of the more abundant water. These insights into the properties of complex cometary organic matter should be of particular interest to both remote observation and space missions involving in situ analyses and sample return of cometary materials.

Selective CO2 conversion to formate conjugated with H2O oxidation utilizing semiconductor/complex hybrid photocatalysts.

PubMed

Sato, Shunsuke; Arai, Takeo; Morikawa, Takeshi; Uemura, Keiko; Suzuki, Tomiko M; Tanaka, Hiromitsu; Kajino, Tsutomu

2011-10-05

Photoelectrochemical reduction of CO(2) to HCOO(-) (formate) over p-type InP/Ru complex polymer hybrid photocatalyst was highly enhanced by introducing an anchoring complex into the polymer. By functionally combining the hybrid photocatalyst with TiO(2) for water oxidation, selective photoreduction of CO(2) to HCOO(-) was achieved in aqueous media, in which H(2)O was used as both an electron donor and a proton source. The so-called Z-scheme (or two-step photoexcitation) system operated with no external electrical bias. The selectivity for HCOO(-) production was >70%, and the conversion efficiency of solar energy to chemical energy was 0.03-0.04%.

Spectroscopic studies of nanoparticle-sensitised photorefractive polymers

NASA Astrophysics Data System (ADS)

Aslam, Farzana; Binks, David J.; Daniels, Steve; Pickett, Nigel; O'Brien, Paul

2005-09-01

We report on the absorbance and photoluminescence spectra of photorefractive polymer composites sensitized by three different types of nanoparticles. Each nanoparticle is passivated by 1-hexadecylamine (HDA) and the composites also consist of the charge transporting matrix poly( N-vinylcarbazole) and the dye 1-(2'-ethylhexyloxy)-2,5-dimethyl-4-(4-nitrophenylazo) benzene. A strong spectral feature is observed that is attributed to a complex formed between the dye and HDA; elemental analysis indicates that the formation of this complex is determined by the metal content of the nanoparticle surface. The photoluminescence quantum yield for the complex is greatly reduced when the HDA is attached to the nanoparticle, indicating that a charge transfer occurs.

Modelling of polymer photodegradation for solar cell modules

NASA Technical Reports Server (NTRS)

Guillet, J. E.

1982-01-01

A computer program which simulates the complex processes of photooxidation which take place in a polymer upon prolonged exposure outdoors causing it to fail in photovoltaic and other applications. The method calculates from an input data set of elementary reactions and rates the concentration profiles of all species over time.

A self-healing PDMS polymer with solvatochromic properties.

PubMed

Jia, Xiao-Yong; Mei, Jin-Feng; Lai, Jian-Cheng; Li, Cheng-Hui; You, Xiao-Zeng

2015-05-28

Coordination bonds are effective for constructing functional self-healing materials due to their tunable bond strength and metal-ion-induced functionalities. In this work, we incorporate a cobalt(II) triazole complex into a polydimethylsiloxane (PDMS) matrix. The resulting polymers show solvatochromic behaviour as well as self-healing properties.

Caveats when Analyzing Ultra-high Molar Mass Polymers by SEC

USDA-ARS?s Scientific Manuscript database

The analysis of ultra-high molar mass (M > 1 million g/mol) polymers via size-exclusion chromatography (SEC) presents a number of non-trivial challenges. Dissolution and full solvation may take days, as is the case for cellulose dissolution in non-complexing non degrading solvents; very low concent...

Communication: The simplified generalized entropy theory of glass-formation in polymer melts.

PubMed

Freed, Karl F

2015-08-07

While a wide range of non-trivial predictions of the generalized entropy theory (GET) of glass-formation in polymer melts agree with a large number of observed universal and non-universal properties of these glass-formers and even for the dependence of these properties on monomer molecular structure, the huge mathematical complexity of the theory precludes its extension to describe, for instance, the perplexing, complex behavior observed for technologically important polymer films with thickness below ∼100 nm and for which a fundamental molecular theory is lacking for the structural relaxation. The present communication describes a hugely simplified version of the theory, called the simplified generalized entropy theory (SGET) that provides one component necessary for devising a theory for the structural relaxation of thin polymer films and thereby supplements the first required ingredient, the recently developed Flory-Huggins level theory for the thermodynamic properties of thin polymer films, before the concluding third step of combining all the components into the SGET for thin polymer films. Comparisons between the predictions of the SGET and the full GET for the four characteristic temperatures of glass-formation provide good agreement for a highly non-trivial model system of polymer melts with chains of the structure of poly(n-α olefins) systems where the GET has produced good agreement with experiment. The comparisons consider values of the relative backbone and side group stiffnesses such that the glass transition temperature decreases as the amount of excess free volume diminishes, contrary to general expectations but in accord with observations for poly(n-alkyl methacrylates). Moreover, the SGET is sufficiently concise to enable its discussion in a standard course on statistical mechanics or polymer physics.

Communication: The simplified generalized entropy theory of glass-formation in polymer melts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freed, Karl F.

2015-08-07

While a wide range of non-trivial predictions of the generalized entropy theory (GET) of glass-formation in polymer melts agree with a large number of observed universal and non-universal properties of these glass-formers and even for the dependence of these properties on monomer molecular structure, the huge mathematical complexity of the theory precludes its extension to describe, for instance, the perplexing, complex behavior observed for technologically important polymer films with thickness below ∼100 nm and for which a fundamental molecular theory is lacking for the structural relaxation. The present communication describes a hugely simplified version of the theory, called the simplifiedmore » generalized entropy theory (SGET) that provides one component necessary for devising a theory for the structural relaxation of thin polymer films and thereby supplements the first required ingredient, the recently developed Flory-Huggins level theory for the thermodynamic properties of thin polymer films, before the concluding third step of combining all the components into the SGET for thin polymer films. Comparisons between the predictions of the SGET and the full GET for the four characteristic temperatures of glass-formation provide good agreement for a highly non-trivial model system of polymer melts with chains of the structure of poly(n-α olefins) systems where the GET has produced good agreement with experiment. The comparisons consider values of the relative backbone and side group stiffnesses such that the glass transition temperature decreases as the amount of excess free volume diminishes, contrary to general expectations but in accord with observations for poly(n-alkyl methacrylates). Moreover, the SGET is sufficiently concise to enable its discussion in a standard course on statistical mechanics or polymer physics.« less

The IAEA stopping power database, following the trends in stopping power of ions in matter

NASA Astrophysics Data System (ADS)

Montanari, C. C.; Dimitriou, P.

2017-10-01

The aim of this work is to present an overview of the state of art of the energy loss of ions in matter, based on the new developments in the stopping power database of the International Atomic Energy Agency (IAEA). This exhaustive collection of experimental data, graphs, programs and comparisons, is the legacy of Helmut Paul, who made it accessible to the global scientific community, and has been extensively employed in theoretical and experimental research during the last 25 years. The field of stopping power in matter is evolving, with new trends in materials of interest, including oxides, nitrides, polymers, and biological targets. Our goal is to identify areas of interest and emerging data needs to meet the requirements of a continuously developing user community.

Polymer electrolyte based on crosslinked poly(glycidyl methacrylate) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fei, Beatrice Wong Chui; Hanifah, Sharina Abu; Ahmad, Azizan

2015-09-25

Polymer electrolytes based on crosslinked poly(glycidyl methacrylate) as polymer host and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BmimTFSI) as incorporated salt were prepared by in-situ photopolymerization technique. The complexes with different mass ratio of glycidyl methacrylate (GMA) monomer to BmimTFSI were investigated. The ionic conductivity of the polymer electrolyte was increased and reach the highest value of 7.50 × 10{sup −4} S cm{sup −1} at the ratio of 3:7 (GMA: BmimTFSI). The interaction between the polymer host and ionic liquid was proved by Attenuated Total Reflectance-Fourier Transformation Infra-Red Spectroscopy (ATR-FTIR). Meanwhile, the X-ray diffraction analysis shows the amorphousity of the polymer electrolyte film increasemore » with the ionic liquid ratio.« less

[Polymer Gel Dosimeter].

PubMed

Hayashi, Shin-Ichiro

2017-01-01

With rapid advances being made in radiotherapy treatment, three-dimensional (3D) dose measurement techniques of great precision are required more than ever before. It is expected that 3D polymer gel dosimeters will satisfy clinical needs for an effective detector that can measure the complex 3D dose distributions. Polymer gel dosimeters are devices that utilize the radiation-induced polymerization reactions of vinyl monomers in a gel to store information about radiation dose. The 3D absorbed dose distribution can be deduced from the resulting polymer distribution using several imaging modalities, such as MRI, X-ray and optical CTs. In this article, the fundamental characteristics of polymer gel dosimeter are reviewed and some challenging keys are also suggested for the widely spread in clinical use.

Structural Peculiarities of Ion-Conductive Organic-Inorganic Polymer Composites Based on Aliphatic Epoxy Resin and Salt of Lithium Perchlorate.

PubMed

Matkovska, Liubov; Iurzhenko, Maksym; Mamunya, Yevgen; Tkachenko, Igor; Demchenko, Valeriy; Synyuk, Volodymyr; Shadrin, Andriy; Boiteux, Gisele

2017-12-01

The article is concerned with hybrid amorphous polymers synthesized basing on epoxy oligomer of diglycide aliphatic ester of polyethylene glycol that was cured by polyethylene polyamine and lithium perchlorate salt. Structural peculiarities of organic-inorganic polymer composites were studied by differential scanning calorimetry, wide-angle X-ray spectra, infrared spectroscopic, scanning electron microscopy, elemental analysis, and transmission and reflective optical microscopy. On the one hand, the results showed that the introduction of LiClO 4 salt into epoxy polymer leads to formation of the coordinative metal-polymer complexes of donor-acceptor type between central Li + ion and ligand. On the other hand, the appearance of amorphous microinclusions, probably of inorganic nature, was also found.

TiO2 as conductivity enhancer in PVdF-HFP polymer electrolyte system

NASA Astrophysics Data System (ADS)

Bhattacharya, Shreya; Manojkumar Ubarhande, Radha; Usha Rani, M.; Shanker Babu, Ravi; Arunkumar, R.

2017-11-01

Composite polymer electrolytes were prepared by incorporating inorganic filler TiO2 into PVdF-HFP-PMMA-EC-LiClO4 system. The electrolyte films were prepared by solvent casting technique. The effect of inorganic filler on the conductivity of the blended polymer electrolyte was studied and it is found that there is a considerable increase in ionic conductivity 1.296 × 10-3 S/cm-1 on the addition of TiO2. X-ray diffraction (XRD) study elucidate the increase in amorphous nature of the polymer electrolyte. This tendency of the polymer electrolyte could be the reason behind the increase in ionic conductivity. Fourier transform infrared spectroscopy (FTIR) spectra show the occurrence of complexation and interaction among the components.

Chemistry of the metal-polymer interfacial region.

PubMed

Leidheiser, H; Deck, P D

1988-09-02

In many polymer-metal systems, chemical bonds are formed that involve metal-oxygen-carbon complexes. Infrared and Mössbauer spectroscopic studies indicate that carboxylate groups play an important role in some systems. The oxygen sources may be the polymer, the oxygen present in the oxide on the metal surface, or atmospheric oxygen. Diffusion of metal ions from the substrate into the polymer interphase may occur in some systems that are cured at elevated temperatures. It is unclear whether a similar, less extensive diffusion occurs over long time periods in systems maintained at room temperature. The interfacial region is dynamic, and chemical changes occur with aging at room temperature. Positron annihilation spectroscopy may have application to characterizing the voids at the metal-polymer interface.

A new metalation complex for organic synthesis and polymerization reactions

NASA Technical Reports Server (NTRS)

Hirshfield, S. M.

1971-01-01

Organometallic complex of N,N,N',N' tetramethyl ethylene diamine /TMEDA/ and lithium acts as metalation intermediate for controlled systhesis of aromatic organic compounds and polymer formation. Complex of TMEDA and lithium aids in preparation of various organic lithium compounds.

Capillary electrophoresis investigation on equilibrium between polymer-related and surfactant-related species in aqueous polymer-surfactant solutions.

PubMed

Wu, Yefan; Chen, Miaomiao; Fang, Yun; Zhu, Meng

2017-03-17

It was inferred from aqueous solution behavior of nonionic polymers and anionic surfactants that the formation of charged polymer-bound surfactant micelle above critical aggregation concentration (cac) and the formation of free surfactant micelle beyond polymer saturation point (psp), but there was still a lack of direct experimental evidence for the considered equilibrium chemical species. Three modes of capillary electrophoresis are applied in this paper to study the complexation between nonionic polymers, polyvinylpyrrolidone (PVP) or polyethylene glycol (PEG), and sodium dodecylbenzenesulfonate (SDBS) by successfully distinguishing the imaginary charged polymer-bound SDBS micelle from nonionic polymer and SDBS molecule. Perhaps even more important, it is the action of SDBS as both a main surfactant and a UV probe that makes the free surfactant micelle emerged in electropherogram beyond psp, and thus makes it possible for the first time to provide the equilibrium relationship of the polymer-related and the surfactant-related species in the concentration regions divided into by cac and psp. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of structures of bidentate Schiff base type bonded-ligands derived from benzaldehyde on the photoluminescence performance of polymer-rare earth complexes.

PubMed

Gao, Baojiao; Zhang, Liqin; Zhang, Dandan

2018-02-07

Two kinds of bidentate Schiff base ligands derived from benzaldehyde, benzaldehyde/m-aminophenol (BAMA) type and benzaldehyde/glutamic acid (BAGL) type ligands, were synchronously synthesized and bonded on the backbone of polysulfone (PSF) through molecular design and by polymer reactions, and two functional polymers, PSF-BAMA and PSF-BAGL, were obtained. Then two series of novel luminescent Schiff base-type polymer-rare earth complexes were prepared via coordination reactions. In this work, the effects of the structures of the bonded ligands on the photoluminescence performance of the complexes were investigated in detail, and for the different photophysical properties of the prepared complexes, relevant theoretical explanations were given. The experimental results show that the bonded ligand BAMA can strongly sensitize the fluorescence emission of Eu(iii) ions, and the binary complex PSF-(BAMA) 3 -Eu(iii) emits strong red fluorescence under UV light. The reason for this lies in the fact that a larger conjugate π-bond system is contained in the structure of BAMA, and so the triplet state of BAMA can be matched with the resonant energy level of the Eu(iii) ion. While the bonded ligand BAGL can effectively sensitize the fluorescence emission of Tb(iii) ions, the binary complex PSF-(BAGL) 3 -Tb(iii) exhibits very strong green fluorescence under UV light. The reason is that a smaller conjugate π-bond system is contained in the structure of BAGL and there is a good energy level matching between the triplet state of BAGL and the resonant energy level of the Tb(iii) ion. The fluorescence intensities of the two ternary complexes, PSF-(BAMA) 3 -Eu(iii)-(Phen) 1 (phenanthroline, Phen) and PSF-(BAGL) 3 -Tb(iii)-(Phen) 1 , are much stronger than that of the corresponding binary complex because Phen as the second ligand has two effects, the effect of synergistic coordination with the first ligand and the effect of replacing the coordinated water around the central ion, and it has been confirmed by fluorescence spectroscopy and thermogravimetric analysis.

Homochiral coordination polymers constructed from aminocarboxylate derivates: Effect of bipyridine on the amidation reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen Jianshan; Sheng Tianlu; Hu Shengmin

2012-08-15

Using aminocarboxylate derivates (S)-N-(4-cyanobenzoic)-glutamic acid (denoted as cbg, 1a) and (S)-N-(4-nitrobenzoic)-glutamic acid (denoted as nbg, 1b) as chiral ligands, five new homochiral coordination polymers formulated as [Cu(cbg)(H{sub 2}O){sub 2}]{sub n} (3), [Cu(cbop){sub 2}(4,4 Prime -bipy)(H{sub 2}O)]{sub n} (4) (cbop=(S)-N-(4-cyanobenzoic)-5-oxoproline, 4,4 Prime -bipy=4,4 Prime -bipyridine), {l_brace}[Cu(nbop){sub 2}(4,4 Prime -bipy)]{center_dot}4H{sub 2}O{r_brace}{sub n} (5) (nbop=(S)-N-(4-nitrobenzoic)-5-oxoproline), {l_brace}[Cd(nbop){sub 2}(4,4 Prime -bipy)]{center_dot}2H{sub 2}O{r_brace}{sub n} (6), and [Ni(nbop){sub 2}(4,4 Prime -bipy)(H{sub 2}O){sub 2}]{sub n} (7) have been hydrothermally synthesized and structurally characterized. Single-crystal X-ray diffraction study reveals that the original chirality of aminocarboxylate derivates is maintained in all these complexes. Complexes 3, 4, and 7 are one-dimensionalmore » infinite chain coordination polymers, while complexes 5 and 6 possess two-dimensional network structures. In situ cyclization of 1a and 1b was taken place in the formation of complexes 4-7, which may be due to the competition of 4,4 Prime -bipyridine with chiral ligands during the coordination process. Preliminary optical behavior investigation indicates that ligands 1a, 1b, and complexes 6, 7 are nonlinear optical active. - Graphical abstract: Using aminocarboxylate derivates as chiral ligands, five new homochiral coordination polymers possessing second harmonic generation activities have been hydrothermally synthesized. Highlights: Black-Right-Pointing-Pointer Two new chiral aminocarboxylate derivates were firstly synthesized. Black-Right-Pointing-Pointer Five new homochiral metal organic complexes were obtained hydrothermally based on these ligands. Black-Right-Pointing-Pointer Intramolecular amidation was taken place on the aminocarboxylate derivates during the formation of these complexes. Black-Right-Pointing-Pointer In situ amidation may be due to the impact of 4,4 Prime -bipyridine. Black-Right-Pointing-Pointer The homochiral complexes are nonlinear optical active.« less

Insight into the Broad Field of Polymer Nanocomposites: From Carbon Nanotubes to Clay Nanoplatelets, via Metal Nanoparticles

PubMed Central

Stefanescu, Eduard A.; Daranga, Codrin; Stefanescu, Cristina

2009-01-01

Highly ordered polymer nanocomposites are complex materials that display a rich morphological behavior owing to variations in composition, structure, and properties on a nanometer length scale. Metal-polymer nanocomposite materials are becoming more popular for applications requiring low cost, high metal surface areas. Catalytic systems seem to be the most prevalent application for a wide range of metals used in polymer nanocomposites, particularly for metals like Pt, Ni, Co, and Au, with known catalytic activities. On the other hand, among the most frequently utilized techniques to prepare polymer/CNT and/or polymer/clay nanocomposites are approaches like melt mixing, solution casting, electrospinning and solid-state shear pulverization. Additionally, some of the current and potential applications of polymer/CNT and/or polymer/clay nanocomposites include photovoltaic devices, optical switches, electromagnetic interference (EMI) shielding, aerospace and automotive materials, packaging, adhesives and coatings. This extensive review covers a broad range of articles, typically from high impact-factor journals, on most of the polymer-nanocomposites known to date: polymer/carbon nanotubes, polymer/metal nanospheres, and polymer/clay nanoplatelets composites. The various types of nanocomposites are described form the preparation stages to performance and applications. Comparisons of the various types of nanocomposites are conducted and conclusions are formulated.

2-(hydroxymethyl)-1H-benzo[d]imidazole-5-carboxylic acid as linker for Co(II)/Ni(II)/Cu(II) coordination polymers: Synthesis, structures and properties

NASA Astrophysics Data System (ADS)

Wang, Duo-Zhi; Wang, Xin-Fang; Du, Jia-Qiang; Dong, Jun-Liang; Xie, Fei

2018-02-01

We report the synthesis and characterization of five transition metal coordination polymers (CPs) based on M(II) (M: Co, Ni and Cu), 2-(hydroxymethyl)-1H-benzo[d]imidazole-5-carboxylic acid (H2L) ligand. They are formulated as {[Co2(HL)2(H2O)3(SO4)]·H2O}n (1), {[Co2(HL)2(H2O)2]·SiF6}n (2), {[Ni2(HL)2(H2O)3(SO4)]·2H2O}n (3), {[Ni2(HL)2(H2O)4]·H2O·SiF6}n (4), {[Cu2(HL)2(H2O)2]·SiF6}n (5). The complexes 1-5 structure were characterized by single-crystal X-ray diffraction, elemental analyses, infrared spectroscopy (IR), powder X-ray diffraction (PXRD), and thermogravimetric analyses (TGA). Complexes 1-5 are two-dimensional (2D) network type coordination polymers that 1-3, 5 crystallize in monoclinic system within the centrosymmetric space group P2(1)/c, and 4 in triclinic system P-1 space group, they show the same coordination modes (κ1-κ1)-(κ1)-(κ1)-μ3 in coordination polymers. Complexes 1 and 3 expand to three-dimensional framework by means of hydrogen bond interactions, and can be rationalized to be three-connected {63} topological network, while 2, 4, 5 exhibit the topological network with a four-connected {44·62} topological sql network. The luminescent properties (for complexes 1, 2) and UV diffuse reflectance (for complexes 1-5) in the solid state at room temperature were also investigated and discussed. Complexes 1-5 act as effective heterogeneous catalysts, under mild conditions, for the homocoupling reaction of 4-substituted aryl iodides bearing electron-donating groups (-CH3, -OCH3).

Rapid removal of organic micropollutants from water by a porous β-cyclodextrin polymer.

PubMed

Alsbaiee, Alaaeddin; Smith, Brian J; Xiao, Leilei; Ling, Yuhan; Helbling, Damian E; Dichtel, William R

2016-01-14

The global occurrence in water resources of organic micropollutants, such as pesticides and pharmaceuticals, has raised concerns about potential negative effects on aquatic ecosystems and human health. Activated carbons are the most widespread adsorbent materials used to remove organic pollutants from water but they have several deficiencies, including slow pollutant uptake (of the order of hours) and poor removal of many relatively hydrophilic micropollutants. Furthermore, regenerating spent activated carbon is energy intensive (requiring heating to 500-900 degrees Celsius) and does not fully restore performance. Insoluble polymers of β-cyclodextrin, an inexpensive, sustainably produced macrocycle of glucose, are likewise of interest for removing micropollutants from water by means of adsorption. β-cyclodextrin is known to encapsulate pollutants to form well-defined host-guest complexes, but until now cross-linked β-cyclodextrin polymers have had low surface areas and poor removal performance compared to conventional activated carbons. Here we crosslink β-cyclodextrin with rigid aromatic groups, providing a high-surface-area, mesoporous polymer of β-cyclodextrin. It rapidly sequesters a variety of organic micropollutants with adsorption rate constants 15 to 200 times greater than those of activated carbons and non-porous β-cyclodextrin adsorbent materials. In addition, the polymer can be regenerated several times using a mild washing procedure with no loss in performance. Finally, the polymer outperformed a leading activated carbon for the rapid removal of a complex mixture of organic micropollutants at environmentally relevant concentrations. These findings demonstrate the promise of porous cyclodextrin-based polymers for rapid, flow-through water treatment.

Rapid removal of organic micropollutants from water by a porous β-cyclodextrin polymer

NASA Astrophysics Data System (ADS)

Alsbaiee, Alaaeddin; Smith, Brian J.; Xiao, Leilei; Ling, Yuhan; Helbling, Damian E.; Dichtel, William R.

2016-01-01

The global occurrence in water resources of organic micropollutants, such as pesticides and pharmaceuticals, has raised concerns about potential negative effects on aquatic ecosystems and human health. Activated carbons are the most widespread adsorbent materials used to remove organic pollutants from water but they have several deficiencies, including slow pollutant uptake (of the order of hours) and poor removal of many relatively hydrophilic micropollutants. Furthermore, regenerating spent activated carbon is energy intensive (requiring heating to 500-900 degrees Celsius) and does not fully restore performance. Insoluble polymers of β-cyclodextrin, an inexpensive, sustainably produced macrocycle of glucose, are likewise of interest for removing micropollutants from water by means of adsorption. β-cyclodextrin is known to encapsulate pollutants to form well-defined host-guest complexes, but until now cross-linked β-cyclodextrin polymers have had low surface areas and poor removal performance compared to conventional activated carbons. Here we crosslink β-cyclodextrin with rigid aromatic groups, providing a high-surface-area, mesoporous polymer of β-cyclodextrin. It rapidly sequesters a variety of organic micropollutants with adsorption rate constants 15 to 200 times greater than those of activated carbons and non-porous β-cyclodextrin adsorbent materials. In addition, the polymer can be regenerated several times using a mild washing procedure with no loss in performance. Finally, the polymer outperformed a leading activated carbon for the rapid removal of a complex mixture of organic micropollutants at environmentally relevant concentrations. These findings demonstrate the promise of porous cyclodextrin-based polymers for rapid, flow-through water treatment.

Molecular dynamics simulation of interactions between a sodium dodecyl sulfate micelle and a poly(ethylene oxide) polymer.

PubMed

Shang, Barry Z; Wang, Zuowei; Larson, Ronald G

2008-03-13

We have performed atomistic molecular dynamics simulations of an anionic sodium dodecyl sulfate (SDS) micelle and a nonionic poly(ethylene oxide) (PEO) polymer in aqueous solution. The micelle consisted of 60 surfactant molecules, and the polymer chain lengths varied from 20 to 40 monomers. The force field parameters for PEO were adjusted by using 1,2-dimethoxymethane (DME) as a model compound and matching its hydration enthalpy and conformational behavior to experiment. Excellent agreement with previous experimental and simulation work was obtained through these modifications. The simulated scaling behavior of the PEO radius of gyration was also in close agreement with experimental results. The SDS-PEO simulations show that the polymer resides on the micelle surface and at the hydrocarbon-water interface, leading to a selective reduction in the hydrophobic contribution to the solvent-accessible surface area of the micelle. The association is mainly driven by hydrophobic interactions between the polymer and surfactant tails, while the interaction between the polymer and sulfate headgroups on the micelle surface is weak. The 40-monomer chain is mostly wrapped around the micelle, and nearly 90% of the monomers are adsorbed at low PEO concentration. Simulations were also performed with multiple 20-monomer chains, and gradual addition of polymer indicates that about 120 monomers are required to saturate the micelle surface. The stoichiometry of the resulting complex is in close agreement with experimental results, and the commonly accepted "beaded necklace" structure of the SDS-PEO complex is recovered by our simulations.

Synthesis and characterization of nanocomposite polymer blend electrolyte thin films by spin-coating method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chapi, Sharanappa; Niranjana, M.; Devendrappa, H., E-mail: dehu2010@gmail.com

2016-05-23

Solid Polymer blend electrolytes based on Polyethylene oxide (PEO) and poly vinyl pyrrolidone (PVP) complexed with zinc oxide nanoparticles (ZnO NPs; Synthesized by Co-precipitation method) thin films have prepared at a different weight percent using the spin-coating method. The complexation of the NPs with the polymer blend was confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR). The variation in film morphology was examined by polarized optical micrographs (POMs). The thermal behavior of blends was investigated under non-isothermal conditions by differential thermal analyses (DTA). A single glass transition temperature for each blend was observed, which supports the existence ofmore » compatibility of such system. The obtained results represent that the ternary based thin films are prominent materials for battery and optoelectronic device applications.« less

Electrical study on Carboxymethyl Cellulose-Polyvinyl alcohol based bio-polymer blend electrolytes

NASA Astrophysics Data System (ADS)

Saadiah, M. A.; Samsudin, A. S.

2018-04-01

The present work deals with the formulation of bio-materials namely carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVA) for bio-polymer blend electrolytes (BBEs) system which was successfully carried out with different ratio of polymer blend. The biopolymer blend was prepared via economical & classical technique that is solution casting technique and was characterized by using impedance spectroscopy (EIS). The ionic conductivity was achieved to optimum value 9.12 x 10-6 S/cm at room temperature for sample containing ratio 80:20 of CMC:PVA. The highest conducting sample was found to obey the Arrhenius behaviour with a function of temperature. The electrical properties were analyzed using complex permittivity ε* and complex electrical modulus M* for BBEs system and it shows the non-Debye characteristics where no single relaxation time has observed.

Color indicator for supramolecular polymer chemistry: phenolphthalein-containing thermo- and pH-sensitive N-(Isopropyl)acrylamide copolymers and β-cyclodextrin complexation.

PubMed

Fleischmann, Carolin; Ritter, Helmut

2013-07-12

The copolymerization parameters of N-(isopropyl)acrylamide (1) and N-(2-hydroxy-5-(1-(4-hydroxyphenyl)-3-oxo-1,3-dihydroisobenzofuran-1-yl)benzyl)acrylamide (2) are determined. For both monomers, the homoaddition proceeds slightly faster than the heteroaddition step; however, the polymer formation occurs in a statistic fashion. Copolymers of different compositions are prepared and the cloud points are determined. Thereby, a significant influence of the concentration of monomer 2 and the pH value is found. For the first time, the complexation of polymer attached phenolphthalein by β-cyclodextrins is shown. Furthermore, it is possible to achieve a decomplexation by the addition of suitable guest molecules. Both procedures can be followed with the naked eye. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spectroscopic properties of (PVA+ZnO):Mn{sup 2+} polymer films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rani, Ch.; Raju, D. Siva; Bindu, S. Hima

2015-05-15

Electron Paramagnetic Resonance (EPR), optical absorption and infrared spectral studies have been carried out on Mn{sup 2+} ions doped in poly(vinyl alcohol) complexed with zinc oxide polymer films prepared by solution cast technique. The EPR spectra of 1 mol% Mn{sup 2+} ions doped polymer complex (PVA+ZnO) at room temperature exhibit sextet hyperfine structure (hfs), centered at 2.01. The spin-Hamiltonian parameter values indicate that the ground state of Mn{sup 2+} ion in d{sup 5} and the site symmetry around Mn{sup 2+} ions in tetragonally distorted octa hedral site. The optical absorption spectra exhibits two bands centered at 275nm at 437nm. Themore » FTIR spectrum exhibits bands characteristic of stretching and banding vibrations of O-H, C-H and C=C groups.« less

Luminescent properties of Europium(III) nitrate with 1,10-phenantroline and cinnamic acid in light - Transforming polymer materials

NASA Astrophysics Data System (ADS)

Kalinovskaya, I. V.; Zadorozhnaya, A. N.

2018-04-01

Influence of cinnamic acid on the luminescent properties of the europium(III) nitrate with 1,10-phenantroline in a polymer materials was studied. It was shown that combined use of these rare earth complexes leads to intense luminescence in the 400-700 nm region. Samples containing polymer europium nitrate with 1,10-phenantroline and cinnamic acid at a molar ratio of 1:2,0 had the maximum luminescence intensity and photostability.

Control of Macromolecular Architectures for Renewable Polymers: Case Studies

NASA Astrophysics Data System (ADS)

Tang, Chuanbing

The development of sustainable polymers from nature biomass is growing, but facing fierce competition from existing petrochemical-based counterparts. Controlling macromolecular architectures to maximize the properties of renewable polymers is a desirable approach to gain advantages. Given the complexity of biomass, there needs special consideration other than traditional design. In the presentation, I will talk about a few case studies on how macromolecular architectures could tune the properties of sustainable bioplastics and elastomers from renewable biomass such as resin acids (natural rosin) and plant oils.

Approaches to polymer-derived CMC matrices

NASA Technical Reports Server (NTRS)

Hurwitz, Frances I.

1992-01-01

The use of polymeric precursors to ceramics permits the fabrication of large, complex-shaped ceramic matrix composites (CMC's) at temperatures which do not degrade the fiber. Processing equipment and techniques readily available in the resin matrix composite industry can be adapted for CMC fabrication using this approach. Criteria which influence the choice of candidate precursor polymers, the use of fillers, and the role of fiber architecture and ply layup are discussed. Three polymer systems, polycarbosilanes, polysilazanes, and polysilsesquioxanes, are compared as candidate ceramic matrix precursors.

Supramolecular Polymers Based on Non-Coplanar AAA-DDD Hydrogen-Bonded Complexes.

PubMed

Mendez, Iamnica J Linares; Wang, Hong-Bo; Yuan, Ying-Xue; Wisner, James A

2018-03-01

Non-coplanar triple-hydrogen-bond arrays are connected as telechelic groups to alkyl chains and their properties as AA/BB type supramolecular polymers are examined. Viscosity studies at three temperatures are used to study the ring-chain equilibrium and determine the critical concentrations where polymer chains are formed. It is observed that neither the temperature range studied nor the alkyl chain length of one component significantly affect the polymerization properties in this system. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nondestructive Evaluation of Advanced Fiber Reinforced Polymer Matrix Composites: A Technology Assessment

NASA Technical Reports Server (NTRS)

Yolken, H. Thomas; Matzkanin, George A.

2009-01-01

Because of their increasing utilization in structural applications, the nondestructive evaluation (NDE) of advanced fiber reinforced polymer composites continues to receive considerable research and development attention. Due to the heterogeneous nature of composites, the form of defects is often very different from a metal and fracture mechanisms are more complex. The purpose of this report is to provide an overview and technology assessment of the current state-of-the-art with respect to NDE of advanced fiber reinforced polymer composites.

Polymer-bound oxidovanadium(IV) and dioxidovanadium(V) complexes as catalysts for the oxidative desulfurization of model fuel diesel.

PubMed

Maurya, Mannar R; Arya, Aarti; Kumar, Amit; Kuznetsov, Maxim L; Avecilla, Fernando; Costa Pessoa, João

2010-07-19

The Schiff base (Hfsal-dmen) derived from 3-formylsalicylic acid and N,N-dimethyl ethylenediamine has been covalently bonded to chloromethylated polystyrene to give the polymer-bound ligand, PS-Hfsal-dmen (I). Treatment of PS-Hfsal-dmen with [V(IV)O(acac)(2)] in the presence of MeOH gave the oxidovanadium(IV) complex PS-[V(IV)O(fsal-dmen)(MeO)] (1). On aerial oxidation in methanol, complex 1 was oxidized to PS-[V(V)O(2)(fsal-dmen)] (2). The corresponding neat complexes, [V(IV)O(sal-dmen)(acac)] (3) and [V(V)O(2)(sal-dmen)] (4) were similarly prepared. All these complexes are characterized by various spectroscopic techniques (IR, electronic, NMR, and electron paramagnetic resonance (EPR)) and thermal as well as field-emission scanning electron micrographs (FE-SEM) studies, and the molecular structures of 3 and 4 were determined by single crystal X-ray diffraction. The EPR spectrum of the polymer supported V(IV)O-complex 1 is characteristic of magnetically diluted V(IV)O-complexes, the resolved EPR pattern indicating that the V(IV)O-centers are well dispersed in the polymer matrix. A good (51)V NMR spectrum could also be measured with 4 suspended in dimethyl sulfoxide (DMSO), the chemical shift (-503 ppm) being compatible with a VO(2)(+)-center and a N,O binding set. The catalytic oxidative desulfurization of organosulfur compounds thiophene, dibenzothiophene, benzothiophene, and 2-methyl thiophene (model of fuel diesel) was carried out using complexes 1 and 2. The sulfur in model organosulfur compounds oxidizes to the corresponding sulfone in the presence of H(2)O(2). The systems 1 and 2 do not loose efficiency for sulfoxidation at least up to the third cycle of reaction, this indicating that they preserve their integrity under the conditions used. Plausible intermediates involved in these catalytic processes are established by UV-vis, EPR, (51)V NMR, and density functional theory (DFT) studies, and an outline of the mechanism is proposed. The (51)V NMR spectra recorded for solutions in methanol confirm that complex 4, on treatment with H(2)O(2), is able to generate peroxo-vanadium(V) complexes, including quite stable protonated peroxo-V(V)-complexes [V(V)O(O)(2)(sal-dmen-NH(+))]. The (51)V NMR and DFT data indicate that formation of the intermediate hydroxido-peroxo-V(V)-complex [V(V)(OH)(O(2))(sal-dmen)](+) does not occur, but instead protonated [V(V)O(O)(2)(sal-dmen-NH(+))] complexes form and are relevant for catalytic action.

A computational investigation of the thermodynamics and structure in colloid and polymer mixtures

NASA Astrophysics Data System (ADS)

Mahynski, Nathan Alexander

In this dissertation I use computational tools to study the structure and thermodynamics of colloid-polymer mixtures. I show that fluid-fluid phase separation in mixtures of colloids and linear polymers cannot be universally reduced using polymer-based scaling principles since these assume the binodals exist in a single scaling regime, whereas accurate simulations clearly demonstrate otherwise. I show that rethinking these solutions in terms of multiple length scales is necessary to properly explain the thermodynamic stability and structure of these fluid phases, and produce phase diagrams in nearly quantitative agreement with experimental results. I then extend this work to encompass more geometrically complex "star" polymers revealing how the phase behavior for many of these binary mixtures may be mapped onto that of mixtures containing only linear polymers. I further consider the depletion-driven crystallization of athermal colloidal hard spheres induced by polymers. I demonstrate how the partitioning of a finite amount of polymer into the colloidal crystal phase implies that the polymer's architecture can be tailored to interact with the internal void structure of different crystal polymorphs uniquely, thus providing a direct route to thermodynamically stabilizing one arbitrarily chosen structure over another, e.g., the hexagonal close-packed crystal over the face-centered cubic. I then begin to generalize this result by considering the consequences of thermal interactions and complex polymer architectures. These principles lay the groundwork for intelligently engineering co-solute additives in crystallizing colloidal suspensions that can be used to thermodynamically isolate single crystal morphologies. Finally, I examine the competition between self-assembly and phase separation in polymer-grafted nanoparticle systems by comparing and contrasting the validity of two different models for grafted nanoparticles: "nanoparticle amphiphiles" versus "patchy particles." The latter suggests these systems have some utility in forming novel "equilibrium gel" phases, however, I find that considering grafted nanoparticles as amphiphiles provides a qualitatively accurate description of their thermodynamics revealing either first-order phase separation into two isotropic phases or continuous self-assembly. I find no signs of empty liquid formation, suggesting that these nanoparticles do not provide a route to such phases.

Constitutive modeling of glassy shape memory polymers

NASA Astrophysics Data System (ADS)

Khanolkar, Mahesh

The aim of this research is to develop constitutive models for non-linear materials. Here, issues related for developing constitutive model for glassy shape memory polymers are addressed in detail. Shape memory polymers are novel material that can be easily formed into complex shapes, retaining memory of their original shape even after undergoing large deformations. The temporary shape is stable and return to the original shape is triggered by a suitable mechanism such heating the polymer above a transition temperature. Glassy shape memory polymers are called glassy because the temporary shape is fixed by the formation of a glassy solid, while return to the original shape is due to the melting of this glassy phase. The constitutive model has been developed to capture the thermo-mechanical behavior of glassy shape memory polymers using elements of nonlinear mechanics and polymer physics. The key feature of this framework is that a body can exist stress free in numerous natural configurations, the underlying natural configuration of the body changing during the process, with the response of the body being elastic from these evolving natural configurations. The aim of this research is to formulate a constitutive model for glassy shape memory polymers (GSMP) which takes in to account the fact that the stress-strain response depends on thermal expansion of polymers. The model developed is for the original amorphous phase, the temporary glassy phase and transition between these phases. The glass transition process has been modeled using a framework that was developed recently for studying crystallization in polymers and is based on the theory of multiple natural configurations. Using the same frame work, the melting of the glassy phase to capture the return of the polymer to its original shape is also modeled. The effect of nanoreinforcement on the response of shape memory polymers (GSMP) is studied and a model is developed. In addition to modeling and solving boundary value problems for GSMP's, problems of importance for CSMP, specifically a shape memory cycle (Torsion of a Cylinder) is solved using the developed crystallizable shape memory polymer model. To solve complex boundary value problems in realistic geometries a user material subroutine (UMAT) for GSMP model has been developed for use in conjunction with the commercial finite element software ABAQUS. The accuracy of the UMAT has been verified by testing it against problems for which the results are known.

Self-assembling nucleic acid delivery vehicles via linear, water-soluble, cyclodextrin-containing polymers.

PubMed

Davis, M E; Pun, S H; Bellocq, N C; Reineke, T M; Popielarski, S R; Mishra, S; Heidel, J D

2004-01-01

Non-viral (synthetic) nucleic acid delivery systems have the potential to provide for the practical application of nucleic acid-based therapeutics. We have designed and prepared a tunable, non-viral nucleic acid delivery system that self-assembles with nucleic acids and centers around a new class of polymeric materials; namely, linear, water-soluble cyclodextrin-containing polymers. The relationships between polymer structure and gene delivery are illustrated, and the roles of the cyclodextrin moieties for minimizing toxicity and forming inclusion complexes in the self-assembly processes are highlighted. This vehicle is the first example of a polymer-based gene delivery system formed entirely by self-assembly.

Sorption of Liquids on Impurities in Polymers, As Affected by the Sorption History

NASA Astrophysics Data System (ADS)

Ageev, E. P.; Strusovskaya, N. L.; Matushkina, N. N.

2018-02-01

An unusual effect is observed that occurs during the sorption of liquids by polymers: The sorption flux directed from the liquid into the polymer bulk transfers only the sorbate, while the spontaneously established backward flux carries a sorbate‒impurity complex into the liquid. It is shown that this effect can be used to remove hydrophilic impurities from a hydrophobic polymer. It is assumed that delocalized (and mobile) sorbent particles participate in this phenomenon and include them in the proposed mechanism of sorption. The inversion of gradient of chemical potential upon the formation of delocalized particles determines the backward material flow.

Method of synthesizing polymers from a solid electrolyte

DOEpatents

Skotheim, Terje A.

1985-01-01

A method of synthesizing electrically conductive polymers from a solvent-free solid polymer electrolyte wherein an assembly of a substrate having an electrode thereon, a thin coating of solid electrolyte including a solution of PEO complexed with an alkali salt, and a thin transparent noble metal electrode are disposed in an evacuated chamber into which a selected monomer vapor is introduced while an electric potential is applied across the solid electrolyte to hold the thin transparent electrode at a positive potential relative to the electrode on the substrate, whereby a highly conductive polymer film is grown on the transparent electrode between it and the solid electrolyte.

Method of synthesizing polymers from a solid electrolyte

DOEpatents

Skotheim, T.A.

1984-10-19

A method of synthesizing electrically conductive polymers from a solvent-free solid polymer electrolyte is disclosed. An assembly of a substrate having an electrode thereon, a thin coating of solid electrolyte including a solution of PEO complexed with an alkali salt, and a thin transparent noble metal electrode are disposed in an evacuated chamber into which a selected monomer vapor is introduced while an electric potential is applied across the solid electrolyte to hold the thin transparent electrode at a positive potential relative to the electrode on the substrate, whereby a highly conductive polymer film is grown on the transparent electrode between it and the solid electrolyte.

Interplay between local dynamics and mechanical reinforcement in glassy polymer nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holt, Adam P.; Bocharova, Vera; Cheng, Shiwang

The modification of polymer dynamics in the presence of strongly interacting nanoparticles has been shown to significantly change themacroscopic properties above the glass transition temperature of polymer nanocomposites (PNCs). However, much less attention has been paid to changes in the dynamics of glassy PNCs. Analysis of neutron and light scattering data presented herein reveals a surprising enhancement of local dynamics, e.g., fast picosecond and secondary relaxations, in glassy PNCs accompanied with a strengthening of mechanical modulus. Here we ascribe this counter-intuitive behavior to the complex interplay between chain packing and stretching within the interfacial layer formed at the polymer-nanoparticle interface.

Interplay between local dynamics and mechanical reinforcement in glassy polymer nanocomposites

DOE PAGES

Holt, Adam P.; Bocharova, Vera; Cheng, Shiwang; ...

2017-11-17

The modification of polymer dynamics in the presence of strongly interacting nanoparticles has been shown to significantly change themacroscopic properties above the glass transition temperature of polymer nanocomposites (PNCs). However, much less attention has been paid to changes in the dynamics of glassy PNCs. Analysis of neutron and light scattering data presented herein reveals a surprising enhancement of local dynamics, e.g., fast picosecond and secondary relaxations, in glassy PNCs accompanied with a strengthening of mechanical modulus. Here we ascribe this counter-intuitive behavior to the complex interplay between chain packing and stretching within the interfacial layer formed at the polymer-nanoparticle interface.

Well-Defined Macromolecules Using Horseradish Peroxidase as a RAFT Initiase.

PubMed

Danielson, Alex P; Bailey-Van Kuren, Dylan; Lucius, Melissa E; Makaroff, Katherine; Williams, Cameron; Page, Richard C; Berberich, Jason A; Konkolewicz, Dominik

2016-02-01

Enzymatic catalysis and control over macromolecular architectures from reversible addition-fragmentation chain transfer polymerization (RAFT) are combined to give a new method of making polymers. Horseradish peroxidase (HRP) is used to catalytically generate radicals using hydrogen peroxide and acetylacetone as a mediator. RAFT is used to control the polymer structure. HRP catalyzed RAFT polymerization gives acrylate and acrylamide polymers with relatively narrow molecular weight distributions. The polymerization is rapid, typically exceeding 90% monomer conversion in 30 min. Complex macromolecular architectures including a block copolymer and a protein-polymer conjugate are synthesized using HRP to catalytically initiate RAFT polymerization. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Design and evaluation of a novel nanoparticulate-based formulation encapsulating a HIP complex of lysozyme.

PubMed

Gaudana, Ripal; Gokulgandhi, Mitan; Khurana, Varun; Kwatra, Deep; Mitra, Ashim K

2013-01-01

Formulation development of protein therapeutics using polymeric nanoparticles has found very little success in recent years. Major formulation challenges include rapid denaturation, susceptibility to lose bioactivity in presence of organic solvents and poor encapsulation in polymeric matrix. In the present study, we have prepared hydrophobic ion pairing (HIP) complex of lysozyme, a model protein, using dextran sulfate (DS) as a complexing polymer. We have optimized the process of formation and dissociation of HIP complex between lysozyme and DS. The effect of HIP complexation on enzymatic activity of lysozyme was also studied. Nanoparticles were prepared and characterized using spontaneous emulsion solvent diffusion method. Furthermore, we have also investigated release of lysozyme from nanoparticles along with its enzymatic activity. Results of this study indicate that nanoparticles can sustain the release of lysozyme without compromising its enzymatic activity. HIP complexation using a polymer may also be employed to formulate sustained release dosage forms of other macromolecules with enhanced encapsulation efficiency.

Metal-metal interactions in tetrakis(diphenylphosphino)benzene-bridged dimetallic complexes and their related coordination polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Pei-Wei; Fox, M.A.

1994-06-22

Electrochemical, EPR, and spectroelectrochemical methods have been used to probe electronic coupling through a 1,2,4,5-tetrakis(diphenylphosphino)benzene bridging ligand connecting metal centers in several Ni-, Pd-, and Pt-containing dimetallic complexes. These dimetalated complexes showed weak intervalence charge transfer (IT) bands and slightly shifted redox potentials in comparison with their monometallic models. A Marcus-Hush analysis of the energies of the IT bands for the electrochemically generated mixed-valence heterodimetallic complexes (Ni{sup o}-Pd{sup II} and Ni{sup o}-Pt{sup II}, respectively) established the magnitude of intermetallic electronic coupling. The weak thermal coupling observed in these dimetalated complexes is consistent with the very low conductivities (10{sup {minus}8}-10{sup {minus}10}{omega}{supmore » -1} cm{sup {minus}1}) observed in the polymeric analogs of these complexes, namely, the newly prepared metal coordination polymers (M = Ni{sup II}, Pd{sup II}, Pt{sup II}) with 1,2,4,5-tetrakis(diphenylphosphino)benzene.« less

Multi-Stimuli-Responsive Polymer Materials: Particles, Films, and Bulk Gels.

PubMed

Cao, Zi-Quan; Wang, Guo-Jie

2016-06-01

Stimuli-responsive polymers have received tremendous attention from scientists and engineers for several decades due to the wide applications of these smart materials in biotechnology and nanotechnology. Driven by the complex functions of living systems, multi-stimuli-responsive polymer materials have been designed and developed in recent years. Compared with conventional single- or dual-stimuli-based polymer materials, multi-stimuli-responsive polymer materials would be more intriguing since more functions and finer modulations can be achieved through more parameters. This critical review highlights the recent advances in this area and focuses on three types of multi-stimuli-responsive polymer materials, namely, multi-stimuli-responsive particles (micelles, micro/nanogels, vesicles, and hybrid particles), multi-stimuli-responsive films (polymer brushes, layer-by-layer polymer films, and porous membranes), and multi-stimuli-responsive bulk gels (hydrogels, organogels, and metallogels) from recent publications. Various stimuli, such as light, temperature, pH, reduction/oxidation, enzymes, ions, glucose, ultrasound, magnetic fields, mechanical stress, solvent, voltage, and electrochemistry, have been combined to switch the functions of polymers. The polymer design, preparation, and function of multi-stimuli-responsive particles, films, and bulk gels are comprehensively discussed here. © 2016 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zr-Containing 4,4'-ODA/PMDA Polyimide Composites. Parts 1 & 2

NASA Technical Reports Server (NTRS)

Illingsworth, M. L.; Betancourt, J. A.; Chen, Y.; Terschak, J. A.; Banks, B. A.; Rutledge, S. K.; Cales, M.; He, L.

2001-01-01

The objective of this research is to improve the atomic oxygen resistance of Kapton(TM), a polyimide (PI) made from pyromellitic acid dianhydride (PMDA) and 4,4'-oxydianiline (ODA), while retaining or enhancing the desirable properties of the pure polymer. Toward this end, zirconium-containing complexes and polymers were used to make composites and blends. Tetra(acetylacetonato)zirconium(IV), Zr(acac)4, which is commercially available, was identified as the best zirconium-containing complex for enhancing the atomic oxygen resistance of polyimide composites of the 10 complexes screened. Films prepared from the commercially available polyamic acid (PAA) of PMDA-ODA (DuPont) have good uniformity, flexibility, and tensile strength. A 24-layer 10% (mol) Zr(acac)4/PI composite film showed significant improvement (ca. 20 fold) of atomic oxygen resistance over the pure polyimide. However, 10% (mol) Zr(acac)4 represents an upper concentration limit, above which films undergo cracking upon thermal imidization. In order to increase the Zr complex concentration in PMDA-ODA PI films, while retaining good film properties, [Zr(adsp)2-PMDA]n coordination polymer [bis(4-amino-N,N'-disalicylidene- 1,2-phenylenediamino)zirconium(IV)-pyromellitic dianhydride] and [Zr(adsp)2-PMDA-ODA-PMDA]n terpolymer were synthesized and blended with commercial PAA, respectively. Several techniques were used to characterize the films made from the polymer containing Zr(acac)4. Plasma studies of films having 2% (mol) incremental concentrations of Zr in the Kapton up to 10% (mol) show that the overall rate of erosion is reduced about 75 percent.

Development of Self-Assembled Nanoscale Templates via Microphase Separation Induced by Polymer Brushes

NASA Astrophysics Data System (ADS)

Chu, Elza

Phase separation in soft matter has been the crucial element in generating hybrid materials, such as polymer blends and mixed polymer brushes. This dissertation discusses two methods of developing self-assembled nanoscale templates via microphase separation induced by polymer brush synthesis. This work introduces a novel soft substrate approach with renewable grafting sites where polyacrylamide is "grafted through" chitosan soft substrates. The mechanism of grafting leads to ordered arrays of filament-like nanostructures spanning the chitosan-air interface. Additionally, the chemical composition of the filaments allows for post-chemical modification to change the physical properties of the filaments, and subsequently tailor surfaces for specific application. Unlike traditional materials, multi-functional or "smart" materials, such as binary polymer brushes (BPB) are capable of spontaneously changing the spatial distribution of functional groups and morphology at the surface upon external stimuli. Although promising in principle, the limited range of available complementary polymers with common non-selective solvents confines the diversity of usable materials and restricts any further advancement in the field. This dissertation also covers the fabrication and characterization of responsive nanoscale polystyrene templates or "mosaic" brushes that are capable of changing interfacial composition upon exposure to varying solvent qualities. Using a "mosaic" brush template is a unique approach that allows the fabrication of strongly immiscible polymer BPB without the need for a common solvent. The synthesis of such BPB is exemplified by two strongly immiscible polymers, i.e. polystyrene (polar) and polyacrylamide (non-polar), where polyacrylamide brush is "graft through" a Si-substrate modified with the polystyrene collapsed "mosaic" brush. The surface exhibits solvent-triggered responses, as well as application potential for anti-biofouling.

Antithrombogenic and antibiotic composition and methods of preparation thereof

DOEpatents

Hermes, R.E.

1990-04-17

Antithrombogenic and antibiotic composition of matter and method of preparation are disclosed. A random copolymer of a component of garlic and a biocompatible polymer has been prepared and found to exhibit antithrombogenic and antibiotic properties. Polymerization occurs selectively at the vinyl moiety in 2-vinyl-4H-1,3-dithiin when copolymerized with N-vinyl pyrrolidone. 4 figs.

Antithrombogenic and antibiotic composition and methods of preparation thereof

DOEpatents

Hermes, Robert E.

1990-01-01

Antithrombogenic and antibiotic composition of matter and method of preparation thereof. A random copolymer of a component of garlic and a biocompatible polymer has been prepared and found to exhibit antithrombogenic and antibiotic properties. Polymerization occurs selectively at the vinyl moiety in 2-vinyl-4H-1,3-dithiin when copolymerized with N-vinyl pyrrolidone.

An Undergraduate Chemistry Laboratory: Synthesis of Well-Defined Polymers by Low-Catalyst-Concentration ATRP and Postpolymerization Modification to Fluorescent Materials

ERIC Educational Resources Information Center

Tsarevsky, Nicolay V.; Woodruf, Shannon R.; Wisian-Neilson, Patty J.

2016-01-01

A two-session experiment is designed to introduce undergraduate students to concepts in catalysis, transition metal complexes, polymer synthesis, and postpolymerization modifications. In the first session, students synthesize poly(glycidyl methacrylate) via low-catalyst-concentration atom transfer radical polymerization (ATRP). The…

Advanced, Non-Toxic, Anti-Corrosion, Anti-Fouling and Foul-Release Coatings Based on Covalently Attached Monolayers, Multilayers and Polymers

DTIC Science & Technology

2007-08-08

McCarthy Polymer Science and Engineering Department, University of Massachusetts, Amherst, Massachusetts 01003 Electrophilic aromatic substitution reactions...with a fluorinated silane reagent. Reduction of the amide groups with borane-THF (BH 3-THF) complex leads to a 69% conversion of surface amides to the

Puncture-Healing Properties of Carbon Nanotube-Filled Ionomers

NASA Technical Reports Server (NTRS)

Ward, Thomas C.

2003-01-01

Ionomers are polymers that contain ionic groups in relatively low concentrations along the polymer backbone. These ionic groups, in the presence of oppositely charged ions, form aggregates that lead to novel physical properties of the polymer. React-A-Seal(trademark) and Surlyn(trademark) are poly(ethylene-co-methacrylic acid) (EMAA) ionomer-based materials and Nucrel(trademark) is the EMAA acid copolymer neutralized to produce Surlyn(trademark). React-A-Seal(trademark), Surlyn(trademark), and Nucrel(trademark) recover into their original shapes following a high impact puncture at velocities ranging from 300 to 1200 ft/s ('self-healing'). This self-healing process may be of great benefit in space applications where structures are exposed to matter impacts. A thermal IR camera indicated a temperature increase to 98 C for Nucrel(trademark) 925, Surlyn(trademark) 8940, React-A-Seal(trademark), and Surlyn(trademark) 8920 after initial penetration. To understand and generalize the observed phenomena, questions concerning the mechanism of the puncture resealing must be answered. One suggestion is that the elastic character of the melt created by the puncture drives the self-healing. This inference is based on the observed temperature rise of approx. 3 C above the melting temperature of the samples (approx. 95 C) during the impact. With the expectation of gaining additional insight into the self-healing phenomenon, a thermodynamic and viscoelastic investigation was conducted using primarily DSC and DMA. Surlyn(trademark) and React-A-Seal(trademark) showed the characteristic order-disorder transition at approx. 52 C that has been reported in literature. Master curves were constructed from the creep isotherms for the four EMAA samples. An aging study was performed to investigate the irreproducibility and "tailing effect" observed in the creep data. The aging study indicated that, with increased aging time and temperature, changes in the polyethylene matrix lead to complexities in morphology resulting in changes in the magnitude and shape of the creep curves.

Thermomechanical Properties and Glass Dynamics of Polymer-Tethered Colloidal Particles and Films

PubMed Central

2017-01-01

Polymer-tethered colloidal particles (aka “particle brush materials”) have attracted interest as a platform for innovative material technologies and as a model system to elucidate glass formation in complex structured media. In this contribution, Brillouin light scattering is used to sequentially evaluate the role of brush architecture on the dynamical properties of brush particles in both the individual and assembled (film) state. In the former state, the analysis reveals that brush–brush interactions as well as global chain relaxation sensitively depend on grafting density; i.e., more polymer-like behavior is observed in sparse brush systems. This is interpreted to be a consequence of more extensive chain entanglement. In contrast, the local relaxation of films does not depend on grafting density. The results highlight that relaxation processes in particle brush-based materials span a wider range of time and length scales as compared to linear chain polymers. Differentiation between relaxation on local and global scale is necessary to reveal the influence of molecular structure and connectivity on the aging behavior of these complex systems. PMID:29755139

Thermomechanical Properties and Glass Dynamics of Polymer-Tethered Colloidal Particles and Films.

PubMed

Cang, Yu; Reuss, Anna N; Lee, Jaejun; Yan, Jiajun; Zhang, Jianan; Alonso-Redondo, Elena; Sainidou, Rebecca; Rembert, Pascal; Matyjaszewski, Krzysztof; Bockstaller, Michael R; Fytas, George

2017-11-14

Polymer-tethered colloidal particles (aka "particle brush materials") have attracted interest as a platform for innovative material technologies and as a model system to elucidate glass formation in complex structured media. In this contribution, Brillouin light scattering is used to sequentially evaluate the role of brush architecture on the dynamical properties of brush particles in both the individual and assembled (film) state. In the former state, the analysis reveals that brush-brush interactions as well as global chain relaxation sensitively depend on grafting density; i.e., more polymer-like behavior is observed in sparse brush systems. This is interpreted to be a consequence of more extensive chain entanglement. In contrast, the local relaxation of films does not depend on grafting density. The results highlight that relaxation processes in particle brush-based materials span a wider range of time and length scales as compared to linear chain polymers. Differentiation between relaxation on local and global scale is necessary to reveal the influence of molecular structure and connectivity on the aging behavior of these complex systems.

Effects of topology on the adsorption of singly tethered ring polymers to attractive surfaces.

PubMed

Li, Bing; Sun, Zhao-Yan; An, Li-Jia

2015-07-14

We investigate the effect of topology on the equilibrium behavior of singly tethered ring polymers adsorbed on an attractive surface. We focus on the change of square radius of gyration Rg(2), the perpendicular component Rg⊥(2) and the parallel component Rg‖(2) to the adsorbing surface, the mean contacting number of monomers with the surface , and the monomer distribution along z-direction during transition from desorption to adsorption. We find that both of the critical point of adsorption εc and the crossover exponent ϕ depend on the knot type when the chain length of ring ranges from 48 to 400. The behaviors of Rg(2), Rg⊥(2), and Rg‖(2) are found to be dependent on the topology and the monomer-surface attractive strength. At weak adsorption, the polymer chains with more complex topology are more adsorbable than those with simple topology. However, at strong adsorption, the polymer chains with complex topology are less adsorbable. By analyzing the distribution of monomer along z-direction, we give a possible mechanism for the effect of topology on the adsorption behavior.

Crystal Structure of Bicc1 SAM Polymer and Mapping of Interactions between the Ciliopathy-Associated Proteins Bicc1, ANKS3, and ANKS6.

PubMed

Rothé, Benjamin; Leettola, Catherine N; Leal-Esteban, Lucia; Cascio, Duilio; Fortier, Simon; Isenschmid, Manuela; Bowie, James U; Constam, Daniel B

2018-02-06

Head-to-tail polymers of sterile alpha motifs (SAM) can scaffold large macromolecular complexes. Several SAM-domain proteins that bind each other are mutated in patients with cystic kidneys or laterality defects, including the Ankyrin (ANK) and SAM domain-containing proteins ANKS6 and ANKS3, and the RNA-binding protein Bicc1. To address how their interactions are regulated, we first determined a high-resolution crystal structure of a Bicc1-SAM polymer, revealing a canonical SAM polymer with a high degree of flexibility in the subunit interface orientations. We further mapped interactions between full-length and distinct domains of Bicc1, ANKS3, and ANKS6. Neither ANKS3 nor ANKS6 alone formed macroscopic homopolymers in vivo. However, ANKS3 recruited ANKS6 to Bicc1, and the three proteins together cooperatively generated giant macromolecular complexes. Thus, the giant assemblies are shaped by SAM domains, their flanking sequences, and SAM-independent protein-protein and protein-mRNA interactions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Applicability of samarium(III) complexes for the role of luminescent molecular sensors for monitoring progress of photopolymerization processes and control of the thickness of polymer coatings

NASA Astrophysics Data System (ADS)

Topa, Monika; Ortyl, Joanna; Chachaj-Brekiesz, Anna; Kamińska-Borek, Iwona; Pilch, Maciej; Popielarz, Roman

2018-06-01

Applicability of 15 trivalent samarium complexes as novel luminescent probes for monitoring progress of photopolymerization processes or thickness of polymer coatings by the Fluorescence Probe Technique (FPT) was studied. Three groups of samarium(III) complexes were evaluated in cationic photopolymerization of triethylene glycol divinyl ether monomer (TEGDVE) and free-radical photopolymerization of trimethylolpropane triacrylate (TMPTA). The complexes were the derivatives of tris(4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionate)samarium(III), tris(4,4,4-trifluoro-1-phenyl-1,3-butanedionate)samarium(III) and tris(4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedionate)samarium(III), which were further coordinated with auxiliary ligands, such as 1,10-phenanthroline, triphenylphosphine oxide, tributylphosphine oxide and trioctylphosphine oxide. It has been found that most of the complexes studied are sensitive enough to be used as luminescent probes for monitoring progress of cationic photopolymerization of vinyl ether monomers over entire range of monomer conversions. In the case of free-radical polymerization processes, the samarium(III) complexes are not sensitive enough to changes of microviscosity and/or micropolarity of the medium, so they cannot be used to monitor progress of the polymerization. However, high stability of luminescence intensity of some of these complexes under free-radical polymerization conditions makes them good candidates for application as thickness sensors for polymer coatings prepared by free-radical photopolymerization. A quantitative relationship between a coating thickness and the luminescence intensity of the samarium(III) probes has been derived and verified experimentally within a broad range of the thicknesses.

Influence of molecular designs on polaronic and vibrational transitions in a conjugated push-pull copolymer

NASA Astrophysics Data System (ADS)

Cobet, Christoph; Gasiorowski, Jacek; Menon, Reghu; Hingerl, Kurt; Schlager, Stefanie; White, Matthew S.; Neugebauer, Helmut; Sariciftci, N. Serdar; Stadler, Philipp

2016-10-01

Electron-phonon interactions of free charge-carriers in doped pi-conjugated polymers are conceptually described by 1-dimensional (1D) delocalization. Thereby, polaronic transitions fit the 1D-Froehlich model in quasi-confined chains. However, recent developments in conjugated polymers have diversified the backbones to become elaborate heterocylcic macromolecules. Their complexity makes it difficult to investigate the electron-phonon coupling. In this work we resolve the electron-phonon interactions in the ground and doped state in a complex push-pull polymer. We focus on the polaronic transitions using in-situ spectroscopy to work out the differences between single-unit and push-pull systems to obtain the desired structural- electronic correlations in the doped state. We apply the classic 1D-Froehlich model to generate optical model fits. Interestingly, we find the 1D-approach in push-pull polarons in agreement to the model, pointing at the strong 1D-character and plain electronic structure of the push-pull structure. In contrast, polarons in the single-unit polymer emerge to a multi- dimensional problem difficult to resolve due to their anisotropy. Thus, we report an enhancement of the 1D-character by the push-pull concept in the doped state - an important view in light of the main purpose of push-pull polymers for photovoltaic devices.

Quantitative validation of a nonlinear histology-MRI coregistration method using Generalized Q-sampling Imaging in complex human cortical white matter

PubMed Central

Gangolli, Mihika; Holleran, Laurena; Kim, Joong Hee; Stein, Thor D.; Alvarez, Victor; McKee, Ann C.; Brody, David L.

2017-01-01

Advanced diffusion MRI methods have recently been proposed for detection of pathologies such as traumatic axonal injury and chronic traumatic encephalopathy which commonly affect complex cortical brain regions. However, radiological-pathological correlations in human brain tissue that detail the relationship between the multi-component diffusion signal and underlying pathology are lacking. We present a nonlinear voxel based two dimensional coregistration method that is useful for matching diffusion signals to quantitative metrics of high resolution histological images. When validated in ex vivo human cortical tissue at a 250 × 250 × 500 micron spatial resolution, the method proved robust in correlations between generalized q-sampling imaging and histologically based white matter fiber orientations, with r = 0.94 for the primary fiber direction and r = 0.88 for secondary fiber direction in each voxel. Importantly, however, the correlation was substantially worse with reduced spatial resolution or with fiber orientations derived using a diffusion tensor model. Furthermore, we have detailed a quantitative histological metric of white matter fiber integrity termed power coherence capable of distinguishing between architecturally complex but intact white matter from disrupted white matter regions. These methods may allow for more sensitive and specific radiological-pathological correlations of neurodegenerative diseases affecting complex gray and white matter. PMID:28365421

Coordination Polymers Containing 1,3-Phenylenebis-((1H-1,2,4-triazol-1-yl)methanone) Ligand: Synthesis and ε-Caprolactone Polymerization Behavior.

PubMed

Bello-Vieda, Nestor J; Murcia, Ricardo A; Muñoz-Castro, Alvaro; Macías, Mario A; Hurtado, John J

2017-11-10

The reaction of isophthaloyl dichloride with 1 H -1,2,4-triazole afforded the new ligand 1,3-phenylenebis(1,2,4-triazole-1-yl)methanone ( 1 ). A series of Co(II), Cu(II), Zn(II) and Ni(II) complexes were synthesized using 1 and then characterized by melting point analysis, elemental analysis, theoretical calculations, thermogravimetric analysis, X-ray powder diffraction, nuclear magnetic resonance, infrared and Raman spectroscopy. Experimental and computational studies predict the formation of coordination polymers (CPs). The cobalt and copper CPs and zinc(II) complex were found to be good initiators for the ring-opening polymerization of ε-caprolactone (CL) under solvent-free conditions. ¹H-NMR analysis showed that the obtained polymers of CL were mainly linear and had terminal hydroxymethylene groups. Differential scanning calorimetry showed that the obtained polycaprolactones had high crystallinity, and TGA showed that they had decomposition temperatures above 400 °C. These results provide insight and guidance for the design of metal complexes with potential applications in the polymerization of CL.

Auto-Origami and Soft Programmable Transformers: Simulation Studies of Liquid Crystal Elastomers and Swelling Polymer Gels

NASA Astrophysics Data System (ADS)

Konya, Andrew; Santangelo, Christian; Selinger, Robin

2014-03-01

When the underlying microstructure of an actuatable material varies in space, simple sheets can transform into complex shapes. Using nonlinear finite element elastodynamic simulations, we explore the design space of two such materials: liquid crystal elastomers and swelling polymer gels. Liquid crystal elastomers (LCE) undergo shape transformations induced by stimuli such as heating/cooling or illumination; complex deformations may be programmed by ``blueprinting'' a non-uniform director field in the sample when the polymer is cross-linked. Similarly, swellable gels can undergo shape change when they are swollen anisotropically as programmed by recently developed halftone gel lithography techniques. For each of these materials we design and test programmable motifs which give rise to complex deformation trajectories including folded structures, soft swimmers, apertures that open and close, bas relief patterns, and other shape transformations inspired by art and nature. In order to accommodate the large computational needs required to model these materials, our 3-d nonlinear finite element elastodynamics simulation algorithm is implemented in CUDA, running on a single GPU-enabled workstation.

In-situ sensory technique for in-service quality monitoring: measurement of the complex Young's modulus of polymers

NASA Astrophysics Data System (ADS)

Zhou, Shunhua; Liang, Chen; Rogers, Craig A.; Sun, Fanping P.; Vick, L.

1993-07-01

Applications of polymeric adhesives in joining different materials have necessitated quantitative health inspection of adhesive joints (coverage, state of cure, adhesive strength, location of voids, etc.). A new in-situ sensory method has been proposed in this paper to inspect the amount and distribution of the critical constituents of polymers and to measure the characteristic parameters (complex Young's modulus and damping). In this technique, ferromagnetic particles have been embedded in a polymeric matrix, similar to a particle- reinforced composite. The dynamic signatures extracted from the tests as a result of magnetic excitation of the embedded ferromagnetic particles are used to evaluate the complex Young's modulus of the host polymers. Moreover, the amplitude of the frequency response is utilized to identify the amount and distribution of embedded particles in polymeric materials or adhesive joints. The results predicted from the theoretical model agree well with the experimental results. The theoretical analyses and the experimental work conducted have demonstrated the utility of the sensory technique presented for in-service health interrogation.

Multiphase Equations of State for Polymer Materials at High Dynamic Pressures

NASA Astrophysics Data System (ADS)

Khishchenko, Konstantin V.

2015-06-01

Equations of state for materials over a wide range of pressures and temperatures are necessary for numerical simulations of shock-wave processes in condensed matter. Accuracy of calculation results is determined mainly by adequacy of equation of state of a medium. In this work, a new multiphase equation-of-state model is proposed with taking into account the polymorphic phase transformations, melting and evaporation. Thermodynamic calculations are carried out for 2 polymer materials (polymethylmethacrylate and polytetrafluoroethylene) in a broad region of the phase diagram. Obtained results are presented in comparison with available data of experiments at high dynamic pressures in shock and release waves. This work is supported by RSF, Grant 14-50-00124.

Easy, fast and environmental friendly method for the simultaneous extraction of the 16 EPA PAHs using magnetic molecular imprinted polymers (mag-MIPs).

PubMed

Villar-Navarro, Mercedes; Martín-Valero, María Jesús; Fernández-Torres, Rut Maria; Callejón-Mochón, Manuel; Bello-López, Miguel Ángel

2017-02-15

An easy and environmental friendly method, based on the use of magnetic molecular imprinted polymers (mag-MIPs) is proposed for the simultaneous extraction of the 16 U.S. EPA polycyclic aromatic hydrocarbons (PAHs) priority pollutants. The mag-MIPs based extraction protocol is simple, more sensitive and low organic solvent consuming compared to official methods and also adequate for those PAHs more retained in the particulate matter. The new proposed extraction method followed by HPLC determination has been validated and applied to different types of water samples: tap water, river water, lake water and mineral water. Copyright © 2017 Elsevier B.V. All rights reserved.

Failure of structural elements made of polymer supported composite materials during the multiyear natural aging

NASA Astrophysics Data System (ADS)

Blinkov, Pavel; Ogorodov, Leonid; Grabovyy, Peter

2018-03-01

Modern high-rise construction introduces a number of limitations and tasks. In addition to durability, comfort and profitability, projects should take into account energy efficiency and environmental problems. Polymer building materials are used as substitutes for materials such as brick, concrete, metal, wood and glass, and in addition to traditional materials. Plastic materials are light, can be formed into complex shapes, durable and low, and also possess a wide range of properties. Plastic materials are available in various forms, colors and textures and require minimal or no color. They are resistant to heat transfer and diffusion of moisture and do not suffer from metal corrosion or microbial attack. Polymeric materials, including thermoplastics, thermoset materials and wood-polymer composites, have many structural and non-structural applications in the construction industry. They provide unique and innovative solutions at a low cost, and their use is likely to grow in the future. A number of polymer composite materials form complex material compositions, which are applied in the construction in order to analyze the processes of damage accumulation under the conditions of complex nonstationary loading modes, and to determine the life of structural elements considering the material aging. This paper present the results of tests on short-term compression loading with a deformation rate of v = 2 mm/min using composite samples of various shapes and sizes.

25th Anniversary Article: Ordered Polymer Structures for the Engineering of Photons and Phonons

PubMed Central

Lee, Jae-Hwang; Koh, Cheong Yang; Singer, Jonathan P; Jeon, Seog-Jin; Maldovan, Martin; Stein, Ori; Thomas, Edwin L

2014-01-01

The engineering of optical and acoustic material functionalities via construction of ordered local and global architectures on various length scales commensurate with and well below the characteristic length scales of photons and phonons in the material is an indispensable and powerful means to develop novel materials. In the current mature status of photonics, polymers hold a pivotal role in various application areas such as light-emission, sensing, energy, and displays, with exclusive advantages despite their relatively low dielectric constants. Moreover, in the nascent field of phononics, polymers are expected to be a superior material platform due to the ability for readily fabricated complex polymer structures possessing a wide range of mechanical behaviors, complete phononic bandgaps, and resonant architectures. In this review, polymer-centric photonic and phononic crystals and metamaterials are highlighted, and basic concepts, fabrication techniques, selected functional polymers, applications, and emerging ideas are introduced. PMID:24338738

Characterization of proton conducting blend polymer electrolyte using PVA-PAN doped with NH{sub 4}SCN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Premalatha, M.; Materials Research Center, Coimbatore-641 045; Mathavan, T., E-mail: tjmathavan@gmail.com, E-mail: kingslin.genova20@gmail.com

2016-05-23

Polymer electrolytes with proton conductivity based on blend polymer using polyvinyl alcohol (PVA) and poly acrylo nitrile (PAN) doped with ammonium thiocyanate have been prepared by solution casting method using DMF as solvent. The complex formation between the blend polymer and the salt has been confirmed by FTIR Spectroscopy. The amorphous nature of the blend polymer electrolytes have been confirmed by XRD analysis. The highest conductivity at 303 K has been found to be 3.25 × 10{sup −3} S cm{sup −1} for 20 mol % NH{sub 4}SCN doped 92.5PVA:7.5PAN system. The increase in conductivity of the doped blend polymer electrolytes with increasingmore » temperature suggests the Arrhenius type thermally activated process. The activation energy is found to be low (0.066 eV) for the highest conductivity sample.« less

Synthesis and Characterization of SF-PPV-I

NASA Technical Reports Server (NTRS)

Wang, Y.; Fan, Z.; Taft, C.; Sun, S.

2001-01-01

Conjugated electro-active polymers find their potential applications in developing variety inexpensive and flexible shaped electronic and photonic devices, such as photovoltaic or photo/electro light emitting devices. In many of these opto-electronic polymeric materials, certain electron rich donors and electron deficient acceptors are needed in order to fine-tune the electronic or photonic properties of the desired materials and structures. While many donor type of conjugated polymers have been widely studied and developed in the past decades, there are relatively fewer acceptor type of conjugated polymers have been developed. Key acceptor type conjugated polymers developed so far include C60 and CN-PPV, and each has its limitations. Due to the complexity and diversity of variety future electronic materials and structural needs, alternative and synthetically amenable acceptor conjugated polymers need to be developed. In this paper, we present the synthesis and characterization of a new acceptor conjugated polymer, a sulfone derivatized polyphenylenevinylene "SF-PPV".

Use of Molecular Dynamics for the Refinement of an Electrostatic Model for the In Silico Design of a Polymer Antidote for the Anticoagulant Fondaparinux

PubMed Central

Kwok, Ezra; Gopaluni, Bhushan; Kizhakkedathu, Jayachandran N.

2013-01-01

Molecular dynamics (MD) simulations results are herein incorporated into an electrostatic model used to determine the structure of an effective polymer-based antidote to the anticoagulant fondaparinux. In silico data for the polymer or its cationic binding groups has not, up to now, been available, and experimental data on the structure of the polymer-fondaparinux complex is extremely limited. Consequently, the task of optimizing the polymer structure is a daunting challenge. MD simulations provided a means to gain microscopic information on the interactions of the binding groups and fondaparinux that would have otherwise been inaccessible. This was used to refine the electrostatic model and improve the quantitative model predictions of binding affinity. Once refined, the model provided guidelines to improve electrostatic forces between candidate polymers and fondaparinux in order to increase association rate constants. PMID:27006916

Effect of polymers on the retention and aging of enzyme on bioactive papers.

PubMed

Khan, Mohidus Samad; Haniffa, Sharon B M; Slater, Alison; Garnier, Gil

2010-08-01

The effect of polymer on the retention and the thermal stability of bioactive enzymatic papers was measured using a colorimetric technique quantifying the intensity of the enzyme-substrate product complex. Alkaline phosphatase (ALP) was used as model enzyme. Three water soluble polymers: a cationic polyacrylamide (CPAM), an anionic polyacrylic acid (PAA) and a neutral polyethylene oxide (PEO) were selected as retention aids. The model polymers increased the enzyme adsorption on paper by around 50% and prevented enzyme desorption upon rewetting of the papers. The thermal deactivation of ALP retained on paper with polymers follows two sequential first order reactions. This was also observed for ALP simply physisorbed on paper. The retention aid polymers instigated a rapid initial deactivation which significantly decreased the longevity of the enzymatic papers. This suggests some enzyme-polymer interaction probably affecting the enzyme tertiary structure. A deactivation mathematical model predicting the enzymatic paper half-life was developed. Crown Copyright 2010. Published by Elsevier B.V. All rights reserved.

Metal Coordination Stoichiometry Controlled Formation of Linear and Hyperbranched Supramolecular Polymers.

PubMed

Lin, Cuiling; Xu, Luonan; Huang, Libo; Chen, Jia; Liu, Yuanyuan; Ma, Yifan; Ye, Feixiang; Qiu, Huayu; He, Tian; Yin, Shouchun

2016-09-01

Controlling the topologies of polymers is a hot topic in polymer chemistry because the physical and/or chemical properties of polymers are determined (at least partially) by their topologies. This study exploits the host-guest interactions between dibenzo-24-crown-8 and secondary ammonium salts and metal coordination interactions between 2,6-bis(benzimidazolyl)-pyridine units with metal ions (Zn(II) and/or Eu(III) ) as orthogonal non-covalent interactions to prepare supramolecular polymers. By changing the ratios of the metal ion additives (Zn(NO3 )2 and Eu(NO3 )3 ) linkers to join the host-guest dimeric complex, the linear supramolecular polymers (100 mol% Zn(NO3 )2 per ligand) and hyperbranched supramolecular polymers (97 mol% Zn(NO3 )2 and 3 mol% Eu(NO3 )3 per ligand) are separately and successfully constructed. This approach not only expands topological control over polymeric systems, but also paves the way for the functionalization of smart and adaptive materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hybrid protein-synthetic polymer nanoparticles for drug delivery.

PubMed

Koseva, Neli S; Rydz, Joanna; Stoyanova, Ekaterina V; Mitova, Violeta A

2015-01-01

Among the most common nanoparticulate systems, the polymeric nanocarriers have a number of key benefits, which give a great choice of delivery platforms. Nevertheless, polymeric nanoparticles possess some limitations that include use of toxic solvents in the production process, polymer degradation, drug leakage outside the diseased tissue, and polymer cytotoxicity. The combination of polymers of biological and synthetic origin is an appealing modern strategy for the production of novel nanocarriers with unprecedented properties. Proteins' interface can play an important role in determining bioactivity and toxicity and gives perspective for future development of the polymer-based nanoparticles. The design of hybrid constructs composed of synthetic polymer and biological molecules such as proteins can be considered as a straightforward tool to integrate a broad spectrum of properties and biofunctions into a single device. This review discusses hybrid protein-synthetic polymer nanoparticles with different structures and levels in complexity and functionality, in view of their applications as drug delivery systems. © 2015 Elsevier Inc. All rights reserved.

Dynamic properties of interfaces in soft matter: Experiments and theory

NASA Astrophysics Data System (ADS)

Sagis, Leonard M. C.

2011-10-01

The dynamic properties of interfaces often play a crucial role in the macroscopic dynamics of multiphase soft condensed matter systems. These properties affect the dynamics of emulsions, of dispersions of vesicles, of biological fluids, of coatings, of free surface flows, of immiscible polymer blends, and of many other complex systems. The study of interfacial dynamic properties, surface rheology, is therefore a relevant discipline for many branches of physics, chemistry, engineering, and life sciences. In the past three to four decades a vast amount of literature has been produced dealing with the rheological properties of interfaces stabilized by low molecular weight surfactants, proteins, (bio)polymers, lipids, colloidal particles, and various mixtures of these surface active components. In this paper recent experiments are reviewed in the field of surface rheology, with particular emphasis on the models used to analyze surface rheological data. Most of the models currently used are straightforward generalizations of models developed for the analysis of rheological data of bulk phases. In general the limits on the validity of these generalizations are not discussed. Not much use is being made of recent advances in nonequilibrium thermodynamic formalisms for multiphase systems, to construct admissible models for the stress-deformation behavior of interfaces. These formalisms are ideally suited to construct thermodynamically admissible constitutive equations for rheological behavior that include the often relevant couplings to other fluxes in the interface (heat and mass), and couplings to the transfer of mass from the bulk phase to the interface. In this review recent advances in the application of classical irreversible thermodynamics, extended irreversible thermodynamics, rational thermodynamics, extended rational thermodynamics, and the general equation for the nonequilibrium reversible-irreversible coupling formalism to multiphase systems are also discussed, and shown how these formalisms can be used to generate a wide range of thermodynamically admissible constitutive models for the surface stress tensor. Some of the generalizations currently in use are shown to have only limited validity. The aim of this review is to stimulate new developments in the fields of experimental surface rheology and constitutive modeling of multiphase systems using nonequilibrium thermodynamic formalisms and to promote a closer integration of these disciplines.

DNA immobilization and detection on cellulose paper using a surface grown cationic polymer via ATRP.

PubMed

Aied, Ahmed; Zheng, Yu; Pandit, Abhay; Wang, Wenxin

2012-02-01

Cationic polymers with various structures have been widely investigated in the areas of medical diagnostics and molecular biology because of their unique binding properties and capability to interact with biological molecules in complex biological environments. In this work, we report the grafting of a linear cationic polymer from an atom transfer radical polymerization (ATRP) initiator bound to cellulose paper surface. We show successful binding of ATRP initiator onto cellulose paper and grafting of polymer chains from the immobilized initiator with ATRP. The cellulose paper grafted polymer was used in combination with PicoGreen (PG) to demonstrate detection of nucleic acids in the nanogram range in homogeneous solution and in a biological sample (serum). The results showed specific identification of hybridized DNA after addition of PG in both solutions.

Conductive polymer-based material

DOEpatents

McDonald, William F [Utica, OH; Koren, Amy B [Lansing, MI; Dourado, Sunil K [Ann Arbor, MI; Dulebohn, Joel I [Lansing, MI; Hanchar, Robert J [Charlotte, MI

2007-04-17

Disclosed are polymer-based coatings and materials comprising (i) a polymeric composition including a polymer having side chains along a backbone forming the polymer, at least two of the side chains being substituted with a heteroatom selected from oxygen, nitrogen, sulfur, and phosphorus and combinations thereof; and (ii) a plurality of metal species distributed within the polymer. At least a portion of the heteroatoms may form part of a chelation complex with some or all of the metal species. In many embodiments, the metal species are present in a sufficient concentration to provide a conductive material, e.g., as a conductive coating on a substrate. The conductive materials may be useful as the thin film conducting or semi-conducting layers in organic electronic devices such as organic electroluminescent devices and organic thin film transistors.

Thermodynamics of the adsorption of flexible polymers on nanowires

NASA Astrophysics Data System (ADS)

Vogel, Thomas; Gross, Jonathan; Bachmann, Michael

2015-03-01

Generalized-ensemble simulations enable the study of complex adsorption scenarios of a coarse-grained model polymer near an attractive nanostring, representing an ultrathin nanowire. We perform canonical and microcanonical statistical analyses to investigate structural transitions of the polymer and discuss their dependence on the temperature and on model parameters such as effective wire thickness and attraction strength. The result is a complete hyperphase diagram of the polymer phases, whose locations and stability are influenced by the effective material properties of the nanowire and the strength of the thermal fluctuations. Major structural polymer phases in the adsorbed state include compact droplets attached to or wrapping around the wire, and tubelike conformations with triangular pattern that resemble ideal boron nanotubes. The classification of the transitions is performed by microcanonical inflection-point analysis.

Thermodynamics of the adsorption of flexible polymers on nanowires.

PubMed

Vogel, Thomas; Gross, Jonathan; Bachmann, Michael

2015-03-14

Generalized-ensemble simulations enable the study of complex adsorption scenarios of a coarse-grained model polymer near an attractive nanostring, representing an ultrathin nanowire. We perform canonical and microcanonical statistical analyses to investigate structural transitions of the polymer and discuss their dependence on the temperature and on model parameters such as effective wire thickness and attraction strength. The result is a complete hyperphase diagram of the polymer phases, whose locations and stability are influenced by the effective material properties of the nanowire and the strength of the thermal fluctuations. Major structural polymer phases in the adsorbed state include compact droplets attached to or wrapping around the wire, and tubelike conformations with triangular pattern that resemble ideal boron nanotubes. The classification of the transitions is performed by microcanonical inflection-point analysis.

Growth of polymer-metal nanocomposites by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Röder, Johanna; Faupel, Jörg; Krebs, Hans-Ulrich

2008-12-01

Complex polymer-metal nanocomposites have a wide range of applications, e.g. as flexible displays and packaging materials. Pulsed laser deposition was applied to form nanostructured materials consisting of metal clusters (Ag, Au, Pd and Cu) embedded in a polymer (polycarbonate, PC) matrix. The size and amount of the metal clusters are controlled by the number of laser pulses hitting the respective targets. For Cu and Pd, smaller clusters and higher cluster densities are obtained as in the cases of Ag and Au due to a stronger reactivity with the polymers and thus a lower diffusivity. Implantation effects, differences in metal diffusivity and reactivity on the polymer surfaces, and the coalescence properties are discussed with respect to the observed microstructures on PC and compared to the metal growth on poly (methyl methacrylate), PMMA.

Controlled Pd(0)/t Bu3P Catalyzed Suzuki Cross-Coupling Polymerization of AB-Type Monomers with ArPd(t Bu3P)X or Pd2(dba)3/t Bu3P/ArX as the Initiator

DOE PAGES

Zhang, Honghai; Xing, Chun-Hui; Hu, Qiao-Sheng; ...

2015-02-05

The synthesis of well-defined and functionalized conjugated polymers, which are essential in the development of efficient organic electronics, through Suzuki cross-coupling polymerizations has been a challenging task. We developed controlled Pd(0)/t-Bu3P-catalyzed Suzuki cross-coupling polymerizations of AB-type monomers via the chain-growth mechanism with a series of in situ generated ArPd(t-Bu3P)X (X = I, Br, Cl) complexes as initiators. Among them, the combinations of Pd2(dba)3/t-Bu3P/p-BrC6H4I, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br were identified as highly robust initiator systems, resulting in polymers with predictable molecular weight and narrow polydispersity (PDI~1.13-1.20). In addition, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br initiator systems afforded functional polymers with >95% fidelity. Our results pavedmore » the road to access well-defined conjugated polymers, including conjugated polymers with complex polymer architectures such as block copolymers and branch copolymers.« less

Accurate determination of dielectric permittivity of polymers from 75  GHz to 1.6  THz using both S-parameters and transmission spectroscopy.

PubMed

Chang, Tianying; Zhang, Xiansheng; Zhang, Xiaoxuan; Cui, Hong-Liang

2017-04-20

Interactions of terahertz (THz) electromagnetic radiation with polymer materials have been studied recently with increasing depth and breadth, for purposes of both using polymers in fabricating THz optical components such as lenses, waveplates, waveguides, and sample holders/containers, and employing THz spectral imaging as a new tool for nondestructive testing of polymer composite structures. Either endeavor cannot even begin without a quantitative knowledge of the complex dielectric permittivity, i.e., the propagation and attenuation properties of such polymers in the requisite wave band. In this paper, a number of non-polar and non-magnetic polymers, such as polytetrafluoroethylene, polypropylene, high-density polyethylene, and polymethyl methacrylate, are studied for the purpose of determining their complex dielectric permittivity, including its real part and imaginary parts, in the wide frequency band from millimeter wave to THz wave (75 GHz-1.6 THz), in two ways. The first is a free space method based on a vector network analyzer covering the frequency region from 75 to 500 GHz, and the second is the THz time-domain spectroscopy (THz-TDS), effective for the region of 100 GHz-1.6 THz. The results are consistent with existing data (with discrepancies less than 1% in most cases for both the index of refraction and the absorption coefficient), and where they overlap in frequency coverage, the two methods yield identical results to within measurement error.

Synthesis of a molecularly imprinted polymer for the selective recognition of carmoisine (Azorubin E122) from pomegranate juice.

PubMed

Ghasempour, Zahra; Alizadeh-Khaledabad, Mohammad; Vardast, Mohammad-Reza; Rezazad-Bari, Mahmoud

2017-02-01

Since natural pigments are lost during the processing of beverages such as pomegranate juice, carmoisine, as an adulterant, is often added into the pure juice to improve color characteristics. In this study, molecularly imprinted polymers, as an adsorbent of carmoisine, were synthesized using acrylamide, methacrylic acid, and 4-vinylpyridine as functional monomers and then they were evaluated in terms of the separation and detection of carmoisine. Experiments on the batch adsorption of carmoisine 10 ppm stock solution revealed a better binding capacity for the 4-vinylpyridine-based polymer in comparison to methacrylic acid and acrylamide polymers. The complexation of carmoisine with the 4-vinylpyridine-based polymer was confirmed by Fourier transform infrared spectroscopy. The synthesized polymer exerted a high thermal degradation point and average diameter of polymer particles were obtained to be 0.2 μm by dynamic light scattering analysis. This work showed that detection of pomegranate juice adulteration with carmoisine is not necessarily difficult, time consuming or expensive with selective separation techniques such as molecularly imprinted polymers. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Catechol-Functionalized Synthetic Polymer as a Dental Adhesive to Contaminated Dentin Surface for a Composite Restoration.

PubMed

Lee, Sang-Bae; González-Cabezas, Carlos; Kim, Kwang-Mahn; Kim, Kyoung-Nam; Kuroda, Kenichi

2015-08-10

This study reports a synthetic polymer functionalized with catechol groups as dental adhesives. We hypothesize that a catechol-functionalized polymer functions as a dental adhesive for wet dentin surfaces, potentially eliminating the complications associated with saliva contamination. We prepared a random copolymer containing catechol and methoxyethyl groups in the side chains. The mechanical and adhesive properties of the polymer to dentin surface in the presence of water and salivary components were determined. It was found that the new polymer combined with an Fe(3+) additive improved bond strength of a commercial dental adhesive to artificial saliva contaminated dentin surface as compared to a control sample without the polymer. Histological analysis of the bonding structures showed no leakage pattern, probably due to the formation of Fe-catechol complexes, which reinforce the bonding structures. Cytotoxicity test showed that the polymers did not inhibit human gingival fibroblast cells proliferation. Results from this study suggest a potential to reduce failure of dental restorations due to saliva contamination using catechol-functionalized polymers as dental adhesives.

Multiple dynamic regimes in colloid-polymer dispersions: New insight using X-ray photon correlation spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Srivastava, Sunita; Kishore, Suhasini; Narayanan, Suresh

We present an X-ray photon correlation spectros- copy (XPCS) study of dynamic transitions in an anisotropic colloid-polymer dispersion with multiple arrested states. The results provide insight into the mechanism for formation of repulsive glasses, attractive glasses, and networked gels of col- loids with weakly adsorbing polymer chains. In the presence of adsorbing polymer chains, we observe three distinct regimes: a state with slow dynamics consisting of finite particles and clusters, for which interparticle interactions are predominantly repulsive; a second dynamic regime occurring above the satu- ration concentration of added polymer, in which small clusters of nanoparticles form via a short-rangemore » depletion attraction; and a third regime above the overlap concentration in which dynamics of clusters are independent of polymer chain length. The observed complex dynamic state diagram is primarily gov- erned by the structural reorganization of a nanoparticle cluster and polymer chains at the nanoparticle-polymer surface and in the concentrated medium, which in turn controls the dynamics of the dispersion« less

Catechol-Functionalized Synthetic Polymer as a Dental Adhesive to Contaminated Dentin Surface for a Composite Restoration

PubMed Central

2015-01-01

This study reports a synthetic polymer functionalized with catechol groups as dental adhesives. We hypothesize that a catechol-functionalized polymer functions as a dental adhesive for wet dentin surfaces, potentially eliminating the complications associated with saliva contamination. We prepared a random copolymer containing catechol and methoxyethyl groups in the side chains. The mechanical and adhesive properties of the polymer to dentin surface in the presence of water and salivary components were determined. It was found that the new polymer combined with an Fe3+ additive improved bond strength of a commercial dental adhesive to artificial saliva contaminated dentin surface as compared to a control sample without the polymer. Histological analysis of the bonding structures showed no leakage pattern, probably due to the formation of Fe–catechol complexes, which reinforce the bonding structures. Cytotoxicity test showed that the polymers did not inhibit human gingival fibroblast cells proliferation. Results from this study suggest a potential to reduce failure of dental restorations due to saliva contamination using catechol-functionalized polymers as dental adhesives. PMID:26176305

Syntheses, structures, electrochemistry and catalytic oxidation degradation of organic dyes of two new coordination polymers derived from Cu(II) and Mn(II) and 1-(tetrazo-5-yl)-4-(triazo-1-yl)benzene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Ming; Mu, Bao; Huang, Ru-Dan, E-mail: huangrd@bit.edu.cn

Two new coordination polymers (CPs), namely, [Cu{sub 2}(ttbz)(H{sub 2}btc){sub 2}(OH)]{sub n} (1) and [Mn(ttbz){sub 2}(H{sub 2}O){sub 2}]{sub n} (2) (Httbz =1-(tetrazo-5-yl)-4-(triazo-1-yl)benzene, H{sub 3}btc =1,3,5-benzenetricarboxylic acid), have been hydrothermally synthesized and structurally characterized. Complex 1 exhibits a (3,5,5,5)-connected 2D layer with a Schläfli symbol of (3·4{sup 2})(3·4{sup 4}0.5{sup 2}0.6{sup 3})(3{sup 2}0.4{sup 4}0.5{sup 2}0.6{sup 2})(3{sup 2}0.4{sup 4}0.5{sup 3}0.6), in which the ttbz{sup -} ligand can be described as μ{sub 5}-bridge, linking Cu(II) ions into a 2D layer and H{sub 2}btc{sup -} ions play a supporting role in complex 1. The ttbz{sup -} ligand in complex 2 represents the bridging coordination mode, connectingmore » two Mn(II) ions to form the infinite 1D zigzag chains, respectively, which are further connected by two different types of hydrogen bonds to form a 3D supramolecular. Furthermore, catalytic oxidation activities toward organic dyes and electrochemical behaviors of the title complexes have been investigated at room temperature in aqueous solutions, indicating these complexes may be applicable to color removal in a textile wastewater stream and practical applications in areas of electrocatalytic reduction toward nitrite, respectively. - Graphical abstract: Two new coordination polymers based on different structural characteristics have been hydrothermally synthesized by the mixed ligands. The catalytic oxidation activities toward organic dyes and electrochemical behaviors of the title complexes have been investigated. - Highlights: • The organic ligand containing the tetrazolyl group and triazolyl group with some advantages has been used. • Two new coordination polymers with different structural characteristics has been discussed in detail. • Catalytic oxidation activities toward organic dyes and electrochemical behaviors of the title complexes have been investigated.« less

Fabrication of complex nanoscale structures on various substrates

NASA Astrophysics Data System (ADS)

Han, Kang-Soo; Hong, Sung-Hoon; Lee, Heon

2007-09-01

Polymer based complex nanoscale structures were fabricated and transferred to various substrates using reverse nanoimprint lithography. To facilitate the fabrication and transference of the large area of the nanostructured layer to the substrates, a water-soluble polyvinyl alcohol mold was used. After generation and transference of the nanostructured layer, the polyvinyl alcohol mold was removed by dissolving in water. A residue-free, UV-curable, glue layer was formulated and used to bond the nanostructured layer onto the substrates. As a result, nanometer scale patterned polymer layers were bonded to various substrates and three-dimensional nanostructures were also fabricated by stacking of the layers.

Ring-Opening Copolymerization of Epoxides and Cyclic Anhydrides with Discrete Metal Complexes: Structure-Property Relationships.

PubMed

Longo, Julie M; Sanford, Maria J; Coates, Geoffrey W

2016-12-28

Polyesters synthesized through the alternating copolymerization of epoxides and cyclic anhydrides compose a growing class of polymers that exhibit an impressive array of chemical and physical properties. Because they are synthesized through the chain-growth polymerization of two variable monomers, their syntheses can be controlled by discrete metal complexes, and the resulting materials vary widely in their functionality and physical properties. This polymer-focused review gives a perspective on the current state of the field of epoxide/anhydride copolymerization mediated by discrete catalysts and the relationships between the structures and properties of these polyesters.

Study of microstructural characterization and ionic conductivity of a chemical-covalent polyether-siloxane hybrid doped with LiClO4.

PubMed

Liang, Wuu-Jyh; Chen, Ying-Pin; Wu, Chien-Pang; Kuo, Ping-Lin

2005-12-29

The chemical-covalent polyether-siloxane hybrids (EDS) doped with various amounts of LiClO4 salt were characterized by FT-IR, DSC, TGA, and solid-state NMR spectra as well as impedance measurements. These observations indicate that different types of complexes by the interactions of Li+ and ClO4- ions are formed within the hybrid host, and the formation of transient cross-links between Li+ ions and ether oxygens results in the increase in T(g) of polyether segments and the decrease in thermal stability of hybrid electrolyte. Initially a cation complexation dominated by the oxirane-cleaved cross-link site and PEO block is present, and after the salt-doped level of O/Li+ = 20, the complexation through the PPO block becomes more prominent. Moreover, a significant degree of ionic association is examined in the polymer-salt complexes at higher salt uptakes. A VTF-like temperature dependence of ionic conductivity is observed in all of the investigated salt concentrations, implying that the diffusion of charge carrier is assisted by the segmental motions of the polymer chains. The behavior of ion transport in these hybrid electrolytes is further correlated with the interactions between ions and polymer host.

Low-temperature relative reflectivity measurements of reflective and scintillating foils used in rare event searches

NASA Astrophysics Data System (ADS)

Langenkämper, A.; Ulrich, A.; Defay, X.; Feilitzsch, F. v.; Lanfranchi, J.-C.; Mondragón, E.; Münster, A.; Oppenheimer, C.; Potzel, W.; Roth, S.; Schönert, S.; Steiger, H.; Trinh Thi, H. H.; Wawoczny, S.; Willers, M.; Zöller, A.

2018-03-01

In this work we investigate the reflectivity of highly reflective multilayer polymer foils used in the CRESST experiment. The CRESST experiment searches directly for dark matter via operating scintillating CaWO4 crystals as targets for elastic dark matter-nucleon scattering. In order to suppress background events, the experiment employs the so-called phonon-light technique which is based on the simultaneous measurement of the heat signal in the main CaWO4 target crystal and of the emitted scintillation light with a separate cryogenic light detector. Both detectors are surrounded by a highly reflective and scintillating multilayer polymer foil to increase the light collection efficiency and to veto surface backgrounds. While this study is motivated by the CRESST experiment, the results are also relevant for other rare event searches using scintillating cryogenic bolometers in the field of the search of dark matter and neutrinoless double beta decay (0 νββ). In this work a dedicated experiment has been set up to determine the relative reflectivity at 300 K and 20 K of three multilayer foils ("VM2000", "VM2002", "Vikuiti") produced by the company 3M. The intensity of a light beam reflected off the foil is measured with a CCD camera. The ratio of the intensities at 300 K and 20 K corresponds to the relative reflectivity change. The measurements performed in this work show no variation of the reflectivity with temperature at a level of ∼1%.

The development of a new technical platform to measure soil organic nitrogen cycling processes by microbes

NASA Astrophysics Data System (ADS)

Hu, Yuntao; Richter, Andreas; Wanek, Wolfgang

2016-04-01

Soil organic matter (SOM) decomposition is one of the most important processes of the global nitrogen cycle, having strong implications on soil N availability, terrestrial carbon cycling and soil carbon sequestration. During SOM decomposition low-molecular weight organic nitrogen (LMWON) is released which can be taken up by microbes (and plants). The breakdown of high-molecular weight organic nitrogen (HMWON, e.g. proteins, peptidoglycan, chitin, nucleic acids) represents the bottleneck of soil HMWON decomposition and is performed by extracellular enzymes released mainly by soil microorganisms. Despite that, the current understanding of the controls of these processes is incomplete. The only way to measure gross decomposition rates of these polymers is to use isotope pool dilution (IPD) techniques. In IPD approaches the product pool is isotopically enriched (by e.g. 15N) and the isotope dilution of this pool is measured over time. We have pioneered an IPD for protein and cellulose depolymerization, but IPD approaches for other polymers, specifically for important microbial necromass components such as chitin (fungi) and peptidoglycan (bacteria), or nucleic acids have not yet been developed. Here we present a workflow based on a universally applicable technical platform that allows to estimate the gross depolymerization rate of SOM (HMWON) at the molecular level, using ultra high performance liquid chromatography/high resolution Orbitrap mass spectrometry (UPLC/HRMS) combined with IPD techniques. The necessary isotopically labeled organic polymers (chitin, peptidoglycan and others) are extracted from laboratory bacterial and fungal cultures grown in fully isotopically labeled nutrient media (15N, 13C or both). A purification scheme for the different polymers is currently established. Labeled potential decomposition products (e.g. amino sugars and muropeptides from peptidoglycan, amino sugars and chitooligosaccharides from chitin, nucleotides and nucleosides from nucleic acids) are prepared by enzymatic and/or acid digestion of the polymers. Different UPLC separation columns (Hypercarb, HiliC and C18) make it possible to separate more than 100 related monomers and oligomers produced during polymer decomposition, a prerequisite for analyzing the concentrations and isotope kinetics of decomposition products in complex soil samples. The benchtop Orbitrap mass analyzer has a nominal mass resolving power of 100,000 (FWHM at m/z 200), which enables us to separate compounds that are 13C- and 15N-labelled (mass difference: 0.00632) in the same compound, allowing tracing carbon and nitrogen isotopes in the same compound in IPD experiments. With the accurate masses, retention times and the isotopic pattern we can quantify and qualify the target decomposition products and their isotope kinetics during soil incubation experiments. This will enable us to estimate in situ decomposition rates of the major organic nitrogen polymers in soils, allowing new insights into the major controls of the most important step in soil organic nitrogen recycling.

Introductory physics going soft

NASA Astrophysics Data System (ADS)

Langbeheim, Elon; Livne, Shelly; Safran, Samuel A.; Yerushalmi, Edit

2012-01-01

We describe an elective course on soft matter at the level of introductory physics. Soft matter physics serves as a context that motivates the presentation of basic ideas in statistical thermodynamics and their applications. It also is an example of a contemporary field that is interdisciplinary and touches on chemistry, biology, and physics. We outline a curriculum that uses the lattice gas model as a quantitative and visual tool, initially to introduce entropy, and later to facilitate the calculation of interactions. We demonstrate how free energy minimization can be used to teach students to understand the properties of soft matter systems such as the phases of fluid mixtures, wetting of interfaces, self-assembly of surfactants, and polymers. We discuss several suggested activities in the form of inquiry projects which allow students to apply the concepts they have learned to experimental systems.

Surface design for controlled crystallization: the role of surface chemistry and nanoscale pores in heterogeneous nucleation.

PubMed

Diao, Ying; Myerson, Allan S; Hatton, T Alan; Trout, Bernhardt L

2011-05-03

Current industrial practice for control of primary nucleation (nucleation from a system without pre-existing crystalline matter) during crystallization from solution involves control of supersaturation generation, impurity levels, and solvent composition. Nucleation behavior remains largely unpredictable, however, due to the presence of container surfaces, dust, dirt, and other impurities that can provide heterogeneous nucleation sites, thus making the control and scale-up of processes that depend on primary nucleation difficult. To develop a basis for the rational design of surfaces to control nucleation during crystallization from solution, we studied the role of surface chemistry and morphology of various polymeric substrates on heterogeneous nucleation using aspirin as a model compound. Nucleation induction time statistics were utilized to investigate and quantify systematically the effectiveness of polymer substrates in inducing nucleation. The nucleation induction time study revealed that poly(4-acryloylmorpholine) and poly(2-carboxyethyl acrylate), each cross-linked by divinylbenzene, significantly lowered the nucleation induction time of aspirin while the other polymers were essentially inactive. In addition, we found the presence of nanoscopic pores on certain polymer surfaces led to order-of-magnitude faster aspirin nucleation rates when compared with surfaces without pores. We studied the preferred orientation of aspirin crystals on polymer films and found the nucleation-active polymer surfaces preferentially nucleated the polar facets of aspirin, guided by hydrogen bonds. A model based on interfacial free energies was also developed which predicted the same trend of polymer surface nucleation activities as indicated by the nucleation induction times.

Characterization of polymeric substance classes in cereal-based beverages using asymmetrical flow field-flow fractionation with a multi-detection system.

PubMed

Krebs, Georg; Becker, Thomas; Gastl, Martina

2017-09-01

Cereal-based beverages contain a complex mixture of various polymeric macromolecules including polysaccharides, peptides, and polyphenols. The molar mass of polymers and their degradation products affect different technological and especially sensory parameters of beverages. Asymmetrical flow field-flow fractionation (AF4) coupled with multi-angle light scattering (MALS) and refractive index detection (dRI) or UV detection (UV) is a technique for structure and molar mass distribution analysis of macromolecules commonly used for pure compound solutions. The objective of this study was to develop a systematic approach for identifying the polymer classes in an AF4//MALS/dRI/UV fractogram of the complex matrix in beer, a yeast-fermented cereal-based beverage. Assignment of fractogram fractions to polymer substance classes was achieved by targeted precipitations, enzymatic hydrolysis, and alignments with purified polymer standards. Corresponding effects on dRI and UV signals were evaluated according to the detector's sensitivities. Using these techniques, the AF4 fractogram of beer was classified into different fractions: (1) the low molar mass fraction was assigned to proteinaceous molecules with different degrees of glycosylation, (2) the middle molar mass fraction was attributed to protein-polyphenol complexes with a coelution of non-starch polysaccharides, and (3) the high molar mass fraction was identified as a mixture of the cell wall polysaccharides (i.e., β-glucan and arabinoxylan) with a low content of polysaccharide-protein association. In addition, dextrins derived from incomplete starch hydrolysis were identified in all fractions and over the complete molar mass range. The ability to assess the components of an AF4 fractogram is beneficial for the targeted design and evaluation of polymers in fermented cereal-based beverages and for controlling and monitoring quality parameters.

Reducible, Dibromomaleimide-linked Polymers for Gene Delivery

PubMed Central

Tan, James-Kevin Y.; Choi, Jennifer L.; Wei, Hua; Schellinger, Joan G.; Pun, Suzie H.

2014-01-01

Polycations have been successfully used as gene transfer vehicles both in vitro and in vivo; however, their cytotoxicity has been associated with increasing molecular weight. Polymers that can be rapidly degraded after internalization are typically better tolerated by mammalian cells compared to their non-degradable counterparts. Here, we report the use of a dibromomaleimide-alkyne (DBM-alkyne) linking agent to reversibly bridge cationic polymer segments for gene delivery and to provide site-specific functionalization by azidealkyne cycloaddition chemistry. A panel of reducible and non-reducible, statistical copolymers of (2-dimethylamino) ethyl methacrylate (DMAEMA) and oligo(ethylene glycol) methyl ether methacrylate (OEGMA) were synthesized and evaluated. When complexed with plasmid DNA, the reducible and non-reducible polymers had comparable DNA condensation properties, sizes, and transfection efficiencies. When comparing cytotoxicity, the DBM-linked, reducible polymers were significantly less toxic than the non-reducible polymers. To demonstrate polymer functionalization by click chemistry, the DBM-linked polymers were tagged with an azidefluorophore and were used to monitor cellular uptake. Overall, this polymer system introduces the use of a reversible linker, DBM-alkyne, to the area of gene delivery and allows for facile, orthogonal, and site-specific functionalization of gene delivery vehicles. PMID:26214195

Hopping Diffusion of Nanoparticles in Polymer Matrices

PubMed Central

2016-01-01

We propose a hopping mechanism for diffusion of large nonsticky nanoparticles subjected to topological constraints in both unentangled and entangled polymer solids (networks and gels) and entangled polymer liquids (melts and solutions). Probe particles with size larger than the mesh size ax of unentangled polymer networks or tube diameter ae of entangled polymer liquids are trapped by the network or entanglement cells. At long time scales, however, these particles can diffuse by overcoming free energy barrier between neighboring confinement cells. The terminal particle diffusion coefficient dominated by this hopping diffusion is appreciable for particles with size moderately larger than the network mesh size ax or tube diameter ae. Much larger particles in polymer solids will be permanently trapped by local network cells, whereas they can still move in polymer liquids by waiting for entanglement cells to rearrange on the relaxation time scales of these liquids. Hopping diffusion in entangled polymer liquids and networks has a weaker dependence on particle size than that in unentangled networks as entanglements can slide along chains under polymer deformation. The proposed novel hopping model enables understanding the motion of large nanoparticles in polymeric nanocomposites and the transport of nano drug carriers in complex biological gels such as mucus. PMID:25691803

Rational approach to polymer-supported catalysts: synergy between catalytic reaction mechanism and polymer design.

PubMed

Madhavan, Nandita; Jones, Christopher W; Weck, Marcus

2008-09-01

Supported catalysis is emerging as a cornerstone of transition metal catalysis, as environmental awareness necessitates "green" methodologies and transition metal resources become scarcer and more expensive. Although these supported systems are quite useful, especially in their capacity for transition metal catalyst recycling and recovery, higher activity and selectivity have been elusive compared with nonsupported catalysts. This Account describes recent developments in polymer-supported metal-salen complexes, which often surpass nonsupported analogues in catalytic activity and selectivity, demonstrating the effectiveness of a systematic, logical approach to designing supported catalysts from a detailed understanding of the catalytic reaction mechanism. Over the past few decades, a large number of transition metal complex catalysts have been supported on a variety of materials ranging from polymers to mesoporous silica. In particular, soluble polymer supports are advantageous because of the development of controlled and living polymerization methods that are tolerant to a wide variety of functional groups, including controlled radical polymerizations and ring-opening metathesis polymerization. These methods allow for tuning the density and structure of the catalyst sites along the polymer chain, thereby enabling the development of structure-property relationships between a catalyst and its polymer support. The fine-tuning of the catalyst-support interface, in combination with a detailed understanding of catalytic reaction mechanisms, not only permits the generation of reusable and recyclable polymer-supported catalysts but also facilitates the design and realization of supported catalysts that are significantly more active and selective than their nonsupported counterparts. These superior supported catalysts are accessible through the optimization of four basic variables in their design: (i) polymer backbone rigidity, (ii) the nature of the linker, (iii) catalyst site density, and (iv) the nature of the catalyst attachment. Herein, we describe the design of polymer supports tuned to enhance the catalytic activity or decrease, or even eliminate, decomposition pathways of salen-based transition metal catalysts that follow either a monometallic or a bimetallic reaction mechanism. These findings result in the creation of some of the most active and selective salen catalysts in the literature.

PREFACE: IUMRS-ICA 2008 Symposium, Sessions 'X. Applications of Synchrotron Radiation and Neutron Beam to Soft Matter Science' and 'Y. Frontier of Polymeric Nano-Soft-Materials - Precision Polymer Synthesis, Self-assembling and Their Functionalization'

NASA Astrophysics Data System (ADS)

Takahara, Atsushi; Kawahara, Seiichi

2009-09-01

Applications of Synchrotron Radiation and Neutron Beam to Soft Matter Science (Symposium X of IUMRS-ICA2008) Toshiji Kanaya, Kohji Tashiro, Kazuo Sakura Keiji Tanaka, Sono Sasaki, Naoya Torikai, Moonhor Ree, Kookheon Char, Charles C Han, Atsushi Takahara This volume contains peer-reviewed invited and contributed papers that were presented in Symposium X 'Applications of Synchrotron Radiation and Neutron Beam to Soft Matter Science' at the IUMRS International Conference in Asia 2008 (IUMRS-ICA 2008), which was held on 9-13 December 2008, at Nagoya Congress Center, Nagoya, Japan. Structure analyses of soft materials based on synchrotron radiation (SR) and neutron beam have been developed steadily. Small-angle scattering and wide-angle diffraction techniques clarified the higher-order structure as well as time dependence of structure development such as crystallization and microphase-separation. On the other hand, reflectivity, grazing-incidence scattering and diffraction techniques revealed the surface and interface structural features of soft materials. From the viewpoint of strong interests on the development of SR and neutron beam techniques for soft materials, the objective of this symposium is to provide an interdisciplinary forum for the discussion of recent advances in research, development, and applications of SR and neutron beams to soft matter science. In this symposium, 21 oral papers containing 16 invited papers and 14 poster papers from China, India, Korea, Taiwan, and Japan were presented during the three-day symposium. As a result of the review of poster and oral presentations of young scientists by symposium chairs, Dr Kummetha Raghunatha Reddy (Toyota Technological Institute) received the IUMRS-ICA 2008 Young Researcher Award. We are grateful to all invited speakers and many participants for valuable contributions and active discussions. Organizing committee of Symposium (IUMRS-ICA 2008) Professor Toshiji Kanaya (Kyoto University) Professor Kohji Tashiro (Toyota Technological Institute) Professor Kazuo Sakurai(Kitakyushu University) Professor Keiji Tanaka (Kyushu University) Dr Sono Sasaki (JASRI/Spring-8) Professor Naoya Torikai (KENS) Professor Moonhor Ree (POSTECH) Professor Kookheon Char (Seoul National University) Professor Charles C Han (CAS) Professor Atsushi Takahara(Kyushu University) Frontier of Polymeric Nano-Soft-Materials, Precision Polymer Synthesis, Self-assembling and Their Functionalization (Symposium Y of IUMRS-ICA2008) Seiichi Kawahara, Rong-Ming Ho, Hiroshi Jinnai, Masami Kamigaito, Takashi Miyata, Hiroshi Morita, Hideyuki Otsuka, Daewon Sohn, Keiji Tanaka It is our great pleasure and honor to publish peer-reviewed papers, presented in Symposium Y 'Frontier of Polymeric Nano-Soft-Materials Precision Polymer Synthesis, Self-assembling and Their Functionalization' at the International Union of Materials Research Societies International Conference in Asia 2008 (IUMRS-ICA2008), which was held on 9-13 December 2008, at Nagoya Congress Center, Nagoya, Japan. 'Polymeric nano-soft-materials' are novel outcomes based on a recent innovative evolution in polymer science, i.e. precision polymer synthesis, self-assembling and functionalization of multi-component systems. The materials are expected to exhibit specific functions and unique properties due to their hierarchic morphologies brought either by naturally-generated ordering or by artificial manipulation of the systems, e.g., crystallization and phase-separation. The emerging precision synthesis has brought out new types of polymers with well-controlled primary structures. Furthermore, the surface and interface of the material are recognized to play an important role in the outstanding mechanical, electrical and optical properties, which are required for medical and engineering applications. In order to understand structure-property relationships in the nano-soft-materials, it is indispensable to develop novel characterization techniques. Symposium Y aimed to provide recent advances in polymer synthesis, self-assembling processes and morphologies, and functionalization of nano-soft-materials in order to initiate mutual and collaborative research interest that is essential to develop revolutionarily new nano-soft-materials in the decades ahead. Four Keynote lectures, 15 invited talks and 30 posters presented important new discoveries in polymeric nano-soft-materials, precision polymer synthesis, self-assembling and their functionalization. As for the precision polymer synthesis, the latest results were provided for studies on synthesis of polyrotaxane with movable graft chains, organic-inorganic hybridization of polymers, supra-molecular coordination assembly of conjugated polymers, precision polymerization of adamantane-containing monomers, production of high density polymer brush and synthesis of rod coil type polymer. The state-of-the-art results were introduced for the formation of nano-helical-structure of block copolymer containing asymmetric carbon atoms, self-assembling of block copolymers under the electric field, self-assembling of liquid crystalline elastomers, preparation of nano cylinder template films and mesoscopic simulation of phase transition of polymers and so forth. Moreover, recent advantages of three-dimensional electron microtomography and scanning force microscopy were proposed for analyses of nano-structures and properties of polymeric multi-component systems. Syntheses, properties and functions of slide-ring-gel, organic-inorganic hybrid hydrogels, hydrogel nano-particles, liquid-crystalline gels, the self-oscillating gels, and double network gels attracted participants' attention. Modifications of naturally occurring polymeric materials with supercritical carbon dioxide were introduced as a novel technology. Some of the attractive topics are presented in this issue. We are grateful to all the speakers and participants for valuable contributions and active discussions. Organizing committee of Symposium Y (IUMRS-ICA 2008) Chair Seiichi Kawahara (Nagaoka University of Technology, Japan) Vice Chairs Rong-Ming Ho (National Tsing Hua University, Taiwan) Hiroshi Jinnai (Kyoto Institute of Technology, Japan) Masami Kamigaito (Nagoya University, Japan) Takashi Miyata (Kansai University, Japan) Hiroshi Morita (National Institute of Advanced Industrial Science and Technology, Japan) Hideyuki Otsuka (Kyushu University, Japan) Daewon Sohn (Hanyang University, Korea) Keiji Tanaka (Kyushu University, Japan)

High-speed electro-optic polymers: mm-Wave applications and silica planar lightwave circuit integration

NASA Astrophysics Data System (ADS)

Chang, Daniel H.

The development of high speed polymer electro-optic modulators has seen steady and significant progress in recent years, enabling novel applications in RF-Photonics. Two of these are described in this Thesis: an Opto-Electronic Oscillator (OEO), which is a hybrid RF and optical oscillator capable of high spectral purity, and Photonic Time-Stretch, which is a signal processing technique for waveform spectral shifting with application to photonically-assisted A/D conversion. In both cases, the operating frequencies achieved have been the highest demonstrated to date. Application of this promising material to more complicated devices, however, is stymied by insertion loss performance. Current loss figures, while acceptable for single modulators, are too high for large arrays of modulators or intrinsically long devices such as AWGs or photonic-RF phase shifters. This is especially frustrating in light of a key virtue which polymers possess as a photonic material: its photolithographic process-ability makes patterning complex devices possible. Indeed, the current ascendancy of silica-based waveguide devices can be attributed largely to the same reason. In this Thesis, we also demonstrate the first hybrid device composed of silica planar lightwave circuits (PLCs) and polymer planar waveguides. Our approach utilizes grayscale lithography to enable vertical coupling between polymer and silica layers, minimizing entanglement of their respective fabrication processes. We have achieved coupling excess loss figures on the order of 1dB. We believe this is the natural next step in the development of electro-optic polymer devices. The two technologies are highly complementary. Silica PLCs, with excellent propagation loss and fiber coupling, are ideally suited for long passive waveguiding. By endowing them with the high-speed phase shifting capability offered by polymers, active wideband photonic devices of increasing complexity and array size can be contemplated.

Compositions containing borane or carborane cage compounds and related applications

DOEpatents

Bowen, III, Daniel E; Eastwood, Eric A

2013-05-28

Compositions comprising a polymer-containing matrix and a filler comprising a cage compound selected from borane cage compounds, carborane cage compounds, metal complexes thereof, residues thereof, mixtures thereof, and/or agglomerations thereof, where the cage compound is not covalently bound to the matrix polymer. Methods of making and applications for using such compositions are also disclosed.

Novel octanuclear copper(I) metallomacrocycles and their transformation into hexanuclear 2-dimensional grids of copper(i) coordination polymers containing cyclodiphosphazanes, [(micro-NtBuP)2(NC4H8X)2] (X = NMe, O).

PubMed

Suresh, D; Balakrishna, Maravanji S; Mague, Joel T

2008-07-07

Novel octanuclear copper(I) macrocyclic complexes and hexanuclear 2-dimensional grid-like polymers containing [P(micro-NR)](2) scaffold in which the anionic moieties are trapped inside the cationic macrocyclic cavities are reported.

Recent Developments in Polymeric Charge Transfer Complexes

DTIC Science & Technology

1994-03-01

systems using dies on nematic phases of polymers involhing p- the Langmuir Blodgett procedure to obtain multi- chiloranil as the acceptor molecule [8...excluded. These applications are: compatibilization of polymer blends, liquid crystalline supramolecular organization, new develoments in...polymner blends, liquid crystalline supra- technological developments. Finally, I will cover in nmlecular organization, ne,’, developments in photo- some

Compositions containing borane or carborane cage compounds and related applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowen, III, Daniel E; Eastwood, Eric A

2014-11-11

Compositions comprising a polymer-containing matrix and a filler comprising a cage compound selected from borane cage compounds, carborane cage compounds, metal complexes thereof, residues thereof, mixtures thereof, and/or agglomerations thereof, where the cage compound is not covalently bound to the matrix polymer. Methods of making and applications for using such compositions are also disclosed.

Compositions containing borane or carborane cage compounds and related applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowen, III, Daniel E.; Eastwood, Eric A.

2015-09-15

Compositions comprising a polymer-containing matrix and a filler comprising a cage compound selected from borane cage compounds, carborane cage compounds, metal complexes thereof, residues thereof, mixtures thereof, and/or agglomerations thereof, where the cage compound is not covalently bound to the matrix polymer. Methods of making and applications for using such compositions are also disclosed.

77 FR 32965 - Certain New Chemicals; Receipt and Status Information

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-04

... importer P-12-0214 03/01/2012 05/01/2012 CBI Laundry and auto Carbohydrate polymers dish wash with acrylic... salt (1:2) initiate. P12-0215 03/01/2012 05/01/2012 CBI Laundry and auto Carbohydrate, polymers dish............ 04/25/2012 04/17/2012 (G) Barium, dialkyl 2-sulfobutanedioate phosphate complexes. P-09-0384...

Polymer-stabilized liquid crystalline topological defect network for micro-pixelated optical devices

NASA Astrophysics Data System (ADS)

Araoka, Fumito; Le, Khoa V.; Fujii, Shuji; Orihara, Hiroshi; Sasaki, Yuji

2018-02-01

Spatially and temporally controlled topological defects in nematic liquid crystals (NLCs) are promising for its potential in optical applications. Utilization of self-organization is a key to fabricate complex micro- and nano-structures which are often difficult to obtain by conventional lithographic tools. Using photo-polymerization technique, here we show a polymer-stabilized NLC having a micro-pixelated structure of regularly ordered umbilical defects which are induced by an electric field. Due to the formation of polymer network, the self-organized pattern is kept stable without deterioration. Moreover, the polymer network allows to template other LCs whose optical properties can be tuned with external stimuli such as temperature and electric fields.

Covalent Polymers Containing Discrete Heterocyclic Anion Receptors

PubMed Central

Rambo, Brett M.; Silver, Eric S.; Bielawski, Christopher W.; Sessler, Jonathan L.

2010-01-01

This chapter covers recent advances in the development of polymeric materials containing discrete heterocyclic anion receptors, and focuses on advances in anion binding and chemosensor chemistry. The development of polymers specific for anionic species is a relatively new and flourishing area of materials chemistry. The incorporation of heterocyclic receptors capable of complexing anions through non-covalent interactions (e.g., hydrogen bonding and electrostatic interactions) provides a route to not only sensitive but also selective polymer materials. Furthermore, these systems have been utilized in the development of polymers capable of extracting anionic species from aqueous environments. These latter materials may lead to advances in water purification and treatment of diseases resulting from surplus ions. PMID:20871791

Electrorotation of novel electroactive polymer composites in uniform DC and AC electric fields

NASA Astrophysics Data System (ADS)

Zrinyi, Miklós; Nakano, Masami; Tsujita, Teppei

2012-06-01

Novel electroactive polymer composites have been developed that could spin in uniform DC and AC electric fields. The angular displacement as well as rotation of polymer disks around an axis that is perpendicular to the direction of the applied electric field was studied. It was found that the dynamics of the polymer rotor is very complex. Depending on the strength of the static DC field, three regimes have been observed: no rotation occurs below a critical threshold field intensity, oscillatory motion takes place just above this value and continuous rotation can be observed above the critical threshold field intensity. It was also found that low frequency AC fields could also induce angular deformation.

Crystallization features of normal alkanes in confined geometry.

PubMed

Su, Yunlan; Liu, Guoming; Xie, Baoquan; Fu, Dongsheng; Wang, Dujin

2014-01-21

How polymers crystallize can greatly affect their thermal and mechanical properties, which influence the practical applications of these materials. Polymeric materials, such as block copolymers, graft polymers, and polymer blends, have complex molecular structures. Due to the multiple hierarchical structures and different size domains in polymer systems, confined hard environments for polymer crystallization exist widely in these materials. The confined geometry is closely related to both the phase metastability and lifetime of polymer. This affects the phase miscibility, microphase separation, and crystallization behaviors and determines both the performance of polymer materials and how easily these materials can be processed. Furthermore, the size effect of metastable states needs to be clarified in polymers. However, scientists find it difficult to propose a quantitative formula to describe the transition dynamics of metastable states in these complex systems. Normal alkanes [CnH2n+2, n-alkanes], especially linear saturated hydrocarbons, can provide a well-defined model system for studying the complex crystallization behaviors of polymer materials, surfactants, and lipids. Therefore, a deeper investigation of normal alkane phase behavior in confinement will help scientists to understand the crystalline phase transition and ultimate properties of many polymeric materials, especially polyolefins. In this Account, we provide an in-depth look at the research concerning the confined crystallization behavior of n-alkanes and binary mixtures in microcapsules by our laboratory and others. Since 2006, our group has developed a technique for synthesizing nearly monodispersed n-alkane containing microcapsules with controllable size and surface porous morphology. We applied an in situ polymerization method, using melamine-formaldehyde resin as shell material and nonionic surfactants as emulsifiers. The solid shell of microcapsules can provide a stable three-dimensional (3-D) confining environment. We have studied multiple parameters of these microencapsulated n-alkanes, including surface freezing, metastability of the rotator phase, and the phase separation behaviors of n-alkane mixtures using differential scanning calorimetry (DSC), temperature-dependent X-ray diffraction (XRD), and variable-temperature solid-state nuclear magnetic resonance (NMR). Our investigations revealed new direct evidence for the existence of surface freezing in microencapsulated n-alkanes. By examining the differences among chain packing and nucleation kinetics between bulk alkane solid solutions and their microencapsulated counterparts, we also discovered a mechanism responsible for the formation of a new metastable bulk phase. In addition, we found that confinement suppresses lamellar ordering and longitudinal diffusion, which play an important role in stabilizing the binary n-alkane solid solution in microcapsules. Our work also provided new insights into the phase separation of other mixed system, such as waxes, lipids, and polymer blends in confined geometry. These works provide a profound understanding of the relationship between molecular structure and material properties in the context of crystallization and therefore advance our ability to improve applications incorporating polymeric and molecular materials.

Porous-Hybrid Polymers as Platforms for Heterogeneous Photochemical Catalysis.

PubMed

Haikal, Rana R; Wang, Xia; Hassan, Youssef S; Parida, Manas R; Murali, Banavoth; Mohammed, Omar F; Pellechia, Perry J; Fontecave, Marc; Alkordi, Mohamed H

2016-08-10

A number of permanently porous polymers containing Ru(bpy)n photosensitizer or a cobaloxime complex, as a proton-reduction catalyst, were constructed via one-pot Sonogashira-Hagihara (SH) cross-coupling reactions. This process required minimal workup to access porous platforms with control over the apparent surface area, pore volume, and chemical functionality from suitable molecular building blocks (MBBs) containing the Ru or Co complexes, as rigid and multitopic nodes. The cobaloxime molecular building block, generated through in situ metalation, afforded a microporous solid that demonstrated noticeable catalytic activity toward hydrogen-evolution reaction (HER) with remarkable recyclability. We further demonstrated, in two cases, the ability to affect the excited-state lifetime of the covalently immobilized Ru(bpy)3 complex attained through deliberate utilization of the organic linkers of variable dimensions. Overall, this approach facilitates construction of tunable porous solids, with hybrid composition and pronounced chemical and physical stability, based on the well-known Ru(bpy)nor the cobaloxime complexes.

Four coordination polymers based on 5-tert-butyl isophthalic acid and rigid bis(imidazol-1yl)benzene linkers: Synthesis, luminescence detection of acetone and optical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arıcı, Mürsel, E-mail: marici@ogu.edu.tr; Zafer Yeşilel, Okan; Büyükgüngör, Orhan

Four coordination polymers including, [Co(µ-Htbip){sub 2}(µ-dib)]{sub n} (1), [Co(µ-tbip)(µ-dmib){sub 0.5}]{sub n} (2), [Zn{sub 2}(µ-tbip)(µ{sub 3}-tbip)(µ-dmib){sub 1.5}]{sub n} (3) and [Cd(µ{sub 3}-tbip)(µ-dib){sub 0.5} (H{sub 2}O)]{sub n} (4) (tbip: 5-tert-butylisophthalate, dib: 1,4-bis(imidazol-1yl)benzene, dmib: 1,4-bis(imidazol-1yl)-2,5-dimethylbenzene), were hydrothermally synthesized and characterized by elemental analysis, IR spectra, single crystal and powder X-ray diffraction and thermal analysis (TG/DTA). The structural diversity is observed depending on ligands and coordination number of metal centers in the synthesized complexes. The tbip ligand displayed five different coordination modes in its complexes. In 1 and 2, complex 1 is 3D framework with the dia topology while complex 2 has 2D structuremore » with the sql topology depending on coordination geometries of Co ions. Complex 3 is 3D framework with the fsh 4,6-conn topology and complex 4 has 2D 4-connected sql topology. Photoluminescent properties of complex 3 dispersed in various organic solvents were investigated and the results showed that 3 dispersed in methanol could be used as a fluorescent sensor for the detection of acetone. Moreover, thermal and optical properties of the complexes were also studied. - Graphical abstract: Four coordination polymers were hydrothermally synthesized and characterized by various techniques. The complexes showed the structural diversity depending on ligands and coordination number of metal centers. The tbip ligand displayed four different coordination modes in its complexes. In 1 and 2, complexes 1 and 2 are 3D and 2D structures with the dia and sql topologies depending on coordination geometries of Co ions, respectively. Complexes 3 and 4 are 3D and 2D structures with the fsh 4,6-conn and sql topology, respectively. Photoluminescent properties of complex 3 dispersed in various organic solvents were investigated and the results showed that 3 dispersed in methanol could be used as a fluorescent sensor for the detection of acetone. Moreover, thermal and optical properties of the complexes were also studied. - Highlights: • Four new 2D and 3D coordination polymers with 5-tert-butyl isophthalic acid and rigid bis(imidazol-1yl)benzene linkers. • The structural diversity depending on ligands and coordination number of metal centers. • Fluorescent sensor for the detection of acetone.« less