The Study of Interpenetration Length between dPS Films and PS-grafted Layers

NASA Astrophysics Data System (ADS)

Lee, Hoyeon; Jo, Seongjun; Hirata, Toyoaki; Yamada, Norifumi L.; Tanaka, Keiji; Ryu, Du Yeol

In polymer thin film system, the type of interfacial interaction is a critical parameter to determining the thermal and physical properties of polymer films. Interestingly, the interfacial energy of grafted substrates with polymer chains is remarkably altered by simply controlling grafting density, which has been referred to as autophobicity. In this study, we investigated the interpenetrating interfaces between deuterated polystyrene (dPS) and grafted substrates with the same chemical identity. PS-grafted substrates were prepared using a grafting-to approach with hydroxyl end-functionalized polystyrene (PSOH) in a dry brush regime, where the brush thickness and grafting density were determined based on the chain length (or molecular weight, Mn) of PSOHs. The interpenetration lengths (ξ) at interfaces between dPS and PS-grafted layers were characterized using neutron reflectivity (NR) measurements (performed at the SOFIA beam-line at J-PARC, Japan). Academic adviser.

Composite solid polymer electrolyte membranes

DOEpatents

Formato, Richard M.; Kovar, Robert F.; Osenar, Paul; Landrau, Nelson; Rubin, Leslie S.

2001-06-19

The present invention relates to composite solid polymer electrolyte membranes (SPEMs) which include a porous polymer substrate interpenetrated with an ion-conducting material. SPEMs of the present invention are useful in electrochemical applications, including fuel cells and electrodialysis.

Composite solid polymer electrolyte membranes

DOEpatents

Formato, Richard M.; Kovar, Robert F.; Osenar, Paul; Landrau, Nelson; Rubin, Leslie S.

2006-05-30

The present invention relates to composite solid polymer electrolyte membranes (SPEMs) which include a porous polymer substrate interpenetrated with an ion-conducting material. SPEMs of the present invention are useful in electrochemical applications, including fuel cells and electrodialysis.

Interpenetrating and non-interpenetrating 3-dimensional coordination polymer frameworks from multiple building blocks

NASA Astrophysics Data System (ADS)

Bradshaw, Darren; Rosseinsky, Matthew J.

2005-12-01

Reaction of Co(NO3)2ṡ6H2O with the multidentate ligands benzene-1,3,5-tricarboxylate (btc) and the flexible bipyridyl ligand 1,2-bis(4-pyridyl)ethane (bpe) affords the 3-dimensional coordination polymers [Co3(btc)2(bpe)3(eg)2]ṡ(guests) 1, where eg = ethylene glycol, and [Co2(Hbtc)2(bpe)2]ṡ(bpe) 2. Both phases are comprised of infinite metal-carboxylate dimer chains, linked into 2-dimensional sheets by the bpe ligands. These sheets are further linked to adjacent sheets through covalent interactions, 1, or through hydrogen-bonding interactions, 2, to yield the 3-dimensional structures. Phase 1 exhibits solvent filled 1-dimensional pores, whereas 2 is triply-interpenetrated to form a dense solid array.

Low Crossover Polymer Electrolyte Membranes for Direct Methanol Fuel Cells

NASA Technical Reports Server (NTRS)

Prakash, G. K. Surya; Smart, Marshall; Atti, Anthony R.; Olah, George A.; Narayanan, S. R.; Valdez, T.; Surampudi, S.

1996-01-01

Direct Methanol Fuel Cells (DMFC's) using polymer electrolyte membranes are promising power sources for portable and vehicular applications. State of the art technology using Nafion(R) 117 membranes (Dupont) are limited by high methanol permeability and cost, resulting in reduced fuel cell efficiencies and impractical commercialization. Therefore, much research in the fuel cell field is focused on the preparation and testing of low crossover and cost efficient polymer electrolyte membranes. The University of Southern California in cooperation with the Jet Propulsion Laboratory is focused on development of such materials. Interpenetrating polymer networks are an effective method used to blend polymer systems without forming chemical links. They provide the ability to modify physical and chemical properties of polymers by optimizing blend compositions. We have developed a novel interpenetrating polymer network based on poly (vinyl - difluoride)/cross-linked polystyrenesulfonic acid polymer composites (PVDF PSSA). Sulfonation of polystyrene accounts for protonic conductivity while the non-polar, PVDF backbone provides structural integrity in addition to methanol rejection. Precursor materials were prepared and analyzed to characterize membrane crystallinity, stability and degree of interpenetration. USC JPL PVDF-PSSA membranes were also characterized to determine methanol permeability, protonic conductivity and sulfur distribution. Membranes were fabricated into membrane electrode assemblies (MEA) and tested for single cell performance. Tests include cell performance over a wide range of temperatures (20 C - 90 C) and cathode conditions (ambient Air/O2). Methanol crossover values are measured in situ using an in-line CO2 analyzer.

Renewable cathode materials from biopolymer/conjugated polymer interpenetrating networks.

PubMed

Milczarek, Grzegorz; Inganäs, Olle

2012-03-23

Renewable and cheap materials in electrodes could meet the need for low-cost, intermittent electrical energy storage in a renewable energy system if sufficient charge density is obtained. Brown liquor, the waste product from paper processing, contains lignin derivatives. Polymer cathodes can be prepared by electrochemical oxidation of pyrrole to polypyrrole in solutions of lignin derivatives. The quinone group in lignin is used for electron and proton storage and exchange during redox cycling, thus combining charge storage in lignin and polypyrrole in an interpenetrating polypyrrole/lignin composite.

Self-supported fibrin-polyvinyl alcohol interpenetrating polymer networks: an easily handled and rehydratable biomaterial.

PubMed

Bidault, Laurent; Deneufchatel, Marie; Vancaeyzeele, Cédric; Fichet, Odile; Larreta-Garde, Véronique

2013-11-11

A fibrin hydrogel at physiological concentration (5 mg/mL) was associated with polyvinyl alcohol (PVA) inside an interpenetrating polymer networks (IPN) architecture. Previously, PVA has been modified with methacrylate functions in order to cross-link it by free-radical polymerization. The fibrin network was synthesized by the enzymatic hydrolysis of fibrinogen by thrombin. The resulting self-supported materials simultaneously exhibit the properties of the fibrin hydrogel and those of the synthetic polymer network. Their storage modulus is 50-fold higher than that of the fibrin hydrogel and they are completely rehydratable. These materials are noncytotoxic toward human fibroblast and the fibrin present on the surface of PVAm-based IPNs favors cell development.

Semi-2-interpenetrating polymer networks of high temperature systems

NASA Technical Reports Server (NTRS)

Hanky, A. O.; St. Clair, T. L.

1985-01-01

A semi-interpenetrating (semi-IPN) polymer system of the semi-2-IPN type is described in which a polymer of acetylene-terminated imidesulfone (ATPISO2) is cross linked in the presence of polyimidesulfone (PISO2). Six different formulations obtained by mixing of either ATPISO2-1n or ATPISO2-3n with PISO2 in three different proportions were characterized in terms of glass transition temperature, thermooxidative stability, inherent viscosity, and dynamic mechanical properties. Adhesive (lap shear) strength was tested at elevated temperatures on aged samples of adhesive scrim cloth prepared from each resin. Woven graphite (Celion 1000)/polyimide composites were tested for flexural strength, flexural modulus, and shear strength. The network polymers have properties intermediate between those of the component polymers alone, have greatly improved processability over either polyimide, and are able to form good adhesive bonds and composites, making the semi-2-IPN systems superior materials for aerospace structures.

Interpenetrating Polymer Networks as Innovative Drug Delivery Systems

PubMed Central

Lohani, Alka; Singh, Garima; Bhattacharya, Shiv Sankar; Verma, Anurag

2014-01-01

Polymers have always been valuable excipients in conventional dosage forms, also have shown excellent performance into the parenteral arena, and are now capable of offering advanced and sophisticated functions such as controlled drug release and drug targeting. Advances in polymer science have led to the development of several novel drug delivery systems. Interpenetrating polymer networks (IPNs) have shown superior performances over the conventional individual polymers and, consequently, the ranges of applications have grown rapidly for such class of materials. The advanced properties of IPNs like swelling capacity, stability, biocompatibility, nontoxicity and biodegradability have attracted considerable attention in pharmaceutical field especially in delivering bioactive molecules to the target site. In the past few years various research reports on the IPN based delivery systems showed that these carriers have emerged as a novel carrier in controlled drug delivery. The present review encompasses IPNs, their types, method of synthesis, factors which affects the morphology of IPNs, extensively studied IPN based drug delivery systems, and some natural polymers widely used for IPNs. PMID:24949205

Semi-Interpenetrating polymer network hydrogels based on aspen hemicellulose and chitosan: Effect of crosslinking sequence on hydrogel properties

Treesearch

Muzaffer Ahmet Karaaslan; Mandla A. Tshabalala; Gisela Buschle-Diller

2012-01-01

Semi-interpenetrating network hydrogel films were prepared using hemicellulose and chemically crosslinked chitosan. Hemicellulose was extracted from aspen by using a novel alkaline treatment and characterized by HPSEC, and consisted of a mixture of high and low molecular weight polymeric fractions. HPLC analysis of the acid hydrolysate of the hemicellulose showed that...

Fibrin-polyethylene oxide interpenetrating polymer networks: new self-supported biomaterials combining the properties of both protein gel and synthetic polymer.

PubMed

Akpalo, E; Bidault, L; Boissière, M; Vancaeyzeele, C; Fichet, O; Larreta-Garde, V

2011-06-01

Interpenetrating polymer network (IPN) architectures were conceived to improve the mechanical properties of a fibrin gel. Conditions allowing an enzymatic reaction to create one of the two networks in IPN architecture were included in the synthesis pathway. Two IPN series were carried out, starting from two polyethylene oxide (PEO) network precursors leading to different cross-linking densities of the PEO phase. The fibrin concentration varied from 5 to 20 wt.% in each series. The behavior of these materials during dehydration/hydration cycles was also studied. The mechanical properties of the resulting IPN were characterized in the wet and dry states. These self-supported biomaterials combine the properties of both a protein gel and a synthetic polymer. Finally, cells were grown on PEO/fibrin IPN, indicating that they are non-cytotoxic. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Tough, processable semi-interpenetrating polymer networks from monomer reactants

NASA Technical Reports Server (NTRS)

Pater, Ruth H. (Inventor)

1994-01-01

A high temperature semi-interpenetrating polymer network (semi-IPN) was developed which had significantly improved processability, damage tolerance, and mechanical performance, when compared to the commercial Thermid materials. This simultaneous semi-IPN was prepared by mixing the monomer precursors of Thermid AL-600 (a thermoset) and NR-150B2 (a thermoplastic) and allowing the monomers to react randomly upon heating. This reaction occurs at a rate which decreases the flow and broadens the processing window. Upon heating at a higher temperature, there is an increase in flow. Because of the improved flow properties, broadened processing window and enhanced toughness, high strength polymer matrix composites, adhesives and molded articles can now be prepared from the acetylene end-capped polyimides which were previously inherently brittle and difficult to process.

Synthesis and Characterization of Conducting Elastomers Based on Interpenetrated C60-Derived Polymer Networks

DTIC Science & Technology

1998-02-24

conducting polyaniline layer . A processing technique was demonstrated for the fabrication of interpenetrating conductive polyaniline networks at the...and sihibits appreciable conductivity in the incorporated, doped polyaniline layer without deteriorating the elasticity and tensile strength of the... Layer Lee Y. Wang and Long Y. Chiang* Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan i Abstract: A synthetic

Clonazepam release from bioerodible hydrogels based on semi-interpenetrating polymer networks composed of poly(epsilon-caprolactone) and poly(ethylene glycol) macromer.

PubMed

Cho, C S; Han, S Y; Ha, J H; Kim, S H; Lim, D Y

1999-04-30

Poly(ethylene glycol)(PEG) macromers terminated with acrylate groups and semi-interpenetrating polymer networks (SIPNs) composed of poly(epsilon-caprolactone)(PCL) and PEG macromer were synthesized to obtain a bioerodible hydrogel. Polymerization of PEG macromer resulted in the formation of cross-linked gels due to the multifunctionality of macromer. Glass transition temperature (Tg) and melting temperature (Tm) of PEG networks and PCL in the SIPNs were inner-shifted, indicating an interpenetration of PCL and PEG chains. Water content in the SIPNs increased with increasing PEG weight fraction due to the hydrophilicity of PEG. The amount of clonazepam (CNZ) released from the SIPNs increased with higher content in the SIPNs, lower drug loading, lower concentration of PEG macromer during the SIPNs preparation, and higher molecular weight of PEG. In particular, a combination with low PEG content and low CNZ solubility in water led to long-term constant release from these matrices in vitro and in vivo. Copyright.

Two-fold interpenetrating btc based cobaltous coordination polymer: A promising catalyst for solvent free oxidation of 1-hexene

NASA Astrophysics Data System (ADS)

Bora, Sanchay J.; Paul, Rima; Nandi, Mithun; Bhattacharyya, Pradip K.

2017-12-01

This work describes the synthesis of a new 2-D coordination polymer (CP), [Co3(btc)2(dmp)8]n (btc = 1,3,5-benzenetricarboxylate and dmp = 3,5-dimethylpyrazole) and its catalytic activity towards the oxidation reaction of 1-hexene to form oxygenated compounds under solvent free condition. Structural analysis reveals that Co(II) cations in this polymeric compound are linked by btc3- anions with alternate tetrahedral/octahedral coordination forming a two-fold interpenetrated 3-connected hcb underlying net. Electronic spectrum of the cobaltous polymer has been calculated using TDDFT/B3LYP method for making the appropriate assignments of electronic transitions. Catalytic results show good conversions of the starting material to oxygenated products with high selectivities for 1,2-epoxyhexane and 1-hexanal.

Conducting Polymeric Hydrogel Electrolyte Based on Carboxymethylcellulose and Polyacrylamide/Polyaniline for Supercapacitor Applications

NASA Astrophysics Data System (ADS)

Suganya, N.; Jaisankar, V.; Sivakumar, E. K. T.

Conducting polymer hydrogels represent a unique class of materials that possess enormous application in flexible electronic devices. In the present work, conducting carboxymethylcellulose (CMC)-co-polyacrylamide (PAAm)/polyaniline was synthesized by a two-step interpenetrating network solution polymerization technique. The synthesized CMC-co-PAAm/polyaniline with interpenetrating network structure was prepared by in situ polymerization of aniline to enhance conductivity. The molecular structure and morphology of the copolymer hydrogels were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The novel conducting polymer hydrogels show good electrical and electrochemical behavior, which makes them potentially useful in electronic devices such as supercapacitors, biosensors, bioelectronics, solar cells and memory devices.

Tough, processable simultaneous semi-interpenetrating polyimides

NASA Technical Reports Server (NTRS)

Pater, Ruth H. (Inventor)

1996-01-01

A high temperature semi-interpenetrating polymer network (semi-IPN) was developed which had significantly improved processability, damage tolerance and mechanical performance, when compared to the commercial Thermid.RTM. materials. This simultaneous semi-IPN was prepared by mixing a thermosetting polyimide with a thermoplastic monomer precursor solution (NR-15082) and allowing them to react upon heating. This reaction occurs at a rate which decreases the flow and broadens the processing window. Upon heating at a higher temperature, there is an increase in flow. Because of the improved flow properties, broadened processing window and enhanced toughness, high strength polymer matrix composites, adhesives and molded articles can now be prepared from the acetylene endcapped polyimides which were previously inherently brittle and difficult to process.

Microstructural Characterization of Semi-Interpenetrating Polymer Networks by Positron Lifetime Spectroscopy

NASA Technical Reports Server (NTRS)

Singh, Jag J.; Pater, Ruth H.; Eftekhari, Abe

1996-01-01

Thermoset and thermoplastic polyimides have complementary physical and mechanical properties. Whereas thermoset polyimides are brittle and generally easier to process, thermoplastic polyimides are tough but harder to process. A combination of these two types of polyimides may help produce polymers more suitable for aerospace applications. Semi-Interpenetrating Polymer Networks (S-IPN) of thermoset LaRC(TM)-RP46 and thermoplastic LaRC(TM)-IA polyimides were prepared in weight percent ratios ranging from 100:0 to 0:100. Positron lifetime measurements were made in these samples to correlate their free volume features with physical and mechanical properties. As expected, positronium atoms are not formed in these samples. The second lifetime component has been used to infer the positron trap dimensions. The 'free volume' goes through a minimum at a ratio of about 50:50, and this suggests that S-IPN samples are not merely solid solutions of the two polymers. These data and related structural properties of the S-IPN samples are discussed.

Robust solid polymer electrolyte for conducting IPN actuators

NASA Astrophysics Data System (ADS)

Festin, Nicolas; Maziz, Ali; Plesse, Cédric; Teyssié, Dominique; Chevrot, Claude; Vidal, Frédéric

2013-10-01

Interpenetrating polymer networks (IPNs) based on nitrile butadiene rubber (NBR) as first component and poly(ethylene oxide) (PEO) as second component were synthesized and used as a solid polymer electrolyte film in the design of a mechanically robust conducting IPN actuator. IPN mechanical properties and morphologies were mainly investigated by dynamic mechanical analysis and transmission electron microscopy. For 1-ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)-imide (EMITFSI) swollen IPNs, conductivity values are close to 1 × 10-3 S cm-1 at 25 ° C. Conducting IPN actuators have been synthesized by chemical polymerization of 3,4-ethylenedioxythiophene (EDOT) within the PEO/NBR IPN. A pseudo-trilayer configuration has been obtained with PEO/NBR IPN sandwiched between two interpenetrated PEDOT electrodes. The robust conducting IPN actuators showed a free strain of 2.4% and a blocking force of 30 mN for a low applied potential of ±2 V.

The Reverse Thermal Effect in Epoxy Resins and Moisture Absorption in Semi-Interpenetrating Polymer Networks.

NASA Astrophysics Data System (ADS)

El-Sa'Ad, Leila

1989-12-01

Available from UMI in association with The British Library. Requires signed TDF. Epoxy resins exhibit many desirable properties which make them ideal subjects for use as matrices of composite materials in many commercial, military and space applications. However, due to their high cross-link density they are often brittle. Epoxy resin networks have been modified by incorporating tough, ductile thermoplastics. Such systems are referred to as Semi-Interpenetrating Polymer Networks (Semi-IPN). Systematic modification to the thermoplastics backbone allowed the morphology of the blend to be controlled from a homogeneous one-phase structure to fully separated structures. The moisture absorption by composites in humid environments has been found to lead to a deterioration in the physical and mechanical properties of the matrix. Therefore, in order to utilize composites to their full potential, their response to hot/wet environments must be known. The aims of this investigation were two-fold. Firstly, to study the effect of varying the temperature of exposure at different stages in the absorption process on the water absorption behaviour of a TGDDM/DDS epoxy resin system. Secondly, to study water absorption characteristics, under isothermal conditions, of Semi-Interpenetrating Polymer Networks possessing different morphologies, and develop a theoretical model to evaluate the diffusion coefficients of the two-phase structures. The mathematical treatment used in this analysis was based on Fick's second law of diffusion. Tests were performed on specimens immersed in water at 10 ^circ, 40^circ and 70^circC, their absorption behaviour and swelling behaviour, as a consequence of water absorption, were investigated. The absorption results of the variable temperature absorption tests indicated a saturation dependence on the absorption behaviour. Specimens saturated at a high temperature will undergo further absorption when transferred to a lower temperature. This behaviour was termed the "reverse thermal effect". The swelling results suggested that it is more tightly bound water in the polymer which takes part in the reverse thermal effect. The absorption results for the Semi-Interpenetrating Polymer Networks suggested that the two key parameters which affected the moisture uptake were the morphology of the network and the percentage of epoxy resin in the system.

Process for controlling morphology and improving thermal-mechanical performance of high performance interpenetrating and semi-interpenetrating polymer networks

NASA Technical Reports Server (NTRS)

Pater, Ruth H. (Inventor); Hansen, Marion G. (Inventor)

1997-01-01

In the process of the present invention, a non-polar, aprotic solvent is removed from an oligomer/polymer solution by freeze-drying in order to produce IPNs and semi-IPNs. By thermally quenching the solution to a solid in a short length of time, the size of the minor constituent-rich regions is greatly reduced as they are excluded along with the major constituent from the regions of crystallizing solvent. The use of this process sequence of controlling phase morphology provides IPNs and semi-IPNs with improved fracture toughness, microcracking resistance, and other physical-mechanical properties as compared to IPNs and semi-IPNs formed when the solvent is evaporated rather than sublimed.

Tough, processable simultaneous semi-interpenetrating polyimides

NASA Technical Reports Server (NTRS)

Pater, Ruth H. (Inventor)

1994-01-01

A high temperature semi-interpenetrating polymer network (semi-IPN) was developed which had significantly improved processability, damage tolerance, and mechanical performance when compared to the commercial Thermid materials. This simultaneous semi-IPN was prepared by mixing a thermosetting polyimide with a thermoplastic monomer precursor solution (NR150B2) and allowing them to react upon heating. This reaction occurs at a rate which decreases the flow and broadens the processing window. Upon heating at a higher temperature, there is an increase in flow. Because of the improved flow properties, broadened processing window and enhanced toughness, high strength polymer matrix composites, adhesives and molded articles can now be prepared from the acetylene endcapped polyimides which were previously inherently brittle and difficult to process.

Processing and Dynamic Failure Characterization of Novel Impact Absorbing Transparent Interpenetrating Polymer Networks (t-IPN)

DTIC Science & Technology

2013-07-05

oven for the same curing treatment as before. The scanning electron microscope (SEM) photo in Figure 19 shows a typical sample with TMSPM and IPTES...Methacrylate-based Polymers,’ S. A . Bird , PhD Dissertation, Department of Polymer and Fiber Engineering, Auburn University, Summer 2013. ’Fracture Behavior...Polymer Networks with Polyurethane-poly(methyl methacrylate),’ K. C. Jajam, S. A . Bird , M. L. Auad, and H. V. Tippur, Polymer Testing, Vol. 32, pp

Polymers functionalized with bronsted acid groups

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

Van Humbeck, Jeffrey; Long, Jeffrey R.; McDonald, Thomas M.

Porous aromatic framework polymers functionalized with Bronsted acid moieties are prepared by polymerization of a three-dimensional organic aryl or heteroaryl monomer and its copolymerization with a second aryl or heteroaryl monomer functionalized with one or more Bronsted acid moiety. The polymers are characterized by a stable three-dimensional structure, which, in exemplary embodiments, includes interpenetrating subunits within one or more domain of the bulk polymer structure. The polymers are of use in methods of adsorbing ammonia and amines and in devices and systems configured for this purpose.

Nuclear Instruments and Methods in Physics Research. Section B; Microstructural Characterization of Semi-Interpenetrating Polymer Networks by Positron Lifetime Spectroscopy

NASA Technical Reports Server (NTRS)

Singh, Jag J.; Pater, Ruth H.; Eftekhari, Abe

1998-01-01

Thermoset and thermoplastic polyimides have complementary physical/mechanical properties. Whereas thermoset polyimides are brittle and generally easier to process, thermoplastic polyimides are tough but harder to process. It is expected that a combination of these two types of polyimides may help produce polymers more suitable for aerospace applications. Semi-Interpenetrating Polymer Networks (S-IPNs) of thermoset LaRC(Trademark)-RP46 and thermoplastic LARC(Trademark)-IA polyimides were prepared in weight percent ratios ranging from 100:0 to 0: 100. Positron lifetime measurements were made in these samples to correlate their free volume features with physical/mechanical properties. As expected, positronium atoms are not formed in these samples. The second life time component has been used to infer the positron trap dimensions. The "free volume" goes through a minimum at about 50:50 ratio, suggesting that S-IPN samples are not merely solid solutions of the two polymers. These data and related structural properties of the S-IPN samples have been discussed in this paper.

Simulation on the Performance of a Driven Fan Made by Polyester/Epoxy interpenetrate polymer network (IPN)

NASA Astrophysics Data System (ADS)

Fahrul Hassan, Mohd; Jamri, Azmil; Nawawi, Azli; Zaini Yunos, Muhamad; Fauzi Ahmad, Md; Adzila, Sharifah; Nasrull Abdol Rahman, Mohd

2017-08-01

The main purpose of this study is to investigate the performance of a driven fan design made by Polyester/Epoxy interpenetrate polymer network (IPN) material that specifically used for turbocharger compressor. Polyester/Epoxy IPN is polymer plastics that was used as replacements for traditional polymers and has been widely used in a variety of applications because of their limitless conformations. Simulation based on several parameters which are air pressure, air velocity and air temperature have been carried out for a driven fan design performance of two different materials, aluminum alloy (existing driven fan design) and Polyester/Epoxy IPN using SolidWorks Flow Simulation software. Results from both simulations were analyzed and compared where both materials show similar performance in terms of air pressure and air velocity due to similar geometric and dimension, but Polyester/Epoxy IPN produces lower air temperature than aluminum alloy. This study shows a preliminary result of the potential Polyester/Epoxy IPN to be used as a driven fan design material. In the future, further studies will be conducted on detail simulation and experimental analysis.

Microstructural Characterization of Polymers with Positrons

NASA Technical Reports Server (NTRS)

Singh, Jag J.

1997-01-01

Positrons provide a versatile probe for monitoring microstructural features of molecular solids. In this paper, we report on positron lifetime measurements in two different types of polymers. The first group comprises polyacrylates processed on earth and in space. The second group includes fully-compatible and totally-incompatible Semi-Interpenetrating polymer networks of thermosetting and thermoplastic polyimides. On the basis of lifetime measurements, it is concluded that free volumes are a direct reflection of physical/electromagnetic properties of the host polymers.

Controlled release of therapeutics using interpenetrating polymeric networks.

PubMed

Aminabhavi, Tejraj M; Nadagouda, Mallikarjuna N; More, Uttam A; Joshi, Shrinivas D; Kulkarni, Venkatrao H; Noolvi, Malleshappa N; Kulkarni, Padmakar V

2015-04-01

The ever-increasing developments in pharmaceutical formulations have led to the widespread use of biodegradable polymers in various forms and configurations. In particular, interpenetrating network (IPN) and semi-IPN polymer structures that are capable of releasing drugs in a controlled manner have gained much wider importance in recent years. Recently, IPNs and semi-IPNs have emerged as innovative materials of choice in controlled release (CR) of drugs as the release from these systems depends on pH of the media and temperature in addition to the nature of the system. These networks can be prepared as smart hydrogels following chemical or physical crosslinking methods to show remarkable drug release patterns compared to single polymer systems. A large number of IPNs and semi-IPNs have been reported in the literature. The present review is focused on the preparation methods and their CR properties with reference to anticancer, anti-asthmatic, antibiotic, anti-inflammatory, anti-tuberculosis and antihypertensive drugs, as majority of these drugs have been reported to be the ideal choices for using IPNs and semi-IPNs.

Microstructural Characterization of Polymers by Positron Lifetime Spectroscopy

NASA Technical Reports Server (NTRS)

Singh, Jag J.

1996-01-01

Positrons provide a versatile probe for monitoring microstructural features of molecular solids. In this paper, we report on positron lifetime measurements in two different types of polymers. The first group comprises polyacrylates processed on earth and in space. The second group includes fully-compatible and totally-incompatible Semi-Interpenetrating polymer networks of thermosetting and thermoplastic polyimides. On the basis of lifetime measurements, it is concluded that free volumes are a direct reflection of physical/electromagnetic properties of the host polymers.

Interpenetrating polymer networks from acetylene terminated materials

NASA Technical Reports Server (NTRS)

Connell, J. W.; Hergenrother, P. M.

1989-01-01

As part of a program to develop high temperature/high performance structural resins for aerospace applications, the chemistry and properties of a novel class of interpenetrating polymer networks (IPNs) were investigated. These IPNs consist of a simple diacetylenic compound (aspartimide) blended with an acetylene terminated arylene ether oligomer. Various compositional blends were prepared and thermally cured to evaluate the effect of crosslink density on resin properties. The cured IPNs exhibited glass transition temperatures ranging from 197 to 254 C depending upon the composition and cure temperature. The solvent resistance, fracture toughness and coefficient of thermal expansion of the cured blends were related to the crosslink density. Isothermal aging of neat resin moldings, adhesive and composite specimens showed a postcure effect which resulted in improved elevated temperature properties. The chemistry, physical and mechanical properties of these materials will be discussed.

Polyethylene oxide-polytetrahydrofurane-PEDOT conducting interpenetrating polymer networks for high speed actuators

NASA Astrophysics Data System (ADS)

Plesse, C.; Khaldi, A.; Wang, Q.; Cattan, E.; Teyssié, D.; Chevrot, C.; Vidal, F.

2011-12-01

In recent years, numerous studies on electro-active polymer (EAP) actuators have been reported. One promising technology is the elaboration of electronic conducting polymer-based actuators with interpenetrating polymer network (IPNs) architecture. In this study, the synthesis and characterisation of conducting IPNs for actuator applications is described. The IPNs are synthesised from polyethylene oxide (PEO) and polytetrahydrofurane (PTHF) networks in which the conducting polymer (poly(3,4-ethylenedioxythiophene)) is incorporated. In a first step, PEO/PTHF IPNs were prepared via an 'in situ' process using poly(ethylene glycol) methacrylate and dimethacrylate and hydroxytelechelic PTHF as starting materials. The IPN mechanical properties were examined by DMA and tensile strength tests. N-ethylmethylimidazolium bis(trifluoromethanesulfonyl)imide (EMITFSI) swollen PEO/PTHF IPNs show ionic conductivities up to 10-3 S cm-1 at 30 °C. In a second step, the conducting IPN actuators were prepared by oxidative polymerisation of 3,4-ethylenedioxithiophene (EDOT) using FeCl3 as an oxidising agent within the PEO/PTHF IPN host matrix. The frequency response performance of the bending conducting IPN actuator was then evaluated. The resulting actuator exhibits a mechanical resonance frequency of up to 125 Hz with 0.75% strain for an applied potential of ± 5 V.

Ion pair reinforced semi-interpenetrating polymer network for direct methanol fuel cell applications.

PubMed

Fang, Chunliu; Julius, David; Tay, Siok Wei; Hong, Liang; Lee, Jim Yang

2012-06-07

This paper describes the synthesis of ion-pair-reinforced semi-interpenetrating polymer networks (SIPNs) as proton exchange membranes (PEMs) for the direct methanol fuel cells (DMFCs). Specifically, sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO), a linear polymer proton source, was immobilized in a brominated PPO (BPPO) network covalently cross-linked by ethylenediamine (EDA). The immobilization of SPPO in the SIPN network was accomplished not only by the usual means of mechanical interlocking but also by ion pair formation between the sulfonic acid groups of SPPO and the amine moieties formed during the cross-linking reaction of BPPO with EDA. Through the ion pair interactions, the immobilization of SPPO polymer in the BPPO network was made more effective, resulting in a greater uniformity of sulfonic acid cluster distribution in the membrane. The hydrophilic amine-containing cross-links also compensated for some of the decrease in proton conductivity caused by ion pair formation. The SIPN membranes prepared as such showed good proton conductivity, low methanol permeability, good mechanical properties, and dimensional stability. Consequently, the PPO based SIPN membranes were able to deliver a higher maximum power density than Nafion, demonstrating the potential of the SIPN structure for PEM designs.

Structural optimization of interpenetrated pillared-layer coordination polymers for ethylene/ethane separation.

PubMed

Kishida, Keisuke; Horike, Satoshi; Watanabe, Yoshihiro; Tahara, Mina; Inubushi, Yasutaka; Kitagawa, Susumu

2014-06-01

With the goal of achieving effective ethylene/ethane separation, we evaluated the gas sorption properties of four pillared-layer-type porous coordination polymers with double interpenetration, [Zn2(tp)2(bpy)]n (1), [Zn2(fm)2(bpe)]n (2), [Zn2(fm)2(bpa)]n (3), and [Zn2(fm)2(bpy)]n (4) (tp = terephthalate, bpy = 4,4'-bipyridyl, fm = fumarate, bpe = 1,2-di(4-pyridyl)ethylene and bpa = 1,2-di(4-pyridyl)ethane). It was found that 4, which contains the narrowest pores of all of these compounds, exhibited ethylene-selective sorption profiles. The ethylene selectivity of 4 was estimated to be 4.6 at 298 K based on breakthrough experiments using ethylene/ethane gas mixtures. In addition, 4 exhibited a good regeneration ability compared with a conventional porous material. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Plastic deformation mechanisms in polyimide resins and their semi-interpenetrating networks

NASA Technical Reports Server (NTRS)

Jang, Bor Z.

1990-01-01

High-performance thermoset resins and composites are critical to the future growth of space, aircraft, and defense industries in the USA. However, the processing-structure-property relationships in these materials remain poorly understood. In the present ASEE/NASA Summer Research Program, the plastic deformation modes and toughening mechanisms in single-phase and multiphase thermoset resins were investigated. Both thermoplastic and thermoset polyimide resins and their interpenetrating networks (IPNs and semi-IPNs) were included. The fundamental tendency to undergo strain localization (crazing and shear banding) as opposed to a more diffuse (or homogeneous) deformation in these polymers were evaluated. Other possible toughening mechanisms in multiphase thermoset resins were also examined. The topological features of network chain configuration/conformation and the multiplicity of phase morphology in INPs and semi-IPNs provide unprecedented opportunities for studying the toughening mechanisms in multiphase thermoset polymers and their fiber composites.

Improving processing and toughness of a high performance composite matrix through an interpenetrating polymer network. VI

NASA Technical Reports Server (NTRS)

Pater, Ruth H.

1990-01-01

A simultaneous semi-interpenetrating polymer network (semi-IPN) concept is presented which combines easy-to-process, but brittle, thermosetting polyimides with tough, but difficult to process, linear thermoplastic polyimides. The combination results in a semi-IPN with the easy processability of a thermoset and good toughness of a thermoplastic. Four simultaneous semi-IPN systems were developed from commercially available NR-150B2 combined with each of the four Thermid materials (LR-600, AL-600, MC-600, and FA-700). It is concluded that there is a significant improvement in resin fracture toughness of Thermid-polyimide-based semi-IPN systems and some improvement in composite microcracking resistance compared to Thermid LR-600. Excellent composite mechanical properties have been achieved. These new semi-IPN materials have the potential to be used as composite matrices, adhesives, and molding materials.

Effect of tethering on the surface dynamics of a thin polymer melt layer

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

Uğur, Gökçe; Akgun, Bulent; Jiang, Zhang

The surface height fluctuations of a layer of low molecular weight (2.2k) untethered perdeuterated polystyrene (dPS) chains adjacent to a densely grafted polystyrene brush are slowed dramatically. Due to the interpenetration of the brush with the layer of “untethered chains” a hydrodynamic continuum theory can only describe the fluctuations when the effective thickness of the film is taken to be that which remains above the swollen brush. Furthermore, the portion of the film of initially untethered chains that interpenetrates with the brush becomes so viscous as to effectively play the role of a rigid substrate. They provide a route formore » tailoring polymer layer surface properties such as wetting, adhesion and friction, since these hybrid samples contain a covalently tethered layer at the bottom, does not readily dewet, and are more robust than thin layers of untethered short chains on rigid substrates.« less

Fortified interpenetrating polymers – bacteria resistant coatings for medical devices† †Electronic supplementary information (ESI) available: Supporting figures and tables, and additional experimental procedures. See DOI: 10.1039/c6tb01110a Click here for additional data file.

PubMed Central

Venkateswaran, Seshasailam; Henrique Dos Santos, Orlando David; Scholefield, Emma; Lilienkampf, Annamaria; Gwynne, Peter J.; Swann, David G.; Dhaliwal, Kevin

2016-01-01

Infections arising from contaminated medical devices are a serious global issue, contributing to antibiotic resistance and imposing significant strain on healthcare systems. Since the majority of medical device-associated infections are biofilm related, efforts are being made to generate either bacteria-repellent or antibacterial coatings aimed at preventing bacterial colonisation. Here, we utilise a nanocapsule mediated slow release of a natural antimicrobial to improve the performance of a bacteria repellent polymer coating. Poly(lauryl acrylate) nanocapsules containing eugenol (4-allyl-2-methoxyphenol) were prepared and entrapped within a interpenetrating network designed to repel bacteria. When coated on a catheter and an endotracheal tube, this hemocompatible system allowed slow-release of eugenol, resulting in notable reduction in surface-bound Klebsiella pneumoniae and methicillin resistant Staphylococcus aureus. PMID:27746915

Effect of tethering on the surface dynamics of a thin polymer melt layer

DOE PAGES

Uğur, Gökçe; Akgun, Bulent; Jiang, Zhang; ...

2016-05-13

The surface height fluctuations of a layer of low molecular weight (2.2k) untethered perdeuterated polystyrene (dPS) chains adjacent to a densely grafted polystyrene brush are slowed dramatically. Due to the interpenetration of the brush with the layer of “untethered chains” a hydrodynamic continuum theory can only describe the fluctuations when the effective thickness of the film is taken to be that which remains above the swollen brush. Furthermore, the portion of the film of initially untethered chains that interpenetrates with the brush becomes so viscous as to effectively play the role of a rigid substrate. They provide a route formore » tailoring polymer layer surface properties such as wetting, adhesion and friction, since these hybrid samples contain a covalently tethered layer at the bottom, does not readily dewet, and are more robust than thin layers of untethered short chains on rigid substrates.« less

Exploring 3D non-interpenetrated metal-organic framework with malonate-bridged Co(II) coordination polymer: structural elucidation and theoretical study

NASA Astrophysics Data System (ADS)

Hossain, Anowar; Mandal, Tripti; Mitra, Monojit; Manna, Prankrishna; Bauzá, Antonio; Frontera, Antonio; Seth, Saikat Kumar; Mukhopadhyay, Subrata

2017-12-01

A Co(II)-based coordination polymer with tetranuclear cobalt(II)-malonate cluster has been easily generated by aqueous medium self-assembly from Cobalt(II) chloride hexahydrate and malonic acid. The structure exhibits a non-interpenetrating, highly undulating two-dimensional (2D) bi-layer network with (4,4) topology. The crystal structure is composed of infinite interdigitated 2D metal-organic bi-layers which extended to an intricate 3D framework through the interbilayer hydrogen bonds. We have studied energetically by means of Density Functional Theory (DFT) calculations the H-bonding interactions that connect the 2D metal-organic bi-layers. The finite theoretical models have been used to compute conventional O‒H•••O and unconventional C‒H•••O interactions which plays a key role to build 3D architecture.

Polyurethane/polymeric N-halamine antimicrobial and biofilm controlling semi-interpenetrating polymer network

NASA Astrophysics Data System (ADS)

Xiu, Kemao

Bacterial infection and biofilm formation cause serious medical, industrial, and environmental problems. In biomedical applications, bacterial contamination of medical devices often leads to infectious diseases accompanied with pain, suffer, and even death. Polyurethane (PU) is widely in biomedical applications due to its good mechanical properties and biocompatibility. However, its vulnerability to bacterial biofilm formation seriously limits its wider uses. Prior studies have shown that N-halamines could be incorporated into PU to achieve antimicrobial and biofilm-controlling effects through grafting, blending, and/or coating. To broaden the selection of modification methods in the development antimicrobial PU, this study synthesized polyurethane/polymeric N-halamine semi-interpenetrating polymer networks (semi-IPN). Polymerizable monomeric N-halamines were swollen into PU with initiators and crosslink agents. Post polymerization of the monomers led to the formation of semi-IPN with linear PU and N-halamine polymer networks. The semi-IPNs showed excellent antimicrobial and biofilm controlling ability towards both gram-positive and gram-negative bacteria. The effects of hydrophilicity, surface grafted N-halamine and structural characteristics of N-halamine on the antimicrobial behavior of the resulting semi-IPNs were also investigated.

Polymer Infiltration Studies

NASA Technical Reports Server (NTRS)

Marchello, Joseph M.

1991-01-01

Progress was made on the preparation of carbon fiber composites using advanced polymer resins. Processes reported include powder towpreg process, weaving towpreg made from dry powder prepreg, composite from powder coated towpreg, and toughening of polyimide resin (PMR) composites by semi-interpenetrating networks. Several important areas of polymer infiltration into fiber bundles will be researched. Preparation to towpreg for textile preform weaving and braiding and for automated tow placement is a major goal, as are the continued development of prepregging technology and the various aspects of composite part fabrication.

Freeze drying for morphological control of inter-penetrating polymer networks

NASA Technical Reports Server (NTRS)

Hansen, Marion G.; Pater, Ruth H.

1990-01-01

The intrinsic brittleness of BMI resins can be reduced through the creation of an interpenetrating network (IPN) of BMI with a reactive-encapped thermoplastic, such as the presently considered polyimidesulfone, PISO2. The PISO2 and BMI were dissolved in a common solvent, which was then removed from the constituents by freeze drying; in an alternative method, an IPN was formed through dissolution of the constituent in a common solvent with either high or low melting point, followed by evaporative removal of the solvent. The effectiveness of the freeze-drying approach for morphological control is evaluated.

Double interpenetration in a chiral three-dimensional magnet with a (10,3)-a structure.

PubMed

Grancha, Thais; Mon, Marta; Lloret, Francesc; Ferrando-Soria, Jesús; Journaux, Yves; Pasán, Jorge; Pardo, Emilio

2015-09-21

A unique chiral three-dimensional magnet with an overall racemic double-interpenetrated (10,3)-a structure of the formula [(S)-(1-PhEt)Me3N]4[Mn4Cu6(Et2pma)12](DMSO)3]·3DMSO·5H2O (1; Et2pma = N-2,6-diethylphenyloxamate) has been synthesized by the self-assembly of a mononuclear copper(II) complex acting as a metalloligand toward Mn(II) ions in the presence of a chiral cationic auxiliary, constituting the first oxamato-based chiral coordination polymer exhibiting long-range magnetic ordering.

Vapor-phase deposition of regioregular and oriented poly(3-hexylthiophene) structures and novel nanostructured composites of interpenetrating poly(3-hexylthiophene) and polyaniline exhibiting full-color wavelength (400-1000 nm) photoluminescence

NASA Astrophysics Data System (ADS)

Biswas, A.; Bayer, I. S.; Karulkar, P. C.; Tripathi, A.; Avasthi, D. K.

2007-10-01

A promising solvent-free technique of electron-beam-assisted vapor-phase codeposition method is presented which allows uniform blending of different conjugated and nonconjugated polymers at the nanoscale. The technique allows direct incorporation of regioregular poly(3-hexylthiophene) (P3HT) polymer with different structural orientations into conventional and semiconducting polymers without fractionation or degradation of P3HT while maintaining the nanoscale morphology of deposited organic films. The results of fabricated novel nanostructured organic composites (˜100-200nm) comprising regioregular and oriented P3HT and different conjugated and nonconjugated polymers including selective assembly of P3HT nanonodules into a copolymer template are presented. We show a typical example of blending of P3HT and polyaniline (PANI) that formed a unique nanoscale morphology comprising interpenetrating networks of different shapes and sizes of nanospherulites (˜100nm) of P3HT in PANI. The so fabricated nanocomposites (˜200nm) exhibited remarkable broadband photoluminescence features covering the entire blue, green, and red wavelength regions between 400 and 1000nm. Such organic nanocomposites might be useful for flexible full-color screen flat panel displays and organic white-light solid-state lighting applications.

Evaluating Multiple Imputation Models for the Southern Annual Forest Inventory

Treesearch

Gregory A. Reams; Joseph M. McCollum

1999-01-01

The USDA Forest Service's Southern Research Station is implementing an annualized forest survey in thirteen states. The sample design is a systematic sample of five interpenetrating grids (panels), where each panel is measured sequentially. For example, panel one information is collected in year one, and panel five in year five. The area representative and time...

Toughening of PMR composites by semi-interpenetrating networks

NASA Technical Reports Server (NTRS)

Tiwari, S. N.; Srinivansan, K.

1991-01-01

Polymerization of monomer reactants (PMR-15) type polyimide and RP46 prepregs were drum wound using IM-7 fibers. Prepregging and processing conditions were optimized to yield good quality laminates with fiber volume fractions of 60 percent (+/- 2 percent). Samples were fabricated and tested to determine comprehensive engineering properties of both systems. These included 0 deg flexure, short beam shear, transverse flexure and tension, 0 deg tension and compression, intralaminar shear, short block compression, mode 1 and 2 fracture toughness, and compression after impact properties. Semi-2-IPN (interpenetrating polymer networks) toughened PMR-15 and RP46 laminates were also fabricated and tested for the same properties.

Multifunctional semi-interpenetrating polymer network-nanoencapsulated cathode materials for high-performance lithium-ion batteries.

PubMed

Kim, Ju-Myung; Park, Jang-Hoon; Lee, Chang Kee; Lee, Sang-Young

2014-04-08

As a promising power source to boost up advent of next-generation ubiquitous era, high-energy density lithium-ion batteries with reliable electrochemical properties are urgently requested. Development of the advanced lithium ion-batteries, however, is staggering with thorny problems of performance deterioration and safety failures. This formidable challenge is highly concerned with electrochemical/thermal instability at electrode material-liquid electrolyte interface, in addition to structural/chemical deficiency of major cell components. Herein, as a new concept of surface engineering to address the abovementioned interfacial issue, multifunctional conformal nanoencapsulating layer based on semi-interpenetrating polymer network (semi-IPN) is presented. This unusual semi-IPN nanoencapsulating layer is composed of thermally-cured polyimide (PI) and polyvinyl pyrrolidone (PVP) bearing Lewis basic site. Owing to the combined effects of morphological uniqueness and chemical functionality (scavenging hydrofluoric acid that poses as a critical threat to trigger unwanted side reactions), the PI/PVP semi-IPN nanoencapsulated-cathode materials enable significant improvement in electrochemical performance and thermal stability of lithium-ion batteries.

Multifunctional semi-interpenetrating polymer network-nanoencapsulated cathode materials for high-performance lithium-ion batteries

NASA Astrophysics Data System (ADS)

Kim, Ju-Myung; Park, Jang-Hoon; Lee, Chang Kee; Lee, Sang-Young

2014-04-01

As a promising power source to boost up advent of next-generation ubiquitous era, high-energy density lithium-ion batteries with reliable electrochemical properties are urgently requested. Development of the advanced lithium ion-batteries, however, is staggering with thorny problems of performance deterioration and safety failures. This formidable challenge is highly concerned with electrochemical/thermal instability at electrode material-liquid electrolyte interface, in addition to structural/chemical deficiency of major cell components. Herein, as a new concept of surface engineering to address the abovementioned interfacial issue, multifunctional conformal nanoencapsulating layer based on semi-interpenetrating polymer network (semi-IPN) is presented. This unusual semi-IPN nanoencapsulating layer is composed of thermally-cured polyimide (PI) and polyvinyl pyrrolidone (PVP) bearing Lewis basic site. Owing to the combined effects of morphological uniqueness and chemical functionality (scavenging hydrofluoric acid that poses as a critical threat to trigger unwanted side reactions), the PI/PVP semi-IPN nanoencapsulated-cathode materials enable significant improvement in electrochemical performance and thermal stability of lithium-ion batteries.

Multifunctional semi-interpenetrating polymer network-nanoencapsulated cathode materials for high-performance lithium-ion batteries

PubMed Central

Kim, Ju-Myung; Park, Jang-Hoon; Lee, Chang Kee; Lee, Sang-Young

2014-01-01

As a promising power source to boost up advent of next-generation ubiquitous era, high-energy density lithium-ion batteries with reliable electrochemical properties are urgently requested. Development of the advanced lithium ion-batteries, however, is staggering with thorny problems of performance deterioration and safety failures. This formidable challenge is highly concerned with electrochemical/thermal instability at electrode material-liquid electrolyte interface, in addition to structural/chemical deficiency of major cell components. Herein, as a new concept of surface engineering to address the abovementioned interfacial issue, multifunctional conformal nanoencapsulating layer based on semi-interpenetrating polymer network (semi-IPN) is presented. This unusual semi-IPN nanoencapsulating layer is composed of thermally-cured polyimide (PI) and polyvinyl pyrrolidone (PVP) bearing Lewis basic site. Owing to the combined effects of morphological uniqueness and chemical functionality (scavenging hydrofluoric acid that poses as a critical threat to trigger unwanted side reactions), the PI/PVP semi-IPN nanoencapsulated-cathode materials enable significant improvement in electrochemical performance and thermal stability of lithium-ion batteries. PMID:24710575

In vitro and in vivo evaluation of novel interpenetrated polymer network microparticles containing repaglinide.

PubMed

Kulkarni, Raghavendra V; Patel, Foram S; Nanjappaiah, H M; Naikawadi, Akram A

2014-08-01

Interpenetrated polymer network (IPN) microparticles of sterculia gum and sodium alginate loaded with repaglinide were developed by ionic gelation and emulsion crosslinking method. The drug entrapment efficiency was as high as 91%. FTIR and TG analyses confirmed the crosslinking and IPN formation. Microparticles have demonstrated the drug release up to 24h depending upon type of crosslinking agents; the glutaraldehyde treatment of ionically crosslinked microparticles has resulted in decreased drug release rate. The in-vivo anti-diabetic activity performed on streptozotocin induced diabetic rats indicated that the pristine repaglinide has shown maximum percentage reduction of elevated blood glucose within 3h and then the percentage reduction in blood glucose was decreased. In the case of rats treated with KA8 IPN microparticles, percentage reduction of elevated glucose was slow as compared to pristine drug within 3h, but it was gradually increased to 81.27% up to 24h. Copyright © 2014 Elsevier B.V. All rights reserved.

Semi-interpenetrating polymer network proton exchange membranes with narrow and well-connected hydrophilic channels

NASA Astrophysics Data System (ADS)

Fang, Chunliu; Toh, Xin Ni; Yao, Qiaofeng; Julius, David; Hong, Liang; Lee, Jim Yang

2013-03-01

Four series of semi-interpenetrating polymer network (SIPN) membranes are fabricated by thermally cross-linking aminated BPPO (brominated poly(2,6-dimethyl-1,4-phenylene oxide)) with different epoxide cross-linkers in the presence of sulfonated PPO (SPPO). The cross-link structure and hydrophobicity are found to impact the membrane morphology strongly - smaller and more hydrophobic cross-links form narrow and well-connected hydrophilic channels whereas bulky and less hydrophobic cross-links form wide but less-connected hydrophilic channels. The membranes of the former can support facile proton transport and suppress methanol crossover to result in higher proton conductivity and lower methanol permeability than the membranes of the latter. The membranes are also fabricated into membrane electrode assemblies (MEAs) and tested in single-stack direct methanol fuel cells (DMFCs). It is found that some of these SIPN membranes can surpass Nafion® 117 in maximum power density, demonstrating their potential as a proton exchange membrane (PEM) for the DMFCs.

A Preliminary Investigation of the E-Beam Induced Polymerization of Maleimide and Norbornene End-capped Polyimides

NASA Technical Reports Server (NTRS)

Palmese, Giuseppe R.; Meador, Michael A. (Technical Monitor)

2005-01-01

A research area of high activity in connection with aerospace engineering has been the development of polymer thermosetting resins that can resist temperature as high as 300 C while maintaining adequate toughness, and providing ease of processing to enable low temperature and low cost composite fabrication methods. In order to meet such requirements, sequential interpenetrating polymer networks (IPNs) based on bismaleimide (BMI) and cyanate ester (CE) monomers were investigated. In these systems, a polycyanurate network is first formed in the presence of BMI and appropriate reactive diluent monomers and in a second step, a network based on the BMI is created in the presence of a fully formed polycyanurate network. The materials developed can be processed at relatively low temperature (less than 150 C) and with the aid of electron beam (EB) curing. Of major importance to the success of this work was the identification of a reactive diluent that improves ease of processing and has tailored reactivity to allow for the controlled synthesis of CE-BMI sequential IPNs. Based on solubility and reactivity of a number of reactive diluents, N-acryloylmorpholine (AMP) was selected as a comonomer for BMI copolymerization. A donor-acceptoreaction mechanism was suggested to explain the relative reactivity of a variety of reactive diluents towards maleimide functionality. The optimum processing parameters for the formation of the first network were determined through the study of metal catalyzed cure and hydrolysis of cyanate esters, whereas the reaction behavior for second network formation in terms of the influence of EB dose rate and temperature was elucidated through an in-situ kinetics study of maleimide and AMP copolymerization. Structure-property relationships were developed which allowed for the design of improved resin systems. In particular, appropriate network coupler possessing cyanate ester and maleimide functionality was synthesized to link the polycyanurate first network to the BMI/AMP second network and thus form linked sequential IPNs (LIPNs). Consequently, Tg as high as 370 C was achieved and a fracture toughness of 120 Joules per square meters was obtained for resin systems that possess adequately low viscosity for processing using liquid molding techniques at low temperature.

1D helix, 2D brick-wall and herringbone, and 3D interpenetration d10 metal-organic framework structures assembled from pyridine-2,6-dicarboxylic acid N-oxide.

PubMed

Wen, Li-Li; Dang, Dong-Bin; Duan, Chun-Ying; Li, Yi-Zhi; Tian, Zheng-Fang; Meng, Qing-Jin

2005-10-03

Five novel interesting d(10) metal coordination polymers, [Zn(PDCO)(H2O)2]n (PDCO = pyridine-2,6-dicarboxylic acid N-oxide) (1), [Zn2(PDCO)2(4,4'-bpy)2(H2O)2.3H2O]n (bpy = bipyridine) (2), [Zn(PDCO)(bix)]n (bix = 1,4-bis(imidazol-1-ylmethyl)benzene) (3), [Zn(PDCO)(bbi).0.5H2O]n (bbi = 1,1'-(1,4-butanediyl)bis(imidazole)) (4), and [Cd(PDCO)(bix)(1.5).1.5H2O]n (5), have been synthesized under hydrothermal conditions and structurally characterized. Polymer 1 possesses a one-dimensional (1D) helical chainlike structure with 4(1) helices running along the c-axis with a pitch of 10.090 Angstroms. Polymer 2 has an infinite chiral two-dimensional (2D) brick-wall-like layer structure in the ac plane built from achiral components, while both 3 and 4 exhibit an infinite 2D herringbone architecture, respectively extended in the ac and ab plane. Polymer 5 features a most remarkable and unique three-dimensional (3D) porous framework with 2-fold interpenetration related by symmetry, which contains channels in the b and c directions, both distributed in a rectangular grid fashion. Compounds 1-5, with systematic variation in dimensionality from 1D to 2D to 3D, are the first examples of d(10) metal coordination polymers into which pyridinedicarboxylic acid N-oxide has been introduced. In addition, polymers 1, 4, and 5 display strong blue fluorescent emissions in the solid state. Polymer 3 exhibits a strong SHG response, estimated to be approximately 0.9 times that of urea.

Effect of pH and temperature upon self-assembling process between poly(aspartic acid) and Pluronic F127.

PubMed

Nita, Loredana E; Chiriac, Aurica P; Bercea, Maria

2014-07-01

The present investigation was made in order to evaluate the capability of self-assembling of the two water soluble polymers, respectively, poly(aspartic acid) and Pluronic F127 into well interpenetrated mixture, and to evidence the connection effects intervened during polymer complex formation to exhibit good stability once formed, as well to understand and correlate the binding strength and the interval between better association domains. The effect of pH and temperature on the interpolymeric complex formation between poly(aspartic acid) and Pluronic F127 was studied by combining rheology with light scattering technique. The solution mixtures between poly(aspartic acid) and Pluronic F127 are Newtonian fluids for all ratios among them. Depending on the polymeric mixture composition and experimental temperature, positive or negative deviations of the experimental values from the additive dependence appear. An interesting behavior was registered around 1/1 wt. ratio between the two polymers, when the hydrodynamic diameter of the interpenetrated polymeric particles decreased suddenly. This allows us to conclude the formation of core-shell micelle structure with poly(aspartic acid) core and Pluronic F127 as shell, performed through strong interactions between polymers. This behavior was sustained by the increase of absolute value of zeta potential owing to the decrease of functional groups number at the surface of micelles. Copyright © 2014 Elsevier B.V. All rights reserved.

Fabrication and characterisation of a novel biomimetic anisotropic ceramic/polymer-infiltrated composite material.

PubMed

Al-Jawoosh, Sara; Ireland, Anthony; Su, Bo

2018-04-10

To fabricate and characterise a novel biomimetic composite material consisting of aligned porous ceramic preforms infiltrated with polymer. Freeze-casting was used to fabricate and control the microstructure and porosity of ceramic preforms, which were subsequently infiltrated with 40-50% by volume UDMA-TEGDMA polymer. The composite materials were then subjected to characterisation, namely density, compression, three-point bend, hardness and fracture toughness testing. Samples were also subjected to scanning electron microscopy and computerised tomography (Micro-CT). Three-dimensional aligned honeycomb-like ceramic structures were produced and full interpenetration of the polymer phase was observed using micro-CT. Depending on the volume fraction of the ceramic preform, the density of the final composite ranged from 2.92 to 3.36g/cm 3 , compressive strength ranged from 206.26 to 253.97MPa, flexural strength from 97.73 to 145.65MPa, hardness ranged from 1.46 to 1.62GPa, and fracture toughness from 3.91 to 4.86MPam 1/2 . Freeze-casting provides a novel method to engineer composite materials with a unique aligned honeycomb-like interpenetrating structure, consisting of two continuous phases, inorganic and organic. There was a correlation between the ceramic fraction and the subsequent, density, strength, hardness and fracture toughness of the composite material. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

The Integration of Nanoscale Techniques for an Improved Battery Technology

DTIC Science & Technology

2012-06-08

anodized aluminum oxide ( AAO ) membranes that were 13...nanoporous anodized aluminum oxide ( AAO ) substrate [13]. During sputtering, thickened columnar growths form around the pores of the substrate...investigates an interpenetrating network structure where ―tubes‖ of polymer electrolyte are placed in the nanopores of anodic aluminum oxide ( AAO

A symmetric, triply interlaced 3-D anionic MOF that exhibits both magnetic order and SMM behaviour.

PubMed

Campo, J; Falvello, L R; Forcén-Vázquez, E; Sáenz de Pipaón, C; Palacio, F; Tomás, M

2016-11-14

A newly prepared 3-D polymer of cobalt citrate cubanes bridged by high-spin Co(ii) centres displays both single-molecule magnet (SMM) behaviour and magnetic ordering. Triple interpenetration of the 3-D diamondoid polymers yields a crystalline solid with channels that host cations and free water molecules, with the SMM behaviour of the Co 4 O 4 cores preserved. The octahedrally coordinated Co(ii) bridges are implicated in the onset of magnetic order at an experimentally accessible temperature.

Bio-based Interpenetrating Network Polymer Composites from Locust Sawdust as Coating Material for Environmentally Friendly Controlled-Release Urea Fertilizers.

PubMed

Zhang, Shugang; Yang, Yuechao; Gao, Bin; Wan, Yongshan; Li, Yuncong C; Zhao, Chenhao

2016-07-20

A novel polymer-coated nitrogen (N) fertilizer was developed using bio-based polyurethane (PU) derived from liquefied locust sawdust as the coating material. The bio-based PU was successfully coated on the surface of the urea fertilizer prills to form polymer-coated urea (PCU) fertilizer for controlled N release. Epoxy resin (EP) was also used to further modify the bio-based PU to synthesize the interpenetrating network (IPN), enhancing the slow-release properties of the PCU. The N release characteristics of the EP-modified PCU (EMPCU) in water were determine at 25 °C and compared to that of PCU and EP-coated urea (ECU). The results showed that the EP modification reduced the N release rate and increased the longevity of the fertilizer coated with bio-based PU. A corn growth study was conducted to further evaluate the filed application of the EMPCU. In comparison to commercial PCU and conventional urea fertilizer, EMPCU was more effective and increased the yield and total dry matter accumulation of the corn. Findings from this work indicated that bio-based PU derived from sawdust can be used as coating materials for PCU, particularly after EP modification. The resulting EMPCU was more environmentally friendly and cost-effective than conventional urea fertilizers coated by EP.

Biodegradability of regenerated cellulose films coated with polyurethane/natural polymers interpenetrating polymer networks

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

Zhang, L.; Zhou, J.; Huang, J.

1999-11-01

Interpenetrating polymer network (IPN) coatings synthesized from castor-oil-based polyurethane (PU) with chitosan, nitrocellulose, or elaeostearin were coated on regenerated cellulose (RC) film for curing at 80--100 C for 2--5 min, providing biodegradable, water-resistant cellulose films coded, respectively, as RCCH, RCNC, and RCEs. The coated films were buried in natural soil for decaying and inoculated with a spore suspension of fungi on the agar medium, respectively, to test biodegradability. The viscosity-average molecular weight, M{sub {eta}}, and the weight of the degraded films decreased sharply with the progress of degradation. The degradation half-lifes, t{sub 1/2}, of the films in soil at 30more » C were found to be 19 days for RC, 25 days for RCNC, 32 days for RCCH, and 45 days for the RCEs films. Scanning electron microscopy (SEM) showed that the extent of decay followed in the order RC {gt} RCNC {gt} RCCH {gt} RCEs. SEM, infrared (IR), high-performance liquid chromatography (HPLC), and CO{sub 2} evolution results indicated that the microorganisms directly attacked the water-resistant coating layer and then penetrated into the cellulose to speedily metabolize, while accompanying with producing CO{sub 2}, H{sub 2}O, glucose cleaved from cellulose, and small molecules decomposed from the coatings.« less

Microwave-assisted synthesis of sucrose polyurethanes and their semi-interpenetrating polymer networks with polycaprolactane and soybean oil

USDA-ARS?s Scientific Manuscript database

Because of the current interest in sustainability, environmental stewardship, and green chemistry, there has been a lot of interest in using agrobased raw materials for the design of polymeric materials. One of the promising biorenewable materials is sucrose, which is inexpensive and widely availabl...

Some experiments to study diffusive transport through a semi interpenetrating polymeric network in the absence and presence of aqueous electrolytes

NASA Astrophysics Data System (ADS)

Biswas, Pritha; Das, Atreyee; Yasmin, Tanvee; Kanjilal, Baishali; Chakrabarti, Haimanti

2018-05-01

The study of ion transport in biological system has become a topic of great current interest. This work presents the diffusive transport properties through a typical semi interpenetrating polymeric network (SIPN) which mimics many characteristic features of the walls of human food pipes. The SIPN matrix has been synthesised from Polyvinyl alcohol, Acrylamide monomer, Glutaraldehyde and Ammonium Per sulphate in our laboratory is utilised to study the diffusive transport in the absence and presence of aqueous electrolyte (KCl) at varying concentrations. The diffusivity of the SIPN polymer hydrogel was estimated by the `Theory of Elastomer' to get an insight into process of Potassium and Chlorine ion transport through the SIPN.

Arginine-glycine-aspartic acid functional branched semi-interpenetrating hydrogels.

PubMed

Plenderleith, Richard A; Pateman, Christopher J; Rodenburg, Cornelia; Haycock, John W; Claeyssens, Frederik; Sammon, Chris; Rimmer, Stephen

2015-10-14

For the first time a series of functional hydrogels based on semi-interpenetrating networks with both branched and crosslinked polymer components have been prepared and we show the successful use of these materials as substrates for cell culture. The materials consist of highly branched poly(N-isopropyl acrylamide)s with peptide functionalised end groups in a continuous phase of crosslinked poly(vinyl pyrrolidone). Functionalisation of the end groups of the branched polymer component with the GRGDS peptide produces a hydrogel that supports cell adhesion and proliferation. The materials provide a new synthetic functional biomaterial that has many of the features of extracellular matrix, and as such can be used to support tissue regeneration and cell culture. This class of high water content hydrogel material has important advantages over other functional hydrogels in its synthesis and does not require post-processing modifications nor are functional-monomers, which change the polymerisation process, required. Thus, the systems are amenable to large scale and bespoke manufacturing using conventional moulding or additive manufacturing techniques. Processing using additive manufacturing is exemplified by producing tubes using microstereolithography.

Assembly of 4-, 6- and 8-connected Cd(II) pseudo-polymorphic coordination polymers: Synthesis, solvent-dependent structural variation and properties

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

Li, Zhao-Hao; Xue, Li-Ping, E-mail: lpxue@163.com; Miao, Shao-Bin

2016-08-15

The reaction of Cd(NO{sub 3}){sub 2}·4H{sub 2}O, 2,5-thiophenedicarboxylic acid (H{sub 2}tdc) and 1,2-bis(imidazol-1′-yl)methane (bimm) by modulating solvent systems yielded three highly connected pseudo-polymorphic coordination polymers based on different dinuclear [Cd{sub 2}(CO{sub 2}){sub 2}] subunits bridged by carboxylate groups. Single crystal structural analyses reveal structural variation from 4-connected 2D sql layer, 6-connected 2-fold interpenetrated 3D pcu to 8-connected 3D bcu-type network in compounds 1–3. The structural dissimilarity in the structures dependent on the coordination environments of Cd(II) ions and linking modes of mixed ligand influenced by different solvent systems during the synthesis process. Moreover, thermogravimetric and photoluminescence behaviors of 1–3 weremore » also investigated for the first time, and all the complexes emit blue luminescence in the solid state. - Graphical abstract: Key Topic. Different solvent systems modulated three Cd(II) pseudo-polymorphic coordination polymers based on thiophene-2,5-dicarboxylate and 1,2-bis(imidazol-1′-yl)methane mixed ligands. Display Omitted - Highlights: • Three solvent-dependent Cd(II) pseudo-polymorphic coordination polymers have been synthesized. • Structural variation from 4-connected 2D layer, 6-connected 2-fold interpenetrated 3D net to 8-connected 3D net. • All complexes emit blue luminescence.« less

Interpenetrated Binary Supramolecular Nanofibers for Sensitive Fluorescence Detection of Six Classes of Explosives.

PubMed

Xiong, Wei; Zhu, Qijian; Gong, Yanjun; Wang, Chen; Che, Yanke; Zhao, Jincai

2018-04-03

In this work, we develop a sequential self-assembly approach to fabricate interpenetrated binary supramolecular nanofibers consisting of carbazole oligomer 1-cobalt(II) (1-Co 2+ ) coordination nanofibers and oligomer 2 nanofibers for the sensitive detection of six classes of explosives. When exposed to peroxide explosives (e.g., H 2 O 2 ), Co 2+ in 1-Co 2+ coordination nanofibers can be reduced to Co + that can transfer an electron to the excited 2 nanofibers and thereby quench their fluorescence. On the other hand, when exposed to the other five classes of explosives, the excited 2 nanofibers can transfer an electron to explosives to quench their fluorescence. On the basis of the distinct fluorescence quenching mechanisms, six classes of explosives can be sensitively detected. Herein, we provide a new strategy to design broad-band fluorescence sensors for a rich identification of threats.

Electroactive polymer gels based on epoxy resin

NASA Astrophysics Data System (ADS)

Samui, A. B.; Jayakumar, S.; Jayalakshmi, C. G.; Pandey, K.; Sivaraman, P.

2007-04-01

Five types of epoxy gels have been synthesized from common epoxy resins and hardeners. Fumed silica and nanoclay, respectively, were used as fillers and butyl methacrylate/acrylamide were used as monomer(s) for making interpenetrating polymer networks (IPNs) in three compositions. Swelling study, tensile property evaluation, dynamic mechanical thermal analysis, thermo-gravimetric analysis, scanning electron microscopy and electroactive property evaluation were done. The gels have sufficient mechanical strength and the time taken for bending to 20° was found to be 22 min for forward bias whereas it was just 12 min for reverse bias.

Starch functionalized biodegradable semi-IPN as a pH-tunable controlled release platform for memantine.

PubMed

Ganguly, Sayan; Maity, Tushar; Mondal, Subhadip; Das, Poushali; Das, Narayan C

2017-02-01

Sequentially prepared semi-interpenetrating polymer network (semi-IPN) has been developed here via Michael type addition of acrylic acid (AA) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) on to starch. The semi-IPN hydrogel have proficiency in fast water imbibition towards gel network and swelling tunable character with pH alteration in ambient condition. The synthesized gel has been characterized by Fourier transformed infrared spectroscopy (FTIR) to confirm Michael type grafting of monomers on to starch. The surface morphology, observed from Scanning Electron Microscopy (SEM) exhibited corrugated rough surface on hydrogel which enhances the fast water uptake feature by anomalous Fickian case II diffusion mechanism. Grafting reaction also improves its thermal stability which has been confirmed by thermogravimetric analysis (TGA). Biodegradation study with hen egg lysozyme medium reveals the accelerated enzymatic scission of the starch backbone and progressive mass loss. Degradation of the hydrogel around 60% of its primary mass has been observed within 7days. The physicochemical characterizations of this hydrogel suggest this as a promising pH-tunable, biodegradable candidate for control drug delivery vehicle. Copyright © 2016 Elsevier B.V. All rights reserved.

Photovoltaic Properties in Interpenetrating Heterojunction Organic Solar Cells Utilizing MoO3 and ZnO Charge Transport Buffer Layers

PubMed Central

Hori, Tetsuro; Moritou, Hiroki; Fukuoka, Naoki; Sakamoto, Junki; Fujii, Akihiko; Ozaki, Masanori

2010-01-01

Organic thin-film solar cells with a conducting polymer (CP)/fullerene (C60) interpenetrating heterojunction structure, fabricated by spin-coating a CP onto a C60 deposit thin film, have been investigated and demonstrated to have high efficiency. The photovoltaic properties of solar cells with a structure of indium-tin-oxide/C60/poly(3-hexylthiophene) (PAT6)/Au have been improved by the insertion of molybdenum trioxide (VI) (MoO3) and zinc oxide charge transport buffer layers. The enhanced photovoltaic properties have been discussed, taking into consideration the ground-state charge transfer between PAT6 and MoO3 by measurement of the differential absorption spectra and the suppressed contact resistance at the interface between the organic and buffer layers. PMID:28883360

Adsorption of ammonium and phosphate by feather protein based semi-interpenetrating polymer networks hydrogel as a controlled-release fertilizer.

PubMed

Su, Yuan; Liu, Jia; Yue, Qinyan; Li, Qian; Gao, Baoyu

2014-01-01

A new feather protein-grafted poly(potassium acrylate)/polyvinyl alcohol (FP-g-PKA/PVA) semi-interpenetrating polymer networks (semi-IPNs) hydrogel was produced through graft copolymerization with FP as a basic macromolecular skeletal material, acrylic acid as a monomer and PVA as a semi-IPNs polymer. The adsorption of ammonium and phosphate ions from aqueous solution using the new hydrogel as N and P controlled-release fertilizer with water-retention capacity was studied. The effects of pH value, concentration, contact time and ion strength on NH4+ and PO3-4 removal by FP-g-PKA/PVA semi-IPNs hydrogel were investigated using batch adsorption experiments. The results indicated that the hydrogel had high adsorption capacities and fast adsorption rates for NH4+ and PO3-4 in wide pH levels ranging from 4.0 to 9.0. Kinetic analysis presented that both NH4+ and PO3-4 removal were closely fitted with the pseudo-second-order model. Furthermore, the adsorption isotherms of hydrogel were best represented by the Freundlich model. The adsorption-desorption experimental results showed the sustainable stability of FP-g-PKA/PVA semi-IPNs hydrogel for NH4+ and PO3-4 removal. Overall, FP-g-PKA/PVA could be considered as an efficient material for the removal and recovery of nitrogen and phosphorus with the agronomic reuse as a fertilizer.

Simple synthesis of nitrogen-rich polymer network and its further amination with PEI for CO2 adsorption

NASA Astrophysics Data System (ADS)

Yin, Fengqin; Zhuang, Linzhou; Luo, Xianyong; Chen, Shuixia

2018-03-01

The nitrogen-rich polymer network (MF/PAM) was synthesized through interpenetration between the molecular chains of melamine-formaldehyde resin(MF) and polyacrylamide (PAM), to which the polyethylene imine (PEI) was grafted to obtain solid amine adsorbent (MF/PAM-g-PEI). Compared with MF, the swelling capacity of MF/PAM was greatly enhanced, it could swell rapidly and directly in water. Although the interpenetration of PAM into MF may reduce the porosity of MF/PAM, the CO2 capture capacity of the solid amine adsorbents (MF/PAM-g-PEI) could still reach 2.8 mmol/g at 273 K. The adsorbents also exhibited promising adsorption kinetics and regeneration performances. The kinetics observation showed that the Avrami model could better descript the CO2 adsorption process compared with the pseudo-first-order model and pseudo-second-order model. Meanwhile, the Avrami kinetic orders (na) range from 1.21 to 1.56, displaying that the both physisorption and chemisorption exist in the adsorption process and the PEI have successfully grafted onto the polymer network, which also can be confirmed by the adsorption activation energy value. After 18 adsorption-desorption recycles, the MF/PAM-g-PEI could preserve its initial capacity without any decrease. Our work provides a new method to achieve promising solid amine adsorbents with higher adsorption capacity and better regeneration performance.

Sequential growth for lifetime extension in biomimetic polypyrrole actuator systems

NASA Astrophysics Data System (ADS)

Sarrazin, J. C.; Mascaro, Stephen A.

2015-04-01

Electroactive polymers (EAPs) present prospective use in actuation and manipulation devices due to their low electrical activation requirements, biocompatibility, and mechanical performance. One of the main drawbacks with EAP actuators is a decrease in performance over extended periods of operation caused by over-oxidation of the polymer and general polymer degradation. Synthesis of the EAP material, polypyrrole with an embedded metal helix allows for sequential growth of the polymer during operation. The helical metal electrode acts as a scaffolding to support the polymer, and direct the 3-dimensional change in volume of the polymer along the axis of the helix during oxidative and reductive cycling. The metal helix also provides a working metal electrode through the entire length of the polymer actuator to distribute charge for actuation, as well as for sequential growth steps during the lifetime of operation of the polymer. This work demonstrates the method of sequential growth can be utilized after extended periods of use to partially restore electrical and mechanical performance of polypyrrole actuators. Since the actuation must be temporarily stopped to allow for a sequential growth cycle to be performed and reverse some of the polymer degradation, these actuator systems more closely mimic natural muscle in their analogous maintenance and repair.

Construction of noninterpenetrating and interpenetrating Co(ii) networks with halogenated carboxylate modulated by auxiliary N-donor co-ligands: structural diversity, electrochemical and photocatalytic properties.

PubMed

Hao, Shao Yun; Hou, Suo Xia; Van Hecke, Kristof; Cui, Guang Hua

2017-02-14

Six Co(ii)-based coordination polymers (CPs) with characteristic frameworks and topologies-namely, [Co(L1)(DCTP)] n (1), [Co(L2)(DCTP)] n (2), [Co(L3)(DCTP)] n (3), {[Co 3 (L4) 3 (DCTP) 3 ·H 2 O]·H 2 O} n (4), [Co(L5) 1.5 (DCTP)] n (5) and [Co(L6)(DCTP)] n (6)-were successfully hydrothermally synthesized by employing the halogenated linear ligand 2,5-dichloroterephthalic acid (H 2 DCTP). The interpenetrated structures could be rationally modulated by auxiliary N-donor co-ligands containing 1,1'-(1,4-butanediyl)bis-1H-benzimidazole (L1), 1,4-bis(5,6-dimethylbenzimidazol-1-yl)-2-butylene (L2), 1,2-bis(2-methylbenzimidazol-1-ylmethyl)benzene (L3), 1,4-bis(2-methylbenzimidazol-1-ylmethyl)benzene (L4), 1,2-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene (L5) and 1,4-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene (L6). These diaphanous crystals were clearly characterized by elemental analysis, infrared (IR) spectra and X-ray powder diffraction (XRPD) as well as single-crystal X-ray diffraction analysis. With the aid of the flexible N-donor co-ligands, CP 1 occupies a non-interpenetrated 2D sheet with the point symbol {4 4 ·6 2 } sql net topology, CP 2 possesses a 3D hexagon-shaped network with the point symbol {6 6 } three-fold interpenetrated sqc6 topology, CP 3 exhibits a 2D layer with the point symbol {4 4 ·6 2 } sql net topology, CP 4 reveals an unusual 3D framework with the point symbol {4 2 ·6 3 ·8} three-fold interpenetrated sra topology, CP 5 has a 3D hexagon-shaped network with the point symbol {6 6 } two-fold interpenetrated sqc6 topology, while CP 6 displays a 3D hexagon-shaped network with the point symbol {6 6 } three-fold interpenetrated sqc6 topology. The diverse structures of CPs 1-6 illustrate that the substitute group and position of the methyl group of the bis(benzimidazole) derivatives play a significant role in the assembly of such interpenetrated frameworks. Moreover, luminescence properties and thermal behavior, as well as the electrochemical and photocatalytic properties of CPs 1-6 on the degradation of methylene blue, are also presented.

Wood hemicellulose/chitosan-based semi-interpenetrating network hydrogels : mechanical swelling and controlled drug release properties

Treesearch

Ahmet M. Karaaslan; Mandla A. Tshabalala; Gisela Buschle-Diller

2010-01-01

The cell wall of most plant biomass from forest and agricultural resources consists of three major polymers, cellulose, hemicellulose, and lignin. Of these, hemicelluloses have gained increasing attention as sustainable raw materials. In this study, novel pH-sensitive semi-IPN hydrogels based on hemicelluloses and chitosan were prepared using glutaraldehyde as the...

Evaluation of Fibrin-Based Interpenetrating Polymer Networks as Potential Biomaterials for Tissue Engineering.

PubMed

Gsib, Olfat; Duval, Jean-Luc; Goczkowski, Mathieu; Deneufchatel, Marie; Fichet, Odile; Larreta-Garde, Véronique; Bencherif, Sidi Ahmed; Egles, Christophe

2017-12-10

Interpenetrating polymer networks (IPNs) have gained great attention for a number of biomedical applications due to their improved properties compared to individual components alone. In this study, we investigated the capacity of newly-developed naturally-derived IPNs as potential biomaterials for tissue engineering. These IPNs combine the biologic properties of a fibrous fibrin network polymerized at the nanoscale and the mechanical stability of polyethylene oxide (PEO). First, we assessed their cytotoxicity in vitro on L929 fibroblasts. We further evaluated their biocompatibility ex vivo with a chick embryo organotypic culture model. Subcutaneous implantations of the matrices were subsequently conducted on nude mice to investigate their biocompatibility in vivo. Our preliminary data highlighted that our biomaterials were non-cytotoxic (viability above 90%). The organotypic culture showed that the IPN matrices induced higher cell adhesion (across all the explanted organ tissues) and migration (skin, intestine) than the control groups, suggesting the advantages of using a biomimetic, yet mechanically-reinforced IPN-based matrix. We observed no major inflammatory response up to 12 weeks post implantation. All together, these data suggest that these fibrin-based IPNs are promising biomaterials for tissue engineering.

Evaluation of Fibrin-Based Interpenetrating Polymer Networks as Potential Biomaterials for Tissue Engineering

PubMed Central

Gsib, Olfat; Duval, Jean-Luc; Goczkowski, Mathieu; Deneufchatel, Marie; Fichet, Odile; Larreta-Garde, Véronique

2017-01-01

Interpenetrating polymer networks (IPNs) have gained great attention for a number of biomedical applications due to their improved properties compared to individual components alone. In this study, we investigated the capacity of newly-developed naturally-derived IPNs as potential biomaterials for tissue engineering. These IPNs combine the biologic properties of a fibrous fibrin network polymerized at the nanoscale and the mechanical stability of polyethylene oxide (PEO). First, we assessed their cytotoxicity in vitro on L929 fibroblasts. We further evaluated their biocompatibility ex vivo with a chick embryo organotypic culture model. Subcutaneous implantations of the matrices were subsequently conducted on nude mice to investigate their biocompatibility in vivo. Our preliminary data highlighted that our biomaterials were non-cytotoxic (viability above 90%). The organotypic culture showed that the IPN matrices induced higher cell adhesion (across all the explanted organ tissues) and migration (skin, intestine) than the control groups, suggesting the advantages of using a biomimetic, yet mechanically-reinforced IPN-based matrix. We observed no major inflammatory response up to 12 weeks post implantation. All together, these data suggest that these fibrin-based IPNs are promising biomaterials for tissue engineering. PMID:29232876

TiO2 quantum dots embedded in bamboo-like porous carbon nanotubes as ultra high power and long life anodes for lithium ion batteries

NASA Astrophysics Data System (ADS)

Tang, Yakun; Liu, Lang; Wang, Xingchao; Jia, Dianzeng; Xia, Wei; Zhao, Zongbin; Qiu, Jieshan

2016-07-01

TiO2 quantum dots embedded in bamboo-like porous carbon nanotubes have been constructed through the pyrolysis of sulfonated polymer nanotubes and TiO2 hybrids. The TiO2 quantum dots are formed during the pyrolysis, due to the space confinement within the highly cross-linked copolymer networks. The sulfonation degree of the polymer nanotubes is a critical factor to ensure the formation of the unique interpenetrating structure. The nanocomposites exhibit high reversible capacity of 523 mAh g-1 at 100 mA g-1 after 200 cycles, excellent rate capability and superior long-term cycling stability at high current density, which could attain a high discharge capacity of 189 mAh g-1 at 2000 mA g-1 for up to 2000 cycles. The enhanced electrochemical performance of the nanocomposites benefit from the uniform distribution of TiO2 quantum dots, high electronic conductivity of porous carbons and unique interpenetrating structure, which simultaneously solved the major problems of TiO2 anode facing the pulverization, loss of electrical contact and particle aggregation.

Wrinkling and folding of nanotube-polymer bilayers

NASA Astrophysics Data System (ADS)

Semler, Matthew R.; Harris, John M.; Hobbie, Erik K.

2014-07-01

The influence of a polymer capping layer on the deformation of purified single-wall carbon nanotube (SWCNT) networks is analyzed through the wrinkling of compressed SWCNT-polymer bilayers on polydimethylsiloxane. The films exhibit both wrinkling and folding under compression and we extract the elastoplastic response using conventional two-plate buckling schemes. The formation of a diffuse interpenetrating nanotube-polymer interface has a dramatic effect on the nanotube layer modulus for both metallic and semiconducting species. In contrast to the usual percolation exhibited by the pure SWCNT films, the capped films show a crossover from "composite" behavior (the modulus of the SWCNT film is enhanced by the polymer) to "plasticized" behavior (the modulus of the SWCNT film is reduced by the polymer) as the SWCNT film thickness increases. For almost all thicknesses, however, the polymer enhances the yield strain of the nanotube network. Conductivity measurements on identical films suggest that the polymer has a modest effect on charge transport, which we interpret as a strain-induced polymer penetration of interfacial nanotube contacts. We use scaling, Flory-Huggins theory, and independently determined nanotube-nanotube and nanotube-polymer Hamaker constants to model the response.

Organic/inorganic nanocomposites, methods of making, and uses as a permeable reactive barrier

DOEpatents

Harrup, Mason K [Idaho Falls, ID; Stewart, Frederick F [Idaho Falls, ID

2007-05-15

Nanocomposite materials having a composition including an inorganic constituent, a preformed organic polymer constituent, and a metal ion sequestration constituent are disclosed. The nanocomposites are characterized by being single phase, substantially homogeneous materials wherein the preformed polymer constituent and the inorganic constituent form an interpenetrating network with each other. The inorganic constituent may be an inorganic oxide, such as silicon dioxide, formed by the in situ catalyzed condensation of an inorganic precursor in the presence of the solvated polymer and metal ion sequestration constituent. The polymer constituent may be any hydrophilic polymer capable of forming a type I nanocomposite such as, polyacrylonitrile (PAN), polyethyleneoxide (PEO), polyethylene glycol (PEG), polyvinyl acetate (PVAc), polyvinyl alcohol (PVA), and combinations thereof. Nanocomposite materials of the present invention may be used as permeable reactive barriers (PRBs) to remediate contaminated groundwater. Methods for making nanocomposite materials, PRB systems, and methods of treating groundwater are also disclosed.

Photonic Shape Memory Polymer with Stable Multiple Colors

PubMed Central

2017-01-01

A photonic shape memory polymer film that shows large color response (∼155 nm) in a wide temperature range has been fabricated from a semi-interpenetrating network of a cholesteric polymer and poly(benzyl acrylate). The large color response is achieved by mechanical embossing of the photonic film above its broad glass transition temperature. The embossed film, as it recovers to its original shape on heating through the broad thermal transition, exhibits multiple structural colors ranging from blue to orange. The relaxation behavior of the embossed film can be fully described using a Kelvin–Voigt model, which reveals that the influence of temperature on the generation of colors is much stronger than that of time, thereby producing stable multiple colors. PMID:28840717

Separation of Water from Ultralow Sulfur Diesel Using Novel Polymer Nanofiber-Coated Glass Fiber Media.

PubMed

Rajgarhia, Stuti S; Jana, Sadhan C; Chase, George G

2016-08-24

Polymer nanofibers with interpenetrating network (IPN) morphology are used in this work for the development of composite, hydrophobic filter media in conjunction with glass fibers for removal of water droplets from ultralow sulfur diesel (ULSD). The nanofibers are produced from hydrophobic polyvinyl acetate (PVAc) and hydrophilic polyvinylpyrrolidone (PVP) by spinning the polymer solutions using gas jet fiber (GJF) method. The nanofibers coat the individual glass fibers due to polar-polar interactions during the spinning process and render the filter media highly hydrophobic with a water contact angle approaching 150°. The efficiency of the resultant filter media is evaluated in terms of separation of water droplets of average size 20 μm from the suspensions in ULSD.

A model of cell wall expansion based on thermodynamics of polymer networks

NASA Technical Reports Server (NTRS)

Veytsman, B. A.; Cosgrove, D. J.

1998-01-01

A theory of cell wall extension is proposed. It is shown that macroscopic properties of cell walls can be explained through the microscopic properties of interpenetrating networks of cellulose and hemicellulose. The qualitative conclusions of the theory agree with the existing experimental data. The dependence of the cell wall yield threshold on the secretion of the wall components is discussed.

Molecular dynamics studies of interpenetrating polymer networks for actuator devices

NASA Astrophysics Data System (ADS)

Brandell, Daniel; Kasemägi, Heiki; Citérin, Johann; Vidal, Frédéric; Chevrot, Claude; Aabloo, Alvo

2008-03-01

Molecular Dynamics (MD) techniques have been used to study the structure and dynamics of a model system of an interpenetrating polymer (IPN) network for actuator devices. The systems simulated were generated using a Monte Carlo-approach, and consisted of poly(ethylene oxide) (PEO) and poly(butadiene) (PB) in a 80-20 percent weight ratio immersed into propylene carbonate (PC) solutions of LiClO 4. The total polymer content was 32%, in order to model experimental conditions. The dependence of LiClO 4 concentration in PC has been studied by studying five different concentrations: 0.25, 0.5, 0.75, 1.0 and 1.25 M. After equilibration, local structural properties and dynamical features such as phase separation, coordination, cluster stability and ion conductivity were studied. In an effort to study the conduction processes more carefully, external electric fields of 1×10 6 V/m and 5×10 6 V/m has been applied to the simulation boxes. A clear relationship between the degree of local phase separation and ion mobility is established. It is also shown that although the ion pairing increases with concentration, there are still significantly more potential charge carriers in the higher concentrated systems, while concentrations around 0.5-0.75 M of LiClO 4 in PC seem to be favorable in terms of ion mobility. Furthermore, the anions exhibit higher conductivity than the cations, and there are tendencies to solvent drag from the PC molecules.

Interpenetrating phase ceramic/polymer composite coatings: Fabrication and characterization

NASA Astrophysics Data System (ADS)

Craig, Bradley Dene

The goals of this thesis research were to fabricate interpenetrating phase composite (IPC) ceramic/polymer coatings and to investigate the effect of the interconnected microstructure on the physical and wear properties of the coatings. IPC coatings with an interpenetrating phase microstructure were successfully fabricated by first forming a porous ceramic with an interconnected microstructure using a chemical bonding route (mainly reacting alpha-alumina (0.3 mum) with orthophosphoric acid to form a phosphate bond). Porosity within these ceramic coatings was easily controlled between 20 and 50 vol. % by phosphoric acid addition, and was measured by a new porosity measurement technique (thermogravimetric volatilization of liquids, or TVL) which was developed. The resulting ceramic preforms were infiltrated with a UV and thermally curable cycloaliphatic epoxide resin and cured. This fabrication route resulted in composite coatings with thicknesses ranging from ˜1mum to 100 mum with complete filling of open pore space. The physical properties of the composite coatings, including microhardness, flexural modulus and wear resistance, were evaluated as a function of processing variables, including orthophosphoric acid content and ceramic phase firing temperature, which affected the microstructure and interparticulate bonding between particles in the coatings. For example, microhardness increased from ˜30 on the Vicker's scale to well over 200 as interparticulate bonding was increased in the ceramic phase. Additionally, Taber wear resistance in the best TPC coatings was found to approach that of fully-densified alumina under certain conditions. Several factors were found to influence the wear mechanism in the IPC coating materials. Forming strong connections between ceramic particles led to up to an order of magnitude increase in the wear resistance. Additionally, coating microhardness and ceramic/polymer interfacial strength were studied and found to be important in determining the wear mechanism and wear resistance of IPC composite coatings. A qualitative theory for wear mechanisms in these coatings was developed. Finally, a series of transparent coatings were developed via a similar processing route, using smaller (˜90 nm) boehmite particles instead of 0.3 mum alpha-alumina. Physical property control was found to mimic that found in opaque coatings, and showed increasing surface adsorption characteristics with increasing phosphoric acid content.

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.

Self-Assembly of Diblock Molecular Polymer Brushes in the Spherical Confinement of Nanoemulsion Droplets.

PubMed

Steinhaus, Andrea; Pelras, Théophile; Chakroun, Ramzi; Gröschel, André H; Müllner, Markus

2018-05-02

Understanding the self-assembly behavior of polymers of various topologies is key to a reliable design of functional polymer materials. Self-assembly under confinement conditions emerges as a versatile avenue to design polymer particles with complex internal morphologies while simultaneously facilitating scale-up. However, only linear block copolymers have been studied to date, despite the increasing control over macromolecule composition and architecture available. This study extends the investigation of polymer self-assembly in confinement from regular diblock copolymers to diblock molecular polymer brushes (MPBs). Block-type MPBs with polystyrene (PS) and polylactide (PLA) compartments of different sizes are incorporated into surfactant-stabilized oil-in-water (chloroform/water) emulsions. The increasing confinement in the nanoemulsion droplets during solvent evaporation directs the MPBs to form solid nano/microparticles. Microscopy studies reveal an intricate internal particle structure, including interpenetrating networks and axially stacked lamellae of PS and PLA, depending on the PS/PLA ratio of the brushes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison of solution-mixed and sequentially processed P3HT: F4TCNQ films: effect of doping-induced aggregation on film morphology

DOE PAGES

Jacobs, Ian E.; Aasen, Erik W.; Oliveira, Julia L.; ...

2016-03-23

Doping polymeric semiconductors often drastically reduces the solubility of the polymer, leading to difficulties in processing doped films. Here, we compare optical, electrical, and morphological properties of P3HT films doped with F4TCNQ, both from mixed solutions and using sequential solution processing with orthogonal solvents. We demonstrate that sequential doping occurs rapidly (<1 s), and that the film doping level can be precisely controlled by varying the concentration of the doping solution. Furthermore, the choice of sequential doping solvent controls whether dopant anions are included or excluded from polymer crystallites. Atomic force microscopy (AFM) reveals that sequential doping produces significantly moremore » uniform films on the nanoscale than the mixed-solution method. In addition, we show that mixed-solution doping induces the formation of aggregates even at low doping levels, resulting in drastic changes to film morphology. Sequentially coated films show 3–15 times higher conductivities at a given doping level than solution-doped films, with sequentially doped films processed to exclude dopant anions from polymer crystallites showing the highest conductivities. In conclusion, we propose a mechanism for doping induced aggregation in which the shift of the polymer HOMO level upon aggregation couples ionization and solvation energies. To show that the methodology is widely applicable, we demonstrate that several different polymer:dopant systems can be prepared by sequential doping.« less

Comparison of solution-mixed and sequentially processed P3HT: F4TCNQ films: effect of doping-induced aggregation on film morphology

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

Jacobs, Ian E.; Aasen, Erik W.; Oliveira, Julia L.

Doping polymeric semiconductors often drastically reduces the solubility of the polymer, leading to difficulties in processing doped films. Here, we compare optical, electrical, and morphological properties of P3HT films doped with F4TCNQ, both from mixed solutions and using sequential solution processing with orthogonal solvents. We demonstrate that sequential doping occurs rapidly (<1 s), and that the film doping level can be precisely controlled by varying the concentration of the doping solution. Furthermore, the choice of sequential doping solvent controls whether dopant anions are included or excluded from polymer crystallites. Atomic force microscopy (AFM) reveals that sequential doping produces significantly moremore » uniform films on the nanoscale than the mixed-solution method. In addition, we show that mixed-solution doping induces the formation of aggregates even at low doping levels, resulting in drastic changes to film morphology. Sequentially coated films show 3–15 times higher conductivities at a given doping level than solution-doped films, with sequentially doped films processed to exclude dopant anions from polymer crystallites showing the highest conductivities. In conclusion, we propose a mechanism for doping induced aggregation in which the shift of the polymer HOMO level upon aggregation couples ionization and solvation energies. To show that the methodology is widely applicable, we demonstrate that several different polymer:dopant systems can be prepared by sequential doping.« less

Organic-Inorganic Hybrid Polymers as Adsorbents for Removal of Heavy Metal Ions from Solutions: A Review

PubMed Central

Samiey, Babak; Cheng, Chil-Hung; Wu, Jiangning

2014-01-01

Over the past decades, organic-inorganic hybrid polymers have been applied in different fields, including the adsorption of pollutants from wastewater and solid-state separations. In this review, firstly, these compounds are classified. These compounds are prepared by sol-gel method, self-assembly process (mesopores), assembling of nanobuilding blocks (e.g., layered or core-shell compounds) and as interpenetrating networks and hierarchically structures. Lastly, the adsorption characteristics of heavy metals of these materials, including different kinds of functional groups, selectivity of them for heavy metals, effect of pH and synthesis conditions on adsorption capacity, are studied. PMID:28788483

Advanced Material Nanotechnology in Israel

NASA Astrophysics Data System (ADS)

Figovsky, O.; Beilin, D.; Blank, N.

One of the most interesting directions in material engineering during the past few years is the technical development of nanocomposite materials consisting from two or more phases with precise interphase border and nanostructured materials based on interpenetrated polymer network. Israel is one of world leaders in fundamental and industrial nanotechnology research, including fostering of start-up companies. Some important developments in the field of nanotechnology material engineering in Israel are summarized in the paper.

A tough high performance composite matrix

NASA Technical Reports Server (NTRS)

Pater, Ruth H. (Inventor); Johnston, Norman J. (Inventor)

1992-01-01

This invention is a semi-interpenetrating polymer network which includes a high performance thermosetting polyimide having a nadic end group acting as a crosslinking site and a high performance linear thermoplastic polyimide. An improved high temperature matrix resin is provided which is capable of performing in the 200 to 300 C range. This resin has significantly improved toughness and microcracking resistance, excellent processability, mechanical performance and moisture and solvent resistances.

Polyvinylpyrrolidone-based semi-interpenetrating polymer networks as highly selective and chemically stable membranes for all vanadium redox flow batteries

NASA Astrophysics Data System (ADS)

Zeng, L.; Zhao, T. S.; Wei, L.; Zeng, Y. K.; Zhang, Z. H.

2016-09-01

Vanadium redox flow batteries (VRFBs) with their high flexibility in configuration and operation, as well as long cycle life are competent for the requirement of future energy storage systems. Nevertheless, due to the application of perfluorinated membranes, VRFBs are plagued by not only the severe migration issue of vanadium ions, but also their high cost. Herein, we fabricate semi-interpenetrating polymer networks (SIPNs), consisting of cross-linked polyvinylpyrrolidone (PVP) and polysulfone (PSF), as alternative membranes for VRFBs. It is demonstrated that the PVP-based SIPNs exhibit extremely low vanadium permeabilities, which contribute to the well-established hydrophilic/hydrophobic microstructures and the Donnan exclusion effect. As a result, the coulombic efficiencies of VRFBs with PVP-based SIPNs reach almost 100% at 40 mA cm-2 to 100 mA cm-2; the energy efficiencies are more than 3% higher than those of VRFBs with Nafion 212. More importantly, the PVP-based SIPNs exhibit a superior chemical stability, as demonstrated both by an ex situ immersion test and continuously cycling test. Hence, all the characterizations and performance tests reported here suggest that PVP-based SIPNs are a promising alternative membrane for redox flow batteries to achieve superior cell performance and excellent cycling stability at the fraction of the cost of perfluorinated membranes.

Novel composite membrane coated with a poly(diallyldimethylammonium chloride)/urushi semi-interpenetrating polymer network for non-aqueous redox flow battery application

NASA Astrophysics Data System (ADS)

Cho, Eunhae; Won, Jongok

2016-12-01

Novel composite membranes of a semi-interpenetrating network (semi-IPN) coated on the surfaces of a porous Celgard 2400 support are prepared and investigate for application in a non-aqueous redox flow battery (RFB). A natural polymer, urushi, is used for the matrix because of its high mechanical robustness, and poly(diallyldimethylammonium chloride) (PDDA) provides anionic exchange sites. The PDDA/urushi (P/U) semi-IPN film is prepared by the photo polymerization of urushiol in the presence of PDDA. The thin layer composed of the P/U semi-IPN on the porous support provides selectivity while maintaining the ion conductivity. The coulombic and energy efficiencies increase with increasing amounts of PDDA in the P/U semi-IPN layer, and the values reach 69.5% and 42.5%, respectively, for the one containing 40 wt% of PDDA. These values are substantially higher than those of the Neosepta AHA membrane and the Celgard membrane, indicating that the selective layer reduces the crossover of the redox active species through the membrane. This result implies that the formation of composite membranes using semi-IPN selective layers on the dimensionally stable porous membrane enable the successful use of a non-aqueous RFB for future energy storage systems.

Solvothermal syntheses, structures, and magnetic properties of three cobalt coordination polymers constructed from naphthalene-1,4-dicarboxylic acid and bis(imidazole) linkers

NASA Astrophysics Data System (ADS)

Dong, Jun-Liang; He, Kun-Huan; Wang, Duo-Zhi; Zhang, Ying-Hui; Wang, Dan-Hong

2018-07-01

Three new Co(II) coordination polymers with formulas of {[Co2(L1)(1,4-NDC)2]·3H2O}n (1), [Co3(L2)2(HCOO)2(1,4-NDC)2]n (2) and [Co2(L2)(μ3-OH)(1,4-NDC)1.5]n (3) (1,4-H2NDC = Naphthalene-1,4-dicarboxylic acid, L1 = di(1H-imidazol-1-yl)methane, L2 = 1,4-di(1H-imidazol-1-yl)benzene) were solvothermal synthesized from 1,4-H2NDC with the aid of three different length-controllable auxiliary ligands and fully characterized. Their structures are determined by single-crystal X-ray diffraction, IR spectra, elemental analysis, powder X-ray diffraction and thermogravimetric analysis. Complexes 1 and 3 display 3D framework structures, corresponding to a 6-connected (412·63) net, a 8-connected (424·5·63) net, respectively. However, it is noteworthy that the complex 1 displays a 2-fold interpenetrating framework structure, complex 3 possesses a self-interpenetrating framework structure. Complex 2 displays 2D 4-connected undulating plane net structure. Moreover, magnetic studies indicate antiferromagnetic interactions between the Co(II) ions in the four complexes.

Self-Supported Crack-Free Conducting Polymer Films with Stabilized Wrinkling Patterns and Their Applications

PubMed Central

Xie, Jixun; Han, Xue; Ji, Haipeng; Wang, Juanjuan; Zhao, Jingxin; Lu, Conghua

2016-01-01

Self-supported conducting polymer films with controlled microarchitectures are highly attractive from fundamental and applied points of view. Here a versatile strategy is demonstrated to fabricate thin free-standing crack-free polyaniline (PANI)-based films with stable wrinkling patterns. It is based on oxidization polymerization of pyrrole inside a pre-wrinkled PANI film, in which the wrinkled PANI film is used both as a template and oxidizing agent for the first time. The subsequently grown polypyrrole (PPy) and the formation of interpenetrated PANI/PPy networks play a decisive role in enhancing the film integrity and the stability of wrinkles. This enhancing effect is attributed to the modification of internal stresses by the interpenetrated PANI/PPy microstructures. Consequently, a crack-free film with stable controlled wrinkles such as the wavelength, orientation and spatial location has been achieved. Moreover, the wrinkling PANI/PPy film can be removed from the initially deposited substrate to become free-standing. It can be further transferred onto target substrates to fabricate hierarchical patterns and functional devices such as flexible electrodes, gas sensors, and surface-enhanced Raman scattering substrates. This simple universal enhancing strategy has been extended to fabrication of other PANI-based composite systems with crack-free film integrity and stabilized surface patterns, irrespective of pattern types and film geometries. PMID:27827459

A threefold interpenetrated two-dimensional zinc(II) supramolecular architecture based on 3-nitrobenzoic acid and 4,4'-bipyridine.

PubMed

Tang, Long; Wang, Ji-Jiang; Fu, Feng; Wang, Sheng-Wen; Liu, Qi-Rui

2016-02-01

With regard to crystal engineering, building block or modular assembly methodologies have shown great success in the design and construction of metal-organic coordination polymers. The critical factor for the construction of coordination polymers is the rational choice of the organic building blocks and the metal centre. The reaction of Zn(OAc)2·2H2O (OAc is acetate) with 3-nitrobenzoic acid (HNBA) and 4,4'-bipyridine (4,4'-bipy) under hydrothermal conditions produced a two-dimensional zinc(II) supramolecular architecture, catena-poly[[bis(3-nitrobenzoato-κ(2)O,O')zinc(II)]-μ-4,4'-bipyridine-κ(2)N:N'], [Zn(C7H4NO4)2(C10H8N2)]n or [Zn(NBA)2(4,4'-bipy)]n, which was characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction analysis. The Zn(II) ions are connected by the 4,4'-bipy ligands to form a one-dimensional zigzag chain and the chains are decorated with anionic NBA ligands which interact further through aromatic π-π stacking interactions, expanding the structure into a threefold interpenetrated two-dimensional supramolecular architecture. The solid-state fluorescence analysis indicates a slight blue shift compared with pure 4,4'-bipyridine and HNBA.

Design and performance of a sericin-alginate interpenetrating network hydrogel for cell and drug delivery.

PubMed

Zhang, Yeshun; Liu, Jia; Huang, Lei; Wang, Zheng; Wang, Lin

2015-07-24

Although alginate hydrogels have been extensively studied for tissue engineering applications, their utilization is limited by poor mechanical strength, rapid drug release, and a lack of cell adhesive ability. Aiming to improve these properties, we employ the interpenetrating hydrogel design rationale. Using alginate and sericin (a natural protein with many unique properties and a major component of silkworm silk), we develop an interpenetrating polymer network (IPN) hydrogel comprising interwoven sericin and alginate double networks. By adjusting the sericin-to-alginate ratios, IPNs' mechanical strength can be adjusted to meet stiffness requirements for various tissue repairs. The IPNs with high sericin content show increased stability during degradation, avoiding pure alginate's early collapse. These IPNs have high swelling ratios, benefiting various applications such as drug delivery. The IPNs sustain controlled drug release with the adjustable rates. Furthermore, these IPNs are adhesive to cells, supporting cell proliferation, long-term survival and migration. Notably, the IPNs inherit sericin's photoluminescent property, enabling bioimaging in vivo. Together, our study indicates that the sericin-alginate IPN hydrogels may serve as a versatile platform for delivering cells and drugs, and suggests that sericin may be a building block broadly applicable for generating IPN networks with other biomaterials for diverse tissue engineering applications.

Design and performance of a sericin-alginate interpenetrating network hydrogel for cell and drug delivery

PubMed Central

Zhang, Yeshun; Liu, Jia; Huang, Lei; Wang, Zheng; Wang, Lin

2015-01-01

Although alginate hydrogels have been extensively studied for tissue engineering applications, their utilization is limited by poor mechanical strength, rapid drug release, and a lack of cell adhesive ability. Aiming to improve these properties, we employ the interpenetrating hydrogel design rationale. Using alginate and sericin (a natural protein with many unique properties and a major component of silkworm silk), we develop an interpenetrating polymer network (IPN) hydrogel comprising interwoven sericin and alginate double networks. By adjusting the sericin-to-alginate ratios, IPNs’ mechanical strength can be adjusted to meet stiffness requirements for various tissue repairs. The IPNs with high sericin content show increased stability during degradation, avoiding pure alginate’s early collapse. These IPNs have high swelling ratios, benefiting various applications such as drug delivery. The IPNs sustain controlled drug release with the adjustable rates. Furthermore, these IPNs are adhesive to cells, supporting cell proliferation, long-term survival and migration. Notably, the IPNs inherit sericin’s photoluminescent property, enabling bioimaging in vivo. Together, our study indicates that the sericin-alginate IPN hydrogels may serve as a versatile platform for delivering cells and drugs, and suggests that sericin may be a building block broadly applicable for generating IPN networks with other biomaterials for diverse tissue engineering applications. PMID:26205586

Design and performance of a sericin-alginate interpenetrating network hydrogel for cell and drug delivery

NASA Astrophysics Data System (ADS)

Zhang, Yeshun; Liu, Jia; Huang, Lei; Wang, Zheng; Wang, Lin

2015-07-01

Although alginate hydrogels have been extensively studied for tissue engineering applications, their utilization is limited by poor mechanical strength, rapid drug release, and a lack of cell adhesive ability. Aiming to improve these properties, we employ the interpenetrating hydrogel design rationale. Using alginate and sericin (a natural protein with many unique properties and a major component of silkworm silk), we develop an interpenetrating polymer network (IPN) hydrogel comprising interwoven sericin and alginate double networks. By adjusting the sericin-to-alginate ratios, IPNs’ mechanical strength can be adjusted to meet stiffness requirements for various tissue repairs. The IPNs with high sericin content show increased stability during degradation, avoiding pure alginate’s early collapse. These IPNs have high swelling ratios, benefiting various applications such as drug delivery. The IPNs sustain controlled drug release with the adjustable rates. Furthermore, these IPNs are adhesive to cells, supporting cell proliferation, long-term survival and migration. Notably, the IPNs inherit sericin’s photoluminescent property, enabling bioimaging in vivo. Together, our study indicates that the sericin-alginate IPN hydrogels may serve as a versatile platform for delivering cells and drugs, and suggests that sericin may be a building block broadly applicable for generating IPN networks with other biomaterials for diverse tissue engineering applications.

Three new 5-fold interpenetrating diamondoid frameworks constructed by rigid diimidazole and dicarboxylate ligands

NASA Astrophysics Data System (ADS)

Huo, Jianqiang; Yan, Shuai; Li, Haiqiang; Yu, Donghui; Arulsamy, Navamoney

2018-03-01

A series of three-dimensional coordination polymers, namely, [Cd(BIMB)(SCA)]n (1), [M(BIMB)(trans-CHDC)]n (2, M = Cd2+; 3, M = Co2+), where BIMB = 1,4-di(1H-imidazol-1-yl)benzene, SCA2- = succinate dianion, CHDC2- = cyclohexane-1,4-dicarboxylate dianion) are synthesized hydro/solvatothermal methods. The products are characterized by elemental analysis and single-crystal X-ray diffraction data. Both the dianion and BIMB bridge different pairs of the metal ions, the three complexes are polymeric and their three-dimensional topology feature a diamond-like metal-organic framework (MOF). Owing to the length of the two bridging ligands, moderate size voids are formed in the diamondoid networks. However, the voids are filled by mutual interpenetration of four independent equivalent frameworks in a 5-fold interpenetrating architecture, and there is no sufficient void volume available for any guest molecules. The phase purity and thermal stability of the compounds are verified by powder X-ray diffraction (PXRD) and thermogravimetric (TG) data. The solid-state fluorescence spectra for the 3d10 Cd2+ MOF's 1 and 2 reveal significant enhancement in their emission intensities in comparison to the non-metallated BIMB. The enhanced emission is attributed to perturbation of intra-ligand emission states due to Cd2+ coordination.

Comparison of precursor infiltration into polymer thin films via atomic layer deposition and sequential vapor infiltration using in-situ quartz crystal microgravimetry

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

Padbury, Richard P.; Jur, Jesse S., E-mail: jsjur@ncsu.edu

Previous research exploring inorganic materials nucleation behavior on polymers via atomic layer deposition indicates the formation of hybrid organic–inorganic materials that form within the subsurface of the polymer. This has inspired adaptations to the process, such as sequential vapor infiltration, which enhances the diffusion of organometallic precursors into the subsurface of the polymer to promote the formation of a hybrid organic–inorganic coating. This work highlights the fundamental difference in mass uptake behavior between atomic layer deposition and sequential vapor infiltration using in-situ methods. In particular, in-situ quartz crystal microgravimetry is used to compare the mass uptake behavior of trimethyl aluminummore » in poly(butylene terephthalate) and polyamide-6 polymer thin films. The importance of trimethyl aluminum diffusion into the polymer subsurface and the subsequent chemical reactions with polymer functional groups are discussed.« less

Antibiotic loading and release studies of LSMO nanoparticles embedded in an acrylic polymer

NASA Astrophysics Data System (ADS)

Biswas, Sonali; Keshri, Sunita; Goswami, Sudipta; Isaac, Jinu; Ganguly, Swastika; Perov, Nikolai

2016-12-01

In this paper, we present the drug loading and release works of ? (LSMO) manganite nanoparticles (NPs). The LSMO NPs, grown using the sol-gel method, were embedded in an acrylic interpenetrating polymer network to make the sample applicable for biomedical purposes. The results of scanning electron microscopy showed that these NPs were well dispersed in the polymer. The grain size of these NPs lies in the range of 25-45 nm, as confirmed by transmission electron microscopy. The measurements of DC magnetization and hysteresis loops reveal that the basic magnetic behaviour of the LSMO NPs remained almost unaltered even after embedding in polymer, but with lower saturation value of magnetization. The drug loading and release studies of the grown sample were carried out using an antibiotic, ciprofloxacin. The minimum inhibitory effect of the sample loaded with this drug has exhibited high activity against different strains of bacteria, comparable to the pure ciprofloxacin.

Attraction between Opposing Planar Dipolar Polymer Brushes

DOE PAGES

Mahalik, J. P.; Sumpter, Bobby G.; Kumar, Rajeev

2017-08-01

In this paper, we use a field theory approach to study the effects of permanent dipoles on interpenetration and free energy changes as a function of distance between two identical planar polymer brushes. Melts (i.e., solvent-free) and solvated brushes made up of polymers grafted on nonadsorbing substrates are studied. In particular, the weak coupling limit of the dipolar interactions is considered, which leads to concentration-dependent pairwise interactions, and the effects of orientational order are neglected. It is predicted that a gradual increase in the dipole moment of the polymer segments can lead to attractive interactions between the brushes at intermediatemore » separation distances. Finally, because classical theory of polymer brushes based on the strong stretching limit (SSL) and the standard self-consistent field theory (SCFT) simulations using the Flory’s χ parameter always predicts repulsive interactions at all separations, our work highlights the importance of dipolar interactions in tailoring and accurately predicting forces between polar polymeric interfaces in contact with each other.« less

Reinforcement of bacterial cellulose aerogels with biocompatible polymers.

PubMed

Pircher, N; Veigel, S; Aigner, N; Nedelec, J M; Rosenau, T; Liebner, F

2014-10-13

Bacterial cellulose (BC) aerogels, which are fragile, ultra-lightweight, open-porous and transversally isotropic materials, have been reinforced with the biocompatible polymers polylactic acid (PLA), polycaprolactone (PCL), cellulose acetate (CA), and poly(methyl methacrylate) (PMMA), respectively, at varying BC/polymer ratios. Supercritical carbon dioxide anti-solvent precipitation and simultaneous extraction of the anti-solvent using scCO2 have been used as core techniques for incorporating the secondary polymer into the BC matrix and to convert the formed composite organogels into aerogels. Uniaxial compression tests revealed a considerable enhancement of the mechanical properties as compared to BC aerogels. Nitrogen sorption experiments at 77K and scanning electron micrographs confirmed the preservation (or even enhancement) of the surface-area-to-volume ratio for most of the samples. The formation of an open-porous, interpenetrating network of the second polymer has been demonstrated by treatment of BC/PMMA hybrid aerogels with EMIM acetate, which exclusively extracted cellulose, leaving behind self-supporting organogels. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Reinforcement of bacterial cellulose aerogels with biocompatible polymers

PubMed Central

Pircher, N.; Veigel, S.; Aigner, N.; Nedelec, J.M.; Rosenau, T.; Liebner, F.

2014-01-01

Bacterial cellulose (BC) aerogels, which are fragile, ultra-lightweight, open-porous and transversally isotropic materials, have been reinforced with the biocompatible polymers polylactic acid (PLA), polycaprolactone (PCL), cellulose acetate (CA), and poly(methyl methacrylate) (PMMA), respectively, at varying BC/polymer ratios. Supercritical carbon dioxide anti-solvent precipitation and simultaneous extraction of the anti-solvent using scCO2 have been used as core techniques for incorporating the secondary polymer into the BC matrix and to convert the formed composite organogels into aerogels. Uniaxial compression tests revealed a considerable enhancement of the mechanical properties as compared to BC aerogels. Nitrogen sorption experiments at 77 K and scanning electron micrographs confirmed the preservation (or even enhancement) of the surface-area-to-volume ratio for most of the samples. The formation of an open-porous, interpenetrating network of the second polymer has been demonstrated by treatment of BC/PMMA hybrid aerogels with EMIM acetate, which exclusively extracted cellulose, leaving behind self-supporting organogels. PMID:25037381

Electroactive semi-interpenetrating polymer networks architecture with tunable IR reflectivity

NASA Astrophysics Data System (ADS)

Chevrot, C.; Teyssié, D.; Verge, P.; Goujon, L.; Tran-Van, F.; Vidal, F.; Aubert, P. H.; Peralta, S.; Sauques, L.

2011-04-01

A promising alternative of multi-layered devices showing electrochromic properties results from the design of a self-supported semi-interpenetrating polymer network (semi-IPN) including an electronic conductive polymer (ECP) formed within. The formation of the ECP in the network has already been described by oxidative polymerization using iron trichloride as an oxidant and leading to conducting semi-IPN with mixed electronic and ionic conductivities as well as convenient mechanical properties. This presentation relates to the elaboration of such semi-IPN using polyethyleneoxide (PEO) network or a PEO/NBR (Nitrile Butadiene Rubber) IPN in which a linear poly (3,4-ethylenedioxythiophene) (PEDOT) is formed symmetrically and selectively as very thin layers very next to the two main faces of the film matrix. PEO/PEDOT semi-IPNs lead to interesting optical reflective properties in the IR between 0.8 and 25 μm. Reflectance contrasts up to 35 % is observed when, after swelling in an ionic liquid, a low voltage is applied between the two main faces of the film. However the low flexibility and brittleness of the film and a slow degradation in air at temperature up from 60°C prompted to replace the PEO matrix by a flexible PEO/NBR IPN one. Indeed, the combination of NBR and PEO in an IPN leads to materials possessing flexible properties, good ionic conductivity at 25°C as well as a better resistance to thermal ageing. Finally, NBR/PEO/PEDOT semi-IPNs allow observing comparable reflectance contrast in the IR range than those shown by PEO/PEDOT semi-IPNs.

Polymer matrix of fiber-reinforced composites: Changes in the semi-interpenetrating polymer network during the shelf life.

PubMed

Khan, Aftab A; Al-Kheraif, Abdulaziz A; Al-Shehri, Abdullah M; Säilynoja, Eija; Vallittu, Pekka K

2018-02-01

This laboratory study was aimed to characterize semi-interpenetrating polymer network (semi-IPN) of fiber-reinforced composite (FRC) prepregs that had been stored for up to two years before curing. Resin impregnated prepregs of everStick C&B (StickTech-GC, Turku, Finland) glass FRC were stored at 4°C for various lengths of time, i.e., two-weeks, 6-months and 2-years. Five samples from each time group were prepared with a light initiated free radical polymerization method, which were embedded to its long axis in self-curing acrylic. The nanoindentation readings on the top surface toward the core of the sample were made for five test groups, which were named as "stage 1-5". To evaluate the nanohardness and modulus of elasticity of the polymer matrix, a total of 4 slices (100µm each) were cut from stage 1 to stage 5. Differences in nanohardness values were evaluated with analysis of variance (ANOVA), and regression model was used to develop contributing effect of the material's different stages to the total variability in the nanomechanical properties. Additional chemical and thermal characterization of the polymer matrix structure of FRC was carried out. It was hypothesized that time of storage may have an influence on the semi-IPN polymer structure of the cured FRC. The two-way ANOVA test revealed that the storage time had no significant effect on the nanohardness of FRC (p = 0.374). However, a highly significant difference in nanohardness values was observed between the different stages of FRC (P<0.001). The regression coefficient suggests nanohardness increased on average by 0.039GPa for every storage group. The increased nanohardness values in the core region of 6-months and 2-years stored prepregs might be due to phase-segregation of components of semi-IPN structure of FRC prepregs before their use. This may have an influence to the surface bonding properties of the cured FRC. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chain Conformation near the Buried Interface in Nanoparticle-Stabilized Polymer Thin Films

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

Barkley, Deborah A.; Jiang, Naisheng; Sen, Mani

It is known that when nanoparticles are added to polymer thin films, they often migrate to the film-substrate interface and form an “immobile interfacial layer”, which has been believed as the origin of suppression of dewetting. We here report an alternative mechanism of dewetting suppression from the structural aspect of a polymer. Dodecane thiol-functionalized gold (Au) nanoparticles embedded in PS thin films prepared on Si substrates were used as a model. It was found that thermal annealing promotes irreversible polymer adsorption onto the substrate surface along with the surface migration of the nanoparticles. We also revealed that the surface migrationmore » causes additional nanoconfined space for the adsorbed polymer chains. As a result, the self-organization process of the strongly adsorbed polymer chains on the solid surface was so hindered that the chain conformations were randomized and expanded in the film normal direction. Here, the resultant chain conformation allows the interpenetration between free chains and the adsorbed chains, promoting adhesion and hence stabilizing the thin film.« less

Chain Conformation near the Buried Interface in Nanoparticle-Stabilized Polymer Thin Films

DOE PAGES

Barkley, Deborah A.; Jiang, Naisheng; Sen, Mani; ...

2017-09-26

It is known that when nanoparticles are added to polymer thin films, they often migrate to the film-substrate interface and form an “immobile interfacial layer”, which has been believed as the origin of suppression of dewetting. We here report an alternative mechanism of dewetting suppression from the structural aspect of a polymer. Dodecane thiol-functionalized gold (Au) nanoparticles embedded in PS thin films prepared on Si substrates were used as a model. It was found that thermal annealing promotes irreversible polymer adsorption onto the substrate surface along with the surface migration of the nanoparticles. We also revealed that the surface migrationmore » causes additional nanoconfined space for the adsorbed polymer chains. As a result, the self-organization process of the strongly adsorbed polymer chains on the solid surface was so hindered that the chain conformations were randomized and expanded in the film normal direction. Here, the resultant chain conformation allows the interpenetration between free chains and the adsorbed chains, promoting adhesion and hence stabilizing the thin film.« less

Peri-implant bone formation and implant integration strength of peptide-modified p(AAM-co-EG/AAC) interpenetrating polymer network-coated titanium implants.

PubMed

Barber, Thomas A; Ho, James E; De Ranieri, Aladino; Virdi, Amarjit S; Sumner, Dale R; Healy, Kevin E

2007-02-01

Interpenetrating polymer networks (IPNs) of poly (acrylamide-co-ethylene glycol/acrylic acid) functionalized with an -Arg-Gly-Asp- (RGD) containing 15 amino acid peptides, derived from rat bone sialoprotein (bsp-RGD(15), were grafted to titanium implants in an effort to modulate bone formation in the peri-implant region in the rat femoral ablation model. Bone-implant contact (BIC) and bone formation within the medullary canal were determined using microcomputed tomography at 2 and 4 weeks postimplantation. BIC for bsp-RGD(15)-IPN implants was enhanced relative to hydroxyapatite tricalcium phosphate (HA-TCP) coated implants, but was similar to all other groups. Aggregate bone formation neither indicated a dose-dependent effect of bsp-RGD(15) nor a meaningful trend. Mechanical testing of implant fixation revealed that only the HA-TCP coated implants supported significant (>1 MPa) interfacial shear strength, despite exhibiting lower overall BIC, an indication that bone ingrowth into the rougher coating was the primary mode of implant fixation. While no evidence was found to support the hypothesis that bsp-RGD(15)-modified IPN coated implants significantly impacted bone-implant bonding, these results point to the lack of correlation between in vitro studies employing primary osteoblasts and in vivo wound healing in the peri-implant region. Copyright 2006 Wiley Periodicals, Inc.

Characterization and preparation of p(U-MMA-An) interpenetrating polymer network damping and absorbing material.

PubMed

Liu, Jun; Li, Qingshan; Zhuo, Yuguo; Hong, Wei; Lv, Wenfeng; Xing, Guangzhong

2014-06-01

P(U-MMA-ANI) interpenetrating polymer network (IPN) damping and absorbing material is successfully synthesized by PANI particles served as an absorbing agent with the microemulsion polymerization and P(U-MMA) foam IPN network structure for substrate materials with foaming way. P(U-MMA-ANI) IPN is characterized by the compression mechanical performance testing, TG-DSC, and DSC. The results verify that the P(U-MMA) IPN foam damping material has a good compressive strength and compaction cycle property, and the optimum content of PMMA was 40% (mass) with which the SEM graphs do not present the phase separation on the macro level between PMMA and PU, while the phase separation was observed on the micro level. The DTG curve indicates that because of the formation of P(U-MMA) IPN, the decomposition temperature of PMMA and the carbamate in PU increases, while that of the polyol segment in PU has almost no change. P(U-MMA-ANI) IPN foam damping and absorbing material is obtained by PANI particles served as absorbing agent in the form of filler, and PMMA in the form of micro area in substrate material. When the content of PANI was up to 2.0% (mass), the dissipation factor of composites increased, and with the increasing of frequency the dissipation factor increased in a straight line.

Characterization and swelling-deswelling properties of wheat straw cellulose based semi-IPNs hydrogel.

PubMed

Liu, Jia; Li, Qian; Su, Yuan; Yue, Qinyan; Gao, Baoyu

2014-07-17

A novel wheat straw cellulose-g-poly(potassium acrylate)/polyvinyl alcohol (WSC-g-PKA/PVA) semi-interpenetrating polymer networks (semi-IPNs) hydrogel was prepared by polymerizing wheat straw and an aqueous solution of acrylic acid (AA), and further semi-interpenetrating with PVA occurred during the chemosynthesis. The swelling and deswelling properties of WSC-g-PKA/PVA semi-IPNs hydrogel and WSC-g-PKA hydrogel were studied and compared in various pH solutions, salt solutions, temperatures, particle sizes and ionic strength. The results indicated that both hydrogels had the largest swelling capacity at pH=6, and the effect of ions on the swelling of hydrogels was in the order: Na(+)>K(+)>Mg(2+)>Ca(2+). The Schott's pseudo second order model can be effectively used to evaluate swelling kinetics of hydrogels. Moreover, the semi-IPNs hydrogel had improved swelling-deswelling properties compared with that of WSC-g-PKA hydrogel. Copyright © 2014 Elsevier Ltd. All rights reserved.

Shell-corona microgels from double interpenetrating networks.

PubMed

Rudyak, Vladimir Yu; Gavrilov, Alexey A; Kozhunova, Elena Yu; Chertovich, Alexander V

2018-04-18

Polymer microgels with a dense outer shell offer outstanding features as universal carriers for different guest molecules. In this paper, microgels formed by an interpenetrating network comprised of collapsed and swollen subnetworks are investigated using dissipative particle dynamics (DPD) computer simulations, and it is found that such systems can form classical core-corona structures, shell-corona structures, and core-shell-corona structures, depending on the subchain length and molecular mass of the system. The core-corona structures consisting of a dense core and soft corona are formed at small microgel sizes when the subnetworks are able to effectively separate in space. The most interesting shell-corona structures consist of a soft cavity in a dense shell surrounded with a loose corona, and are found at intermediate gel sizes; the area of their existence depends on the subchain length and the corresponding mesh size. At larger molecular masses the collapsing network forms additional cores inside the soft cavity, leading to the core-shell-corona structure.

Preparation and Reinforcement of Dual-Porous Biocompatible Cellulose Scaffolds for Tissue Engineering.

PubMed

Pircher, Nicole; Fischhuber, David; Carbajal, Leticia; Strauß, Christine; Nedelec, Jean-Marie; Kasper, Cornelia; Rosenau, Thomas; Liebner, Falk

2015-09-01

1Biocompatible cellulose-based aerogels composed of nanoporous struts, which embed interconnected voids of controlled micron-size, have been prepared employing temporary templates of fused porogens, reinforcement by interpenetrating PMMA networks and supercritical carbon dioxide drying. Different combinations of cellulose solvent (Ca(SCN) 2 /H 2 O/LiCl or [EMIm][OAc]/DMSO) and anti-solvent (EtOH), porogen type (paraffin wax or PMMA spheres) and porogen size (various fractions in the range of 100-500 μm) as well as intensity of PMMA reinforcement have been investigated to tailor the materials for cell scaffolding applications. All aerogels exhibited an open and dual porosity (micronporosity >100 μm and nanoporosity extending to the low micrometer range). Mechanical properties of the dual-porous aerogels under compressive stress were considerably improved by introduction of interpenetrating PMMA networks. The effect of the reinforcing polymer on attachment, spreading, and proliferation of NIH 3T3 fibroblast cells, cultivated on selected dual-porous aerogels to pre-evaluate their biocompatibility was similarly positive.

Enthalpic and Entropic Competition in Blends of Self-Suspended Hairy Nanoparticles

NASA Astrophysics Data System (ADS)

Choudhury, Snehashis; Agrawal, Akanksha; Archer, Lynden

Self-suspended hairy nanoparticles, where polymer chains are grafted onto nanoparticles, have attracted significant recent attention. These materials have been reported to manifest several interesting phenomena like thermal jamming, slowing-down of polymer chain dynamics, as well as small-strain stress overshoots during start-up of steady shear. The entropic penalty on tethered polymers produced by the requirement that they fill the space between the nanoparticle cores explain most of these behaviors. Here, we show that the entropic attraction between tethered polymer chains can be manipulated in mixtures of hairy nanoparticles using different polymer chemistry to design materials with unusual characteristics. Specifically, the degree of interpenetration of polymer chains can be controlled by tuning their interaction parameter (χ) . For SiO2-PEG/SiO2-PMMA blends, oscillatory rheological measurements show that the plateau modulus and yielding energy are significantly increased, while an opposite effect is seen with SiO2-PEG/SiO2-PI blends. More subtle effects of this enthalpy-entropy competition are well captured in Dielectric Spectroscopy measurements and SAXS experiments that can be used to quantify the degree of stretch and interdigitation of polymer chains.

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

Mahalik, J. P.; Sumpter, Bobby G.; Kumar, Rajeev

In this paper, we use a field theory approach to study the effects of permanent dipoles on interpenetration and free energy changes as a function of distance between two identical planar polymer brushes. Melts (i.e., solvent-free) and solvated brushes made up of polymers grafted on nonadsorbing substrates are studied. In particular, the weak coupling limit of the dipolar interactions is considered, which leads to concentration-dependent pairwise interactions, and the effects of orientational order are neglected. It is predicted that a gradual increase in the dipole moment of the polymer segments can lead to attractive interactions between the brushes at intermediatemore » separation distances. Finally, because classical theory of polymer brushes based on the strong stretching limit (SSL) and the standard self-consistent field theory (SCFT) simulations using the Flory’s χ parameter always predicts repulsive interactions at all separations, our work highlights the importance of dipolar interactions in tailoring and accurately predicting forces between polar polymeric interfaces in contact with each other.« less

A new three-dimensional bis(benzimidazole)-based cadmium(II) coordination polymer

NASA Astrophysics Data System (ADS)

Hao, Shao Yun; Hou, Suo Xia; Hao, Zeng Chuan; Cui, Guang Hua

2018-01-01

A new coordination polymer (CP), formulated as [Cd(L)(DCTP)]n (1) (L = 1,1‧-(1,4-butanediyl)bis(2-methylbenzimidazole), H2DCTP = 2,5-dichloroterephthalic acid), was synthesized under hydrothermal conditions and the performance as luminescent probe was also investigated. Single-crystal X-ray diffraction reveals CP 1 is a 3D 3-fold interpenetrated dia network with large well-defined pores. It is found that CP 1 revealed highly sensitive luminescence sensing for Fe3 + ions in acetonitrile solution with a high quenching efficiency of KSV = 2541.238 L·mol- 1 and a low detection limit of 3.2 μM (S/N = 3). Moreover, the photocatalytic efficiency of 1 for degradation of methylene blue could reach 82.8% after 135 min. Therefore, this coordination polymer could be viewed as multifunctional material for selectively sensing Fe3 + ions and effectively degrading dyes.

Zinc coordination polymers containing substituted isophthalate ligands and fragments from in situ hydrolysis of 4-pyridylisonicotinamide

NASA Astrophysics Data System (ADS)

O'Donovan, Megan E.; LaDuca, Robert L.

2015-03-01

Hydrothermal treatment of zinc nitrate, a 5-substituted isophthalic acid, and 4-pyridylisonicotinamide (4-pina) resulted in crystalline coordination polymers that incorporated different fragments formed by in situ hydrolysis of the 4-pina precursor. These materials were characterized by single crystal X-ray diffraction. In the case of {[4-ampyrH]2[Zn(hip)2]·H2O}n (1, 4-ampyrH = 4-aminopyridinium, hip = 5-hydroxyisophthalate), anionic [Zn(hip)2]n2n- (4,4) grid layers co-crystallize with protonated 4-ampyr cations. Using 5-nitroisophthalic acid (H2nip), [Zn7(isonic)4(OH)6(nip)2]n (2, isonic = isonicotinate) was formed. This material manifests [Zn7(OH)6]n cationic inorganic chain motifs linked by isonic and nip ligands into a non-interpenetrated 3-D coordination polymer network with pcu topology. Luminescent behavior is attributed to intra-ligand molecular orbital transitions.

Polymer-Cement Composites Containing Waste Perlite Powder

PubMed Central

Łukowski, Paweł

2016-01-01

Polymer-cement composites (PCCs) are materials in which the polymer and mineral binder create an interpenetrating network and co-operate, significantly improving the performance of the material. On the other hand, the need for the utilization of waste materials is a demand of sustainable construction. Various mineral powders, such as fly ash or blast-furnace slag, are successfully used for the production of cement and concrete. This paper deals with the use of perlite powder, which is a burdensome waste from the process of thermal expansion of the raw perlite, as a component of PCCs. The results of the testing of the mechanical properties of the composite and some microscopic observations are presented, indicating that there is a possibility to rationally and efficiently utilize waste perlite powder as a component of the PCC. This would lead to creating a new type of building material that successfully meets the requirements of sustainable construction. PMID:28773961

Synchrotron-based X-ray Fluorescence Microscopy in Conjunction with Nanoindentation to Study Molecular-Scale Interactions of Phenol-Formaldehyde in Wood Cell Walls

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

Jakes, Joseph E.; Hunt, Chris G.; Yelle, Daniel J.

Understanding and controlling molecular-scale interactions between adhesives and wood polymers are critical to accelerate the development of improved adhesives for advanced wood-based materials. The submicrometer resolution of synchrotron-based X-ray fluorescence microscopy (XFM) was found capable of mapping and quantifying infiltration of Br-labeled phenolformaldehyde (BrPF) into wood cell walls. Cell wall infiltration of five BrPF adhesives with different average molecular weights (MWs) was mapped. Nanoindentation on the same cell walls was performed to assess the effects of BrPF infiltration on cell wall hygromechanical properties. For the same amount of weight uptake, lower MW BrPF adhesives were found to be more effectivemore » at decreasing moisture-induced mechanical softening. This greater effectiveness of lower MW phenolic adhesives likely resulted from their ability to more intimately associate with water sorption sites in the wood polymers. Evidence also suggests that a BrPF interpenetrating polymer network (IPN) formed within the wood polymers, which might also decrease moisture sorption by mechanically restraining wood polymers during swelling.« less

Tactile Feedback Display with Spatial and Temporal Resolutions

PubMed Central

Vishniakou, Siarhei; Lewis, Brian W.; Niu, Xiaofan; Kargar, Alireza; Sun, Ke; Kalajian, Michael; Park, Namseok; Yang, Muchuan; Jing, Yi; Brochu, Paul; Sun, Zhelin; Li, Chun; Nguyen, Truong; Pei, Qibing; Wang, Deli

2013-01-01

We report the electronic recording of the touch contact and pressure using an active matrix pressure sensor array made of transparent zinc oxide thin-film transistors and tactile feedback display using an array of diaphragm actuators made of an interpenetrating polymer elastomer network. Digital replay, editing and manipulation of the recorded touch events were demonstrated with both spatial and temporal resolutions. Analog reproduction of the force is also shown possible using the polymer actuators, despite of the high driving voltage. The ability to record, store, edit, and replay touch information adds an additional dimension to digital technologies and extends the capabilities of modern information exchange with the potential to revolutionize physical learning, social networking, e-commerce, robotics, gaming, medical and military applications. PMID:23982053

Tactile feedback display with spatial and temporal resolutions.

PubMed

Vishniakou, Siarhei; Lewis, Brian W; Niu, Xiaofan; Kargar, Alireza; Sun, Ke; Kalajian, Michael; Park, Namseok; Yang, Muchuan; Jing, Yi; Brochu, Paul; Sun, Zhelin; Li, Chun; Nguyen, Truong; Pei, Qibing; Wang, Deli

2013-01-01

We report the electronic recording of the touch contact and pressure using an active matrix pressure sensor array made of transparent zinc oxide thin-film transistors and tactile feedback display using an array of diaphragm actuators made of an interpenetrating polymer elastomer network. Digital replay, editing and manipulation of the recorded touch events were demonstrated with both spatial and temporal resolutions. Analog reproduction of the force is also shown possible using the polymer actuators, despite of the high driving voltage. The ability to record, store, edit, and replay touch information adds an additional dimension to digital technologies and extends the capabilities of modern information exchange with the potential to revolutionize physical learning, social networking, e-commerce, robotics, gaming, medical and military applications.

Process for controlling morphology and improving thermal mechanical performance of high performance interpenetrating and semiinterpenetrating polymer networks

NASA Technical Reports Server (NTRS)

Pater, Ruth H. (Inventor); Hansen, Marion G. (Inventor)

1998-01-01

In the process of the present invention, a non-polar, aprotic solvent is removed from an oligomer/polymer solution by freeze-drying in order to produce IPNs and semi-IPNs. By thermally quenching the solution to a solid in a short length of time, the size of the minor constituent-rich regions is greatly reduced as they are excluded along with the major constituent from the regions of crystallizing solvent. The use of this process sequence of controlling phase morphology provides IPNs and semi-IPNs with improved fracture toughness, microcracking resistance, and other physical-mechanical properties as compared to IPNs and semi-IPNs formed when the solvent is evaporated rather than sublimed.

Tactile Feedback Display with Spatial and Temporal Resolutions

NASA Astrophysics Data System (ADS)

Vishniakou, Siarhei; Lewis, Brian W.; Niu, Xiaofan; Kargar, Alireza; Sun, Ke; Kalajian, Michael; Park, Namseok; Yang, Muchuan; Jing, Yi; Brochu, Paul; Sun, Zhelin; Li, Chun; Nguyen, Truong; Pei, Qibing; Wang, Deli

2013-08-01

We report the electronic recording of the touch contact and pressure using an active matrix pressure sensor array made of transparent zinc oxide thin-film transistors and tactile feedback display using an array of diaphragm actuators made of an interpenetrating polymer elastomer network. Digital replay, editing and manipulation of the recorded touch events were demonstrated with both spatial and temporal resolutions. Analog reproduction of the force is also shown possible using the polymer actuators, despite of the high driving voltage. The ability to record, store, edit, and replay touch information adds an additional dimension to digital technologies and extends the capabilities of modern information exchange with the potential to revolutionize physical learning, social networking, e-commerce, robotics, gaming, medical and military applications.

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.

Injectable and inherently vascularizing semi-interpenetrating polymer network for delivering cells to the subcutaneous space.

PubMed

Mahou, Redouan; Zhang, David K Y; Vlahos, Alexander E; Sefton, Michael V

2017-07-01

Injectable hydrogels are suitable for local cell delivery to the subcutaneous space, but the lack of vasculature remains a limiting factor. Previously we demonstrated that biomaterials containing methacrylic acid promoted vascularization. Here we report the preparation of a semi-interpenetrating polymer network (SIPN), and its evaluation as an injectable carrier to deliver cells and generate blood vessels in a subcutaneous implantation site. The SIPN was prepared by reacting a blend of vinyl sulfone-terminated polyethylene glycol (PEG-VS) and sodium polymethacrylate (PMAA-Na) with dithiothreitol. The swelling of SIPN was sensitive to the PMAA-Na content but only small differences in gelation time, permeability and stiffness were noted. SIPN containing 20 mol% PMAA-Na generated a vascular network in the surrounding tissues, with 2-3 times as many vessels as was obtained with 10 mol% PMAA-Na or PEG alone. Perfusion studies showed that the generated vessels were perfused and connected to the host vasculature as early as seven days after transplantation. Islets embedded in SIPN were viable and responsive to glucose stimulation in vitro. In a proof of concept study in a streptozotocin-induced diabetic mouse model, a progressive return to normoglycemia was observed and the presence of insulin positive islets was confirmed when islets were embedded in SIPN prior to delivery. Our approach proposes a biomaterial-mediated strategy to deliver cells while enhancing vascularization. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development of biopolymers based interpenetrating polymeric network of capecitabine: A drug delivery vehicle to extend the release of the model drug.

PubMed

Upadhyay, Mansi; Adena, Sandeep Kumar Reddy; Vardhan, Harsh; Yadav, Sarita K; Mishra, Brahmeshwar

2018-04-27

The research aims the development and optimization of capecitabine loaded interpenetrating polymeric network by ionotropic gelation method using polymers locust bean gum and sodium alginate by QbD approach. FMEA was performed to recognize the risks influencing CQAs. BBD was applied to study the effect of factors (polymer ratio, amount of cross-linker and curing time) on responses (particle size, % drug entrapment and % drug release). Polynomial equations and 3-D graphs were plotted to relate between factors and responses. The results of the optimized batch viz. particle size (457.92 ± 1.6 μm), % drug entrapment (74.11 ± 3.1%) and % drug release (90.23 ± 2.1%) were close to the predicted values generated by Minitab® 17. Characterization techniques SEM, EDX, FTIR, DSC and XRD were also performed for the optimized batch. To study the water transport inside IPN microbeads, swelling study was done. In vitro drug release of optimized batch showed controlled drug release for 12 h. Pharmacokinetic study carried out following oral administration in Albino Wistar rats exhibited that optimized microbeads had better PK parameters than free drug. In vitro cytotoxicity against HT-29 cells revealed significant reduction of the cell growth when treated with optimized formulation indicating IPN microbeads as effective dosage form for treating colon cancer. Copyright © 2018. Published by Elsevier B.V.

Semi-interpenetrating solid polymer electrolyte based on thiol-ene cross-linker for all-solid-state lithium batteries

NASA Astrophysics Data System (ADS)

Suk, Jungdon; Lee, Yu Hwa; Kim, Do Youb; Kim, Dong Wook; Cho, Song Yun; Kim, Ji Man; Kang, Yongku

2016-12-01

We developed highly promising solid polymer electrolytes (SPEs) based on a novel cross-linker containing star-shaped phosphazene with poly(ethylene oxide) (PEO) branches with very high ionic conductivity (7.6 × 10-4 S cm-1), improved mechanical stability, and good electrochemical stability for all-solid-state lithium batteries. In particular, allyl groups were introduced at the ends of the cross-linker in order to overcome the easy self-polymerization of existing cross-linking acrylate end groups. A novel semi-interpenetrating network (semi-IPN) SPE was prepared by in-situ radical polymerization of a precursor solution containing lithium salt, poly(ethylene glycol) dimethyl ether as a plasticizer, and a mixture of pentaerythritol tetrakis(3-mercaptopropionate) and a synthesized hexakis(allyloxy)cyclotriphosphazene (thiol-ene PAL) as the cross-linker. Batteries employing LiFePO4 as the cathode, lithium foil as the anode, and the SPE thin film as the electrolyte were assembled and tested. At ambient temperature, the initial discharge capacity was 147 mAh/g at 0.1 °C and 132 mAh/g at 0.5 °C, and 97% of the capacity was retained at the 100th cycle. All-solid-state pouch-package lithium cells assembled with the SPEs exhibited stable electrochemical performance, even under a severely wrinkled state. These outstanding properties of SPEs based on thiol-ene PAL demonstrate feasibility for practical battery applications with improved reliability and safety.

Synthesis and Properties of pH-, Thermo-, and Salt-Sensitive Modified Poly(aspartic acid)/Poly(vinyl alcohol) IPN Hydrogel and Its Drug Controlled Release.

PubMed

Lu, Jingqiong; Li, Yinhui; Hu, Deng; Chen, Xiaoling; Liu, Yongmei; Wang, Liping; Zhao, Yansheng

2015-01-01

Modified poly(aspartic acid)/poly(vinyl alcohol) interpenetrating polymer network (KPAsp/PVA IPN) hydrogel for drug controlled release was synthesized by a simple one-step method in aqueous system using poly(aspartic acid) grafting 3-aminopropyltriethoxysilane (KH-550) and poly(vinyl alcohol) (PVA) as materials. The hydrogel surface morphology and composition were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The thermal stability was analyzed by thermogravimetric analysis (TGA). The swelling properties and pH, temperature, and salt sensitivities of KPAsp, KPAsp/PVA semi-interpenetrating polymer network (semi-IPN), and KPAsp/PVA IPN hydrogels were also investigated. All of the three hydrogels showed ampholytic pH-responsive properties, and swelling behavior was also extremely sensitive to the temperature, ionic strength, and cationic species. Finally, the drug controlled release properties of the three hydrogels were evaluated and results indicated that three hydrogels could control drug release by external surroundings stimuli. The drug controlled release properties of KPAsp/PVA IPN hydrogel are the most outstanding, and the correlative measured release profiles of salicylic acid at 37°C were 32.6 wt% at pH = 1.2 (simulated gastric fluid) and 62.5 wt% at pH = 7.4 (simulated intestinal fluid), respectively. These results indicated that KPAsp/PVA IPN hydrogels are a promising carrier system for controlled drug delivery.

Recent Developments in Thiolated Polymeric Hydrogels for Tissue Engineering Applications.

PubMed

Gajendiran, Mani; Rhee, Jae-Sung; Kim, Kyobum

2018-02-01

This review focuses on the recent strategy in the preparation of thiolated polymers and fabrication of their hydrogel matrices. The mechanism involved in the synthesis of thiolated polymers and fabrication of thiolated polymer hydrogels is exemplified with suitable schematic representations reported in the recent literature. The 2-iminothiolane namely "Traut's reagent" has been widely used for effectively thiolating the natural polymers such as collagen and gelatin, which contain free amino group in their backbone. The free carboxylic acid group containing polymers such as hyaluronic acid and heparin have been thiolated by using the bifunctional molecules such as cysteamine and L-cysteine via N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide/N-hydroxysuccinimide (EDC/NHS) coupling reaction. The degree of thiolation in the polymer chain has been widely determined by using Ellman's assay method. The thiolated polymer hydrogels are prepared by disulfide bond formation (or) thiol-ene reaction (or) Michael-type addition reaction. The thiolated polymers such as thiolated gelatin are reacted with polyethylene glycol diacrylate for obtaining interpenetrating polymer network hydrogel scaffolds. Several in vitro cell culture experiments indicate that the developed thiolated polymer hydrogels exhibited biocompatibility and cellular mimicking properties. The developed hydrogel scaffolds efficiently support proliferation and differentiation of various cell types. In the present review article, the thiol-functionalized protein-based biopolymers, carbohydrate-based polymers, and some synthetic polymers have been covered with recently published research articles. In addition, the usage of new thiolated nanomaterials as a crosslinking agent for the preparation of three-dimensional tissue-engineered hydrogels is highlighted.

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

Ye, Gan; Zou, Kang-Yu; Yang, Ying

In this work, the rod-like ligand 1,4-bis(imidazol-1-yl)-benzene (bib) has been utilized as a building block to perform counterion researches on the structural diversities of coordination polymers. A series of new manganese compounds, ([Mn(bib){sub 3}(ClO{sub 4}){sub 2}](CHCl{sub 3}){sub 2}){sub n} (1), [Mn(bib){sub 2}(N{sub 3}){sub 2}]{sub n} (2), [Mn(bib){sub 2}(HCO{sub 2}){sub 2}]{sub n} (3), [Mn(bib){sub 2}(Ac){sub 2}]{sub n} (4), ([Mn(bib){sub 2}(CF{sub 3}SO{sub 3}){sub 2}](CH{sub 2}Cl{sub 2}){sub 4}){sub n} (5), and [Mn(bib){sub 2}(SO{sub 4})]{sub n} (6) have been successfully synthesized. Compound 1 shows a 3D interpenetrating α-Po network only based on the bib linker. Compounds 2 and 3 exhibit a 2D (4,4) layermore » with parallel and incline interpenetration, respectively. Compounds 4 and 5 display a parallel-packing 2D (4,4) layer with the porosity of 23.4% and 61.4%, respectively. Compound 6 furnishes a 3D α-Po framework with a 2D (4,4) layer pillared by the μ{sub 2}-SO{sub 4}{sup 2−} ion. The structural diversities among 1–6 have been carefully discussed, and the roles of counterions (from coordination affinity and molecular size) in the self-assembly of coordination polymers have also been well documented. Furthermore, magnetic properties of 6 have been carefully studied. - Graphical abstract: Six new compounds have been successfully synthesized. Structural studies reveal that the topology, entanglement and porosity are tunable by the counterion. Furthermore, the weak ferromagnetic coupling is conducted in 6. - Highlights: • Six new Mn{sup II} compounds have been synthesized. • Compounds 1–3 exhibit diverse interpenetrating frameworks. • Compounds 4 and 5 exhibit 3D packing porous architectures. • The tunable effect of counterion has been documented. • Magnetic properties of 6 have been studied by fitting the data.« less

Realization of highly efficient polymer solar cell based on PBDTTT-EFT and [71]PCBM

NASA Astrophysics Data System (ADS)

Bharti, Vishal; Chand, Suresh; Dutta, Viresh

2018-04-01

In this work, we have fabricated highly efficient polymer solar cells based on the blend of PBDTTT-EFT:PC71BM in the inverted device configuration. By using low temperature processed zinc oxide (ZnO) nanoparticles as an electron-transport layer (ETL) and 1,8-diiodooctane (DIO) as additive in chlorobenzene (CB) solvent we have achieved PCE of 9.43% with an excellent short-circuit current density (Jsc) of 17.6 mAcm-2, open circuit voltage (Voc) of 0.80 V and fill factor (FF) of 0.67. These results reveals that addition of 3% DIO additive in CB solvent improve the morphology (lower charge carrier recombination and better metal/organic semiconductor interface) and provide uniform interpenetrating networks in PBDTTT-EFT:PC71BM blend active layer.

Understanding and Controlling Nanoscale Morphology in Self-Assembled Semiconducting Materials

NASA Astrophysics Data System (ADS)

Kang, Hyeyeon

Self-assembled semiconducting materials have been rapidly developed for a range of applications. This work aims to control the morphology of nanostructured semiconductors to understand how their functions arise from the structural properties. The first part of this dissertation focuses on the formation of a bulk-heterojunction (BHJ) in the active layer of organic photovoltaics (OPV). A BHJ is a bicontinuous interpenetrating network of organic components. The phase separation of the electron donor and the acceptor is required to achieve a BHJ structure in the nanostructured morphology, which promotes an efficient charge transportation. The use of solvent additive is one of the strategies to control the spontaneous phase separation during the film formation. Low vapor pressure solvent additives are introduced to a polymer casting solution in a sequentially processed OPV system, to study the swelling effect on the phase separation. In particular, the change in crystallinity and vertical mixing will be intensively studied upon polymer swelling. As another strategy, we introduce a molecular structure change to fullerene derivatives. A small structural variation leads to a large enough contrast of their surface energy, which is attributed to different vertical phase separation in the active layer. It eventually allows us to examine photovoltaic performance and device physics. In the second part, mesoporous inorganic films are investigated by preparation from a nanocrystal solution or sol-gel precursors for solar energy applications. Mesoporous nanocrystal-based titania is synthesized for inorganic/organic hybrid solar cells. The effect of surface modification is examined by anchoring a fullerene derivative on to titania surface. 3D interconnected mesoporous tantalum nitride films are prepared via sol-gel method as photoanodes in solar water splitting. The simple synthetic method using polymer template enables us to successfully prepare nitride films with excellent pore periodicity. The porous tantalum nitride film is examined with photoelectrochemical measurement to investigate the correlation between nanostructuring and photocatalytic activity. For the final part of this dissertation, porous cobalt ferrite and cadmium sulfide films are studied using ellipsometric porosimetry. Understanding the nature of their pores allows us to tune the intrinsic properties of the materials or prove the newly designed synthetic method.

Preparation and Reinforcement of Dual‐Porous Biocompatible Cellulose Scaffolds for Tissue Engineering

PubMed Central

Pircher, Nicole; Fischhuber, David; Carbajal, Leticia; Strauß, Christine; Nedelec, Jean‐Marie; Kasper, Cornelia; Rosenau, Thomas

2015-01-01

1 Biocompatible cellulose‐based aerogels composed of nanoporous struts, which embed interconnected voids of controlled micron‐size, have been prepared employing temporary templates of fused porogens, reinforcement by interpenetrating PMMA networks and supercritical carbon dioxide drying. Different combinations of cellulose solvent (Ca(SCN)2/H2O/LiCl or [EMIm][OAc]/DMSO) and anti‐solvent (EtOH), porogen type (paraffin wax or PMMA spheres) and porogen size (various fractions in the range of 100–500 μm) as well as intensity of PMMA reinforcement have been investigated to tailor the materials for cell scaffolding applications. All aerogels exhibited an open and dual porosity (micronporosity >100 μm and nanoporosity extending to the low micrometer range). Mechanical properties of the dual‐porous aerogels under compressive stress were considerably improved by introduction of interpenetrating PMMA networks. The effect of the reinforcing polymer on attachment, spreading, and proliferation of NIH 3T3 fibroblast cells, cultivated on selected dual‐porous aerogels to pre‐evaluate their biocompatibility was similarly positive. PMID:26941565

Dynamic Coordination of Eu-Iminodiacetate to Control Fluorochromic Response of Polymer Hydrogels to Multistimuli.

PubMed

Weng, Gengsheng; Thanneeru, Srinivas; He, Jie

2018-03-01

New fluorochromic materials that reversibly change their emission properties in response to their environment are of interest for the development of sensors and light-emitting materials. A new design of Eu-containing polymer hydrogels showing fast self-healing and tunable fluorochromic properties in response to five different stimuli, including pH, temperature, metal ions, sonication, and force, is reported. The polymer hydrogels are fabricated using Eu-iminodiacetate (IDA) coordination in a hydrophilic poly(N,N-dimethylacrylamide) matrix. Dynamic metal-ligand coordination allows reversible formation and disruption of hydrogel networks under various stimuli which makes hydrogels self-healable and injectable. Such hydrogels show interesting switchable ON/OFF luminescence along with the sol-gel transition through the reversible formation and dissociation of Eu-IDA complexes upon various stimuli. It is demonstrated that Eu-containing hydrogels display fast and reversible mechanochromic response as well in hydrogels having interpenetrating polymer network. Those multistimuli responsive fluorochromic hydrogels illustrate a new pathway to make smart optical materials, particularly for biological sensors where multistimuli response is required. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solution-Processed Donor-Acceptor Polymer Nanowire Network Semiconductors For High-Performance Field-Effect Transistors

PubMed Central

Lei, Yanlian; Deng, Ping; Li, Jun; Lin, Ming; Zhu, Furong; Ng, Tsz-Wai; Lee, Chun-Sing; Ong, Beng S.

2016-01-01

Organic field-effect transistors (OFETs) represent a low-cost transistor technology for creating next-generation large-area, flexible and ultra-low-cost electronics. Conjugated electron donor-acceptor (D-A) polymers have surfaced as ideal channel semiconductor candidates for OFETs. However, high-molecular weight (MW) D-A polymer semiconductors, which offer high field-effect mobility, generally suffer from processing complications due to limited solubility. Conversely, the readily soluble, low-MW D-A polymers give low mobility. We report herein a facile solution process which transformed a lower-MW, low-mobility diketopyrrolopyrrole-dithienylthieno[3,2-b]thiophene (I) into a high crystalline order and high-mobility semiconductor for OFETs applications. The process involved solution fabrication of a channel semiconductor film from a lower-MW (I) and polystyrene blends. With the help of cooperative shifting motion of polystyrene chain segments, (I) readily self-assembled and crystallized out in the polystyrene matrix as an interpenetrating, nanowire semiconductor network, providing significantly enhanced mobility (over 8 cm2V−1s−1), on/off ratio (107), and other desirable field-effect properties that meet impactful OFET application requirements. PMID:27091315

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

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

Investigation of the interfacial properties of polyurethane/carbon nanotube hybrid composites: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Goclon, Jakub; Panczyk, Tomasz; Winkler, Krzysztof

2018-03-01

Considering the varied applications of hybrid polymer/carbon nanotube composites and the constant progress in the synthesis methods of such materials, we report a theoretical study of interfacial layer formation between pristine single-wall carbon nanotubes (SWCNTs) and polyurethane (PU) using molecular dynamic simulations. We vary the SWCNT diameter and the number of PU chains to examine various PU-SWCNT interaction patterns. Our simulations indicate the important role of intra-chain forces in PU. No regular polymeric structures could be identified on the carbon nanotube surface during the simulations. We find that increasing the SWCNT diameter results in stronger polymer binding. However, higher surface loadings of PU lead to stronger interpenetration by the polymeric segments; this effect is more apparent for SWCNTs with small diameters. Our core finding is that the attached PU binds most strongly to the carbon nanotubes with the largest diameters. Polymer dynamics reveal the loose distribution of PU chains in these systems.

Toughening and functionalization of bioactive ceramic and glass bone scaffolds by biopolymer coatings and infiltration: a review of the last 5 years.

PubMed

Philippart, Anahí; Boccaccini, Aldo R; Fleck, Claudia; Schubert, Dirk W; Roether, Judith A

2015-01-01

Inorganic scaffolds with high interconnected porosity based on bioactive glasses and ceramics are prime candidates for applications in bone tissue engineering. These materials however exhibit relatively low fracture strength and high brittleness. A simple and effective approach to improve the toughness is to combine the basic scaffold structure with polymer coatings or through the formation of interpenetrating polymer-bioactive ceramic microstructures. The polymeric phase can additionally serve as a carrier for growth factors and therapeutic drugs, thus adding biological functionalities. The present paper reviews the state-of-the art in the field of polymer coated and infiltrated bioactive inorganic scaffolds. Based on the notable combination of bioactivity, improved mechanical properties and drug or growth factor delivery capability, this scaffold type is a candidate for bone and osteochondral regeneration strategies. Remaining challenges for the improvement of the materials are discussed and opportunities to broaden the application potential of this scaffold type are also highlighted.

Aromatic carboxylate effect on dimensionality of three bis(benzimidazole)-based cobalt(II) coordination polymers: Syntheses, structures and properties

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

Zhang, Ju-Wen; Gong, Chun-Hua; Hou, Li-Li

2013-09-15

Three new metal-organic coordination polymers [Co(4-bbc){sub 2}(bbbm)] (1), [Co(3,5-pdc)(bbbm)]·2H{sub 2}O (2) and [Co(1,4-ndc)(bbbm)] (3) (4-Hbbc=4-bromobenzoic acid, 3,5-H{sub 2}pdc=3,5-pyridinedicarboxylic acid, 1,4-H{sub 2}ndc=1,4-naphthalenedicarboxylic acid and bbbm=1,1-(1,4-butanediyl)bis-1H-benzimidazole) were hydrothermally synthesized and structurally characterized. Polymer 1 is a 1D chain formed by the bbbm ligands and Co{sup II} ions. Polymer 2 exhibits a 2D network with a (3·4·5)(3{sup 2}·4·5·6{sup 2}·7{sup 4}) topology. Polymer 3 possesses a 3D three-fold interpenetrating framework. The versatile structures of title polymers indicate that the aromatic carboxylates have an important influence on the dimensionality of 1–3. Moreover, the thermal stability, electrochemical and luminescent properties of 1–3 were investigated. - graphicalmore » abstract: Three bis(benzimidazole)-based cobalt(II) coordination polymers tuned by aromatic carboxylates were hydrothermally synthesized and structurally characterized. The aromatic carboxylates play a key role in the dimensionality of three polymers. The electrochemical and luminescent properties of three polymers were investigated. Display Omitted - Highlights: • Three bis(benzimidazole)-based cobalt(II) coordination polymers tuned by aromatic carboxylates were obtained. • The aromatic carboxylates have an important influence on the dimensionality of three polymers. • The electrochemical and luminescent properties of three polymers were investigated.« less

Tuning the formations of metal-1,3,5-benzenetricarboxylate frameworks via the assistance of amino acids

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

Lei, Xiao-Ping; Lian, Ting-Ting; Chen, Shu-Mei, E-mail: csm@fzu.edu.cn

Seven new metal-1,3,5-benzenetricarboxylate coordination polymers have been synthesized by modification of auxiliary components during the assembly reactions. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by XRD and TGA. Interestingly, they show fascinating topological structures. Compounds 1 and 2 possess the undulating layer structure with 3-connected hcb network and (3,6)-connected kgd network. Compound 3 possesses three-dimensional (3D) pillared-layer structure with 3-connected 2-fold interpenetrating srs net. Compound 4 also has the 3D 2-fold interpenetrating pillared-layer structure; however, it has (3,5)-connected hms topology because the Cd(II) center is 5-connected. Compound 5 possess 3D structure through hydrogen bondingmore » interactions between ladder-like layers. Compounds 6 and 7 have the similar 3D frameworks with 4-connected umc net and (3,7)-connected (3.4.5)(3{sup 2}.4{sup 6}.5{sup 5}.6{sup 8}) topology, respectively. The photoluminescent properties of compounds 2–7 were also investigated. - Graphical abstract: Presented here are seven new metal-1,3,5-benzenetricarboxylate coordination polymers with diverse structures from 2D layers to 3D open frameworks. The synthesis and structural diversity of these compounds are determined by the additional amino acids as unusual buffering agents. - Highlights: • Structural diversity of metal-1,3,5-benzenetricarboxylate frameworks. • Tuning structural topologies of MOFs via the assistance of amino acids. • Amino acids as unusual buffering agents for the synthesis of MOFs.« less

Development and optimization of locust bean gum and sodium alginate interpenetrating polymeric network of capecitabine.

PubMed

Upadhyay, Mansi; Adena, Sandeep Kumar Reddy; Vardhan, Harsh; Pandey, Sureshwar; Mishra, Brahmeshwar

2018-03-01

The objective of the study was to develop interpenetrating polymeric network (IPN) of capecitabine (CAP) using natural polymers locust bean gum (LBG) and sodium alginate (NaAlg). The IPN microbeads were optimized by Box-Behnken Design (BBD) to provide anticipated particle size with good drug entrapment efficiency. The comparative dissolution profile of IPN microbeads of CAP with the marketed preparation proved an excellent sustained drug delivery vehicle. Ionotropic gelation method utilizing metal ion calcium (Ca 2+ ) as a cross-linker was used to prepare IPN microbeads. The optimization study was done by response surface methodology based Box-Behnken Design. The effect of the factors on the responses of optimized batch was exhibited through response surface and contour plots. The optimized batch was analyzed for particle size, % drug entrapment, pharmacokinetic study, in vitro drug release study and further characterized by FTIR, XRD, and SEM. To study the water uptake capacity and hydrodynamic activity of the polymers, swelling studies and viscosity measurement were performed, respectively. The particle size and % drug entrapment of the optimized batch was 494.37 ± 1.4 µm and 81.39 ± 2.9%, respectively, closer to the value predicted by Minitab 17 software. The in vitro drug release study showed sustained release of 92% for 12 h and followed anomalous drug release pattern. The derived pharmacokinetic parameters of optimized batch showed improved results than pure CAP. Thus, the formed IPN microbeads of CAP proved to be an effective extended drug delivery vehicle for the water soluble antineoplastic drug.

Synthesis, kinetics and characterizations of polyimide based semi-IPN systems

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

Tai, H.J.

1992-01-01

The PMR-15 polyimide is the leading matrix resin for high performance composites for use in high temperature and thermo-oxidative environments. This resin has superior mechanical properties, good processability and a high working temperature at around 300[degrees]C. It has the disadvantages of being brittle and high susceptibility to microcracking from thermal cycling that limit its widespread application. To improve the fracture toughness, a thermoplastic polyimide, LARC-TPI, and a thermoplastic poly (amide imide), Amoco AI-10, were added individually to PMR-15 resin to form sequential semi-interpenetrating polymer networks (semi-2-IPNs). the kinetics of imidization of LARC-TPI were studied using TGA technique. Both the solventmore » and the glass transition temperature were found to greatly affect the imidization kinetics. The kinetics could be well modeled by a two-step reaction: the first step being a second order reaction followed by a first order diffusion controlled reaction as the second step. The curing of PMR-15 and PMR-15/LARC-TPI semi-IPN was investigated by DSC. A first order reaction kinetics could describe the curing process adequately, implying that the reverse Diels-Alder reaction of the Norbornene end group was the rate controlling step. The glass transition temperature played an important role. The higher the fraction LARC-TPI, the higher the glass transition temperature of the semi-IPN prepolymer, and the slower the cure reaction. From a knowledge of kinetics, the molding cycle of PMR-15 and PMR-15/LARC-TPI semi-IPNs were determined. Both PMR-15/LARC-TPI and PMR-15/AI-10 semi-IPN systems exhibited much higher fracture toughness than PMR-15, but at the compromise of a reduction in the glass transition temperature. A single glass transition temperature for each semi-IPN was observed but there was presence of special intermolecular interaction. Tg measurements and IR spectroscopy indicated that both semi-IPN systems were compatible polymer pairs.« less

Hybrid nanocomposites of CdSe nanocrystals distributed in complexing thiophene-based copolymers.

PubMed

Aldakov, Dmitry; Jiu, Tonggang; Zagorska, Malgorzata; de Bettignies, Rémi; Jouneau, Pierre-Henri; Pron, Adam; Chandezon, Frédéric

2010-07-21

Two types of conjugated polymers were prepared with the goal to blend them with rod-like CdSe nanocrystals. The polymers of the first type were synthesized through copolymerization of 3-octylthiophene and 3-methylene-ethylcarboxylate-thiophene to give polythiophene with solubilizing alkyl groups and methylene ester functional groups (PE series). Post-polymerization hydrolysis of the ester type polymers yielded acid-type ones (PA series). Photoluminescence (PL) quenching in these polymers induced by their titration with nanocrystals solution was chosen as a measure of the polymer-nanocrystal interactions. PL of polyacids turned out to be more efficiently quenched as compared to the case of polymers with ester groups which was interpreted as an indication of better electronic communication between the hybrid components. Infrared (IR) spectroscopy confirmed efficient coordination of the carboxylic groups to CdSe. Voltammetric studies combined with UV-vis spectroelectrochemistry enabled the determination of energy levels alignment of the molecular composite components which turned out to be of staggered type-appropriate for photovoltaic applications. The obtained blends of polyacids with CdSe nanocrystals, when studied by transmission electron microscopy (TEM), revealed the presence of an interpenetrating network in which nanorods were homogeneously distributed within the polymer matrix without any indication of agglomerates formation both on the film surface and in the cross-section. Blends with polymers containing ester groups were less homogeneous which could be explained by weaker polymer-nanocrystals interactions. Photovoltaic cells based on these hybrid materials are also discussed.

Two novel penetrating coordination polymers based on flexible S-containing dicarboxylate acid with sensing properties towards Fe3+ and Cr2O72- ions

NASA Astrophysics Data System (ADS)

Chen, Zhiwei; Mi, Xiuna; Wang, Suna; Lu, Jing; Li, Yunwu; Li, Dacheng; Dou, Jianmin

2018-05-01

Two new coordination polymers (CPs), namely, {[Zn(L)(bpp)]·DMF}n (1) and {[Zn(L)(bpe)]·DMF}n (2) (L = 2,2'-[benzene-1,3-diylbis(methanediylsulfanediyl)]dibenzoic acid, bpp= 1,3-bis(4-pyridyl)propane, bpe = 1,2-Bis(4-pyridyl)ethylene, DMF = N,N-Dimethylformamide), have been solvothermally synthesized and fully characterized. Complex 1 displays a 2D→2D three-fold"false" interpenetrating structure while complex 2 possesses a novel 3-D 4-connected structure with fascinating self-penetrating moieties. The luminescence studies reveal that these complexes exhibited excellent selectivity for Fe3+ and Cr2O72- ions in DMF. The sensing mechanism was investigated through PXRD, XPS , EDS mapping measurements, and discussed in details.

In situ creation of reactive polymer nanoparticles and resulting polymer layers formed at the interfaces of liquid crystals (Conference Presentation)

NASA Astrophysics Data System (ADS)

Kang, Shin-Woong; Kundu, Sudarshan; Park, Heung-Shik; Oh, Keun Chan; Lyu, Jae Jin

2017-02-01

We report the in situ creation of reactive polymer nanoparticles and resulting polymer networks formed at the interfaces of liquid crystals. It is known that polymerization-induced phase separation proceeds in two distinct regimes depending on the concentration of monomer. For a high monomer concentration, phase separation occurs mainly through the spinodal decomposition process, consequently resulting in interpenetrating polymer networks. For a dilute system, however, the phase separation mainly proceeds and completes in the binodal decomposition regime. The system resembles the aggregation process of colloidal particle. In this case, the reaction kinetics is limited by the reaction between in situ created polymer aggregates and hence the network morphologies are greatly influenced by the diffusion of reactive polymer particles. The thin polymer layers localized at the surface of substrate are inevitably observed and can be comprehended by the interfacial adsorption and further cross-linking reaction of reactive polymer aggregates at the interface. This process provides a direct perception on understanding polymer stabilized liquid crystals accomplished by the interfacial polymer layer. The detailed study has been performed for an extremely dilute condition (below 0.5 wt%) by employing systematic experimental approaches. Creation and growth of polymer nanoparticles have been measured by particle size analyzer. The interfacial localization of polymer aggregates and resulting interfacial layer formation with a tens of nanometer scale have been exploited at various interfaces such as liquid-solid, liquid-liquid, and liquid-gas interfaces. The resulting interfacial layers have been characterized by using fuorescent confocal microscope and field emission scanning electron microscope. The detailed processes of the polymer stabilized vertically aligned liquid crystals will be discussed in support of the reported study.

Advanced composite structural concepts and materials technologies for primary aircraft structures: Advanced material concepts

NASA Technical Reports Server (NTRS)

Lau, Kreisler S. Y.; Landis, Abraham L.; Chow, Andrea W.; Hamlin, Richard D.

1993-01-01

To achieve acceptable performance and long-term durability at elevated temperatures (350 to 600 F) for high-speed transport systems, further improvements of the high-performance matrix materials will be necessary to achieve very long-term (60,000-120,000 service hours) retention of mechanical properties and damage tolerance. This report emphasizes isoimide modification as a complementary technique to semi-interpenetrating polymer networks (SIPN's) to achieve greater processibility, better curing dynamics, and possibly enhanced thermo-mechanical properties in composites. A key result is the demonstration of enhanced processibility of isoimide-modified linear and thermo-setting polyimide systems.

Modification of epoxy-reinforced glass-cloth composites with a perfluorinated alkyl ether elastomer

NASA Technical Reports Server (NTRS)

Rosser, R. W.; Chen, T. S.; Taylor, M.

1984-01-01

A perfluorinated alkyl ether diacyl fluoride prepolymer (molecular weight about 1500) was coreacted with Epon 828 epoxy resin and diamino diphenyl sulfone to obtain an elastomer-toughened, glass-cloth composite. Improvements in flexural toughness, impact resistance, and water resistance, without loss of strength, modulus of elasticity or a lowering of the glass-transition temperature, were realized over those of the unmodified composite. Factors concerning optimization of the process are discussed. Results suggest that a simultaneously interpenetrating polymer network may be formed which gives rise to a measured improvement in composite mechanical properties.

Sequential intravenous injection of anionic polymer and cationic lipoplex of siRNA could effectively deliver siRNA to the liver.

PubMed

Hattori, Yoshiyuki; Arai, Shohei; Okamoto, Ryou; Hamada, Megumi; Kawano, Kumi; Yonemochi, Etsuo

2014-12-10

In this study, we developed novel siRNA transfer method to the liver by sequential intravenous injection of anionic polymer and cationic liposome/cholesterol-modified siRNA complex (cationic lipoplex). When cationic lipoplex was intravenously injected into mice, the accumulation of siRNA was mainly observed in the lungs. In contrast, when cationic lipoplex was intravenously injected at 1 min after intravenous injection of poly-L-glutamic acid (PGA) or chondroitin sulfate C (CS), siRNA was accumulated in the liver. In terms of suppression of gene expression in vivo, apolipoprotein B (ApoB) mRNA in the liver and low-density-lipoprotein (LDL) and very low-density-lipoprotein (VLDL) cholesterol level in serum were reduced at 48 h after single sequential injection of PGA or CS plus cationic lipoplex of cholesterol-modified ApoB siRNA. Furthermore, sequential injections of PGA plus cationic lipoplex of cholesterol-modified luciferase siRNA could reduce luciferase activity in tumor xenografts bearing liver metastasis of human breast tumor MCF-7-Luc. From these findings, sequential injection of anionic polymer and cationic lipoplex of siRNA might produce a systemic vector of siRNA to the liver. Copyright © 2014 Elsevier B.V. All rights reserved.

Self-Assembled Polymeric Ionic Liquid-Functionalized Cellulose Nano-crystals: Constructing 3D Ion-conducting Channels Within Ionic Liquid-based Composite Polymer Electrolytes.

PubMed

Shi, Qing Xuan; Xia, Qing; Xiang, Xiao; Ye, Yun Sheng; Peng, Hai Yan; Xue, Zhi Gang; Xie, Xiao Lin; Mai, Yiu-Wing

2017-09-04

Composite polymeric and ionic liquid (IL) electrolytes are some of the most promising electrolyte systems for safer battery technology. Although much effort has been directed towards enhancing the transport properties of polymer electrolytes (PEs) through nanoscopic modification by incorporating nano-fillers, it is still difficult to construct ideal ion conducting networks. Here, a novel class of three-dimensional self-assembled polymeric ionic liquid (PIL)-functionalized cellulose nano-crystals (CNC) confining ILs in surface-grafted PIL polymer chains, able to form colloidal crystal polymer electrolytes (CCPE), is reported. The high-strength CNC nano-fibers, decorated with PIL polymer chains, can spontaneously form three-dimensional interpenetrating nano-network scaffolds capable of supporting electrolytes with continuously connected ion conducting networks with IL being concentrated in conducting domains. These new CCPE have exceptional ionic conductivities, low activation energies (close to bulk IL electrolyte with dissolved Li salt), high Li + transport numbers, low interface resistances and improved interface compatibilities. Furthermore, the CCPE displays good electrochemical properties and a good battery performance. This approach offers a route to leak-free, non-flammable and high ionic conductivity solid-state PE in energy conversion devices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Syringe injectable electronics

PubMed Central

Hong, Guosong; Zhou, Tao; Jin, Lihua; Duvvuri, Madhavi; Jiang, Zhe; Kruskal, Peter; Xie, Chong; Suo, Zhigang; Fang, Ying; Lieber, Charles M.

2015-01-01

Seamless and minimally-invasive three-dimensional (3D) interpenetration of electronics within artificial or natural structures could allow for continuous monitoring and manipulation of their properties. Flexible electronics provide a means for conforming electronics to non-planar surfaces, yet targeted delivery of flexible electronics to internal regions remains difficult. Here, we overcome this challenge by demonstrating syringe injection and subsequent unfolding of submicrometer-thick, centimeter-scale macroporous mesh electronics through needles with a diameter as small as 100 micrometers. Our results show that electronic components can be injected into man-made and biological cavities, as well as dense gels and tissue, with > 90% device yield. We demonstrate several applications of syringe injectable electronics as a general approach for interpenetrating flexible electronics with 3D structures, including (i) monitoring of internal mechanical strains in polymer cavities, (ii) tight integration and low chronic immunoreactivity with several distinct regions of the brain, and (iii) in vivo multiplexed neural recording. Moreover, syringe injection enables delivery of flexible electronics through a rigid shell, delivery of large volume flexible electronics that can fill internal cavities and co-injection of electronics with other materials into host structures, opening up unique applications for flexible electronics. PMID:26053995

Syringe-injectable electronics.

PubMed

Liu, Jia; Fu, Tian-Ming; Cheng, Zengguang; Hong, Guosong; Zhou, Tao; Jin, Lihua; Duvvuri, Madhavi; Jiang, Zhe; Kruskal, Peter; Xie, Chong; Suo, Zhigang; Fang, Ying; Lieber, Charles M

2015-07-01

Seamless and minimally invasive three-dimensional interpenetration of electronics within artificial or natural structures could allow for continuous monitoring and manipulation of their properties. Flexible electronics provide a means for conforming electronics to non-planar surfaces, yet targeted delivery of flexible electronics to internal regions remains difficult. Here, we overcome this challenge by demonstrating the syringe injection (and subsequent unfolding) of sub-micrometre-thick, centimetre-scale macroporous mesh electronics through needles with a diameter as small as 100 μm. Our results show that electronic components can be injected into man-made and biological cavities, as well as dense gels and tissue, with >90% device yield. We demonstrate several applications of syringe-injectable electronics as a general approach for interpenetrating flexible electronics with three-dimensional structures, including (1) monitoring internal mechanical strains in polymer cavities, (2) tight integration and low chronic immunoreactivity with several distinct regions of the brain, and (3) in vivo multiplexed neural recording. Moreover, syringe injection enables the delivery of flexible electronics through a rigid shell, the delivery of large-volume flexible electronics that can fill internal cavities, and co-injection of electronics with other materials into host structures, opening up unique applications for flexible electronics.

Syringe-injectable electronics

NASA Astrophysics Data System (ADS)

Liu, Jia; Fu, Tian-Ming; Cheng, Zengguang; Hong, Guosong; Zhou, Tao; Jin, Lihua; Duvvuri, Madhavi; Jiang, Zhe; Kruskal, Peter; Xie, Chong; Suo, Zhigang; Fang, Ying; Lieber, Charles M.

2015-07-01

Seamless and minimally invasive three-dimensional interpenetration of electronics within artificial or natural structures could allow for continuous monitoring and manipulation of their properties. Flexible electronics provide a means for conforming electronics to non-planar surfaces, yet targeted delivery of flexible electronics to internal regions remains difficult. Here, we overcome this challenge by demonstrating the syringe injection (and subsequent unfolding) of sub-micrometre-thick, centimetre-scale macroporous mesh electronics through needles with a diameter as small as 100 μm. Our results show that electronic components can be injected into man-made and biological cavities, as well as dense gels and tissue, with >90% device yield. We demonstrate several applications of syringe-injectable electronics as a general approach for interpenetrating flexible electronics with three-dimensional structures, including (1) monitoring internal mechanical strains in polymer cavities, (2) tight integration and low chronic immunoreactivity with several distinct regions of the brain, and (3) in vivo multiplexed neural recording. Moreover, syringe injection enables the delivery of flexible electronics through a rigid shell, the delivery of large-volume flexible electronics that can fill internal cavities, and co-injection of electronics with other materials into host structures, opening up unique applications for flexible electronics.

Poly(Ionic Liquid) Semi-Interpenetrating Network Multi-Responsive Hydrogels

PubMed Central

Tudor, Alexandru; Florea, Larisa; Gallagher, Simon; Burns, John; Diamond, Dermot

2016-01-01

Herein we describe poly(ionic liquid) hydrogel actuators that are capable of responding to multiple stimuli, namely temperature, ionic strength and white light irradiation. Using two starting materials, a crosslinked poly ionic liquid (PIL) and a linear poly(N-isopropylacrylamide-co-spiropyran-co-acrylic acid), several semi-interpenetrating (sIPN) hydrogels were synthesised. The dimensions of hydrogels discs were measured before and after applying the stimuli, to quantify their response. Samples composed of 100% crosslinked PIL alone showed an average area reduction value of ~53% when the temperature was raised from 20 °C to 70 °C, ~24% when immersed in 1% w/w NaF salt solution and no observable photo-response. In comparison, sIPNs containing 300% w/w linear polymer showed an average area reduction of ~45% when the temperature was raised from 20 °C to 70 °C, ~36% when immersed in 1% NaF w/w salt solution and ~10% after 30 min exposure to white light irradiation, respectively. Moreover, by varying the content of the linear component, fine-control over the photo-, thermo- and salt response, swelling-deswelling rate and mechanical properties of the resulting sIPN was achieved. PMID:26861339

Injectable glycosaminoglycan-protein nano-complex in semi-interpenetrating networks: A biphasic hydrogel for hyaline cartilage regeneration.

PubMed

Radhakrishnan, Janani; Subramanian, Anuradha; Sethuraman, Swaminathan

2017-11-01

Articular hyaline cartilage regeneration remains challenging due to its less intrinsic reparability. The study develops injectable biphasic semi-interpenetrating polymer networks (SIPN) hydrogel impregnated with chondroitin sulfate (ChS) nanoparticles for functional cartilage restoration. ChS loaded zein nanoparticles (∼150nm) prepared by polyelectrolyte-protein complexation were interspersed into injectable SIPNs developed by blending alginate with poly(vinyl alcohol) and calcium crosslinking. The hydrogel exhibited interconnected porous microstructure (39.9±5.8μm pore diameter, 57.7±5.9% porosity), 92% swellability and >350Pa elastic modulus. Primary chondrocytes compatibility, chondrocyte-matrix interaction with cell-cell clustering and spheroidal morphology was demonstrated in ChS loaded hydrogel and long-term (42days) proliferation was also determined. Higher fold expression of cartilage-specific genes sox9, aggrecan and collagen-II was observed in ChS loaded hydrogel while exhibiting poor expression of collagen-I. Immunoblotting of aggregan and collagen II demonstrate favorable positive influence of ChS on chondrocytes. Thus, the injectable biphasic SIPNs could be promising composition-mimetic substitute for cartilage restoration at irregular defects. Copyright © 2017 Elsevier Ltd. All rights reserved.

Novel metal(II) coordination polymers based on N,N'-bis-(4-pyridyl)phthalamide as supercapacitor electrode materials in an aqueous electrolyte.

PubMed

Gong, Yun; Li, Jian; Jiang, Peng-Gang; Li, Qing-Fang; Lin, Jian-Hua

2013-02-07

Based on the redox-active L (N,N'-bis-(4-pyridyl)phthalamide) ligand, two porous MOFs formulated as Zn(6)(BPC)(6)(L)(3)·9DMF (H(2)BPC = 4,4'-biphenyldicarboxylic acid) (1) and Cd(2)(TDC)(2)(L)(2)·4H(2)O (H(2)TDC = 2,5-thiophenedicarboxylic acid) (2) were synthesized and structurally characterized by single-crystal X-ray diffractions. Complex 1 features a uninodal 5-connected 3-fold interpenetrated 3D framework with {4(6).6(4)}-bnn hexagonal BN topology. Complex 2 displays a uninodal 6-connected 2-fold interpenetrated 3D framework with {4(12).6(3)}-pcu topology. When complexes 1 and 2 are used as supercapacitor electrode materials, they can provide a large voltage window as high as 2.6 V in an aqueous electrolyte, and their specific capacitances are much more than the value for the bare carbon glassy electrode. It is observed that the more the current density, the less the specific capacitance for the two kinds of supercapacitor electrode materials. The two complexes show different thermal stabilities, UV absorption and photoluminescence properties.

Positron annihilation spectroscopic study of high performance semi-interpenetrating network polyimids

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

Ray, A.K.

1995-12-01

Semi-interpenetrating (S-IPN) network polyimids were made from different proportions of LaRC RP46 (a thermosetpolyimid) and LaRC BDTA-ODA (a thermoplastic polyimid). The ultimate goal of this networking is to improve the mechanical properties of the thermoset polyimid. Positron lifetime study was made to calculate lifetime based on second component of the life time spectra and the free volume & microvoid size. All these properties tend to decrease steadily with increasing thermoset content except at the 50 percent thermoset level where these properties show sudden drop. This result contradicts with the initial expectation that the blend properties should change gradually if itmore » were a solid solution of thermoset (TSP) and thermoplastic (TPP) components. Thermal analyses (TMA, DSC, DMA & TGA) were run to complement the positron life time studies. The TMA and DSC studies confirm the contradiction mentioned above. Further experimentation with S-IPN polymers made at TSP/TTP content around 50/50 level are being conducted to explain this anomaly. Scanning electron microscope study of the S-IPN polyimid samples is under way in order to detect morphological differences which might help explain the phenomenon mentioned above.« less

Inorganic-organic nanocomposites formed using porous ceramic particles

NASA Astrophysics Data System (ADS)

Luo, Jiazhong

Inorganic-organic nanocomposites are expected to be of great significance in new material technologies impacting many different fields. We develop new nanomaterials of this type that have an interpenetrating network structure via in-situ polymerization of monomer within the nanopores of inorganic gel particles (porosity 20-80 vol.%). Due to strong nanomechanical bonding, these thermosetting polymer composites are expected to exhibit improved mechanical performance. Particle porosity is a primary factor. In contrast to HCl-catalyzed gels, more porous HF-catalyzed gels (porosity 62 vol.%) produced higher composite wear-resistance. At the same loading, the wear rates decrease linearly with increasing filler porosity. Better wear resistance is associated with fine-scale plastic deformation as opposed to brittle fracture and particle pull-out. For the coupling of HF-catalyzed particles with gamma-methacryloxypropyl trimethoxysilane, FTIR and solid-state sp{13}C/sp{29}Si NMR show that the use of a catalyst (n-propylamine) and a nonpolar solvent (cyclohexane), causes the degree of coupling and self-condensation to increase. Ethanol competes with the silane for the surface and results in less silane self-condensation. Surprisingly, the silane diminishes the composite wear resistance due to its pore-filling effect and the subsequent decrease in polymer interpenetration. A transition from plastic deformation to brittle fracture is involved. A new sol-gel technique was found to prepare porous (up to 76.54 vol.%) silica nanoparticles from solution via sodium fluoride (NaF) salt catalysis. Full interpenetration is achieved without the use of silane coupling agents. The resulting composites displayed improved wear resistance, toughness, modulus, hardness and high compressive strength. Toughening and reinforcement can be explained by pore confinement. DMA and DEA were combined with TEM to investigate related structure and property issues. The filler matrix effect on composite wear was evaluated utilizing the phase transformation of porous alumina gels from the stable monohydrate to the gamma-alumina form between 300 and 400sp°C; conveniently the total amount of porosity remains the same. gamma-alumina is more efficient than the monohydrate in improving wear resistance. The susceptibility of the monohydrate to 'transgranular' deformation and the crack-deflection of gamma-alumina in an 'intergranular' mode are responsible for the similar toughening effect of these two reinforcements.

Synthesis, crystal structure, and magnetic properties of a two-fold interpenetrated diamondoid open framework

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

Wu, Jing-Yun, E-mail: jyunwu@ncnu.edu.tw; Cheng, Fu-Yin; Chiang, Ming-Hsi, E-mail: mhchiang@chem.sinica.edu.tw

2016-10-15

Self-assembly of an enlarged angular pyridinecarboxylate ligand and cobalt(II) acetate under mild conditions afforded a three-dimensional open-framework coordination polymer, [Co{sub 2}(μ-H{sub 2}O)(pyca-43){sub 4}]{sub n} (1, Hpyca-43=(E)−3-((pyridin-4-yl)methyleneamino)benzoic acid). The molecular structure of 1 has rationalized to be a porous two-fold interpenetrated diamondoid-like network, with dinuclear Co{sub 2}(μ-H{sub 2}O)(O{sub 2}C){sub 4}N{sub 4} clusters as tetrahedral secondary building units (SBUs), possessing highly solvent accessible volume of approximately 53.0%. Least-squares fit of the magnetic susceptibility data (20–300 K) of 1 yields Curie constant C=6.15 cm{sup 3} mol{sup –1} K and Weiss constant θ=–11.6 K. Every Co{sub 2} subunit within the network is magnetically insulatedmore » to other dimers. The magnetic exchange parameter between Co(II) centers is estimated to −0.72 cm{sup –1}, suggesting a weak antiferromagnetic interaction. The g{sub av} value of 4.65 from fitting to the Lines model indicates that the decrease of the χ{sub M}T value upon cooling is dominated by depopulation of the excited Kramer's states to the effective ground singlet. In addition, the thermal stability and adsorption properties of 1 are also reported. - Graphical abstract: This work has synthesized and structurally characterized a porous two-fold interpenetrated diamondoid-like network, which possesses highly solvent accessible volume of approximately 53.0% and shows a weak antiferromagnetic interaction between the Co(II) centers.« less

Substituent-induced effects on dimensionality in cadmium isophthalate coordination polymers containing 3-pyridylisonicotinamide

NASA Astrophysics Data System (ADS)

O'Donovan, Megan E.; Wudkewych, Megan J.; LaDuca, Robert L.

2015-08-01

Hydrothermal treatment of cadmium nitrate, a 5-substituted isophthalic acid, and 3-pyridylisonicotinamide (3-pina) resulted in three coordination polymers whose dimensionality depended critically on the nature of the aromatic ring substituent. These three new phases were characterized by single crystal X-ray diffraction. {[Cd(hip)(3-pina)(H2O)2]·2H2O}n (1, hip = 5-hydroxyisophthalate) and {[Cd(meoip)(3-pina)(H2O)2]·H2O}n (2, meoip = 5-methoxyisophthalate) both manifest simple 1-D chain structures with pendant 3-pina ligands. [Cd(mip)(3-pina)]n (3, mip = 5-methylisophthalate) possesses [Cd(mip)]n 1-D chains featuring {Cd2(OCO)2} dimeric units, linked by tethering 3-pina ligands into a non-interpenetrated 3-D 6-connected 41263 pcu network. Luminescent behavior in all cases is attributed to intra-ligand molecular orbital transitions.

Self-assembly of star micelle into vesicle in solvents of variable quality: the star micelle retains its core-shell nanostructure in the vesicle.

PubMed

Liu, Nijuan; He, Qun; Bu, Weifeng

2015-03-03

Intra- and intermolecular interactions of star polymers in dilute solutions are of fundamental importance for both theoretical interest and hierarchical self-assembly into functional nanostructures. Here, star micelles with a polystyrene corona and a small ionic core bearing platinum(II) complexes have been regarded as a model of star polymers to mimic their intra- and interstar interactions and self-assembled behaviors in solvents of weakening quality. In the chloroform/methanol mixture solvents, the star micelles can self-assemble to form vesicles, in which the star micelles shrink significantly and are homogeneously distributed on the vesicle surface. Unlike the morphological evolution of conventional amphiphiles from micellar to vesicular, during which the amphiphilic molecules are commonly reorganized, the star micelles still retain their core-shell nanostructures in the vesicles and the coronal chains of the star micelle between the ionic cores are fully interpenetrated.

Cellulose nanofibers reinforced sodium alginate-polyvinyl alcohol hydrogels: Core-shell structure formation and property characterization.

PubMed

Yue, Yiying; Han, Jingquan; Han, Guangping; French, Alfred D; Qi, Yadong; Wu, Qinglin

2016-08-20

Core-shell structured hydrogels consisting of a flexible interpenetrating polymer network (IPN) core and a rigid semi-IPN shell were prepared through chemical crosslinking of polyvinyl alcohol (PVA) and sodium alginate (SA) with Ca(2+) and glutaraldehyde. Short cellulose nanofibers (CNFs) extracted from energycane bagasse were incorporated in the hydrogel. The shell was micro-porous and the core was macro-porous. The hydrogels could be used in multiple adsorption-desorption cycles for dyes, and the maximum methyl blue adsorption capacity had a 10% increase after incorporating CNFs. The homogeneous distribution of CNFs in PVA-SA matrix generated additional hydrogen bonds among the polymer molecular chains, resulting in enhanced density, viscoelasticity, and mechanical strength for the hydrogel. Specifically, the compressive strength of the hydrogel reached 79.5kPa, 3.2 times higher than that of the neat hydrogel. Copyright © 2016 Elsevier Ltd. All rights reserved.

Tuning zinc coordination architectures by benzenedicarboxylate position isomers and bis(triazole)

NASA Astrophysics Data System (ADS)

Peng, Yan-fen; Li, Ke; Zhao, Shan; Han, Shan-shan; Li, Bao-long; Li, Hai-Yan

2015-08-01

Three position isomers 1,2-, 1,3-, 1,4-benzenedicarboxylate and 1,4-bis(1,2,4-triazol-4-yl)benzene were used to assembly zinc(II) coordination polymers {[Zn2(btx)0.5(1,2-bdc)2(H2O)]·H2O}n (1), {[Zn(btx)(1,3-bdc)]·2H2O·(DMF)}n (2) and {[Zn(btx)(1,4-bdc)]·3H2O}n (3). 1 is a (3,4,4,4)-connected two-dimensional network with point symbol (42·6)(44·62)(43·62·8)(42·6·103). 2 shows a two-dimensional (4,4) network. 3 exhibits a 5-fold interpenetrated three-dimensional diamondoid network. The structural versatility shows that the structures of coordination polymers can be tuned by the position isomers ligands. The luminescence and thermal stability were investigated.

Thermo-responsive gels that absorb moisture and ooze water.

PubMed

Matsumoto, Kazuya; Sakikawa, Nobuki; Miyata, Takashi

2018-06-13

The water content of thermo-responsive hydrogels can be drastically altered by small changes in temperature because their polymer chains change from hydrophilic to hydrophobic above their low critical solution temperature (LCST). In general, such smart hydrogels have been utilized in aqueous solutions or in their wet state, and no attempt has been made to determine the phase-transition behavior of the gels in their dried states. Here we demonstrate an application of the thermo-responsive behavior of an interpenetrating polymer network (IPN) gel comprising thermo-responsive poly(N-isopropylacrylamide) and hydrophilic sodium alginate networks in their dried states. The dried IPN gel absorbs considerable moisture from air at temperatures below its LCST and oozes the absorbed moisture as liquid water above its LCST. These phenomena provide energy exchange systems in which moisture from air can be condensed to liquid water using the controllable hydrophilic/hydrophobic properties of thermo-responsive gels with a small temperature change.

Characterization of a polymer-infiltrated ceramic-network material

PubMed Central

Corazza, Pedro H.; Zhang, Yu

2015-01-01

Objectives To characterize the microstructure and determine some mechanical properties of a polymer-ingfiltrated ceramic-network (PICN) material (Vita Enamic, Vita Zahnfabrik) available for CAD–CAM systems. Methods Specimens were fabricated to perform quantitative and qualitative analyses of the material’s microstructure and to determine the fracture toughness (KIc), density (ρ), Poisson’s ratio (v) and Young’s modulus (E). KIc was determined using V-notched specimens and the short beam toughness method, where bar-shaped specimens were notched and 3-point loaded to fracture. ρ was calculated using Archimedes principle, and v and E were measured using an ultrasonic thickness gauge with a combination of a pulse generator and an oscilloscope. Results Microstructural analyses showed a ceramic- and a polymer-based interpenetrating network. Mean and standard deviation values for the properties evaluated were: KIc = 1.09 ± 0.05 MPa m1/2, ρ = 2.09 ± 0.01 g/cm3, v = 0.23 ± 0.002 and E = 37.95 ± 0.34 GPa. Significance The PICN material showed mechanical properties between porcelains and resin-based composites, reflecting its microstructural components. PMID:24656471

Characterization of a polymer-infiltrated ceramic-network material.

PubMed

Della Bona, Alvaro; Corazza, Pedro H; Zhang, Yu

2014-05-01

To characterize the microstructure and determine some mechanical properties of a polymer-infiltrated ceramic-network (PICN) material (Vita Enamic, Vita Zahnfabrik) available for CAD-CAM systems. Specimens were fabricated to perform quantitative and qualitative analyses of the material's microstructure and to determine the fracture toughness (KIc), density (ρ), Poisson's ratio (ν) and Young's modulus (E). KIc was determined using V-notched specimens and the short beam toughness method, where bar-shaped specimens were notched and 3-point loaded to fracture. ρ was calculated using Archimedes principle, and ν and E were measured using an ultrasonic thickness gauge with a combination of a pulse generator and an oscilloscope. Microstructural analyses showed a ceramic- and a polymer-based interpenetrating network. Mean and standard deviation values for the properties evaluated were: KIc=1.09±0.05MPam(1/2), ρ=2.09±0.01g/cm(3), ν=0.23±0.002 and E=37.95±0.34GPa. The PICN material showed mechanical properties between porcelains and resin-based composites, reflecting its microstructural components. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Polyelectrolyte brush bilayers in weak interpenetration regime: Scaling theory and molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Desai, Parth Rakesh; Sinha, Shayandev; Das, Siddhartha

2018-03-01

We employ molecular dynamics (MD) simulations and develop scaling theories to quantify the equilibrium behavior of polyelectrolyte (PE) brush bilayers (BBLs) in the weakly interpenetrated regime, which is characterized by d0

Enhanced adsorption of methyl violet and congo red by using semi and full IPN of polymethacrylic acid and chitosan.

PubMed

Maity, Jayabrata; Ray, Samit Kumar

2014-04-15

Semi and full interpenetrating polymer network (IPN) type hydrogels were prepared by free radical in situ polymerization of methacrylic acid in presence of chitosan using N,N'-methylene-bis-acrylamide (MBA) and glutaraldehyde (for full IPN) as crosslinker. Several semi and full IPN type hydrogels were prepared by varying initiator and crosslinker concentration and also monomer to chitosan mass ratio. These hydrogels were characterized and used for removal of methyl violet and congo red dye from water. Isotherms and kinetics of dye adsorption were also evaluated. Copyright © 2014 Elsevier Ltd. All rights reserved.

Molecular packing and electronic processes in amorphous-like polymer bulk heterojunction solar cells with fullerene intercalation.

PubMed

Xiao, Ting; Xu, Haihua; Grancini, Giulia; Mai, Jiangquan; Petrozza, Annamaria; Jeng, U-Ser; Wang, Yan; Xin, Xin; Lu, Yong; Choon, Ng Siu; Xiao, Hu; Ong, Beng S; Lu, Xinhui; Zhao, Ni

2014-06-09

The interpenetrating morphology formed by the electron donor and acceptor materials is critical for the performance of polymer:fullerene bulk heterojunction (BHJ) photovoltaic (PV) cells. In this work we carried out a systematic investigation on a high PV efficiency (>6%) BHJ system consisting of a newly developed 5,6-difluorobenzo[c] thiadiazole-based copolymer, PFBT-T20TT, and a fullerene derivative. Grazing incidence X-ray scattering measurements reveal the lower-ordered nature of the BHJ system as well as an intermixing morphology with intercalation of fullerene molecules between the PFBT-T20TT lamella. Steady-state and transient photo-induced absorption spectroscopy reveal ultrafast charge transfer (CT) at the PFBT-T20TT/fullerene interface, indicating that the CT process is no longer limited by exciton diffusion. Furthermore, we extracted the hole mobility based on the space limited current (SCLC) model and found that more efficient hole transport is achieved in the PFBT-T20TT:fullerene BHJ as compared to pure PFBT-T20TT, showing a different trend as compared to the previously reported highly crystalline polymer:fullerene blend with a similar intercalation manner. Our study correlates the fullerene intercalated polymer lamella morphology with device performance and provides a coherent model to interpret the high photovoltaic performance of some of the recently developed weakly-ordered BHJ systems based on conjugated polymers with branched side-chain.

Therapeutic effect for liver-metastasized tumor by sequential intravenous injection of anionic polymer and cationic lipoplex of siRNA.

PubMed

Hattori, Yoshiyuki; Arai, Shohei; Kikuchi, Takuto; Ozaki, Kei-Ichi; Kawano, Kumi; Yonemochi, Etsuo

2016-04-01

Previously, we developed a novel siRNA transfer method to the liver by sequential intravenous injection of anionic polymer and cationic liposome/siRNA complex (cationic lipoplex). In this study, we investigated whether siRNA delivered by this sequential injection could significantly suppress mRNA expression of the targeted gene in liver metastasis and inhibit tumor growth. When cationic lipoplex was intravenously injected into mice bearing liver metastasis of human breast tumor MCF-7 at 1 min after intravenous injection of chondroitin sulfate C (CS) or poly-l-glutamic acid (PGA), siRNA was accumulated in tumor-metastasized liver. In terms of a gene silencing effect, sequential injections of CS or PGA plus cationic lipoplex of luciferase siRNA could reduce luciferase activity in liver MCF-7-Luc metastasis. Regarding the side effects, sequential injections of CS plus cationic lipoplex did not exhibit hepatic damage or induction of inflammatory cytokines in serum after repeated injections, but sequential injections of PGA plus cationic lipoplex did. Finally, sequential injections of CS plus cationic lipoplex of protein kinase N3 siRNA could suppress tumor growth in the mice bearing liver metastasis. From these findings, sequential injection of CS and cationic lipoplex of siRNA might be a novel systemic method of delivering siRNA to liver metastasis.

Interpenetrating polyaniline-gold electrodes for SERS and electrochemical measurements

NASA Astrophysics Data System (ADS)

West, R. M.; Semancik, S.

2016-11-01

Facile fabrication of nanostructured electrode arrays is critical for development of bimodal SERS and electrochemical biosensors. In this paper, the variation of applied potential at a polyaniline-coated Pt electrode is used to selectivity deposit Au on the polyaniline amine sites or on the underlying Pt electrode. By alternating the applied potential, the Au is grown simultaneously from the top and the bottom of the polyaniline film, leading to an interpenetrated, nanostructured polymer-metal composite extending from the Pt electrode to the electrolyte solution. The resulting films have unique pH-dependent electrochemical properties, e.g. they retain electrochemical activity in both acidic and neutral solutions, and they also include SERS-active nanostructures. By varying the concentration of chloroaurate used during deposition, Au nanoparticles, nanodendrites, or nanosheets can be selectively grown. For the films deposited under optimal conditions, using 5 mmol/L chloroaurate, the SERS enhancement factor for Rhodamine 6G was found to be as high as 1.1 × 106 with spot-to-spot and electrode-to-electrode relative standard deviations as low as 8% and 12%, respectively. The advantages of the reported PANI-Au composite electrodes lie in their facile fabrication, enabling the targeted deposition of tunable nanostructures on sensing arrays, and their ability to produce orthogonal optical and electrochemical analytical results.

Development of a multilayered association polymer system for sequential drug delivery

NASA Astrophysics Data System (ADS)

Chinnakavanam Sundararaj, Sharath kumar

As all the physiological processes in our body 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 primary objective of this research was to develop a multilayered, polymer-based system for sequential delivery of multiple drugs. This particular device was designed aimed at the treatment of periodontitis, a highly prevalent oral inflammatory disease that affects 90% of the world population. This condition is caused by bacterial biofilm on the teeth, resulting in a chronic inflammatory response that leads to loss of alveolar bone and, ultimately, the tooth. Current treatment methods for periodontitis address specific parts of the disease, with no individual treatment serving as a complete therapy. The polymers used for the fabrication of this multilayered device consists of 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 property 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. After the initial characterization of the CAPP system, the device was specifically modified to achieve sequential release of drugs aimed at the treatment of periodontitis. The four types of drugs used were metronidazole, ketoprofen, doxycycline, and simvastatin to eliminate infection, inhibit inflammation, prevent tissue destruction, and aid bone regeneration, respectively. To obtain different erosion times and achieve appropriate release profiles specific to the disease condition, the device was modified by increasing the number of layers or by inclusion of a slower eroding polymer layer. In all the cases, the device was able to release the four different drugs in the designed temporal sequence. Analysis of antibiotic and antiinflammatory bioactivity showed that drugs released from the devices retained 100% bioactivity. Following extensive studies on the in vitro sequential drug release from these devices, the in vivo drug release profiles were investigated. The CAPP devices with different release rates and dosage formulations were implanted in a rat calvarial onlay model, and the in vivo drug release and erosion was compared with in vitro results. In vivo studies showed sequential release of drugs comparable to those measured in vitro, with some difference in drug release rates observed. 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. KEYWORDS: Multiple drug delivery, Periodontitis, Cellulose acetate phthalate, Pluronic F-127, Sequential drug release, in vitro drug release, in vivo drug release.

Cloning strategy for producing brush-forming protein-based polymers.

PubMed

Henderson, Douglas B; Davis, Richey M; Ducker, William A; Van Cott, Kevin E

2005-01-01

Brush-forming polymers are being used in a variety of applications, and by using recombinant DNA technology, there exists the potential to produce protein-based polymers that incorporate unique structures and functions in these brush layers. Despite this potential, production of protein-based brush-forming polymers is not routinely performed. For the design and production of new protein-based polymers with optimal brush-forming properties, it would be desirable to have a cloning strategy that allows an iterative approach wherein the protein based-polymer product can be produced and evaluated, and then if necessary, it can be sequentially modified in a controlled manner to obtain optimal surface density and brush extension. In this work, we report on the development of a cloning strategy intended for the production of protein-based brush-forming polymers. This strategy is based on the assembly of modules of DNA that encode for blocks of protein-based polymers into a commercially available expression vector; there is no need for custom-modified vectors and no need for intermediate cloning vectors. Additionally, because the design of new protein-based biopolymers can be an iterative process, our method enables sequential modification of a protein-based polymer product. With at least 21 bacterial expression vectors and 11 yeast expression vectors compatible with this strategy, there are a number of options available for production of protein-based polymers. It is our intent that this strategy will aid in advancing the production of protein-based brush-forming polymers.

Structural diversification and photocatalytic properties of three Cd(II) coordination polymers decorated with different auxiliary ligands

NASA Astrophysics Data System (ADS)

Yin, Wen-Yu; Zhuang, Guo-Yong; Huang, Zuo-Long; Cheng, Hong-Jian; Zhou, Li; Ma, Man-Hong; Wang, Hao; Tang, Xiao-Yan; Ma, Yun-Sheng; Yuan, Rong-Xin

2016-03-01

Three cadmium coordination polymers, [Cd(bismip)]n (1), {[Cd(bismip)(phen)]·H2O}n (2) and {[Cd2(bismip)2(4,4‧-bipy)]·2H2O}n (3) (H2bismip=5-(1H-benzoimidazol-2-ylsulfanylmethyl)-isophthalic acid, phen=1,10-phenanthroline, 4,4‧-bipy=4,4‧-bipyridine) have been prepared under solvothermal conditions. In 1, the [Cd4(bismip)3] units are jointed by bismip ligands to afford a three-dimensional (3D) architecture. Complex 2 exhibits a 3D supramolecular framework based on the interconnection of 1D chains through hydrogen bonding interactions and π-π packing interactions. 3 is a two-fold interpenetrating 3D architecture with a (4·82)(42·84) Schläfli symbol in which 2D layers are interlinked by 4,4‧-bipy ligands. The diverse structures of compounds 1-3 indicate that the auxiliary ligands have significant effects on the final structures. The photoluminescent properties and photocatalytic properties of these coordination polymers in the solid state were also investigated. Remarkably, 3 shows the wide gap semiconductor nature and exhibit excellent photocatalytic performance.

Preparation and in vitro evaluation of xanthan gum facilitated superabsorbent polymeric microspheres.

PubMed

Bhattacharya, Shiv Sankar; Mazahir, Farhan; Banerjee, Subham; Verma, Anurag; Ghosh, Amitava

2013-10-15

Interpenetrating polymer network (IPN) hydrogel microspheres of xanthan gum (XG) based superabsorbent polymer (SAP) and poly(vinyl alcohol) (PVA) were prepared by water-in-oil (w/o) emulsion crosslinking method for sustained release of ciprofloxacin hydrochloride (CIPRO). The microspheres were prepared with various ratios of hydrolyzed SAP to PVA and extent of crosslinking density. The prepared microspheres with loose and rigid surfaces were evidenced by scanning electron microscope (SEM). Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the IPN formation. Differential scanning calorimetry (DSC) study was performed to understand the dispersion nature of drug after encapsulation. The in vitro drug release study was extensively evaluated depending on the process variables in both acidic and alkaline media. All the formulations exhibited satisfactory physicochemical and in vitro release characteristics. Release data indicated a non-Fickian trend of drug release from the formulations. Based on the results, this study suggest that CIPRO loaded IPN microspheres were suitable for sustained release application. Copyright © 2013 Elsevier Ltd. All rights reserved.

Homoleptic ligands vs heteroleptic ligands on coordination polymerizations: Construction and properties of silver(I) coordination polymers containing dialkylbis(4-pyridy)silanes

NASA Astrophysics Data System (ADS)

Park, Minwoo; Jang, Jaeseong; Moon, So Yun; Jung, Ok-Sang

2014-03-01

Investigations into pure bidentate ligand vs mixed bidentate ligands on self-assembly of AgPF6 with the respective L1, L2, L3, L1/L2, L1/L3, and L2/L3 (L1 = diethylbis(4-pyridyl)silane; L2 = ethylmethylbis(4-pyridyl)silane; L3 = cyclotetramethylenebis(4-pyridyl)silane) were carried out. The self-assembly reactions of AgPF6 with the respective ligand system produce desirable homoleptic or heteroleptic silver(I) coordination polymers. [Ag(L1)2](PF6) gives rise to a tubular loop chain whereas the other five products lead to a twofold interpenetration diamonoid structure. [Ag(L1)2](PF6) shows a strong blue luminescence at 453 nm (λex = 270 nm), which is useful to recognize alcohols. All products were characterized by thermal analyses, and in particular, calcination of [Ag(L3)2](PF6)ṡCH3OH at 600 °C finally produces silver(0) microcrystalline morphology.

Stability of the sectored morphology of polymer crystallites

NASA Astrophysics Data System (ADS)

Alageshan, Jaya Kumar; Hatwalne, Yashodhan; Muthukumar, Murugappan

2016-09-01

When an entangled interpenetrating collection of long flexible polymer chains dispersed in a suitable solvent is cooled to low enough temperatures, thin lamellar crystals form. Remarkably, these lamellae are sectored, with several growth sectors that have differing melting temperatures and growth kinetics, eluding so far an understanding of their origins. We present a theoretical model to explain this six-decade-old challenge by addressing the elasticity of fold surfaces of finite-sized lamella in the presence of disclination-type topological defects arising from anisotropic line tension. Entrapment of a disclination defect in a lamella results in sectors separated by walls, which are soliton solutions of a two-dimensional elliptic sine-Gordon equation. For flat square morphologies, exact results show that sectored squares are more stable than plain squares if the dimensionless anisotropic line tension parameter α =γa n/√{h4Kϕ } (γa n = anisotropic line tension, h4 = fold energy parameter, Kϕ = elastic constant for two-dimensional orientational deformation) is above a critical value, which depends on the size of the square.

Syntheses and structural characterization of Co(II) and Cd(II) coordination polymers with 1,4-bis(imidazolyl)butane ligand

NASA Astrophysics Data System (ADS)

Lalegani, Arash; Khalaj, Mehdi; Sedaghat, Sajjad; Łyczko, Krzysztof; Lipkowski, Janusz

2017-11-01

Two new coordination polymers, {[Co(bib)3](PF6)2}n (1) and [Cd (bib) Cl2]n (2), were prepared at room temperature by the reaction of appropriate salts of cobalt (II) and cadmium (II) with the flexible linker ligands 1,4-bis(imidazolyl) butane (bib). The compounds were characterized by elemental analyses, IR spectroscopy and single crystal X-ray diffraction. In the polymeric structure of 1, the Co(II) ion lies on an inversion centre and adopts the CoN6 octahedral geometry, while in the structure of 2, the Cd(II) ions adopt the CdN2Cl4 pseudo-octahedral geometry. In compound 1, six bib ligands are coordinated to one central cobalt (II) to form an open 3D 2-fold interpenetrating framework of the α-polonium (pcu) type topology, while in compound 2 two bib ligands are coordinated to one central cadmium (II) to form 2D network structure.

Poly(phenylene)-based anion exchange membrane

DOEpatents

Hibbs, Michael [Albuquerque, NM; Cornelius, Christopher J [Albuquerque, NM; Fujimoto, Cy H [Albuquerque, NM

2011-02-15

A poly(phenylene) compound of copolymers that can be prepared with either random or multiblock structures where a first polymer has a repeat unit with a structure of four sequentially connected phenyl rings with a total of 2 pendant phenyl groups and 4 pendant tolyl groups and the second polymer has a repeat unit with a structure of four sequentially connected phenyl rings with a total of 6 pendant phenyl groups. The second polymer has chemical groups attached to some of the pendant phenyl groups selected from CH.sub.3, CH.sub.2Br, and CH.sub.2N(CH.sub.3).sub.3Br groups. When at least one group is CH.sub.2N(CH.sub.3).sub.3Br, the material functions as an anion exchange membrane.

Tuning different kinds of entangled metal-organic frameworks by modifying the spacer group of aliphatic dicarboxylate ligands and the reactant ratio.

PubMed

Yang, Jin-Xia; Zhai, Ji-Quan; Zhang, Xin; Qin, Ye-Yan; Yao, Yuan-Gen

2016-01-14

Taking advantage of the conformational flexibility of the bpp ligand and aliphatic dicarboxylic acids, six interesting entangled coordination polymers, {[Cd(fum)(bpp)(H2O)]·(H2O)}n (), {[Cd(fum)(bpp)2]·(H2O)5}n (), {[Cd2(suc)1.5(bpp)2(NO3)(H2O)2]·6H2O}n (), {[Cd(suc)(bpp)2]·(H2O)1.5}n (), {[Cd2(glu)2(bpp)3]·10H2O}n (), and {Cd(adp)(bpp)(H2O)}n () have been prepared and structurally characterized (bpp = 1,3-bi(4-pyridyl)propane, fum = fumaric, suc = succinate, glu = glutaric, adp = adipic). Compounds and are comprised of undulated 2D 4(4)-sql networks. In the structure of compound , two identical undulated layers are parallelly interpenetrated with each other to give a 2D → 2D interpenetrating framework. For , the dangling arms projected from 2D layers are intercalated into the neighboring sheets, producing a 2D → 3D polythreading framework. Compound shows a rare example of a 2D self-penetrating framework with a (3,4)-connected (4(2)·6(3)·8)(4(2)·6) topology. Compound presents an unusual 2D self-threading network with a novel 4-connected {4(2)·6(3)·8} topology. Compound displays a 3D self-penetrating system based on a 2D → 3D parallel polycatenation array. Compound exhibits an unprecedented 3D self-penetrating structure having both 1D + 1D → 1D polycatenation and 3D + 3D → 3D interpenetration characteristics. A comparison of these six compounds demonstrates that both the different spacer lengths of the aliphatic dicarboxylates and reactant ratios appear to play a significant role in the assembly of entangled frameworks. In addition, thermal stabilities and photoluminescence properties of have been examined in the solid state at room temperature.

Spatiotemporally and Sequentially-Controlled Drug Release from Polymer Gatekeeper-Hollow Silica Nanoparticles

NASA Astrophysics Data System (ADS)

Palanikumar, L.; Jeena, M. T.; Kim, Kibeom; Yong Oh, Jun; Kim, Chaekyu; Park, Myoung-Hwan; Ryu, Ja-Hyoung

2017-04-01

Combination chemotherapy has become the primary strategy against cancer multidrug resistance; however, accomplishing optimal pharmacokinetic delivery of multiple drugs is still challenging. Herein, we report a sequential combination drug delivery strategy exploiting a pH-triggerable and redox switch to release cargos from hollow silica nanoparticles in a spatiotemporal manner. This versatile system further enables a large loading efficiency for both hydrophobic and hydrophilic drugs inside the nanoparticles, followed by self-crosslinking with disulfide and diisopropylamine-functionalized polymers. In acidic tumour environments, the positive charge generated by the protonation of the diisopropylamine moiety facilitated the cellular uptake of the particles. Upon internalization, the acidic endosomal pH condition and intracellular glutathione regulated the sequential release of the drugs in a time-dependent manner, providing a promising therapeutic approach to overcoming drug resistance during cancer treatment.

A versatile semi-permanent sequential bilayer/diblock polymer coating for capillary isoelectric focusing.

PubMed

Bahnasy, Mahmoud F; Lucy, Charles A

2012-12-07

A sequential surfactant bilayer/diblock copolymer coating was previously developed for the separation of proteins. The coating is formed by flushing the capillary with the cationic surfactant dioctadecyldimethylammonium bromide (DODAB) followed by the neutral polymer poly-oxyethylene (POE) stearate. Herein we show the method development and optimization for capillary isoelectric focusing (cIEF) separations based on the developed sequential coating. Electroosmotic flow can be tuned by varying the POE chain length which allows optimization of resolution and analysis time. DODAB/POE 40 stearate can be used to perform single-step cIEF, while both DODAB/POE 40 and DODAB/POE 100 stearate allow performing two-step cIEF methodologies. A set of peptide markers is used to assess the coating performance. The sequential coating has been applied successfully to cIEF separations using different capillary lengths and inner diameters. A linear pH gradient is established only in two-step CIEF methodology using 3-10 pH 2.5% (v/v) carrier ampholyte. Hemoglobin A(0) and S variants are successfully resolved on DODAB/POE 40 stearate sequentially coated capillaries. Copyright © 2012 Elsevier B.V. All rights reserved.

Highly stretchable HA/SA hydrogels for tissue engineering.

PubMed

Zhu, Chengcheng; Yang, Rui; Hua, Xiaobin; Chen, Hong; Xu, Jumei; Wu, Rile; Cen, Lian

2018-04-01

A highly stretchable hyaluronic acid (HA)/sodium alginate (SA) hydrogel was developed in this study based on an interpenetrating polymer network. HA/SA hydrogels were prepared by mixing two polysaccharides followed by covalent crosslinking via epoxy groups on HA molecules and ionic crosslinking via divalent ions on SA chains sequentially. The effect of HA/SA ratio on the pore size and distribution, swelling ratio, elongation and rheological properties as well as protein loading and release properties of HA/SA hydrogels was explored. Moreover, a surface modification method, layer-by-layer (LBL) assembly technique, was applied to modify the hydrogel to evaluate the hydrogel's tenability in varying biological performance. It was then shown that the hydrogels had the pore sizes ranging from 100 to 50 μm. With the increase in SA content of the resulting hydrogels, the pore size, swelling ratio, and storage modulus (G') and loss modulus (G″) of the hydrogel all decreased, whereas the in vitro bulk weight loss was fastened. Moreover, elongation at break (EB) value increased first, reached a peak value and then decreased, that is HA8/SA1 (HA:SA = 8:1) had the highest EB value of 417%. This hydrogel could retain 33.2% of the pre-loaded protein even after 72 h, which could be further attenuated when LBL was used to shell the hydrogel. The growth of fibroblasts on HA8/SA1 hydrogel gave preliminary assessment on its suitability as a cellular carrier, while the LBL modified HA8/SA1 hydrogel also favored the anchoring of keratinocytes, further enhancing its cell carrier role for tissue regeneration, especially skin engineering.

A rheological assessment of the nature of interactions between mucoadhesive polymers and a homogenised mucus gel.

PubMed

Madsen, F; Eberth, K; Smart, J D

1998-06-01

The ability of mucoadhesive materials to produce a large increase in the resistance to deformation when incorporated into a mucus gel, relative to when the mucus gel and test materials are evaluated separately at the same concentration, has been reported in several previous studies. It has been proposed that this phenomenon, termed rheological synergism, can be used as a measure of the strength of the mucoadhesive interaction. This study investigated the interactions between four putative mucoadhesive polymers (Noveon, Pemulen TR-2, carageenan and sodium carboxymethylcellulose) and a homogenised mucus gel, using dynamic oscillatory rheology. It was shown that, with the exception of sodium carboxymethylcellulose, incorporating a mucoadhesive polymer into a mucus gel produces rheological behaviour indicative of a weakly cross-linked gel network, which suggested a structure containing physical chain entanglements and non-covalent (probably hydrogen) bonds. Optimum gel strengthening occurred in a weakly acidic environment, suggesting an optimum conformation and degree of ionisation of the polymer and mucus molecules. Subsequent work suggested that the macromolecular interactions between polymer and mucus are sensitive to temperature, with the dynamic moduli decreasing with increasing temperature, further indicating bonding of a non-covalent nature. This work provide further evidence that rheological methods can be used as a tool to evaluate the interactions between a mucoadhesive macromolecule and a mucus gel. It also adds to the perception that molecular interpenetration may be an important factor in mucoadhesion by strengthening the mucus in the mucoadhesive/mucosal interfacial layer.

Four-Dimensional Printing Hierarchy Scaffolds with Highly Biocompatible Smart Polymers for Tissue Engineering Applications.

PubMed

Miao, Shida; Zhu, Wei; Castro, Nathan J; Leng, Jinsong; Zhang, Lijie Grace

2016-10-01

The objective of this study was to four-dimensional (4D) print novel biomimetic gradient tissue scaffolds with highly biocompatible naturally derived smart polymers. The term "4D printing" refers to the inherent smart shape transformation of fabricated constructs when implanted minimally invasively for seamless and dynamic integration. For this purpose, a series of novel shape memory polymers with excellent biocompatibility and tunable shape changing effects were synthesized and cured in the presence of three-dimensional printed sacrificial molds, which were subsequently dissolved to create controllable and graded porosity within the scaffold. Surface morphology, thermal, mechanical, and biocompatible properties as well as shape memory effects of the synthesized smart polymers and resultant porous scaffolds were characterized. Fourier transform infrared spectroscopy and gel content analysis confirmed the formation of chemical crosslinking by reacting polycaprolactone triol and castor oil with multi-isocyanate groups. Differential scanning calorimetry revealed an adjustable glass transition temperature in a range from -8°C to 35°C. Uniaxial compression testing indicated that the obtained polymers, possessing a highly crosslinked interpenetrating polymeric networks, have similar compressive modulus to polycaprolactone. Shape memory tests revealed that the smart polymers display finely tunable recovery speed and exhibit greater than 92% shape fixing at -18°C or 0°C and full shape recovery at physiological temperature. Scanning electron microscopy analysis of fabricated scaffolds revealed a graded microporous structure, which mimics the nonuniform distribution of porosity found within natural tissues. With polycaprolactone serving as a control, human bone marrow-derived mesenchymal stem cell adhesion, proliferation, and differentiation greatly increased on our novel smart polymers. The current work will significantly advance the future design and development of novel and functional biomedical scaffolds with advanced 4D printing technology and highly biocompatible smart biomaterials.

Four-Dimensional Printing Hierarchy Scaffolds with Highly Biocompatible Smart Polymers for Tissue Engineering Applications

PubMed Central

Miao, Shida; Zhu, Wei; Castro, Nathan J.; Leng, Jinsong

2016-01-01

The objective of this study was to four-dimensional (4D) print novel biomimetic gradient tissue scaffolds with highly biocompatible naturally derived smart polymers. The term “4D printing” refers to the inherent smart shape transformation of fabricated constructs when implanted minimally invasively for seamless and dynamic integration. For this purpose, a series of novel shape memory polymers with excellent biocompatibility and tunable shape changing effects were synthesized and cured in the presence of three-dimensional printed sacrificial molds, which were subsequently dissolved to create controllable and graded porosity within the scaffold. Surface morphology, thermal, mechanical, and biocompatible properties as well as shape memory effects of the synthesized smart polymers and resultant porous scaffolds were characterized. Fourier transform infrared spectroscopy and gel content analysis confirmed the formation of chemical crosslinking by reacting polycaprolactone triol and castor oil with multi-isocyanate groups. Differential scanning calorimetry revealed an adjustable glass transition temperature in a range from −8°C to 35°C. Uniaxial compression testing indicated that the obtained polymers, possessing a highly crosslinked interpenetrating polymeric networks, have similar compressive modulus to polycaprolactone. Shape memory tests revealed that the smart polymers display finely tunable recovery speed and exhibit greater than 92% shape fixing at −18°C or 0°C and full shape recovery at physiological temperature. Scanning electron microscopy analysis of fabricated scaffolds revealed a graded microporous structure, which mimics the nonuniform distribution of porosity found within natural tissues. With polycaprolactone serving as a control, human bone marrow-derived mesenchymal stem cell adhesion, proliferation, and differentiation greatly increased on our novel smart polymers. The current work will significantly advance the future design and development of novel and functional biomedical scaffolds with advanced 4D printing technology and highly biocompatible smart biomaterials. PMID:28195832

Modulator-Controlled Synthesis of Microporous STA-26, an Interpenetrated 8,3-Connected Zirconium MOF with the the-i Topology, and its Reversible Lattice Shift.

PubMed

Bumstead, Alice M; Cordes, David B; Dawson, Daniel M; Chakarova, Kristina K; Mihaylov, Mihail Y; Hobday, Claire L; Düren, Tina; Hadjiivanov, Konstantin I; Slawin, Alexandra M Z; Ashbrook, Sharon E; Prasad, Ram R R; Wright, Paul A

2018-04-20

A fully interpenetrated 8,3-connected zirconium MOF with the the-i topology type, STA-26 (St Andrews porous material-26), has been prepared using the 4,4',4"-(2,4,6-trimethylbenzene-1,3,5-triyl)tribenzoate (TMTB) tritopic linker with formic acid as a modulating agent. In the as-prepared form STA-26 possesses Im3‾ m symmetry compared with the Pm3‾ m symmetry of the non-interpenetrated analogue, NU-1200, prepared using benzoic acid as a modulator. Upon removal of residual solvent there is a shift between the interpenetrating lattices and a resultant symmetry change to Cmcm which is fully reversible. This is observed by X-ray diffraction and 13 C MAS NMR is also found to be remarkably sensitive to the structural transition. Furthermore, heating STA-26(Zr) in vacuum dehydroxylates the Zr 6 nodes leaving coordinatively unsaturated Zr 4+ sites, as shown by IR spectroscopy using CO and CD 3 CN as probe molecules. Nitrogen adsorption at 77 K together with grand canonical Monte Carlo simulations confirms a microporous, fully interpenetrated, structure with pore volume 0.53 cm 3  g -1 while CO 2 adsorption at 196 K reaches 300 cm 3 STP g -1 at 1 bar. While the pore volume is smaller than that of its non-interpenetrated mesoporous analogue, interpenetration makes the structure more stable to moisture adsorption and introduces shape selectivity in adsorption. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Catalytic molecularly imprinted polymer membranes: development of the biomimetic sensor for phenols detection.

PubMed

Sergeyeva, T A; Slinchenko, O A; Gorbach, L A; Matyushov, V F; Brovko, O O; Piletsky, S A; Sergeeva, L M; Elska, G V

2010-02-05

Portable biomimetic sensor devices for the express control of phenols content in water were developed. The synthetic binding sites mimicking active site of the enzyme tyrosinase were formed in the structure of free-standing molecularly imprinted polymer membranes. Molecularly imprinted polymer membranes with the catalytic activity were obtained by co-polymerization of the complex Cu(II)-catechol-urocanic acid ethyl ester with (tri)ethyleneglycoldimethacrylate, and oligourethaneacrylate. Addition of the elastic component oligourethaneacrylate provided formation of the highly cross-linked polymer with the catalytic activity in a form of thin, flexible, and mechanically stable membrane. High accessibility of the artificial catalytic sites for the interaction with the analyzed phenol molecules was achieved due to addition of linear polymer (polyethyleneglycol Mw 20,000) to the initial monomer mixture before the polymerization. As a result, typical semi-interpenetrating polymer networks (semi-IPNs) were formed. The cross-linked component of the semi-IPN was represented by the highly cross-linked catalytic molecularly imprinted polymer, while the linear one was represented by polyethyleneglycol Mw 20,000. Extraction of the linear polymer from the fully formed semi-IPN resulted in formation of large pores in the membranes' structure. Concentration of phenols in the analyzed samples was detected using universal portable device oxymeter with the oxygen electrode in a close contact with the catalytic molecularly imprinted polymer membrane as a transducer. The detection limit of phenols detection using the developed sensor system based on polymers-biomimics with the optimized composition comprised 0.063 mM, while the linear range of the sensor comprised 0.063-1 mM. The working characteristics of the portable sensor devices were investigated. Storage stability of sensor systems at room temperature comprised 12 months (87%). As compared to traditional methods of phenols detection the developed sensor system is characterized by simplicity of operation, compactness, and low cost. Copyright 2009 Elsevier B.V. All rights reserved.

Development and Characterization of Mechanically Robust, 3D-Printable Photopolymers

NASA Astrophysics Data System (ADS)

Sycks, Dalton George

3D printing has seen an explosion of interest and growth in recent years, especially within the biomedical space. Prized for its efficiency, ability to produce complex geometries, and facile material processing, additive manufacturing is rapidly being used to create medical devices ranging from orthopedic implants to tissue scaffolds. However, 3D printing is currently limited to a select few material choices, especially when one considers soft tissue replacement or augmentation. To this end, my research focuses on developing material systems that are simultaneously 1) 3D printable, 2) biocompatible, and 3) mechanically robust with properties appropriate for soft-tissue replacement or augmentation applications. Two systems were developed toward this goal: an interpenetrating network (IPN) hydrogel consisting of covalently crosslinked poly (ethylene glycol) diacrylate (PEGDA) and ionically crosslinked brown sodium alginate, and semi-crystalline thiol-ene photopolymers containing spiroacetal molecules in the polymer main-chain backbone. In addition to successfully being incorporated into existing 3D printing systems (extrusion-deposition for the PEGDA-alginate hydrogel and digital light processing for the thiol-ene polymers) both systems exhibited biocompatibility and superior thermomechanical properties such as tensile modulus, failure strain, and toughness. This work offers two fully-developed, novel polymer platforms with outstanding performance; further, structure-property relationships are highlighted and discussed on a molecular and morphological level to provide material insights that are useful to researchers and engineers in the design of highly tuned and mechanically robust polymers.

Encapsulation of an interpenetrated diamondoid inorganic building block in a metal-organic framework.

PubMed

Zhang, Huabin; Lin, Ping; Chen, Erxia; Tan, Yanxi; Wen, Tian; Aldalbahi, Ali; Alshehri, Saad M; Yamauchi, Yusuke; Du, Shaowu; Zhang, Jian

2015-03-23

The first example of an inorganic-organic composite framework with an interpenetrated diamondoid inorganic building block, featuring unique {InNa}n helices and {In12 Na16 } nano-rings, has been constructed and structurally characterized. This framework also represents a unique example of encapsulation of an interpenetrated diamondoid inorganic building block in a metal-organic framework. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Composite carbohydrate interpenetrating polyelectrolyte nano-complexes (IPNC) as a controlled oral delivery system of citalopram HCl for pediatric use: in-vitro/in-vivo evaluation and histopathological examination.

PubMed

Kamel, Rabab; Abbas, Haidy; El-Naa, Mona

2018-06-01

Citalopram HCl (CH) is one of the few drugs which can be used safely in childhood psychiatric disorders. This study was focused on the preparation of interpenetrating polyelectrolytes nano-complexes (IPNC) to transform the hydrophilic carbohydrate polymers into an insoluble form. The IPNCs were loaded with CH to sustain its effect. The IPNC2 (composed of chitosan:pectin in a 3:1 ratio) showed the most extended drug release pattern (P < 0.05) and followed a Higuchi-order kinetics model. It was characterized using SEM, X-rays diffractometry, and FTIR. In-vivo studies were performed using immature rats with induced depression, and were based on the investigation of behavioral, biochemical, and histopathological changes at different time intervals up to 24 h. Rats treated with IPNC2 showed a significant more rapid onset of action and more extended effect in the behavioral tests, in addition to a significantly higher serotonin brain level up to 24 h, compared to rats treated with the market product (P < 0.05). The histopathological examination showed a profound amelioration of the cerebral cortex features of the depressed rats after IPNC2 administration. This study proves the higher efficacy and more extended effect of the new polyelectrolytes nano-complexes compared to the market product.

Overcoming Film Quality Issues for Conjugated Polymers Doped with F4TCNQ by Solution Sequential Processing: Hall Effect, Structural, and Optical Measurements.

PubMed

Scholes, D Tyler; Hawks, Steven A; Yee, Patrick Y; Wu, Hao; Lindemuth, Jeffrey R; Tolbert, Sarah H; Schwartz, Benjamin J

2015-12-03

We demonstrate that solution-sequential processing (SqP) can yield heavily doped pristine-quality films when used to infiltrate the molecular dopant 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) into pure poly(3-hexylthiophene) (P3HT) polymer layers. Profilometry measurements show that the SqP method produces doped films with essentially the same surface roughness as pristine films, and 2-D grazing-incidence wide-angle X-ray scattering (GIWAXS) confirms that SqP preserves both the size and orientation of the pristine polymer's crystallites. Unlike traditional blend-cast F4TCNQ/P3HT doped films, our sequentially processed layers have tunable and reproducible conductivities reaching as high as 5.5 S/cm even when measured over macroscopic (>1 cm) distances. The high conductivity and superb film quality allow for meaningful Hall effect measurements, which reveal p-type conduction and carrier concentrations tunable from 10(16) to 10(20) cm(-3) and hole mobilities ranging from ∼0.003 to 0.02 cm(2) V(-1) s(-1) at room temperature over the doping levels examined.

Ordered alternating binary polymer nanodroplet array by sequential spin dewetting.

PubMed

Bhandaru, Nandini; Das, Anuja; Salunke, Namrata; Mukherjee, Rabibrata

2014-12-10

We report a facile technique for fabricating an ordered array of nearly equal-sized mesoscale polymer droplets of two constituent polymers (polystyrene, PS and poly(methyl methacrylate), PMMA) arranged in an alternating manner on a topographically patterned substrate. The self-organized array of binary polymers is realized by sequential spin dewetting. First, a dilute solution of PMMA is spin-dewetted on a patterned substrate, resulting in an array of isolated PMMA droplets arranged along the substrate grooves due to self-organization during spin coating itself. The sample is then silanized with octadecyltrichlorosilane (OTS), and subsequently, a dilute solution of PS is spin-coated on to it, which also undergoes spin dewetting. The spin-dewetted PS drops having a size nearly equal to the pre-existing PMMA droplets position themselves between two adjacent PMMA drops under appropriate conditions, forming an alternating binary polymer droplet array. The alternating array formation takes place for a narrow range of solution concentration for both the polymers and depends on the geometry of the substrate. The size of the droplets depends on the extent of confinement, and droplets as small as 100 nm can be obtained by this method, on a suitable template. The findings open up the possibility of creating novel surfaces having ordered multimaterial domains with a potential multifunctional capability.

Copper coordination polymers from cavitand ligands: hierarchical spaces from cage and capsule motifs, and other topologies† †Electronic supplementary information (ESI) available: Further details of crystallographic studies, thermogravimetric analyses, Raman spectroscopy. CCDC 1401250–1401256. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5sc01801c Click here for additional data file. Click here for additional data file.

PubMed Central

Thorp-Greenwood, Flora L.; Ronson, Tanya K.

2015-01-01

The cyclotriveratrylene-type ligands (±)-tris(iso-nicotinoyl)cyclotriguaiacylene L1 (±)-tris(4-pyridylmethyl)cyclotriguaiacylene L2 and (±)-tris{4-(4-pyridyl)benzyl}cyclotriguaiacylene L3 all feature 4-pyridyl donor groups and all form coordination polymers with CuI and/or CuII cations that show a remarkable range of framework topologies and structures. Complex [CuI 4CuII 1.5(L1)3(CN)6]·CN·n(DMF) 1 features a novel 3,4-connected framework of cyano-linked hexagonal metallo-cages. In complexes [Cu3(L2)4(H2O)3]·6(OTf)·n(DMSO) 2 and [Cu2(L3)2Br2(H2O)(DMSO)]·2Br·n(DMSO) 3 capsule-like metallo-cryptophane motifs are formed which linked through their metal vertices into a hexagonal 2D network of (43.123)(42.122) topology or a coordination chain. Complex [Cu2(L1)2(OTf)2(NMP)2(H2O)2]·2(OTf)·2NMP 4 has an interpenetrating 2D 3,4-connected framework of (4.62.8)(62.8)(4.62.82) topology with tubular channels. Complex [Cu(L1)(NCMe)]·BF4·2(CH3CN)·H2O 5 features a 2D network of 63 topology while the CuII analogue [Cu2(L1)2(NMP)(H2O)]·4BF4·12NMP·1.5H2O 6 has an interpenetrating (10,3)-b type structure and complex [Cu2(L2)2Br3(DMSO)]·Br·n(DMSO) 7 has a 2D network of 4.82 topology. Strategies for formation of coordination polymers with hierarchical spaces emerge in this work and complex 2 is shown to absorb fullerene-C60 through soaking the crystals in a toluene solution. PMID:28791086

Mixed polymer brushes by sequential polymer addition: anchoring layer effect.

PubMed

Draper, John; Luzinov, Igor; Minko, Sergiy; Tokarev, Igor; Stamm, Manfred

2004-05-11

Smart surfaces can be described as surfaces that have the ability to respond in a controllable fashion to specific environmental stimuli. A heterogeneous (mixed) polymer brush (HPB) can provide a synthetic route to designing smart polymer surfaces. In this research we study HPB comprised of end-grafted polystyrene (PS) and poly(2-vinyl pyridine) (P2VP). The synthesis of the HPB involves the use of an "intermolecular glue" acting as a binding/anchoring interlayer between the polymer brush and the substrate, a silicon wafer. We compare anchoring layers of epoxysilane (GPS), which forms a self-assembled monolayer with epoxy functionality, to poly(glycidyl methacrylate) (PGMA), which forms a macromolecular monolayer with epoxy functionality. The PS and P2VP were deposited onto the wafers in a sequential fashion to chemically graft PS in a first step and subsequently graft P2VP. Rinsing the HPB in selective solvents and observing the change in water contact angle as a function of the HPB composition studied the switching nature of the HPB. Scanning probe microscopy was used to probe the topography and phase imagery of the HPB. The nature of the anchoring layer significantly affected the wettability and morphology of the mixed brushes.

Synthesis and Examination of Nanocomposites Based on Poly(2-hydroxyethyl methacrylate) for Medicinal Use

NASA Astrophysics Data System (ADS)

Kukolevska, Olena S.; Gerashchenko, Igor I.; Borysenko, Mykola V.; Pakhlov, Evgenii M.; Machovsky, Michal; Yushchenko, Tetyana I.

2017-02-01

Preparation of poly(2-hydroxyethyl methacrylate) (PHEMA) based nanocomposites using different approaches such as synthesis with water as the porogen, filling of polymer matrix by silica and formation of interpenetrating polymer networks with polyurethane was demonstrated. Incorporation of various biologically active compounds (BAC) such as metronidazole, decamethoxin, zinc sulphate, silver nitrate or amino acids glycine and tryptophan into nanocomposites was achieved. BAC were introduced into the polymer matrix either (1) directly, or (2) with a solution of colloidal silica, or (3) through immobilization on silica (sol-densil). Morphology of prepared materials was investigated by laser scanning microscopy and low-vacuum scanning electron microscopy. In vacuum freeze-drying, prior imaging was proposed for improving visualization of the porous structure of composites. The interaction between PHEMA matrix and silica filler was investigated by IR spectroscopy. Adsorption of 2-hydroxyethyl methacrylate and BAC from aqueous solution on the silica surface was also examined. Phase composition and thermal stability of composites were studied by the differential thermogravimetry/differential thermal analysis. Release of BAC into water medium from prepared composites were shown to depend on the synthetic method and differed significantly. Obtained PHEMA-base materials which are characterized by controlled release of BAC have a strong potential for application in manufacturing of different surgical devices like implants, catheters and drainages.

Novel patternable and conducting metal-polymer nanocomposites: a step towards advanced mutlifunctional materials

NASA Astrophysics Data System (ADS)

Rodríguez-Cantó, Pedro J.; Martínez-Marco, Mariluz; Abargues, Rafael; Latorre-Garrido, Victor; Martínez-Pastor, Juan P.

2013-03-01

In this work, we present a novel patternable conducting nanocomposite containing gold nanoparticles. Here, the in-situ polymerization of 3T is carried out using HAuCl4 as oxidizing agent inside PMMA as host matrix. During the bake step, the gold salt is also reduced from Au(III) to Au(0) generating Au nanoparticles in the interpenetrating polymer network (IPN) system. We found that this novel multifunctional resist shows electrical conductivity and plasmonic properties as well as potential patterning capability provided by the host matrix. The resulting nanocomposite has been investigated by TEM and UV-Vis spectroscopy. Electrical characterization was also conducted for different concentration of 3T and Au(III) following a characteristic percolation behaviour. Conductivities values from 10-5 to 10 S/cm were successfully obtained depending on the IPN formulation. Moreover, The Au nanoparticles generated exhibited a localized surface plasmon resonance at around 520 nm. This synthetic approach is of potential application to modify the conductivity of numerous insulating polymers and synthesize Au nanoparticles preserving to some extent their physical and chemical properties. In addition, combination of optical properties (Plasmonics), electrical, and lithographic capability in the same material allows for the design of materials with novel functionalities and provides the basis for next generation devices.

Accelerated Combinatorial High Throughput Star Polymer Synthesis via a Rapid One-Pot Sequential Aqueous RAFT (rosa-RAFT) Polymerization Scheme.

PubMed

Cosson, Steffen; Danial, Maarten; Saint-Amans, Julien Rosselgong; Cooper-White, Justin J

2017-04-01

Advanced polymerization methodologies, such as reversible addition-fragmentation transfer (RAFT), allow unprecedented control over star polymer composition, topology, and functionality. However, using RAFT to produce high throughput (HTP) combinatorial star polymer libraries remains, to date, impracticable due to several technical limitations. Herein, the methodology "rapid one-pot sequential aqueous RAFT" or "rosa-RAFT," in which well-defined homo-, copolymer, and mikto-arm star polymers can be prepared in very low to medium reaction volumes (50 µL to 2 mL) via an "arm-first" approach in air within minutes, is reported. Due to the high conversion of a variety of acrylamide/acrylate monomers achieved during each successive short reaction step (each taking 3 min), the requirement for intermediary purification is avoided, drastically facilitating and accelerating the star synthesis process. The presented methodology enables RAFT to be applied to HTP polymeric bio/nanomaterials discovery pipelines, in which hundreds of complex polymeric formulations can be rapidly produced, screened, and scaled up for assessment in a wide range of applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Foldable interpenetrated metal-organic frameworks/carbon nanotubes thin film for lithium-sulfur batteries

NASA Astrophysics Data System (ADS)

Mao, Yiyin; Li, Gaoran; Guo, Yi; Li, Zhoupeng; Liang, Chengdu; Peng, Xinsheng; Lin, Zhan

2017-03-01

Lithium-sulfur batteries are promising technologies for powering flexible devices due to their high energy density, low cost and environmental friendliness, when the insulating nature, shuttle effect and volume expansion of sulfur electrodes are well addressed. Here, we report a strategy of using foldable interpenetrated metal-organic frameworks/carbon nanotubes thin film for binder-free advanced lithium-sulfur batteries through a facile confinement conversion. The carbon nanotubes interpenetrate through the metal-organic frameworks crystal and interweave the electrode into a stratified structure to provide both conductivity and structural integrity, while the highly porous metal-organic frameworks endow the electrode with strong sulfur confinement to achieve good cyclability. These hierarchical porous interpenetrated three-dimensional conductive networks with well confined S8 lead to high sulfur loading and utilization, as well as high volumetric energy density.

Foldable interpenetrated metal-organic frameworks/carbon nanotubes thin film for lithium–sulfur batteries

PubMed Central

Mao, Yiyin; Li, Gaoran; Guo, Yi; Li, Zhoupeng; Liang, Chengdu; Peng, Xinsheng; Lin, Zhan

2017-01-01

Lithium–sulfur batteries are promising technologies for powering flexible devices due to their high energy density, low cost and environmental friendliness, when the insulating nature, shuttle effect and volume expansion of sulfur electrodes are well addressed. Here, we report a strategy of using foldable interpenetrated metal-organic frameworks/carbon nanotubes thin film for binder-free advanced lithium–sulfur batteries through a facile confinement conversion. The carbon nanotubes interpenetrate through the metal-organic frameworks crystal and interweave the electrode into a stratified structure to provide both conductivity and structural integrity, while the highly porous metal-organic frameworks endow the electrode with strong sulfur confinement to achieve good cyclability. These hierarchical porous interpenetrated three-dimensional conductive networks with well confined S8 lead to high sulfur loading and utilization, as well as high volumetric energy density. PMID:28262801

3D Printing of Highly Stretchable, Shape-Memory, and Self-Healing Elastomer toward Novel 4D Printing.

PubMed

Kuang, Xiao; Chen, Kaijuan; Dunn, Conner K; Wu, Jiangtao; Li, Vincent C F; Qi, H Jerry

2018-02-28

The three-dimensional (3D) printing of flexible and stretchable materials with smart functions such as shape memory (SM) and self-healing (SH) is highly desirable for the development of future 4D printing technology for myriad applications, such as soft actuators, deployable smart medical devices, and flexible electronics. Here, we report a novel ink that can be used for the 3D printing of highly stretchable, SM, and SH elastomer via UV-light-assisted direct-ink-write printing. An ink containing urethane diacrylate and a linear semicrystalline polymer is developed for the 3D printing of a semi-interpenetrating polymer network elastomer that can be stretched by up to 600%. The 3D-printed complex structures show interesting functional properties, such as high strain SM and SM -assisted SH capability. We demonstrate that such a 3D-printed SM elastomer has the potential application for biomedical devices, such as vascular repair devices. This research paves a new way for the further development of novel 4D printing, soft robotics, and biomedical devices.

Construction, Structural Diversity and Properties of Five Coordination Polymers Based on 5-Nitroisophthalate and Bis(imidazole) Linkers

NASA Astrophysics Data System (ADS)

Arıcı, Mürsel

2018-06-01

Five coordination polymers, namely, [Cd(μ3-5-nip)(μ-obix)]n (1), [Co(μ3-5-nip)(μ-obix)]n (2), [Zn(μ-5-nip)(μ-obix)]n (3 and 4) and [Cd(μ-5-nip)(μ-bisobix)]n (5) (5-nip: 5-nitroisophthalate, obix: 1,2-bis(imidazol-1ylmethyl)benzene, bisobix: 1,2-bis(2-isopropylimidazol-1ylmethyl)benzene) were hydrothermally synthesized and characterized by IR spectroscopy, elemental analysis, single crystal and powder X-ray diffraction and thermal analysis (TG/DTA). X-ray results showed that the complexes displayed structural diversity depending on metal ions and conformations of bis(imidazole) linkers. Complexes 1 and 2 were 1D structures and obix ligand displayed cis-conformation. Complexes 3 and 4 exhibited 2D and 3D structures with same components depending on obix conformation. In complex 5, 3D+3D→3D interpenetrated structure was obtained with dia topology when bisobix having sterically hindered groups on imidazole rings was used. Moreover, thermal, photoluminescence and optical properties of the complexes were also investigated.

Direct Visualization of Conformation and Dense Packing of DNA-Based Soft Colloids

NASA Astrophysics Data System (ADS)

Zhang, Jing; Lettinga, Paul M.; Dhont, Jan K. G.; Stiakakis, Emmanuel

2014-12-01

Soft colloids—such as polymer-coated particles, star polymers, block-copolymer micelles, microgels—constitute a broad class of materials where microscopic properties such as deformability and penetrability of the particle play a key role in tailoring their macroscopic properties which is of interest in many technological areas. The ability to access these microscopic properties is not yet demonstrated despite its great importance. Here we introduce novel DNA-coated colloids with star-shaped architecture that allows accessing the above local structural information by directly visualizing their intramolecular monomer density profile and arm's free-end locations with confocal fluorescent microscopy. Compression experiments on a two-dimensional hexagonal lattice formed by these macromolecular assemblies reveal an exceptional resistance to mutual interpenetration of their charged corona at pressures approaching the MPa range. Furthermore, we find that this lattice, in a close packing configuration, is surprisingly tolerant to particle size variation. We anticipate that these stimuli-responsive materials could aid to get deeper insight in a wide range of problems in soft matter, including the study and design of biomimetic lubricated surfaces.

Contribution of Charges in Polyvinyl Alcohol Networks to Marine Antifouling.

PubMed

Yang, Wufang; Lin, Peng; Cheng, Daocang; Zhang, Longzhou; Wu, Yang; Liu, Yupeng; Pei, Xiaowei; Zhou, Feng

2017-05-31

Semi-interpenetrated polyvinyl alcohol polymer networks (SIPNs) were prepared by integrating various charged components into polyvinyl alcohol polymer. Contact angle measurement, attenuated total reflection Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and tensile tests were used to characterize the physicochemical properties of the prepared SIPNs. To investigate the contribution of charges to marine antifouling, the adhesion behaviors of green algae Dunaliella tertiolecta and diatoms Navicula sp. in the laboratory and of the actual marine animals in field test were studied for biofouling assays. The results suggest that less algae accumulation densities are observed for neutral-, anionic-, and zwitterionic-component-integrated SIPNs. However, for the cationic SIPNs, despite the hydration shell induced by the ion-dipole interaction, the resistance to biofouling largely depends on the amount of cationic component because of the possible favorable electrostatic attraction between the cationic groups in SIPNs and the negatively charged algae. Considering that the preparation of novel nontoxic antifouling coating is a long-standing and cosmopolitan industrial challenge, the SIPNs may provide a useful reference for marine antifouling and some other relevant fields.

A new zinc coordination polymer in (10, 3)-d framework with unusual redox property

NASA Astrophysics Data System (ADS)

Huo, Jianqiang; Yan, Shuai; Arulsamy, Navamoney

2017-11-01

A new coordination polymer, [Zn(H1dimb)(Cl)]n (1) (H1dimb = 2,5-di (1H-imidazol-1-yl)benzoate), is obtained by hydrothermal synthesis and characterized by single crystal X-ray diffraction data and elemental analysis. Compound 1 crystallizes in the orthorhombic space group Pccn, and its structure exhibits a rarely observed ultimate racemic 3D network with 2-fold interpenetrating (10, 3)-d (or utp) topology due to the presence of alternating arrays of left- and right-handed helices. Thermo-gravimetric analysis (TGA) data for 1 reveals that the metal-organic framework (MOF) is thermally stable up to 350 °C under a N2 atmosphere. Compound 1 also possesses interesting photoluminescent properties as expected for Zn2+ complexes of aromatic ligands. Photoemission spectra measured in the solid state reveal a very strong emission band centered at 417 nm. Cyclic voltammetric data reveal that the compound exhibits quasi reversible two-electron redox process in acidic aqueous solution and the surprising electrochemical behavior is attributed to the Zn/Zn2+ process.

New coordination polymers from 1D chain, 2D layer to 3D framework constructed from 1,2-phenylenediacetic acid and 1,3-bis(4-pyridyl)propane flexible ligands

NASA Astrophysics Data System (ADS)

Xin, Ling-Yun; Liu, Guang-Zhen; Wang, Li-Ya

2011-06-01

The hydrothermal reactions of Cd, Zn, or Cu(II) acetate salts with H 2PHDA and BPP flexible ligands afford three new coordination polymers, including [Cd(PHDA)(BPP)(H 2O)] n(1), [Zn(PHDA)(BPP)] n(2), and [Cu 2(PHDA) 2(BPP)] n(3) (H 2PHDA=1,2-phenylenediacetic acid, BPP=1,3-bis(4-pyridyl)propane). The single-crystal X-ray diffractions reveal that all three complexes feature various metal carboxylate subunits extended further by the BPP ligands to form a diverse range of structures, displaying a remarked structural sensitivity to metal(II) cation. Complex 1 containing PHDA-bridged binuclear cadmium generates 1D double-stranded chain, complex 2 results in 2D→2D interpenetrated (4,4) grids, and complex 3 displays a 3D self-penetrated framework with 4 86 68 rob topology. In addition, fluorescent analyses show that both 1 and 2 exhibit intense blue-violet photoluminescence in the solid state.

Current progress and technical challenges of flexible liquid crystal displays

NASA Astrophysics Data System (ADS)

Fujikake, Hideo; Sato, Hiroto

2009-02-01

We focused on several technical approaches to flexible liquid crystal (LC) display in this report. We have been developing flexible displays using plastic film substrates based on polymer-dispersed LC technology with molecular alignment control. In our representative devices, molecular-aligned polymer walls keep plastic-substrate gap constant without LC alignment disorder, and aligned polymer networks create monostable switching of fast-response ferroelectric LC (FLC) for grayscale capability. In the fabrication process, a high-viscosity FLC/monomer solution was printed, sandwiched and pressed between plastic substrates. Then the polymer walls and networks were sequentially formed based on photo-polymerization-induced phase separation in the nematic phase by two exposure processes of patterned and uniform ultraviolet light. The two flexible backlight films of direct illumination and light-guide methods using small three-primary-color light-emitting diodes were fabricated to obtain high-visibility display images. The fabricated flexible FLC panels were driven by external transistor arrays, internal organic thin film transistor (TFT) arrays, and poly-Si TFT arrays. We achieved full-color moving-image displays using the flexible FLC panel and the flexible backlight film based on field-sequential-color driving technique. Otherwise, for backlight-free flexible LC displays, flexible reflective devices of twisted guest-host nematic LC and cholesteric LC were discussed with molecular-aligned polymer walls. Singlesubstrate device structure and fabrication method using self-standing polymer-stabilized nematic LC film and polymer ceiling layer were also proposed for obtaining LC devices with excellent flexibility.

Identification of polymer types and additives in marine microplastic particles using pyrolysis-GC/MS and scanning electron microscopy.

PubMed

Fries, Elke; Dekiff, Jens H; Willmeyer, Jana; Nuelle, Marie-Theres; Ebert, Martin; Remy, Dominique

2013-10-01

Any assessment of plastic contamination in the marine environment requires knowledge of the polymer type and the additive content of microplastics. Sequential pyrolysis-gas chromatography coupled to mass spectrometry (Pyr-GC/MS) was applied to simultaneously identify polymer types of microplastic particles and associated organic plastic additives (OPAs). In addition, a scanning electron microscope equipped with an energy-dispersive X-ray microanalyser was used to identify the inorganic plastic additives (IPAs) contained in these particles. A total of ten particles, which were optically identified as potentially being plastics, were extracted from two sediment samples collected from Norderney, a North Sea island, by density separation in sodium chloride. The weights of these blue, white and transparent fragments varied between 10 and 350 μg. Polymer types were identified by comparing the resulting pyrograms with those obtained from the pyrolysis of selected standard polymers. The particles consisted of polyethylene (PE), polypropylene, polystyrene, polyamide, chlorinated PE and chlorosulfonated PE. The polymers contained diethylhexyl phthalate, dibutyl phthalate, diethyl phthalate, diisobutyl phthalate, dimethyl phthalate, benzaldehyde and 2,4-di-tert-butylphenol. Sequential Py-GC/MS was found to be an appropriate tool for identifying marine microplastics for polymer types and OPAs. The IPAs identified were titanium dioxide nanoparticles (TiO2-NPs), barium, sulphur and zinc. When polymer-TiO2 composites are degraded in the marine environment, TiO2-NPs are probably released. Thus, marine microplastics may act as a TiO2-NP source, which has not yet been considered.

Comparison of Sequential Drug Release in Vitro and in Vivo

PubMed Central

Sundararaj, Sharath C.; Al-Sabbagh, Mohanad; Rabek, Cheryl L.; Dziubla, Thomas D.; Thomas, Mark V.; Puleo, David A.

2015-01-01

Development of drug delivery devices typically involves characterizing in vitro release performance with the inherent assumption that this will closely approximate in vivo performance. Yet, as delivery devices become more complex, for instance with a sequential drug release pattern, it is important to confirm that in vivo properties correlate with the expected “programming” achieved in vitro. In this work, a systematic comparison between in vitro and in vivo biomaterial erosion and sequential release was performed for a multilayered association polymer system comprising cellulose acetate phthalate and Pluronic F-127. After assessing the materials during incubation in phosphate-buffered saline, devices were implanted supracalvarially in rats. Devices with two different doses and with different erosion rates were harvested at increasing times post-implantation, and the in vivo thickness loss, mass loss, and the drug release profiles were compared with their in vitro counterparts. The sequential release of four different drugs observed in vitro was successfully translated to in vivo conditions. Results suggest, however, that the total erosion time of the devices was longer and release rates of the four drugs were different, with drugs initially released more quickly and then more slowly in vivo. Whereas many comparative studies of in vitro and in vivo drug release from biodegradable polymers involved a single drug, the present research demonstrated that sequential release of four drugs can be maintained following implantation. PMID:26111338

Unit: Polymers, Inspection Pack, National Trial Print.

ERIC Educational Resources Information Center

Australian Science Education Project, Toorak, Victoria.

This unit is one of a series developed by the Australian Science Education Project (ASEP) for use by students at the junior secondary level (grades 7-10) in Australian schools. The unit is a trial version dealing with polymers, and may be used independently or integrated into a sequential program with other units. All students complete the…

Exploring the Properties of Genetically Engineered Silk-Elastin-Like Protein Films.

PubMed

Machado, Raul; da Costa, André; Sencadas, Vitor; Pereira, Ana Margarida; Collins, Tony; Rodríguez-Cabello, José Carlos; Lanceros-Méndez, Senentxu; Casal, Margarida

2015-12-01

Free standing films of a genetically engineered silk-elastin-like protein (SELP) were prepared using water and formic acid as solvents. Exposure to methanol-saturated air promoted the formation of aggregated β-strands rendering aqueous insolubility and improved the mechanical properties leading to a 10-fold increase in strain-to-failure. The films were optically clear with resistivity values similar to natural rubber and thermally stable up to 180 °C. Addition of glycerol showed to enhance the flexibility of SELP/glycerol films by interacting with SELP molecules through hydrogen bonding, interpenetrating between the polymer chains and granting more conformational freedom. This detailed characterization provides cues for future and unique applications using SELP based biopolymers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Folic acid conjugated cross-linked acrylic polymer (FA-CLAP) hydrogel for site specific delivery of hydrophobic drugs to cancer cells.

PubMed

Pillai, Jisha Jayadevan; Thulasidasan, Arun Kumar Theralikattu; Anto, Ruby John; Chithralekha, Devika Nandan; Narayanan, Ashwanikumar; Kumar, Gopalakrishnapillai Sankaramangalam Vinod

2014-07-15

The hydrogel based system is found to be rarely reported for the delivery of hydrophobic drug due to the incompatibility of hydrophilicity of the polymer network and the hydrophobicity of drug. This problem can be solved by preparing semi-interpenetrating network of cross-linked polymer for tuning the hydrophilicity so as to entrap the hydrophobic drugs. The current study is to develop a folic acid conjugated cross-linked pH sensitive, biocompatible polymeric hydrogel to achieve a site specific drug delivery. For that, we have synthesized a folic acid conjugated PEG cross-linked acrylic polymer (FA-CLAP) hydrogel and investigated its loading and release of curcumin. The formed polymer hydrogel was then conjugated with folic acid for the site specific delivery of curcumin to cancer cells and then further characterized and conducted the cell uptake and cytotoxicity studies on human cervical cancer cell lines (HeLa). In this study, we synthesized folic acid conjugated cross-linked acrylic hydrogel for the delivery of hydrophobic drugs to the cancer site. Poly (ethyleneglycol) (PEG) diacrylate cross-linked acrylic polymer (PAA) was prepared via inverse emulsion polymerization technique and later conjugated it with folic acid (FA-CLAP). Hydrophobic drug curcumin is entrapped into it and investigated the entrapment efficiency. Characterization of synthesized hydogel was done by using Fourier Transform-Infrared spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), Differential Scanning Calorimetry (DSC). Polymerization and folate conjugation was confirmed by FT-IR spectroscopy. The release kinetics of drug from the entrapped form was studied which showed initial burst release followed by sustained release due to swelling and increased cross-linking. In vitro cytotoxicity and cell uptake studies were conducted in human cervical cancer (HeLa) cell lines. Results showed that curcumin entrapped folate conjugated cross-linked acrylic polymer (FA-CLAP) hydrogel showed higher cellular uptake than the non folate conjugated form. So this can be suggested as a better delivery system for site specific release of hydrophobic cancer drugs.

High-Speed 3D Printing of High-Performance Thermosetting Polymers via Two-Stage Curing.

PubMed

Kuang, Xiao; Zhao, Zeang; Chen, Kaijuan; Fang, Daining; Kang, Guozheng; Qi, Hang Jerry

2018-04-01

Design and direct fabrication of high-performance thermosets and composites via 3D printing are highly desirable in engineering applications. Most 3D printed thermosetting polymers to date suffer from poor mechanical properties and low printing speed. Here, a novel ink for high-speed 3D printing of high-performance epoxy thermosets via a two-stage curing approach is presented. The ink containing photocurable resin and thermally curable epoxy resin is used for the digital light processing (DLP) 3D printing. After printing, the part is thermally cured at elevated temperature to yield an interpenetrating polymer network epoxy composite, whose mechanical properties are comparable to engineering epoxy. The printing speed is accelerated by the continuous liquid interface production assisted DLP 3D printing method, achieving a printing speed as high as 216 mm h -1 . It is also demonstrated that 3D printing structural electronics can be achieved by combining the 3D printed epoxy composites with infilled silver ink in the hollow channels. The new 3D printing method via two-stage curing combines the attributes of outstanding printing speed, high resolution, low volume shrinkage, and excellent mechanical properties, and provides a new avenue to fabricate 3D thermosetting composites with excellent mechanical properties and high efficiency toward high-performance and functional applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-standing gel polymer electrolyte for improving supercapacitor thermal and electrochemical stability

NASA Astrophysics Data System (ADS)

Dagousset, Laure; Pognon, Grégory; Nguyen, Giao T. M.; Vidal, Frédéric; Jus, Sébastien; Aubert, Pierre-Henri

2018-07-01

Electrochemical energy storage is a very active research topic. However, the use of liquid electrolyte in such systems as supercacitors presents several drawbacks on security and packaging. One way to overcome these issues is to design supercapacitors using solid-state electrolytes. We report here the one-pot synthesis and the characterization of self-standing gel polymer electrolyte (SGPE) composed of semi-Interpenetrating Polymer Networks (semi-IPN) based on poly(ethylene oxide) (PEO) network and non cross-linked nitrile butadiene rubber (NBR), self-containing EMITFSI/γ-Butyrolactone (50/50 wt%/wt%) binary mixtures. The SGPE under the form of a thin film are then used as solid electrolyte and also as separator in supercapacitors with Single Wall Carbon Nanotubes (SWCNTs) bucky paper as electrodes. Thermal characterization revealed the suitability of all synthesized membrane in wide range of operating temperature. Electrochemical stabilities of SGPE were close to that of a cellulose separator system (ESW∼3.2-3.6 V) at 20 °C, and were relatively higher than a cellulose system at 100 °C: 2.1-2.5 V and 1.8 V respectively. Furthermore, floating experiments at 100 °C (holding voltage at 2 V) revealed the exceptionally high stability of SGPE, with a residual capacitance of 93% after 500 h. This high electrochemical performance demonstrated the potential of semi-IPN SGPE as separator/electrolyte for high performance supercapacitors.

From Comb-like Polymers to Bottle-Brushes

NASA Astrophysics Data System (ADS)

Liang, Heyi; Cao, Zhen; Dobrynin, Andrey; Sheiko, Sergei

We use a combination of the coarse-grained molecular dynamics simulations and scaling analysis to study conformations of bottle-brushes and comb-like polymers in a melt. Our analysis show that bottle-brushes and comb-like polymers can be in four different conformation regimes depending on the number of monomers between grafted side chains and side chain degree of polymerization. In loosely-grafted comb regime (LC) the degree of polymerization between side chains is longer than side chain degree of polymerization, such that the side chains belonging to the same macromolecule do not overlap. Crossover to a new densely-grafted comb regime (DC) takes place when side chains begin to overlap reducing interpenetration of side chains belonging to different macromolecules. In these two regimes both side-chains and backbone behave as unperturbed linear chains with the effective Kuhn length of the backbone being close to that of linear chain. Further decrease spacer degree of polymerization results in crossover to loosely-grafted bottle-brush regime (LB). In this regime, the bottle-brush backbone is stretched while the side-chains still maintain ideal chain conformation. Finally, for even shorter spacer between grafted side chains, which corresponds to densely-grafted bottle-brush regime (DB), the backbone adopts a fully extended chain conformation, and side-chains begin to stretch to maintain a constant monomer density. NSF DMR-1409710, DMR-1407645, DMR-1624569, DMR-1436201.

Selective Adsorption of Ethane over Ethylene in PCN-245: Impacts of Interpenetrated Adsorbent.

PubMed

Lv, Daofei; Shi, Renfeng; Chen, Yongwei; Wu, Ying; Wu, Houxiao; Xi, Hongxia; Xia, Qibin; Li, Zhong

2018-03-07

The separation of ethane from ethylene using cryogenic distillation is an energy-intensive process in the industry. With lower energetic consumption, the adsorption technology provides the opportunities for developing the industry with economic sustainability. We report an iron-based metal-organic framework PCN-245 with interpenetrated structures as an ethane-selective adsorbent for ethylene/ethane separation. The material maintains stability up to 625 K, even after exposure to 80% humid atmosphere for 20 days. Adsorptive separation experiments on PCN-245 at 100 kPa and 298 K indicated that ethane and ethylene uptakes of PCN-245 were 3.27 and 2.39 mmol, respectively, and the selectivity of ethane over ethylene was up to 1.9. Metropolis Monte Carlo calculations suggested that the interpenetrated structure of PCN-245 created greater interaction affinity for ethane than ethylene through the crossing organic linkers, which is consistent with the experimental results. This work highlights the potential application of adsorbents with the interpenetrated structure for ethane separation from ethylene.

Organometallic exposure dependence on organic–inorganic hybrid material formation in polyethylene terephthalate and polyamide 6 polymer fibers

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

Akyildiz, Halil I.; Jur, Jesse S., E-mail: jsjur@ncsu.edu

2015-03-15

The effect of exposure conditions and surface area on hybrid material formation during sequential vapor infiltrations of trimethylaluminum (TMA) into polyamide 6 (PA6) and polyethylene terephthalate (PET) fibers is investigated. Mass gain of the fabric samples after infiltration was examined to elucidate the reaction extent with increasing number of sequential TMA single exposures, defined as the times for a TMA dose and a hold period. An interdependent relationship between dosing time and holding time on the hybrid material formation is observed for TMA exposure PET, exhibited as a linear trend between the mass gain and total exposure (dose time ×more » hold time × number of sequential exposures). Deviation from this linear relationship is only observed under very long dose or hold times. In comparison, amount of hybrid material formed during sequential exposures to PA6 fibers is found to be highly dependent on amount of TMA dosed. Increasing the surface area of the fiber by altering its cross-sectional dimension is shown to have little on the reaction behavior but does allow for improved diffusion of the TMA into the fiber. This work allows for the projection of exposure parameters necessary for future high-throughput hybrid modifications to polymer materials.« less

Novel High Efficient Organic Photovoltaic Materials: Appendix for Summary of Research. Appendix

NASA Technical Reports Server (NTRS)

Sun, Sam

2002-01-01

There are many different kinds of conjugated polymers that may be useful in photovoltaic devices. So far, the most popular and successful conjugated polymers used in photovoltaic devices include poly(1,4-)phenylenevinylenes (PPV), C60 and their derivatives. The discovery of electro-luminescence in PPV has stimulated a great deal of interest in developing "plastic" solid-state semiconductor devices. The overall synthetic methodology for the preparation of PPV can be divided into three main categories: (1) side chain derivatization, (2) precursor approach, and (3) in-situ polymerization. In this project, the first method was adopted. As discussed in project proposal and literatures, the overall efficiency of photovoltaic devices containing conjugated polymers is determined by the materials ability to generate excitons from incoming radiation, and then to separate the charges at donor/acceptor interfaces, and then to transport charges to respective electrodes. Given that effective exciton diffusion range are typical less then 30 nm, unique morphological structures are needed. This need led to several research groups to the idea that interpenetrating or bi-continuous networks of donor (electron donating) and acceptor (electron withdrawing) polymers should give better results. One approach involved the use of functionalized PPV. The attachment of electron withdrawing cyano groups to a PPV forms the CN-PPV, making it a strong electron acceptor. Underivatized PPV is a generally considered a hole-transporting material. Using blends of MEH-PPV, a soluble donor PPV derivative, as a hole transporter and CN-PPV as an electron transporter, a quantum efficiencies of up to 6% was achieved.

Atmospheric pressure synthesis of photoluminescent hybrid materials by sequential organometallic vapor infiltration into polyethylene terephthalate fibers

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

Akyildiz, Halil I.; Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695; Mousa, Moataz Bellah M.

Exposing a polymer to sequential organometallic vapor infiltration (SVI) under low pressure conditions can significantly modify the polymer's chemical, mechanical, and optical properties. We demonstrate that SVI of trimethylaluminum into polyethylene terephthalate (PET) can also proceed readily at atmospheric pressure, and at 60 °C the extent of reaction determined by mass uptake is independent of pressure between 2.5 Torr and 760 Torr. At 120 °C, however, the mass gain is 50% larger at 2.5 Torr relative to that at 760 Torr, indicating that the precursor diffusion in the chamber and fiber matrix decreases at higher source pressure. Mass gain decreases, in general, as the SVI processmore » temperature increases both at 2.5 Torr and 760 Torr attributed to the faster reaction kinetics forming a barrier layer, which prevents further diffusion of the reactive species. The resulting PET/Al-O{sub x} product shows high photoluminescence compared to untreated fibers. A physical mask on the polymer during infiltration at 760 Torr is replicated in the underlying polymer, producing an image in the polymer that is visible under UV illumination. Because of the reduced precursor diffusivity during exposure at 760 Torr, the image shows improved resolution compared to SVI performed under typical 2.5 Torr conditions.« less

A ligand exchange strategy for one-pot sequential synthesis of (hyperbranched polyethylene)-b-(linear polyketone) block polymers.

PubMed

Zhang, Zhichao; Ye, Zhibin

2012-08-18

Upon the addition of an equimolar amount of 2,2'-bipyridine, a cationic Pd-diimine complex capable of facilitating "living" ethylene polymerization is switched to catalyze "living" alternating copolymerization of 4-tertbutylstyrene and CO. This unique chemistry is thus employed to synthesize a range of well-defined treelike (hyperbranched polyethylene)-b-(linear polyketone) block polymers.

Pros and Cons of the Interpenetrating Panel Design

Treesearch

Paul C. Van Deusen

2000-01-01

The interpenetrating sample design has been selected for the USDA Forest Service's Annual Forest Inventory System. The advantages and disadvantages of this design are discussed by considering alternatives such as the formerly used periodic design, a concentrated grid design, and disturbance based sampling. Factors considered for each design include fulfilling 1998...

Zinc(II) and cadmium(II) coordination polymers containing phenylenediacetate and 4,4‧-azobis(pyridine) ligands: Syntheses, structures, dye adsorption properties and molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Sezer, Güneş Günay; Arıcı, Mürsel; Erucar, İlknur; Yeşilel, Okan Zafer; Özel, Handan Ucun; Gemici, Betül Tuba; Erer, Hakan

2017-11-01

Two new coordination polymers (CPs) - [Zn(μ4-ppda)(μ-abpy)0.5]n(1) and [Cd(μ3-opda)(μ-abpy)0.5(H2O)]n(2) (o/ppda = 1,2/1,4-phenylenediacetate, abpy = 4,4‧-azobis(pyridine)) - have been synthesized by using Zn(II)/Cd(II) salts in the presence of o- and p-phenylenediacetic acid and abpy under hydrothermal conditions. Their structures have been characterized by FT-IR spectroscopy, elemental analysis, X-ray powder diffraction and single crystal X-ray diffraction techniques. The structural diversities were observed depending on anionic ligands and metal centers in the synthesized complexes. Complex 1 consists of a 2-fold interpenetrated 3D+3D→3D framework with pcu topology while complex 2 has a 2D structure with sql topology. The adsorption of methylene blue (MB) was studied to examine the potential of the title CPs for removal of dyes from aqueous solution. Molecular dynamics (MD) simulations were also performed to examine diffusion of MB in 1 and 2. Thermal and optical properties of two complexes were also discussed.

Impregnation of β-tricalcium phosphate robocast scaffolds by in situ polymerization.

PubMed

Martínez-Vázquez, Francisco J; Perera, Fidel H; van der Meulen, Inge; Heise, Andreas; Pajares, Antonia; Miranda, Pedro

2013-11-01

Ring-opening polymerization of ε-caprolactone (ε-CL) and L-lactide (LLA) was performed to impregnate β-tricalcium phosphate (β-TCP) scaffolds fabricated by robocasting. Concentrated colloidal inks prepared from β-TCP commercial powders were used to fabricate porous structures consisting of a 3D mesh of interpenetrating rods. ε-CL and LLA were in situ polymerized within the ceramic structure by using a lipase and stannous octanoate, respectively, as catalysts. The results show that both the macropores inside the ceramic mesh and the micropores within the ceramic rods are full of polymer in either case. The mechanical properties of scaffolds impregnated by in situ polymerization (ISP) are significantly increased over those of the bare structures, exhibiting similar values than those obtained by other, more aggressive, impregnation methods such as melt-immersion (MI). ISP using enzymatic catalysts requires a reduced processing temperature which could facilitate the incorporation of growth factors and other drugs into the polymer composition, thus enhancing the bioactivity of the composite scaffold. The implications of these results for the optimization of the mechanical and biological performance of scaffolds for bone tissue engineering applications are discussed. Copyright © 2013 Wiley Periodicals, Inc.

3D Structural Model of High-Performance Non-Fullerene Polymer Solar Cells as Revealed by High-Resolution AFM.

PubMed

Shi, Shaowei; Chen, Xiaofeng; Liu, Xubo; Wu, Xuefei; Liu, Feng; Zhang, Zhi-Guo; Li, Yongfang; Russell, Thomas P; Wang, Dong

2017-07-26

Rapid improvements in nonfullerene polymer solar cells (PSCs) have brought power conversion efficiencies to greater than 12%. To further improve device performance, a fundamental understanding of the correlations between structure and performance is essential. In this paper, based on a typical high-performance system consisting of J61(one donor-acceptor (D-A) copolymer of benzodithiophene and fluorine substituted benzotriazole) and ITIC (3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']-dithiophene), a 3D structural model is directly imaged by employing high-resolution atomic force microscopy (AFM). Hierarchical morphologies ranging from fiberlike crystallites, several nanometers in size, to a bicontinuous morphology, having domains tens of nanometers in size, are observed. A fibrillar interpenetrating networks of J61-rich domains embedded in a matrix comprised of a J61/ITIC is seen, reflecting the partial miscibility of J61 with ITIC. These hierarchical nanostructural characteristics are coupled to significantly enhanced exciton dissociation, and further contribute to photocurrent and final device performance.

Fabrication of a biodegradable calcium polyphosphate/polyvinyl-urethane carbonate composite for high load bearing osteosynthesis applications.

PubMed

Ramsay, Scott D; Pilliar, Robert M; Santerre, J Paul

2010-07-01

The formation of biodegradable implants for use in osteosynthesis has been a major goal of biomaterials research for the past 2-3 decades. Self-reinforced polylactide systems represent the most significant success of this research to date, however, with elastic constants up to 12-15 GPa at best, they fail to provide the initial stiffness required of devices for stabilizing fractures of major load-bearing bones. Our research has investigated the use of calcium polyphosphate (CPP), an inorganic polymer in combination with polyvinyl-urethane carbonate (PVUC) organic polymers for such applications. Initial studies indicated that composite samples formed as interpenetrating phase composites (IPC) exhibited suitable as-made strength and stiffness, however, they displayed a rapid loss of properties when exposed to in vitro aging. An investigation to determine the mechanism of this accelerated in vitro degradation for the IPCs as well as to identify possible design changes to overcome this drawback was undertaken using a model IPC system. It was found that strong interfacial strength and minimal swelling of the PVUC are very important for obtaining and maintaining appropriate mechanical properties in vitro. (c) 2010 Wiley Periodicals, Inc.

Effect of Silane Coupling Agent on the Creep Behavior and Mechanical Properties of Carbon Fibers/Acrylonitrile Butadiene Rubber Composites.

PubMed

Choi, Woong-Ki; Park, Gil-Young; Kim, Byoung-Shuk; Seo, Min-Kang

2018-09-01

In this study, we investigated the effect of the silane coupling agent on the relationship between the surface free energy of carbon fibers (CFs) and the mechanical strength of CFs/acrylonitrile butadiene rubber (NBR) composites. Moreover, the creep behavior of the CF/NBR composites at surface energetic point of view were studied. The specific component of the surface free energy of the carbon fibers was found to increase upon grafting of the silane coupling agent, resulting in an increase in the tensile strength of the CF/NBR composites. On the other hand, the compressive creep strength was found to follow a slightly different trend. These results indicate the possible formation of a complex interpenetrating polymer network depending on the molecular size of the organic functional groups of the silane coupling agent.

Method of making organic light emitting devices

DOEpatents

Shiang, Joseph John [Niskayuna, NY; Janora, Kevin Henry [Schenectady, NY; Parthasarathy, Gautam [Saratoga Springs, NY; Cella, James Anthony [Clifton Park, NY; Chichak, Kelly Scott [Clifton Park, NY

2011-03-22

The present invention provides a method for the preparation of organic light-emitting devices comprising a bilayer structure made by forming a first film layer comprising an electroactive material and an INP precursor material, and exposing the first film layer to a radiation source under an inert atmosphere to generate an interpenetrating network polymer composition comprising the electroactive material. At least one additional layer is disposed on the reacted first film layer to complete the bilayer structure. The bilayer structure is comprised within an organic light-emitting device comprising standard features such as electrodes and optionally one or more additional layers serving as a bipolar emission layer, a hole injection layer, an electron injection layer, an electron transport layer, a hole transport layer, exciton-hole transporting layer, exciton-electron transporting layer, a hole transporting emission layer, or an electron transporting emission layer.

High-Performance Flexible Solid-State Supercapacitor with an Extended Nanoregime Interface through in Situ Polymer Electrolyte Generation.

PubMed

Anothumakkool, Bihag; Torris A T, Arun; Veeliyath, Sajna; Vijayakumar, Vidyanand; Badiger, Manohar V; Kurungot, Sreekumar

2016-01-20

Here, we report an efficient strategy by which a significantly enhanced electrode-electrolyte interface in an electrode for supercapacitor application could be accomplished by allowing in situ polymer gel electrolyte generation inside the nanopores of the electrodes. This unique and highly efficient strategy could be conceived by judiciously maintaining ultraviolet-triggered polymerization of a monomer mixture in the presence of a high-surface-area porous carbon. The method is very simple and scalable, and a prototype, flexible solid-state supercapacitor could even be demonstrated in an encapsulation-free condition by using the commercial-grade electrodes (thickness = 150 μm, area = 12 cm(2), and mass loading = 7.3 mg/cm(2)). This prototype device shows a capacitance of 130 F/g at a substantially reduced internal resistance of 0.5 Ω and a high capacitance retention of 84% after 32000 cycles. The present system is found to be clearly outperforming a similar system derived by using the conventional polymer electrolyte (PVA-H3PO4 as the electrolyte), which could display a capacitance of only 95 F/g, and this value falls to nearly 50% in just 5000 cycles. The superior performance in the present case is credited primarily to the excellent interface formation of the in situ generated polymer electrolyte inside the nanopores of the electrode. Further, the interpenetrated nature of the polymer also helps the device to show a low electron spin resonance and power rate and, most importantly, excellent shelf-life in the unsealed flexible conditions. Because the nature of the electrode-electrolyte interface is the major performance-determining factor in the case of many electrochemical energy storage/conversion systems, along with the supercapacitors, the developed process can also find applications in preparing electrodes for the devices such as lithium-ion batteries, metal-air batteries, polymer electrolyte membrane fuel cells, etc.

Interpenetrated Uranyl-Organic Frameworks with bor and pts Topology: Structure, Spectroscopy, and Computation.

PubMed

Liu, Chao; Chen, Fang-Yuan; Tian, Hong-Rui; Ai, Jing; Yang, Weiting; Pan, Qing-Jiang; Sun, Zhong-Ming

2017-11-20

Two novel three-dimensional interpenetrated uranyl-organic frameworks, (NH 4 ) 4 [(UO 2 ) 4 (L 1 ) 3 ]·6H 2 O (1) and [(UO 2 ) 2 (H 2 O) 2 L 2 ]·2H 2 O (2), where L 1 = tetrakis(3-carboxyphenyl)silicon and L 2 = tetrakis(4-carboxyphenyl)silicon, were synthesized by a combination of two isomeric tetrahedral silicon-centered ligands with 3-connected triangular [(UO 2 )(COO) 3 ] - and 4-connected dinuclear [(UO 2 ) 2 (COO) 4 ] units, respectively. Structural analyses indicate that 1 possesses a 2-fold interpenetrating anion bor network, while 2 exhibits a 3-fold interpenetrated 4,4-connected neutral network with pts topology. Both compounds were characterized by thermogravimetric analysis and IR, UV-vis, and photoluminescence spectroscopy. A relativistic density functional theory (DFT) investigation on 10 model compounds of 1 and 2 shows good agreement of the structural parameters, stretching vibrational frequencies, and absorption with experimental results; the time-dependent DFT calculations unravel that low-energy absorption bands originate from ligand-to-uranium charge transfer.

Chiral direction and interconnection of helical three-connected networks in metal-organic frameworks.

PubMed

Prior, T J; Rosseinsky, M J

2003-03-10

The control of the interpenetration and chirality of a family of metal-organic frameworks is discussed. These systems contain two- (A) and four-fold (B) interpenetration of helical three-connected networks generated by binding the 1,3,5-benzenetricarboxylate (btc) ligand to a metal center. These frameworks have the general formula Ni(3)(btc)(2)X(m)Y(n).solvent (where X = pyridine or 4-picoline, Y = ethylene glycol, 1,2-propanediol, 1,4-butanediol, meso-2,3-butanediol, 1,2,6-hexanetriol, glycerol). The structural and chemical effects of modifying the alcohol and aromatic amine ligands bound to the metal center include controlling the thermal stability and the degree of interpenetration. Covalent linking of the four interpenetrating networks in the A family and the switching of diol binding from mono- to bidentate are demonstrated. Recognition of chiral diols by the hand of the network helices is investigated by binding an alcohol ligand with two chiral centers of opposite sense to the same helix. This reveals the subtle nature of the helix-ligand interaction.

Tribological Properties of AlSi12-Al₂O₃ Interpenetrating Composite Layers in Comparison with Unreinforced Matrix Alloy.

PubMed

Dolata, Anna Janina

2017-09-06

Alumina-Aluminum composites with interpenetrating network structures are a new class of advanced materials with potentially better properties than composites reinforced by particles or fibers. Local casting reinforcement was proposed to take into account problems with the machinability of this type of materials and the shaping of the finished products. The centrifugal infiltration process fabricated composite castings in the form of locally reinforced shafts. The main objective of the research presented in this work was to compare the tribological properties (friction coefficient, wear resistance) of AlSi12/Al₂O₃ interpenetrating composite layers with unreinforced AlSi12 matrix areas. Profilometric tests enabled both quantitative and qualitative analyses of the wear trace that formed on investigated surfaces. It has been shown that interpenetrating composite layers are characterized by lower and more stable coefficients of friction (μ), as well as higher wear resistance than unreinforced matrix areas. At the present stage, the study confirmed that the tribological properties of the composite layers depend on the spatial structure of the ceramic reinforcement, and primarily the volume and size of alumina foam cells.

Immobilization of metals in contaminated soils using natural polymer-based stabilizers.

PubMed

Tao, Xue; Li, Aimin; Yang, Hu

2017-03-01

Three low-cost natural polymer materials, namely, lignin (Ln), carboxymethyl cellulose, and sodium alginate, were used for soil amendment to immobilize lead and cadmium in two contaminated soil samples collected from a mining area in Nanjing, China. The remediation effects of the aforementioned natural polymers were evaluated by toxicity characteristic leaching procedure (TCLP) and sequential extractions. The stabilizers could lower the bioavailability of Pb and Cd in the contaminated soils, and the amount of the exchangeable forms of the aforementioned two metals were reduced evidently. TCLP results showed that the leaching concentrations of Pb and Cd were decreased by 5.46%-71.1% and 4.25%-49.6%, respectively, in the treated soils. The contents of the organic forms of the two metals both increased with the increase in stabilizer dose on the basis of the redistribution of metal forms by sequential extractions. These findings were due to the fact that the abundant oxygen-containing groups on the polymeric amendments were effective in chelating and immobilizing Pb and Cd, which have been further confirmed from the metal adsorptions in aqueous solutions. Moreover, Ln achieved the greatest effect among the three polymers under study because of the former's distinct three-dimensional molecular structure, showing the preferential immobilization of Pb over Cd in soils also. Thus, the above-mentioned natural polymers hold great application potentials for reducing metal ion entry into the food chain at a field scale. Copyright © 2016 Elsevier Ltd. All rights reserved.

Self-Assembling Brush Polymers Bearing Multisaccharides.

PubMed

Lee, Jongchan; Kim, Jin Chul; Lee, Hoyeol; Song, Sungjin; Kim, Heesoo; Ree, Moonhor

2017-06-01

Three different series of brush polymers bearing glucosyl, maltosyl, or maltotriosyl moiety at the bristle end are successfully prepared by using cationic ring-opening polymerization and two sequential postmodification reactions. All brush polymers, except for the polymer containing 100 mol% maltotriosyl moiety, demonstrate the formation of multibilayer structure in films, always providing saccharide-enriched surface. These self-assembling features are remarkable, regarding the bulkiness of saccharide moieties and the kink in the bristle due to the triazole linker. The saccharide-enriched film surfaces reveal exceptionally high specific binding affinity to concanavalin A but suppress nonspecific binding of plasma proteins severely. Overall, the brush polymers bearing saccharide moieties of various kinds in this study are highly suitable materials for biomedical applications including biosensors. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly Efficient Cooperative Catalysis by Co III (Porphyrin) Pairs in Interpenetrating Metal-Organic Frameworks

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

Lin, Zekai; Zhang, Zhi-Ming; Chen, Yu-Sheng

2016-12-02

A series of porous twofold interpenetrated In-Co III(porphyrin) metal–organic frameworks (MOFs) were constructed by in situ metalation of porphyrin bridging ligands and used as efficient cooperative catalysts for the hydration of terminal alkynes. The twofold interpenetrating structure brings adjacent Co III(porphyrins) in the two networks parallel to each other with a distance of about 8.8 Å, an ideal distance for the simultaneous activation of both substrates in alkyne hydration reactions. As a result, the In-Co III(porphyrin) MOFs exhibit much higher (up to 38 times) catalytic activity than either homogeneous catalysts or MOF controls with isolated Co III(porphyrin) centers, thus highlightingmore » the potential application of MOFs in cooperative catalysis.« less

FCC-HCP coexistence in dense thermo-responsive microgel crystals

NASA Astrophysics Data System (ADS)

Karthickeyan, D.; Joshi, R. G.; Tata, B. V. R.

2017-06-01

Analogous to hard-sphere suspensions, monodisperse thermo-responsive poly (N-isopropyl acrylamide) (PNIPAM) microgel particles beyond a volume fraction (ϕ) of 0.5 freeze into face centered cubic (FCC)-hexagonal close packed (HCP) coexistence under as prepared conditions and into an FCC structure upon annealing. We report here FCC-HCP coexistence to be stable in dense PNIPAM microgel crystals (ϕ > 0.74) with particles in their deswollen state (referred to as osmotically compressed microgel crystals) and the FCC structure with particles in their swollen state by performing annealing studies with different cooling rates. The structure of PNIPAM microgel crystals is characterized using static light scattering technique and UV-Visible spectroscopy and dynamics by dynamic light scattering (DLS). DLS studies reveal that the particle motion is diffusive at short times in crystals with ϕ < 0.74 and sub-diffusive at short times in PNIPAM crystals with ϕ > 0.74. The observed sub-diffusive behavior at short times is due to the overlap (interpenetration) of the dangling polymer chains between the shells of neighbouring PNIPAM microgel particles. Overlap is found to disappear upon heating the crystals well above their melting temperature, Tm due to reduction in the particle size. Annealing studies confirm that the overlap of dangling polymer chains between the shells of neighbouring PNIPAM spheres is responsible for the stability of FCC-HCP coexistence observed in osmotically compressed PNIPAM microgel crystals. Results are discussed in the light of recent reports of stabilizing the HCP structure in hard sphere crystals by adding interacting polymer chains.

Honeycomb-shaped coordination polymers based on the self-assembly of long flexible ligands and alkaline-earth ions

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

Lian, Chen; Liu, Liu; Guo, Xu

2016-01-15

Two novel coordination polymers, namely, [Ca(NCP){sub 2}]{sub ∞} (I) and [Sr(NCP){sub 2}]{sub ∞} (II) were synthesized under hydrothermal conditions based on 2-(4-carboxyphenyl)imidazo(4,5-f)-(1,10)phenanthroline (HNCP) and characterized by elemental analysis, infrared spectrometry, X-ray powder diffraction and single crystal X-ray diffraction. Findings indicate that I and II are isomorphous and isostructural, containing the unit of M(NCP{sup −}){sub 4} (M=Ca(II) and Sr(II)), based on which to assemble into three-dimensional (3D) porous 4-fold interpenetration honeycomb-shaped neutral coordination polymers (CPs). Between the adjacent lamellar structures in I and II, there exist π–π interactions between the pyridine rings belonging to phenanthroline of NCP{sup −} which stabilize themore » frameworks. Both I and II display stronger fluorescence emissions as well as high thermal stability. - Graphical abstract: One-dimensional nanotubular channels with the cross dimension of 37.1959(20)×23.6141(11)Å{sup 2} in the three-dimensional honeycomb-shaped coordination network of II are observed. The topological analysis of II indicates that there exists a typical diamond framework possessing large adamantanoid cages, which containing four cyclohexane-shaped patterns in chair conformations. - Highlights: • Two isomorphous and isostructural coordination polymers based on flexible ligand and two alkaline-earth metal salts have been synthesized and characterized. • Structural analysis indicates that I and II are assembled into 3D porous honeycomb-shaped metal-organic frameworks. • Both I and II display stronger fluorescence emissions and higher thermal stability.« less

Designed drug-release systems having various breathable polyurethane film-backed hydrocolloid acrylated adhesive layers for moisture healing.

PubMed

Chang, Ching-Hsien; Liu, Hsia-Wei; Huang, Ching-Cheng

2014-01-01

A series of designed drug-release systems were prepared and established for clear moisture healing. These systems were designed to have an interpenetrating polymer network (IPN) structure, which contained a breathable polyurethane film, hydrocolloidlayer, and polyacrylate adhesive layer. Breathable polyurethane film (2000 g/m(2)/24 hr) with high moisture permeability was employed as a base for new drug-release systems or wound dressings. All drug-release systems having a polyurethane film-backed hydrocolloid acrylated adhesive layer showed an increase of water uptakes with increasing time. After 114 hours, high water uptakes of drug-release systems with 20% hydrocolloid components were observed in the values of 160, 1100, and 1870% for different additional hydrocolloid components of carboxymethylcellulose, sodium alginate, and carbomer U10, respectively. New drug-release systems of polyurethane film-backed hydrocolloid/adhesive layers could be designed and established for wound care managements.

[Study on preparation of the pH sensitive hydroxyethyl chitin/poly (acrylic acid) hydrogel and its drug release property].

PubMed

Zhao, Yu; Chen, Guohua; Sun, Mingkun; Jin, Zhitao; Gao, Congjie

2006-04-01

Hydroxyethyl chitin (HECH) is a water soluble chitin derivative made by etherification of chitin, ethylene chlorohydrin was used as etherification reagent in this reaction. A novel interpenetrating polymer network (IPN) composed of HECH/PAA was prepared. The IR spectra confirmed that HECH/PAA was formed through chemical bond interaction. The sensitivity of this hydrogel to temperature and pH was studied. The swelling ratio of this hydrogel in artificial intestinal juice is much greater than that in artificial gastric juice. The IPN hydrogel exhibited a typical pH-sensitivity, and its degree of swelling ratio increased with the increase of temperature. The sustained-release drug system of Dichlofenac potassium was prepared by using HECH/PAA as the drug carrier. The release experiment showed a perfect release behavior in artificial intestinal juice. This IPN is expected to be used as a good drug delivery system of enteric medicine.

Preparation and Properties of a Novel Semi-IPN Slow-Release Fertilizer with the Function of Water Retention.

PubMed

Xiang, Yang; Ru, Xudong; Shi, Jinguo; Song, Jiang; Zhao, Haidong; Liu, Yaqing; Guo, Dongdong; Lu, Xin

2017-12-20

A new semi-interpenetrating polymer network (semi-IPN) slow-release fertilizer (SISRF) with water absorbency, based on the kaolin-g-poly(acrylic acid-co-acrylic amide) (kaolin-g-P(AA-co-AM)) network and linear urea-formaldehyde oligomers (UF), was prepared by solution polymerization. Nutrients phosphorus and potassium were supplied by adding dipotassium hydrogen phosphate during the preparation process. The structure and properties of SISRF were characterized by various characterization methods. SISRF showed excellent water absorbency of 68 g g -1 in tap water. The slow-release behavior of nutrients and water-retention capacity of SISRF were also measured. Meanwhile, the swelling kinetics was well described by a pseudo-second-order kinetics model. Results suggested the formation of SISRF with simultaneously good slow-release and water-retention capacity, which was expected to apply in modern agriculture and horticulture.

Tribological Properties of AlSi12-Al2O3 Interpenetrating Composite Layers in Comparison with Unreinforced Matrix Alloy

PubMed Central

Dolata, Anna Janina

2017-01-01

Alumina–Aluminum composites with interpenetrating network structures are a new class of advanced materials with potentially better properties than composites reinforced by particles or fibers. Local casting reinforcement was proposed to take into account problems with the machinability of this type of materials and the shaping of the finished products. The centrifugal infiltration process fabricated composite castings in the form of locally reinforced shafts. The main objective of the research presented in this work was to compare the tribological properties (friction coefficient, wear resistance) of AlSi12/Al2O3 interpenetrating composite layers with unreinforced AlSi12 matrix areas. Profilometric tests enabled both quantitative and qualitative analyses of the wear trace that formed on investigated surfaces. It has been shown that interpenetrating composite layers are characterized by lower and more stable coefficients of friction (μ), as well as higher wear resistance than unreinforced matrix areas. At the present stage, the study confirmed that the tribological properties of the composite layers depend on the spatial structure of the ceramic reinforcement, and primarily the volume and size of alumina foam cells. PMID:28878162

Self-penetration--a structural compromise between single networks and interpenetration: magnetic properties and crystal structures of

PubMed

Jensen; Price; Batten; Moubaraki; Murray

2000-09-01

The three-dimensional coordination polymers [Mn(dca)2(H2O)] (1) and [M(dca)(tcm)], M =Co (2), Ni (3), Cu (4), dca =dicyanamide, N(CN)2-, tcm = tricyanomethanide, C(CN)3-, have isomorphous structures. In 1 half the dca ligands coordinate directly (through all three nitrogen atoms) to three Mn atoms (all metal atoms are six-coordinate), while the other half coordinate to two Mn atoms (through the nitrile nitrogens) and hydrogen bond to water molecules coordinated to a third Mn atom (through the amide nitrogen). This dca. H2O structural moiety is disordered over a mirror plane, and is replaced by the structurally equivalent tcm ligand in compounds 2-4. The resulting structures display a new self-penetrating 3,6-connected (2:1) network topology that can be related to, but is different from, the rutile net. The self-penetrating [M(dca)(tcm)] network can be viewed as a structural compromise between the two interpenetrating rutile-like networks of [M(tcm)2] and the single rutile-like network of alpha-[M(dca)2]. The temperature and field dependence of the DC and AC magnetic susceptibilities and magnetisations has been measured for complexes 1-4. Compounds 1-3 exhibit long-range magnetic order with critical temperatures of 6.3 K for 1, 3.5 K for 2 and 8.0 K for 3. The Cu11 compound 4 does not order and is essentially a paramagnet. Hysteresis measurements of coercive field and remnant magnetisation show that 1, 2 and 3 are soft magnets, 1 being a canted-spin antiferromagnet (weak ferromagnet), while 2 and 3 are ferromagnets that display some unusual features in their high-field magnetisation isotherms in comparison to their related alpha-[M(dca)2] phases.

A series of transition metal-organic frameworks based on a bipyridinium carboxylate ligand: Syntheses, structures and photoluminescent properties

NASA Astrophysics Data System (ADS)

Pei, Ru-Bo; Cao, Ming-Yang; Li, Lin-Ke; Dong, Xi-Yan; Zang, Shuang-Quan

2017-09-01

Based on a bipyridinium carboxylate ligand 1-(3,5-dicarboxy)-benzyl-1,2-di(pyridine-4-yl)ethylene chloride (H2L+Cl-), eight transition metal coordination polymers, namely, {[Zn(L)Cl]ṡ4H2O}n (1), {[Zn(L)H2O]ṡNO3ṡ2H2O}n (2), {[Zn(L) (H2O)]ṡ(NO3)0.5ṡ(Cl)0.5ṡ2H2O}n (3), {[Cd(L)(H2O)(NO3)]ṡ2H2O}n (4), {[Cd1.5(L) (Cl)2]ṡ2H2O}n (5), {[Cu(L)(H2O)]ṡNO3ṡH2O}n (6), {[Cu(HL)2(H2O)2]·Cl2·6H2O}n (7) and {[Ni(L)(H2O)Cl]ṡ4H2O}n (8) have been synthesized and characterized by single-crystal X-ray diffraction analyses. Complexes 1 and 8 display 2D wave-like layer structures with a 3-connected 63 topology. Complexes 2 and 6 demonstrate 3D 2-fold interpenetrating frameworks with uninodal, 3-connected (10,3)-d utp-topology. Another pair of 3D 2-fold interpenetrating frameworks 3 and 4 possess 3-connected, uninodal 103ThSi2 (ths)-topology. Complex 5 shows a 2D layer structure based on the extending of trinuclear Cd(II) subunits. Complex 7 presents 1D double-chain structure, in which the central Cu(II) ions are connected by the partially deprotonated ligand HL. Additionally, powder X-ray diffractions (PXRD) and thermogravimetric analyses of complexes 1-8, as well as the solid-state luminescent properties of d10 metal complexes 1-4 at room temperature have also been discussed.

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.

Simulated Space Vacuum Ultraviolet (VUV) Exposure Testing for Polymer Films

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; Pietromica, Anthony J.; Stueber, Thomas J.; Sechkar, Edward A.; Messer, Russell K.

2002-01-01

Vacuum ultraviolet (VUV) radiation of wavelengths between 115 and 200 nm produced by the sun in the space environment can cause degradation to polymer films producing changes in optical, mechanical, and chemical properties. These effects are particularly important for thin polymer films being considered for ultra-lightweight space structures, because, for most polymers, VUV radiation is absorbed in a thin surface layer. NASA Glenn Research Center has developed facilities and methods for long-term ground testing of polymer films to evaluate space environmental VUV radiation effects. VUV exposure can also be used as part of sequential simulated space environmental exposures to determine combined damaging effects. This paper will describe the effects of VUV on polymer films and the necessity for ground testing. Testing practices used at Glenn Research Center for VUV exposure testing will be described including characterization of the VUV radiation source used, calibration procedures traceable to the National Institute of Standards and Technology (NIST), and testing techniques for VUV exposure of polymer surfaces.

Sequential pH-dependent adsorption of ionic amphiphilic diblock copolymer micelles and choline oxidase onto conductive substrates: toward the design of biosensors.

PubMed

Sigolaeva, Larisa V; Günther, Ulrike; Pergushov, Dmitry V; Gladyr, Snezhana Yu; Kurochkin, Ilya N; Schacher, Felix H

2014-07-01

This work examines the fabrication regime and the properties of polymer-enzyme thin-films adsorbed onto conductive substrates (graphite or gold). The films are formed via two-steps, sequential adsorption of poly(n-butylmethacrylate)-block-poly(N,N-dimethylaminoethyl methacrylate) (PnBMA-b-PDMAEMA) diblock copolymer micelles (1st step of adsorption), followed by the enzyme choline oxidase (ChO) (2nd step of adsorption). The solution properties of both adsorbed components are studied and the pH-dependent step-by-step fabrication of polymer-enzyme biosensor coatings reveals rather drastic differences in their enzymatic activities in dependence on the pH of both adsorption steps. The resulting hybrid thin-films represent highly active biosensors for choline with a low detection limit of 30 nM and a good linearity in a range between 30 nM and 100 μM. The sensitivity is found to be 175 μA mM(-1) cm(-2) and the operational stability of the polymer-enzyme thin-films can be additionally improved via enzyme-to-enzyme crosslinking with glutaraldehyde. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Top-down Approach for the Direct Synthesis, Patterning, and Operation of Artificial Micromuscles on Flexible Substrates.

PubMed

Maziz, Ali; Plesse, Cédric; Soyer, Caroline; Cattan, Eric; Vidal, Frédéric

2016-01-27

Recent progress in the field of microsystems on flexible substrates raises the need for alternatives to the stiffness of classical actuation technologies. This paper reports a top-down process to microfabricate soft conducting polymer actuators on substrates on which they ultimately operate. The bending microactuators were fabricated by sequentially stacking layers using a layer polymerization by layer polymerization of conducting polymer electrodes and a solid polymer electrolyte. Standalone microbeams thinner than 10 μm were fabricated on SU-8 substrates associated with a bottom gold electrical contact. The operation of microactuators was demonstrated in air and at low voltage (±4 V).

Material and fabrication strategies for artificial muscles (Conference Presentation)

NASA Astrophysics Data System (ADS)

Spinks, Geoffrey M.

2017-04-01

Soft robotic and wearable robotic devices seek to exploit polymer based artificial muscles and sensor materials to generate biomimetic movements and forces. A challenge is to integrate the active materials into a complex, three-dimensional device with integrated electronics, power supplies and support structures. Both 3D printing and textiles technologies offer attractive fabrication strategies, but require suitable functional materials. 3D printing of actuating hydrogels has been developed to produce simple devices, such as a prototype valve. Tough hydrogels based on interpenetrating networks of ionicially crosslinked alginate and covalently crosslinked polyacrylamide and poly(N-isopropylacrylamide) have been developed in a form suitable for extrusion printing with UV curing. Combined with UV-curable and extrudable rigid acrylated urethanes, the tough hydrogels can be 3D printed into composite materials or complex shapes with multiple different materials. An actuating valve was printed that operated thermally to open or close the flow path using 6 parallel hydrogel actuators. Textile processing methods such as knitting and weaving can be used to generate assemblies of actuating fibres. Low cost and high performance coiled fibres made from oriented polymers have been used for developing actuating textiles. Similarly, braiding methods have been developed to fabricate new forms of McKibben muscles that operate without any external apparatus, such as pumps, compressors or piping.

Extraction of Lanthanide and Actinide Ions from Aqueous Mixtures Using a Carboxylic Acid-Functionalized Porous Aromatic Framework

DOE PAGES

Demir, Selvan; Brune, Nicholas K.; Van Humbeck, Jeffrey F.; ...

2016-04-08

Porous aromatic frameworks (PAFs) incorporating a high concentration of acid functional groups possess characteristics that are promising for use in separating lanthanide and actinide metal ions, as required in the treatment of radioactive waste. These materials have been shown to be indefinitely stable to concentrated acids and bases, potentially allowing for multiple adsorption/stripping cycles. Additionally, the PAFs combine exceptional features from MOFs and inorganic/ activated carbons giving rise to tunable pore surfaces and maximum chemical stability. Herein, we present a study of the adsorption of selected metal ions, Sr 2+, Fe 3+, Nd 3+, and Am 3+, from aqueous solutionsmore » employing a carbon-based porous aromatic framework, BPP-7 (Berkeley Porous Polymer-7). This material displays high metal loading capacities together with excellent adsorption selectivity for neodymium over strontium based on Langmuir adsorption isotherms and ideal adsorbed solution theory (IAST) calculations. Based in part upon X-ray absorption spectroscopy studies, the stronger adsorption of neodymium is attributed to multiple metal ion and binding site interactions resulting from the densely functionalized and highly interpenetrated structure of BPP-7. Finally, recyclability and combustibility experiments demonstrate that multiple adsorption/stripping cycles can be completed with minimal degradation of the polymer adsorption capacity.« less

Mixed ligand coordination polymers with flexible bis-imidazole linker and angular sulfonyldibenzoate: Crystal structure, photoluminescence and photocatalytic activity

NASA Astrophysics Data System (ADS)

Bisht, Kamal Kumar; Rachuri, Yadagiri; Parmar, Bhavesh; Suresh, Eringathodi

2014-05-01

Four ternary coordination polymers (CPs) namely, {[Ni(SDB)(BITMB)(H2O)]·H2O}n (CP1), {[Cd(SDB)(BITMB) (H2O)]·(THF)(H2O)}n (CP2), {[Zn2(SDB)2(BITMB)]·(THF)2}n (CP3) and {[Co2(SDB)2(BITMB)]·(Dioxane)3}n (CP4) composed of angular dicarboxylate SDB (4,4'-sulfonyldibenzoate) and N-donor BITMB (1,3-bis(imidazol-1-ylmethyl)-2,4,6-trimethyl benzene) have been synthesized by solvothermal reactions and characterized by single crystal X-ray diffraction and other physico-chemical techniques. CP1 possesses one-dimensional ribbon type metal-organic motifs glued together by H-bonds and π⋯π interactions, whereas CP2-CP4, exhibit non-interpenetrated sql networks supported by weak supramolecular interactions. Structural diversity of these CPs can be attributed to the coordination geometry adopted by the metal nodes, versatile coordination modes of SDB and conformational flexibility of BITMB. Solid state luminescence properties of CP1-CP4 were explored. Photocatalytic performance of all CPs for the decomposition of metanil yellow by dilute hydrogen peroxide in the presence of visible light was also investigated. 25-83% dye removal from aqueous solutions in the presence of CP1-CP4 was observed.

Functionalizable hydrogel microparticles of tunable size and stiffness for soft-tissue filler applications

PubMed Central

Chan, Ka Man Carmen; Li, Randolph H.; Chapman, Joseph W.; Trac, Eric M.; Kobler, James B.; Zeitels, Steven M.; Langer, Robert; Karajanagi, Sandeep S.

2014-01-01

Particle size, stiffness and surface functionality are important in determining the injection site, safety and efficacy of injectable soft-tissue fillers. Methods to produce soft injectable biomaterials with controlled particle characteristics are therefore desirable. Here we report a method based on suspension photopolymerization and semi-interpenetrating network (semi-IPN) to synthesize soft, functionalizable, spherical hydrogel microparticles (MP) of independently tunable size and stiffness. MP were prepared using acrylated forms of polyethylene glycol (PEG), gelatin and hyaluronic acid. Semi-IPN MP of PEG-diacrylate and PEG were used to study the effect of process parameters on particle characteristics. The process parameters were systematically varied to produce MP with size ranging from 115 to 515 μm and stiffness ranging from 190 to 1600 Pa. In vitro studies showed that the MP thus prepared were cytocompatible. The ratio and identity of the polymers used to make the semi-IPN MP were varied to control their stiffness and to introduce amine groups for potential functionalization. Slow-release polymeric particles loaded with Rhodamine or dexamethasone were incorporated in the MP as a proof-of-principle of drug incorporation and release from the MP. This work has implications in preparing injectable biomaterials of natural or synthetic polymers for applications as soft-tissue fillers. PMID:24561708

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).

Extraction of Lanthanide and Actinide Ions from Aqueous Mixtures Using a Carboxylic Acid-Functionalized Porous Aromatic Framework

PubMed Central

2016-01-01

Porous aromatic frameworks (PAFs) incorporating a high concentration of acid functional groups possess characteristics that are promising for use in separating lanthanide and actinide metal ions, as required in the treatment of radioactive waste. These materials have been shown to be indefinitely stable to concentrated acids and bases, potentially allowing for multiple adsorption/stripping cycles. Additionally, the PAFs combine exceptional features from MOFs and inorganic/activated carbons giving rise to tunable pore surfaces and maximum chemical stability. Herein, we present a study of the adsorption of selected metal ions, Sr2+, Fe3+, Nd3+, and Am3+, from aqueous solutions employing a carbon-based porous aromatic framework, BPP-7 (Berkeley Porous Polymer-7). This material displays high metal loading capacities together with excellent adsorption selectivity for neodymium over strontium based on Langmuir adsorption isotherms and ideal adsorbed solution theory (IAST) calculations. Based in part upon X-ray absorption spectroscopy studies, the stronger adsorption of neodymium is attributed to multiple metal ion and binding site interactions resulting from the densely functionalized and highly interpenetrated structure of BPP-7. Recyclability and combustibility experiments demonstrate that multiple adsorption/stripping cycles can be completed with minimal degradation of the polymer adsorption capacity. PMID:27163056

Transition metal coordination polymers based on tetrabromoterephthalic and bis(imidazole) ligands: Syntheses, structures, topological analysis and photoluminescence properties

NASA Astrophysics Data System (ADS)

Zhang, Xiaowei; Xing, Peiqi; Geng, Xiujuan; Sun, Daofeng; Xiao, Zhenyu; Wang, Lei

2015-09-01

Eight new coordination polymers (CPs), namely, [Zn(1,2-mbix)(tbtpa)]n (1), [Co(1,2-mbix)(tbtpa)]n (2), [CdCl(1,2-mbix)(tbtpa)0.5]n (3), {[Cd(1,2-bix)(tbtpa)]·H2O}n (4), {[Cd0.5(1,2-bix)(tbtpa)0.5]·H2O}n (5), {[Co0.5(1,2-bix)(tbtpa)0.5]·2H2O}n (6), {[Co(1,2-bix)(tbtpa)]·H2O}n (7) and {[Co(1,2-bix)(tbtpa)]·Diox·2H2O}n (8), were synthesized under solvothermal conditions based on mix-ligand strategy (H2tbtpa=tetrabromoterephthalic acid and 1,2-mbix=1,2-bis((2-methyl-1H-imidazol-1-yl)methyl)benzene, 1,2-bix=1,2-bis(imidazol-1-ylmethyl)benzene). All of the CPs have been structurally characterized by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectroscopy, powder X-ray diffraction (PXRD), and thermogravimetric analyses (TGA). X-ray diffraction analyses show that 1 and 2 are isotypics which have 2D highly undulated networks with (4,4)-sql topology with the existence of C-H ⋯Br interactions; for 3, it has a 2D planar network with (4,4)-sql topology with the occurrence of C-H ⋯Cl interactions other than C-H ⋯Br interactions; 4 shows a 3D 2-fold interpenetrated nets with rare 65·8-mok topology which has a self-catention property. As the same case as 1 and 2, 5 and 6 are also isostructural with planar layers with 44-sql topology which further assembled into 3D supramolecular structure through the interdigitated stacking fashion and the C-Br ⋯Cph interactions. As for 7, it has a 2D slightly undulated networks with (4,4)-sql topology which has one dimension channel. While 8 has a 2-fold interpenetrated networks with (3,4)-connect jeb topology with point symbol {63}{65·8}. And their structures can be tuned by conformations of bis(imidazol) ligands and solvent mixture. Besides, the TGA properties for all compounds and the luminescent properties for 1, 3, 4, 5 are discussed in detail.

Release of DNA from polyelectrolyte multilayers fabricated using 'charge-shifting' cationic polymers: tunable temporal control and sequential, multi-agent release.

PubMed

Sun, Bin; Lynn, David M

2010-11-20

We report an approach to the design of multilayered polyelectrolyte thin films (or 'polyelectrolyte multilayers', PEMs) that can be used to provide tunable control over the release of plasmid DNA (or multiple different DNA constructs) from film-coated surfaces. Our approach is based upon methods for the layer-by-layer assembly of DNA-containing thin films, and exploits the properties of a new class of cationic 'charge-shifting' polymers (amine functionalized polymers that undergo gradual changes in net charge upon side chain ester hydrolysis) to provide control over the rates at which these films erode and release DNA. We synthesized two 'charge-shifting' polymers (polymers 1 and 2) containing different side chain structures by ring-opening reactions of poly(2-alkenyl azlactone)s with two different tertiary amine functionalized alcohols (3-dimethylamino-1-propanol and 2-dimethylaminoethanol, respectively). Subsequent characterization revealed large changes in the rates of side chain ester hydrolysis for these two polymers; whereas the half-life for the hydrolysis of the esters in polymer 1 was ~200 days, the half-life for polymer 2 was ~6 days. We demonstrate that these large differences in side chain hydrolysis make possible the design of PEMs that erode and promote the surface-mediated release of DNA either rapidly (e.g., over ~3 days for films fabricated using polymer 2) or slowly (e.g., over ~1 month for films fabricated using polymer 1). We demonstrate further that it is possible to design films with release profiles that are intermediate to these two extremes by fabricating films using solutions containing different mixtures of these two polymers. This approach can thus expand the usefulness of these two polymers and achieve a broader range of DNA release profiles without the need to synthesize polymers with new structures or properties. Finally, we demonstrate that polymers 1 and 2 can be used to fabricate multilayered films with hierarchical structures that promote the sequential release of two different DNA constructs with separate and distinct release profiles (e.g., the release of a first construct over a period of ~3 days, followed by the sustained release of a second for a period of ~70 days). With further development, this approach could contribute to the design of functional thin films and surface coatings that provide sophisticated control over the timing and the order of the release of two or more DNA constructs (or other agents) of interest in a range of biomedical contexts. Copyright © 2010 Elsevier B.V. All rights reserved.

Neuron-Inspired Interpenetrative Network Composed of Cobalt-Phosphorus-Derived Nanoparticles Embedded within Porous Carbon Nanotubes for Efficient Hydrogen Production.

PubMed

Shen, Juanxia; Yang, Zhi; Ge, Mengzhan; Li, Ping; Nie, Huagui; Cai, Qiran; Gu, Cancan; Yang, Keqin; Huang, Shaoming

2016-07-13

The ongoing search for cheap and efficient hydrogen evolution reaction (HER) electrocatalysts to replace currently used catalysts based on Pt or its alloys has been considered as an prevalent strategy to produce renewable and clean hydrogen energy. Herein, inspired by the neuron structure in biological systems, we demonstrate a novel fabrication strategy via a simple two-step method for the synthesis of a neuronlike interpenetrative nanocomposite network of Co-P embedded in porous carbon nanotubes (NIN-Co-P/PCNTs). It is found that the interpenetrative network provides a natural transport path to accelerate the hydrogen production process. The embedded-type structure improves the utilization ratio of Co-P and the hollow, tubelike, and porous structure of PCNTs further promote charge and reactant transport. These factors allow the as-prepared NIN-Co-P/PCNTs to achieve a onset potential low to 43 mV, a Tafel slope as small as 40 mV/decade, an excellent stability, and a high turnover frequency value of 3.2 s(-1) at η = 0.2 V in acidic conditions. These encouraging properties derived from the neuronlike interpenetrative network structure might offer new inspiration for the preparation of more nanocomposites for applications in other catalytic and optoelectronic field.

Potassium fulvate as co-interpenetrating agent during graft polymerization of acrylic acid from cellulose.

PubMed

Ghazy, Mohamed B M; El-Hai, Farag Abd; Mohamed, Magdy F; Essawy, Hisham A

2016-10-01

Grafting polymerization of acrylic acid onto cellulose in presence of potassium fulvate (KF) as a co-interpenetrating agent results enhanced water sorption compared to materials prepared similarly in its absence. The insertion of potassium fulvate (KF) did not affect the grafting process and is thought to proceed in parallel to the graft polymerization via intensive polycondensation reactions of its function groups (-COOH and OH) with COOH of the monomer and OH groups of cellulose. The combination of graft copolymerization and polycondensation reactions is assumed to produce interpenetrating network structure. Fourier transform infrared (FTIR) confirmed successful incorporation within the network structure which is an evidence for formation of interpenetrating network. The obtained structures showed homogeneous uniform surface as revealed by scanning electron microscopy (SEM). The obtained superabsorbent possessed high water absorbency 422 and 48.8g/g in distilled water and saline (0.9wt.% NaCl solution), respectively, and enhanced water retention even at elevated temperatures as revealed by thermogravimetric analysis (TGA). This could be explained by the high content of hydrophilic groups. The new superabsorbents proved to be efficient devices for controlled release of fertilizers which expands their use in agricultural applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Motors and Their Tethers: The Role of Secondary Binding Sites in Processive Motility

PubMed Central

Kincaid, Margaret M.; King, Stephen J.

2007-01-01

Cytoskeletal motors convert the energy from binding and hydrolyzing ATP into conformational changes that direct movement along a cytoskeletal polymer substrate. These enzymes utilize different mechanisms to generate long-range motion on the order of a micron or more that is required for functions ranging from muscle contraction to transport of growth factors along a nerve axon. Several of the individual cytoskeletal motors are processive, meaning that they have the ability to take sequential steps along their polymer substrate without dissociating from the polymer. This ability to maintain contact with the polymer allows individual motors to move cargos quickly from one cellular location to another. Many of the processive motors have now been found to utilize secondary binding sites that aid in motor processivity. PMID:17172850

Metallized Nanotube Polymer Composite (MNPC) and Methods for Making Same

NASA Technical Reports Server (NTRS)

Harrison, Joycelyn S. (Inventor); Lowther, Sharon E. (Inventor); Lillehei, Peter T. (Inventor); Park, Cheol (Inventor); Taylor, Larry (Inventor); Kang, Jin Ho (Inventor); Nazem, Negin (Inventor); Kim, Jae-Woo (Inventor); Sauti, Godfrey (Inventor)

2017-01-01

A novel method to develop highly conductive functional materials which can effectively shield various electromagnetic effects (EMEs) and harmful radiations. Metallized nanotube polymer composites (MNPC) are composed of a lightweight polymer matrix, superstrong nanotubes (NT), and functional nanoparticle inclusions. MNPC is prepared by supercritical fluid infusion of various metal precursors (Au, Pt, Fe, and Ni salts), incorporated simultaneously or sequentially, into a solid NT-polymer composite followed by thermal reduction. The infused metal precursor tends to diffuse toward the nanotube surface preferentially as well as the surfaces of the NT-polymer matrix, and is reduced to form nanometer-scale metal particles or metal coatings. The conductivity of the MNPC increases with the metallization, which provides better shielding capabilities against various EMEs and radiations by reflecting and absorbing EM waves more efficiently. Furthermore, the supercritical fluid infusion process aids to improve the toughness of the composite films significantly regardless of the existence of metal.

Solution Exchange Lithography: A Versatile Tool for Sequential Surface Engineering

NASA Astrophysics Data System (ADS)

Pester, Christian; Mattson, Kaila; Bothman, David; Klinger, Daniel; Lee, Kenneth; Discekici, Emre; Narupai, Benjaporn; Hawker, Craig

The covalent attachment of polymers has emerged as a viable strategy for the preparation of multi-functional surfaces. Patterned, surface-grafted polymer brushes provide spatial control over wetting, mechanical, biological or electronic properties, and allow fabrication of `intelligent' substrates which selectively adapt to their environment. However, the route towards patterned polymer brush surfaces often remains challenging, creating a demand for more efficient and less complicated fabrication strategies. We describe the design and application of a novel experimental setup to combine light-mediated and flow chemistry for the fabrication of hierarchical surface-grafted polymer brushes. Using light-mediated, surface initiated controlled radical polymerization and post-functionalization via well-established, and highly efficient chemistries, polymer brush films of previously unimaginable complexity are now shown to be accessible. This methodology allows full flexibility to exchange both lithographic photomasks and chemical environments in-situ, readily affording multidimensional thin film architectures, all from uniformly functionalized substrates.

Bonding of fibre-reinforced composite post to root canal dentin.

PubMed

Bell, Anna-Maria Le; Lassila, Lippo V J; Kangasniemi, Ilkka; Vallittu, Pekka K

2005-08-01

The aim of this study was to determine bonding properties of two types of fibre-reinforced composite (FRC) posts cemented into root canals of molars. Serrated titanium posts served as reference. Prefabricated carbon/graphite FRC posts with cross-linked polymer matrix and individually formed glass FRC posts with interpenetrating polymer network (IPN) polymer matrix were compared. The crowns of extracted third molars were removed and post space (diameter: 1.5mm) was drilled, etched and bonded. The posts were treated with dimethacrylate adhesive resin, light-polymerized and cemented with a dual-polymerizing composite resin luting cement. After thermocycling (6000x) the samples were cut into discs of thicknesses: 1, 2 and 4mm (n=12/group). Push-out force was measured by pushing the post from one end. Assessment of failure mode was made under a stereomicroscope (1, adhesive failure between post and cement; 2, cohesive failure of post-system; 3, adhesive failure between cement and dentin). The push-out force increased with increased height of dentin disc in all groups (ANOVA, p<0.001). In the 4mm thick dentin discs the individually formed glass FRC posts showed highest push-out force and the difference to that of the titanium posts was significant (ANOVA, p<0.001). The other differences were not statistically significant. None of the individually formed glass FRC posts showed adhesive failures between the post and the cement. Contrary to the other posts, there were no adhesive (post-cement) failures with the individually formed glass FRC posts, suggesting better interfacial adhesion of cement to these posts.

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

Yin, Wen-Yu; Zhuang, Guo-Yong; Huang, Zuo-Long

Three cadmium coordination polymers, [Cd(bismip)]{sub n} (1), {[Cd(bismip)(phen)]·H_2O}{sub n} (2) and {[Cd_2(bismip)_2(4,4′-bipy)]·2H_2O}{sub n} (3) (H{sub 2}bismip=5-(1H-benzoimidazol-2-ylsulfanylmethyl)-isophthalic acid, phen=1,10-phenanthroline, 4,4′-bipy=4,4′-bipyridine) have been prepared under solvothermal conditions. In 1, the [Cd{sub 4}(bismip){sub 3}] units are jointed by bismip ligands to afford a three-dimensional (3D) architecture. Complex 2 exhibits a 3D supramolecular framework based on the interconnection of 1D chains through hydrogen bonding interactions and π-π packing interactions. 3 is a two-fold interpenetrating 3D architecture with a (4·8{sup 2})(4{sup 2}·8{sup 4}) Schläfli symbol in which 2D layers are interlinked by 4,4′-bipy ligands. The diverse structures of compounds 1–3 indicate that the auxiliary ligandsmore » have significant effects on the final structures. The photoluminescent properties and photocatalytic properties of these coordination polymers in the solid state were also investigated. Remarkably, 3 shows the wide gap semiconductor nature and exhibit excellent photocatalytic performance. - Graphical abstract: Three cadmium coordination polymers with different architectures based on 5-(1H-benzoimidazol-2-ylsulfanylmethyl)-isophthalic acid have been prepared. Their photoluminescent properties were also investigated. - Highlights: • Three new Cd(II) Cps were synthesized based on H{sub 2}bismip. • Compounds 1 and 3 show 3D networks and 2 exhibits a 1D chain. • Compoud 3 exhibits good catalytic activity of methylene blue photodegradation.« less

Triconstituent co-assembly to ordered mesostructured polymer-silica and carbon-silica nanocomposites and large-pore mesoporous carbons with high surface areas.

PubMed

Liu, Ruili; Shi, Yifeng; Wan, Ying; Meng, Yan; Zhang, Fuqiang; Gu, Dong; Chen, Zhenxia; Tu, Bo; Zhao, Dongyuan

2006-09-06

Highly ordered mesoporous polymer-silica and carbon-silica nanocomposites with interpenetrating networks have been successfully synthesized by the evaporation-induced triconstituent co-assembly method, wherein soluble resol polymer is used as an organic precursor, prehydrolyzed TEOS is used as an inorganic precursor, and triblock copolymer F127 is used as a template. It is proposed for the first time that ordered mesoporous nanocomposites have "reinforced concrete"-structured frameworks. By adjusting the initial mass ratios of TEOS to resol, we determined the obtained nanocomposites possess continuous composition with the ratios ranging from zero to infinity for the two constituents that are "homogeneously" dispersed inside the pore walls. The presence of silicates in nanocomposites dramatically inhibits framework shrinkage during the calcination, resulting in highly ordered large-pore mesoporous carbon-silica nanocomposites. Combustion in air or etching in HF solution can remove carbon or silica from the carbon-silica nanocomposites and yield ordered mesoporous pure silica or carbon frameworks. The process generates plenty of small pores in carbon or/and silica pore walls. Ordered mesoporous carbons can then be obtained with large pore sizes of approximately 6.7 nm, pore volumes of approximately 2.0 cm(3)/g, and high surface areas of approximately 2470 m(2)/g. The pore structures and textures can be controlled by varying the sizes and polymerization degrees of two constituent precursors. Accordingly, by simply tuning the aging time of TEOS, ordered mesoporous carbons with evident bimodal pores at 2.6 and 5.8 nm can be synthesized.

Photoluminescence of Sequential Infiltration Synthesized ZnO nanostructures

NASA Astrophysics Data System (ADS)

Ocola, Leonidas; Gosztola, David; Yanguas-Gil, Angel; Connolly, Aine

We have investigated a variation of atomic layer deposition (ALD), called sequential infiltration synthesis (SiS), as an alternate method to incorporate ZnO and other oxides inside polymethylmethacrylate (PMMA) and other polymers. Energy dispersive spectroscopy (EDS) results show that we synthesize ZnO up to 300 nm inside a PMMA film. Photoluminescence data on a PMMA film shows that we achieve a factor of 400X increase in photoluminescence (PL) intensity when comparing a blank Si sample and a 270 nm thick PMMA film, where both were treated with the same 12 alternating cycles of H2O and diethyl zinc (DEZ). PMMA is a well-known ebeam resist. We can expose and develop patterns useful for photonics or sensing applications first, and then convert them afterwards into a hybrid polymer-oxide material. We show that patterning does indeed affect the photoluminescence signature of native ZnO. We demonstrate we can track the growth of the ZnO inside the PMMA polymer using both photoluminescence and Raman spectroscopy and determine the point in the process where ZnO is first photoluminescent and also at which point ZnO first exhibits long range order in the polymer. This work was supported by the Department of Energy under Contract No. DE-AC02-06CH11357. Use of the Center for Nanoscale Materials was supported by the U. S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

A new type of polyhedron-based metal-organic frameworks with interpenetrating cationic and anionic nets demonstrating ion exchange, adsorption and luminescent properties.

PubMed

Zhang, Zheng-Jie; Shi, Wei; Niu, Zheng; Li, Huan-Huan; Zhao, Bin; Cheng, Peng; Liao, Dai-Zheng; Yan, Shi-Ping

2011-06-14

An interesting new MOF, built with interpenetrating cationic (MOF-A(+)) and anionic (MOF-B(-)) nets that do not require counter ions to balance charge, together with an architectural strategy focused on the use of MOPs as nodes and MOCs as spacers for the generation of 3D frameworks, is reported. This journal is © The Royal Society of Chemistry 2011

Controlled catalytic and thermal sequential pyrolysis and hydrolysis of mixed polymer waste streams to sequentially recover monomers or other high value products

DOEpatents

Evans, Robert J.; Chum, Helena L.

1994-01-01

A process of using fast pyrolysis in a carrier gas to convert a plastic waste feedstream having a mixed polymeric composition in a manner such that pyrolysis of a given polymer to its high value monomeric constituent occurs prior to pyrolysis of other plastic components therein comprising: selecting a first temperature program range to cause pyrolysis of said given polymer to its high value monomeric constituent prior to a temperature range that causes pyrolysis of other plastic components; selecting a catalyst and support for treating said feed streams with said catalyst to effect acid or base catalyzed reaction pathways to maximize yield or enhance separation of said high value monomeric constituent in said temperature program range; differentially heating said feed stream at a heat rate within the first temperature program range to provide differential pyrolysis for selective recovery of optimum quantities of the high value monomeric constituent prior to pyrolysis of other plastic components; separating the high value monomeric constituents, selecting a second higher temperature range to cause pyrolysis of a different high value monomeric constituent of said plastic waste and differentially heating the feedstream at the higher temperature program range to cause pyrolysis of the different high value monomeric constituent; and separating the different high value monomeric constituent.

Controlled catalytic and thermal sequential pyrolysis and hydrolysis of mixed polymer waste streams to sequentially recover monomers or other high value products

DOEpatents

Evans, Robert J.; Chum, Helena L.

1994-01-01

A process of using fast pyrolysis in a carrier gas to convert a plastic waste feedstream having a mixed polymeric composition in a manner such that pyrolysis of a given polymer to its high value monomeric constituent occurs prior to pyrolysis of other plastic components therein comprising: selecting a first temperature program range to cause pyrolysis of said given polymer to its high value monomeric constituent prior to a temperature range that causes pyrolysis of other plastic components; selecting a catalyst and support for treating said feed streams with said catalyst to effect acid or base catalyzed reaction pathways to maximize yield or enhance separation of said high value monomeric constituent in said temperature program range; differentially heating said feed stream at a heat rate within the first temperature program range to provide differential pyrolysis for selective recovery of optimum quantities of the high value monomeric constituent prior to pyrolysis of other plastic components; separating the high value monomeric constituents; selecting a second higher temperature range to cause pyrolysis of a different high value monomeric constituent of said plastic waste and differentially heating the feedstream at the higher temperature program range to cause pyrolysis of the different high value monomeric constituent; and separating the different high value monomeric constituent.

Controlled catalytic and thermal sequential pyrolysis and hydrolysis of mixed polymer waste streams to sequentially recover monomers or other high value products

DOEpatents

Evans, Robert J.; Chum, Helena L.

1993-01-01

A process of using fast pyrolysis in a carrier gas to convert a plastic waste feedstream having a mixed polymeric composition in a manner such that pyrolysis of a given polymer to its high value monomeric constituent occurs prior to pyrolysis of other plastic components therein comprising: selecting a first temperature program range to cause pyrolysis of said given polymer to its high value monomeric constituent prior to a temperature range that causes pyrolysis of other plastic components; selecting a catalyst and support for treating said feed streams with said catalyst to effect acid or base catalyzed reaction pathways to maximize yield or enhance separation of said high value monomeric constituent in said temperature program range; differentially heating said feed stream at a heat rate within the first temperature program range to provide differential pyrolysis for selective recovery of optimum quantities of the high value monomeric constituent prior to pyrolysis of other plastic components; separating the high value monomeric constituents; selecting a second higher temperature range to cause pyrolysis of a different high value monomeric constituent of said plastic waste and differentially heating the feedstream at the higher temperature program range to cause pyrolysis of the different high value monomeric constituent; and separating the different high value monomeric constituent.

Sequential Self-Folding Structures by 3D Printed Digital Shape Memory Polymers

NASA Astrophysics Data System (ADS)

Mao, Yiqi; Yu, Kai; Isakov, Michael S.; Wu, Jiangtao; Dunn, Martin L.; Jerry Qi, H.

2015-09-01

Folding is ubiquitous in nature with examples ranging from the formation of cellular components to winged insects. It finds technological applications including packaging of solar cells and space structures, deployable biomedical devices, and self-assembling robots and airbags. Here we demonstrate sequential self-folding structures realized by thermal activation of spatially-variable patterns that are 3D printed with digital shape memory polymers, which are digital materials with different shape memory behaviors. The time-dependent behavior of each polymer allows the temporal sequencing of activation when the structure is subjected to a uniform temperature. This is demonstrated via a series of 3D printed structures that respond rapidly to a thermal stimulus, and self-fold to specified shapes in controlled shape changing sequences. Measurements of the spatial and temporal nature of self-folding structures are in good agreement with the companion finite element simulations. A simplified reduced-order model is also developed to rapidly and accurately describe the self-folding physics. An important aspect of self-folding is the management of self-collisions, where different portions of the folding structure contact and then block further folding. A metric is developed to predict collisions and is used together with the reduced-order model to design self-folding structures that lock themselves into stable desired configurations.

Mechanisms of Hydrocarbon Based Polymer Etch

NASA Astrophysics Data System (ADS)

Lane, Barton; Ventzek, Peter; Matsukuma, Masaaki; Suzuki, Ayuta; Koshiishi, Akira

2015-09-01

Dry etch of hydrocarbon based polymers is important for semiconductor device manufacturing. The etch mechanisms for oxygen rich plasma etch of hydrocarbon based polymers has been studied but the mechanism for lean chemistries has received little attention. We report on an experimental and analytic study of the mechanism for etching of a hydrocarbon based polymer using an Ar/O2 chemistry in a single frequency 13.56 MHz test bed. The experimental study employs an analysis of transients from sequential oxidation and Ar sputtering steps using OES and surface analytics to constrain conceptual models for the etch mechanism. The conceptual model is consistent with observations from MD studies and surface analysis performed by Vegh et al. and Oehrlein et al. and other similar studies. Parameters of the model are fit using published data and the experimentally observed time scales.

Study of a binary interpenetrated polymeric complex by correlation of rheological parameters with zeta potential and conductivity.

PubMed

Nita, Loredana Elena; Chiriac, Aurica P; Neamtu, Iordana; Bercea, Maria

2010-03-01

The interpenetrated macromolecular chains complexation between poly(aspartic acid) and poly(vinyl alcohol) in aqueous solution it was investigated. The interpolymer complexation process was evaluated through dynamic rheology. The aspects concerning the stability of the tested homopolymers and the prepared interpolymeric complex there were achieved from the evaluation of the aqueous solutions'zeta potential and also by determining the pH influence upon the zeta potential and the conductivity. The data obtained through the rheological dynamic measurements were correlated with the composition of the polymeric mixture, the dependence of zeta potential and conductivity. The study reveals the conditions for the formation of interpenetrated polymeric complex as being a ratio of 70wt.% PAS to 30wt.% PVA at 22 degrees C and 50/50 PAS/PVA ratio at 37 degrees C temperature. From the pH influence upon the zeta potential values it was evidenced the PAS aqueous solution does not reach the isoelectric point. At the same time, PVA solution and the complex PAS/PVA reaches the isoelectric point at strongly acid pH. The better stability of PAS, PVA and their mixture in solution is recorded in the alkaline domain (7.5or=12). The conductivity increases with the rising of the PAS content, pH and temperature. Other characteristics of the prepared interpenetrated polymeric structure, as for example thermal stability, there are also presented.

Cholesteric metronomes with flexoelectrically programmable amplitude

NASA Astrophysics Data System (ADS)

Joshi, Vinay; Varanytsia, A.; Chang, Kai-Han; Paterson, Daniel A.; Storey, John M. D.; Imrie, Corrie T.; Chien, Liang-Chy

2018-02-01

We experimentally demonstrate fast flexoelectro-optic switching in a liquid crystal cell containing bimesogen-doped and polymer-stabilized cholesteric. The device exhibits a response time of less than 0.7 ms and with low hysteresis and color dispersion which is suitable for potential applications including field-sequential color displays.

Structural diversity of a series of terpyridyl carboxylate coordination polymers: Luminescent sensor and magnetic properties

NASA Astrophysics Data System (ADS)

Yuan, Fei; Yuan, Chun-Mei; Hu, Huai-Ming; Wang, Ting-Ting; Zhou, Chun-Sheng

2018-02-01

Eleven new coordination polymers, [Zn2(ctpy)2(HCOO)2]n·3nH2O (1), [Zn2(ctpy)2(HCOO)2(H2O)2]n·nH2O (2), [Zn2(ctpy)2(H2O)4]n·2n(CH3COO)·nH2O (3), [Zn2(ctpy)2(CH3COO)2]n·nH2O (4), [Zn(ctpy)2]n·nH2O (5), [Zn2(ctpy)2(Hidc)(H2O)2]n(6), [Cd2(ctpy)4]n(7), [Cd2(ctpy)2(Hidc)]n(8), [Co2(ctpy)2(HCOO)2(H2O)2]n·nH2O (9), [Co(ctpy)(DMF)(ox)0.5]n(10), [Co(ctpy)(ox)0.5]n(11) and the closely related compound [Zn(ctpy)(ox)0.5]n·0.5nH2O (12) (Hctpy = 4‧-carboxy-4,2‧:6‧,4‧‧-terpyridine, H2ox = oxalic acid and H3idc = imidazole-4,5-dicarboxylic acid) have been synthesized by hydro(solvo)thermal reaction of 4‧-carboxy-4,2‧:6‧,4‧‧-terpyridine with divalent metal salts and characterized by elemental analysis, IR spectra, single crystal X-ray diffraction. Compounds 1 and 4 have similar structure which demonstrate a two-fold interpenetrating 3D framework with a 3-connected utp topological net, which contains the same number of left and right-handed 21 helical chains. Compounds 2 and 9 are isostructural 2D layer with a 3-connected hcb topological net. Similar to 2, compound 3 also displays a 3-connected 2D hcb topological net. Compounds 5 and 10 are a 2D layer with a 4-connected sql topological net. Compound 6 shows a chiral 2D layer based on a 1D left- or right-handed helical chains, which are further extended into an achiral 2D + 2D→3D supramolecular network by hydrogen bonds with alternately arrangement. Compound 7 features an unusual 2-fold interpenetrating 3D coordination network which exhibits a new intriguing (3,5)-connected binodal topological net with the Schläfli symbol of (52·6)(53·63·73·8). Compound 8 shows a 2D→3D supramolecular structure based on (3,4)-connected 2D bilayers with the Schläfli symbol of (44·62). Compound 11 displays an unusual three-dimensional coordination network which exhibits an intriguing (3,8)-connected binodal new topological net with Schläfli symbol (42·62)2(42·623·83). Compound 12 features a two-fold interpenetrating (3,4)-connected 3D framework with the fsc topological net. Compounds 1-12 were obtained under similar reaction conditions. The diverse structures indicate that rational selection of the second ligand, metal salt, counter anion and solvent are good methods to further design metal-organic compounds with new structures and properties. Moreover, their thermal stabilities, photoluminescent and magnetic properties were also investigated. More importantly, compound 12 has been successfully applied in the detection of Fe3+ ion in DMF solutions and nitrobenzene and the possible detecting mechanism was also discussed.

Approximation of a Brittle Fracture Energy with a Constraint of Non-interpenetration

NASA Astrophysics Data System (ADS)

Chambolle, Antonin; Conti, Sergio; Francfort, Gilles A.

2018-06-01

Linear fracture mechanics (or at least the initiation part of that theory) can be framed in a variational context as a minimization problem over an SBD type space. The corresponding functional can in turn be approximated in the sense of {Γ}-convergence by a sequence of functionals involving a phase field as well as the displacement field. We show that a similar approximation persists if additionally imposing a non-interpenetration constraint in the minimization, namely that only nonnegative normal jumps should be permissible.

A green approach to prepare silver nanoparticles loaded gum acacia/poly(acrylate) hydrogels.

PubMed

Bajpai, S K; Kumari, Mamta

2015-09-01

In this work, gum acacia (GA)/poly(sodium acrylate) semi-interpenetrating polymer networks (Semi-IPN) have been fabricated via free radical initiated aqueous polymerization of monomer sodium acrylate (SA) in the presence of dissolved Gum acacia (GA), using N,N'-methylenebisacrylamide (MB) as cross-linker and potassium persulphate (KPS) as initiator. The semi-IPNs, synthesized, were characterized by various techniques such as X-ray diffraction (XRD), thermo gravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. The dynamic water uptake behavior of semi-IPNs was investigated and the data were interpreted by various kinetic models. The equilibrium swelling data were used to evaluate various network parameters. The semi-IPNs were used as template for the in situ preparation of silver nanoparticles using extract of Syzygium aromaticum (clove). The formation of silver nanoparticles was confirmed by surface plasmon resonance (SPR), XRD and transmission electron microscopy (TEM). Finally, the antibacterial activity of GA/poly(SA)/silver nanocomposites was tested against E. coli. Copyright © 2015 Elsevier B.V. All rights reserved.

Superparamagnetic IPN gels of carrageenan/PHEMA excelling in shape retention.

PubMed

Tsuru, Takahiro; Sugimura, Kazuki; Nishio, Yoshiyuki

2017-12-15

Iron oxide nanoparticles-incorporated carrageenan (CAR)/PHEMA composites of interpenetrating network (IPN) type were successfully prepared by in situ ferrite synthesis in the polymer network. The IPN structure was constructed at CAR/PHEMA compositions of 15/85 and 40/60 (wt/wt) by polymerization and cross-linking of 2-hydroxyethylmethacrylate as an impregnating solvent of CAR gels. As a result of this IPN construction, the composites were firm and showed a good shape-retentivity in their gelatinous state. SQUID magnetometry and X-ray diffractometry were conducted for evaluation of the magnetic property of the inorganic-hybridized IPN composites. Magnetite particles with 10-30nm sizes were distributed inside the IPNs treated with the repeatable ferrite synthesis; thereby, the hybrids displayed a superparamagnetic character at ambient temperature. Specifically, the 40/60 CAR/PHEMA IPN imparted a practically passable value (10-15emu (g sample) -1 ) of saturation magnetization. The present IPN system offers a potential for application as a biocompatible magnetic material used in hydro-surroundings. Copyright © 2017 Elsevier Ltd. All rights reserved.

Functionalized gold nanoparticles as additive to form polymer/metal composite matrix for improved DNA sequencing by capillary electrophoresis.

PubMed

Zhou, Dan; Yang, Liping; Yang, Runmiao; Song, Weihua; Peng, Shuhua; Wang, Yanmei

2009-11-15

A new matrix additive, poly (N,N-dimethylacrylamide)-functionalized gold nanoparticle (GNP-PDMA), was prepared by "grafting-to" approach, and then incorporated into quasi-interpenetrating network (quasi-IPN) composed of linear polyacrylamide (LPA, 3.3 MDa) and PDMA to form novel polymer/metal composite sieving matrix (quasi-IPN/GNP-PDMA) for DNA sequencing by capillary electrophoresis. Without complete optimization, quasi-IPN/GNP-PDMA yielded a readlength of 801 bases at 98% accuracy in about 64 min by using the ABI 310 Genetic Analyzer at 50 degrees C and 150 V/cm. Compared with previous quasi-IPN/GNPs, quasi-IPN/GNP-PDMA can further improve DNA sequencing performances. This is because the presence of GNP-PDMA can improve the compatibility of GNPs with the whole sequencing system, enhance the entanglement degree of networks, and increase the GNP concentration in system, which consequently lead to higher restriction and stability, higher apparent molecular weight (MW), and smaller pore size of the total sieving networks. Furthermore, the composite matrix was also compared with quasi-IPN containing higher-MW LPA and commercial POP-6. The results indicate that the composite matrix is a promising one for DNA sequencing to achieve full automation due to the separation provided with high resolution, speediness, excellent reproducibility, and easy loading in the presence of GNP-PDMA.

Three-dimensional morphology of CuInS2:P3HT hybrid blends for photovoltaic applications

NASA Astrophysics Data System (ADS)

Krause, Christopher; Scheunemann, Dorothea; Parisi, Jürgen; Borchert, Holger

2015-11-01

Despite potential advantages, the performance of hybrid solar cells with colloidal nanocrystals remains low compared to pure organic solar cells, in particular, when Cd- and Pb-free nanocrystals are employed. To understand this discrepancy, we analyzed possible limiting factors of the performance of hybrid solar cells with CuInS2 nanoparticles and the polymer poly(3-hexylthiophene) (P3HT). Optimizing the thickness of the active layer indicated that charge transport limits the performance of the solar cells. Since charge transport is among others influenced by the morphology of the bulk heterojunction layer, we performed a detailed analysis of the blend morphology. Therefore, we used electron tomography which provides three-dimensional information on the interpenetrating network formed by the hybrid CuInS2:P3HT system. Using statistical methods, we analyzed the distribution of the nanoparticles inside the polymer matrix and the structure of the percolation paths. We found that the morphology appears well suited for application in hybrid solar cells, meaning that other factors must be the bottleneck. Therefore, we investigated in a second step the influence of a post-deposition ligand exchange with acetic acid. This strategy resulted in a strong relative improvement of the solar cell performance, although absolute performance parameters remain low in comparison to hybrid solar cells with colloidal cadmium or lead chalcogenide nanocrystals.

A review of integrating electroactive polymers as responsive systems for specialized drug delivery applications.

PubMed

Pillay, Viness; Tsai, Tong-Sheng; Choonara, Yahya E; du Toit, Lisa C; Kumar, Pradeep; Modi, Girish; Naidoo, Dinesh; Tomar, Lomas K; Tyagi, Charu; Ndesendo, Valence M K

2014-06-01

Electroactive polymers (EAPs) are promising candidate materials for the design of drug delivery technologies, especially in conditions where an "on-off" drug release mechanism is required. To achieve this, EAPs such as polyaniline, polypyrrole, polythiophene, ethylene vinyl acetate, and polyethylene may be blended into responsive hydrogels in conjunction with the desired drug to obtain a patient-controlled drug release system. The "on-off" drug release mechanism can be achieved through the environmental-responsive nature of the interpenetrating hydrogel-EAP complex via (i) charged ions initiated diffusion of drug molecules; (ii) conformational changes that occur during redox switching of EAPs; or (iii) electroerosion. These release mechanisms are not exhaustive and new release mechanisms are still under investigation. Therefore, this review seeks to provide a concise incursion and critical overview of EAPs and responsive hydrogels as a strategy for advanced drug delivery, for example, controlled release of neurotransmitters, sulfosalicyclic acid from cross-linked hydrogel, and vaccine delivery. The review further discusses techniques such as linear sweep voltammetry, cyclic voltammetry, impedance spectroscopy, and chronoamperometry for the determination of the redox capability of EAPs. The future implications of the hydrogel-EAP composites include, but not limited to, application toward biosensors, DNA hybridizations, microsurgical tools, and miniature bioreactors and may be utilized to their full potential in the form of injectable devices as nanorobots or nanobiosensors. Copyright © 2013 Wiley Periodicals, Inc.

Nanoscale control of the network morphology of high efficiency polymer fullerene solar cells by the use of high material concentration in the liquid phase

NASA Astrophysics Data System (ADS)

Radbeh, R.; Parbaile, E.; Bouclé, J.; Di Bin, C.; Moliton, A.; Coudert, V.; Rossignol, F.; Ratier, B.

2010-01-01

Despite the constant improvement of their power conversion efficiencies, organic solar cells based on an interpenetrating network of a conjugated polymer as donor and fullerene derivatives as acceptor materials still need to be improved for commercial use. In this context, we present a study on the optimization of solar cells based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) by varying a specific cell parameter, namely the concentration of the active layer components in the liquid phase before blend film deposition, in order to improve device performance and to better understand the relation between morphology and device operation. Our study shows a significant increase of the short-circuit current, open-circuit voltage and cell efficiency by properly choosing the formulation of the initial blend before film deposition. We demonstrate that the active layer morphology, which is strongly dependent on the initial material concentrations and the processing conditions, can greatly impact the electronic characteristics of the device, especially regarding charge recombination dynamics at the donor-acceptor interface. Our optimized P3HT:PCBM device exhibits both slow recombination and high photocurrent generation associated with an overall power conversion efficiency of 4.25% under 100 mW cm-2 illumination (AM1.5G).

Four thiophene-pyridyl-amide-based Zn{sup II}/Cd{sup II} coordination polymers: Assembly, structures, photocatalytic properties and fluorescent recognition for Fe{sup 3+}

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

Wang, Xiu-Li; Wu, Xiao-Mei; Liu, Guo-Cheng

By tuning metal ions and combining with different dicarboxylates, four new semi-rigid thiophene-bis-pyridyl-bis-amide-based coordination polymers, namely, [Zn(3-bptpa)(1,3-BDC)]·DMA·2H{sub 2}O (1), [Zn(3-bptpa)(5-MIP)] (2), [Cd(3-bptpa)(1,3-BDC)]·2H{sub 2}O (3) and [Cd(3-bptpa)(5-MIP)]·4H{sub 2}O (4) (3-bptpa=N,N′-bis(pyridine-3-yl)thiophene-2,5-dicarboxamide, 1,3-H{sub 2}BDC=1,3-benzenedicarboxylic acid, 5-H{sub 2}MIP=5-methylisophthalic acid, DMA=N,N-dimethylacetamide), were solvothermally/hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction analyses, IR spectra, UV–vis diffuse-reflectance spectra (DRS), powder X-ray diffraction (PXRD) and thermal gravimetric analyses (TG). The structural analysis reveals that Zn-complexes 1 and 2 are similar 2D networks. While Cd-complexes 3 and 4 exhibit similar 2-fold interpenetrating 3D α-Po frameworks with the (4{sup 12}·6{sup 3}) topology. The photocatalytic properties for the degradation ofmore » methylene blue (MB) under ultraviolet light irradiation of the title complexes have been investigated in detail. Furthermore, the luminescent sensing behaviors for metal cations of 1–4 have been studied, the results indicate that 3 is an excellent fluorescent probe, with high sensitivity, selectivity, and simple regeneration, for environmentally relevant Fe{sup 3+} ions. - Graphical abstract: Four Zn{sup II}/Cd{sup II} coordination polymers with a thiophene-pyridyl-amide ligand have been prepared. The photocatalytic activities and fluorescent sensing properties for metal ions of the title complexes have been investigated. - Highlights: • Four coordination polymers with thiophene-pyridyl-amide ligands have been obtained. • The central metal ions play an important role in the formation of the frameworks. • The photoluminescent sensing and the photocatalytic properties have been investigated.« less

Preparation of Bottlebrush Polymers via a One-Pot Ring-Opening Polymerization (ROP) and Ring-Opening Metathesis Polymerization (ROMP) Grafting-Through Strategy.

PubMed

Radzinski, Scott C; Foster, Jeffrey C; Matson, John B

2016-04-01

Bottlebrush polymers are synthesized using a tandem ring-opening polymerization (ROP) and ring-opening metathesis polymerization (ROMP) strategy. For the first time, ROP and ROMP are conducted sequentially in the same pot to yield well-defined bottlebrush polymers with molecular weights in excess of 10(6) Da. The first step of this process involves the synthesis of a polylactide macromonomer (MM) via ROP of d,l-lactide initiated by an alcohol-functionalized norbornene. ROMP grafting-through is then carried out in the same pot to produce the bottlebrush polymer. The applicability of this methodology is evaluated for different MM molecular weights and bottlebrush backbone degrees of polymerization. Size-exclusion chromatographic and (1)H NMR spectroscopic analyses confirm excellent control over both polymerization steps. In addition, bottlebrush polymers are imaged using atomic force microscopy and stain-free transmission electron microscopy on graphene oxide. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The effect of oxyalkylation and application of polymer dispersions on the thermoformability and extensibility of paper.

PubMed

Kouko, Jarmo; Setälä, Harri; Tanaka, Atsushi; Khakalo, Alexey; Ropponen, Jarmo; Retulainen, Elias

2018-04-15

Wood fiber-based packaging materials, as renewable materials, have growing market potential due to their sustainability. A new breakthrough in cellulose-based packaging requires some improvement in the mechanical properties of paper. Bleached softwood kraft pulp was mechanically treated, in two stages, using high- and low-consistency refining, sequentially. Chemical treatment of pulp using the oxyalkylation method was applied to modify a portion of fiber material, especially the fiber surface, and its compatibility with polymer dispersions including one carbohydrate polymer. The results showed that the compatibility of the cellulosic fibers with some polymers could be improved with oxyalkylation. By adjusting mechanical and chemical treatments, and the thermoforming conditions, the formability of paper was improved, but simultaneously the strength and stiffness decreased. The results suggest that the formability of the paper is not a direct function of the extensibility of the applied polymer, but also depends on the fiber network structure and surface energy. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

An interpenetrating HA/G/CS biomimic hydrogel via Diels-Alder click chemistry for cartilage tissue engineering.

PubMed

Yu, Feng; Cao, Xiaodong; Zeng, Lei; Zhang, Qing; Chen, Xiaofeng

2013-08-14

In order to mimic the natural cartilage extracellular matrix, a novel biological degradable interpenetrating network hydrogel was synthesized from the gelatin (G), hyaluronic acid (HA) and chondroitin sulfate (CS) by Diels-Alder "click" chemistry. HA was modified with furylamine and G was modified with furancarboxylic acid respectively. (1)H NMR spectra and elemental analysis showed that the substitution degrees of HA-furan and G-furan were 71.5% and 44.5%. Then the hydrogels were finally synthesized by cross-linking furan-modified HA and G derivatives with dimaleimide poly(ethylene glycol) (MAL-PEG-MAL). The mechanical and degradation properties of the hydrogels could be tuned simply through varying the molar ratio between furan and maleimide. Rheological, mechanical and degradation studies demonstrated that the Diels-Alder "click" chemistry is an efficient method for preparing high performance biological interpenetrating hydrogels. This biomimic hydrogel with improved mechanical properties could have great potential applications in cartilage tissue engineering. Copyright © 2013 Elsevier Ltd. All rights reserved.

Dynamic properties of hydrogels and fiber-reinforced hydrogels.

PubMed

Martin, Nicholas; Youssef, George

2018-06-07

Hydrophilic polymers, or hydrogels, are used for a wide variety of biomedical applications, due to their inherent ability to withhold a high-water content. In recent years, a large effort has been focused on tailoring the mechanical properties of these hydrogels to become more appropriate materials for use as anatomical and physiological structural supports. A few of these such methods include using diverse types of polymers, both natural and synthetic, varying the type of molecular cross-linking, as well as combining these efforts to form interpenetrating polymer network hydrogels. While multiple research groups have characterized these various hydrogels under quasi-static conditions, their dynamic properties, representative of native physiological loading scenarios, have been scarcely reported. In this study, an E-glass fiber reinforced family of alginate/PAAm hydrogels cross-linked by both divalent and trivalent cations are fabricated and investigated. The effect of the reinforcement phase on the dynamic and hydration behaviors is then explicated. Additionally, a micromechanics framework for short cylindrical chopped fibers is utilized to discern the contribution of the matrix and fiber constituents on the hydrogel composite. The addition of E-glass fibers resulted in the storage modulus exhibiting a ~50%, 5%, and ~120%, increase with a mere addition of 2 wt% of the reinforcing fibers to Na-, Sr-, and Al-alginate/PAAm, respectively. In studying the cross-linking effect of various divalent (Ba, Ca, Sr) and trivalent (Al, Fe) cations, it was noteworthy that the hydrogels were found to be effective in dissipating energy while resisting mechanical deformation when they are cross-linked with higher molecular weight elements, regardless of valency. This report on the dynamic properties of these hydrogels will help to improve their optimization for future use in biomedical load-bearing applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

[Plastics on the eye - plastics in the eye. Human-optic materials].

PubMed

Geyer, Otto-Christian; Schwabe, Peter; Wingler, Frank

2002-01-01

Materials of identical or similiar chemical classes are used for contact optics as well as for implantable intraocular devices. All of them derive from the chemistry of industrial product developments. Materials used in and on the eye should behave indifferent. They should not provoke any reaction in the eye and not themselves be altered by the biological surroundings. For materials used in the eye an especially high purity of the polymers utilized as well as a long term light stability is to be demanded. Optical properties like transparency have to be stable over extended time periods under normal light influence. The long time stability of UV-absorbing additives in the materials used has to be verified. All materials used for IOL's - with the exception of the homopolymer of methylmethacrylate - consist of polymer mixtures forming socalled interpenetrating networks which appear as an uniform material. For the manufacturing of intraocular lense materials standardized or unanimous producer prescriptions are not existing. Based on the different polymer formulations different aging and fatigue properties are the outcome. In addition only inadequate knowledge about the long term light stability of the incorporated UV blockers is submitted. Polymeric materials used for IOL's should be subjected in addition to the test methods listed in EN-ISO 11 979/5 to chemical, polymeranalytic and mechanical substance examinations. As a standard in such examinations a polymethylmethacrylate, free of methylacrylate is proposed. Examinations of each lot should be compulsory. Identification of all ingredients of the intraocular materials should be prescribed and labeled in line with the revelations of common medical drugs prescriptions. The relevations commit the medical doctor to inform his patient about possible side effects of the intraocular implants.

Mechanisms of Morphology Development and Control in Polymer- Polymer Blends

NASA Astrophysics Data System (ADS)

Macosko, Christopher W.

1998-03-01

Polymer-polymer blends continue to be the most important method for achieving optimization of properties in plastics products. Over 30 percent of all plastics are blends. While miscible blends generally give average properties between the components, immiscible blends offer synergistic possibilities such as high modulus with high toughness; high flow with high impact strength or diffusion barriers with good mechanical properties and low cost. The key to performance of these immiscible blends is their morphology. There are several important types of morphology which can lead to valuable property improvement: emulsion - small polymer spheres well dispersed in a polymer matrix. double emulsion - spheres inside spheres which are dispersed in another matrix. microlayer - thin, parallel layers of one polymer in a matrix. cocontinuous - two (or more) continuous, interpenetrating polymer phases. To be economical it is desirable to create these morphologies via melt mixing of powder or pellets in conventional compounding equipment. The melting stage during compounding is very important for morphology development. This presentation will demonstrate the role of melting or softening of each phase as well as their viscosity, elasticity and interfacial tension in morphology development. Interfacial modification with premade block copolymers or reactively formed copolymers can greatly alter morphology formation and stability. Experimental results will be presented which quantify the role of these additives. References to recent work in this area by our group are listed below: DeBrule, M. B., L. Levitt and C.W. Macosko, "The Rheology and Morphology of Layered Polymer Melts in Shear," Soc. Plastics Eng. Tech Papers (ANTEC), 84-89 (1996). Guegan, P., C. W. Macosko, T. Ishizone, A. Hirao and S. Nakahama, "Kinetics of Chain Coupling at Melt Interfaces, Macromol. 27, 4993-4997 (1994). Lee, M. S., T.P. Lodge, and C. W. Macosko, "Can Random Copolymers Serve as Effective Polymeric Compatibilizers?" accepted for publication by Journal of Polymer Science, Polymer Physics Edition, 1997. Levitt, L. and C. W. Macosko, "Extensional Rheometry of Polymer Multilayers: A Sensitive Probe of Interfaces," J. Rheol, 41, 3, 671-685, (1997). Levitt, L., C.W. Macosko and S.D. Pearson, "Influence of Normal Stress Difference on Polymer Drop Deformation," Polym. Eng. Sci., 36, Part 12, 1647-1655 (1996). Nakayama, A., T. Inoue, A. Hirao, P. Guegan, A. Khandpur, and C. W. Macosko, "Compatibilization of Blends: Effect of Reaction Rate," PPS Proceedings, Sorrento, May 1996. Levitt, L., "Microlayer Morphology Via Polymer Melt Processing, Ph.D. Thesis, Department of Chemical Engineering & Materials Science, University of Minnesota, 1997. Orr, C. A., A. Adedeji, A. Hirao, F. S. Bates, and C. W. Macosko, "Flow-Induced Reactive Self-Assembly", Macromolecules, 30, 4, 1243-1246, (1997). Orr, C. A., "Reactive Compatibilization of Polymer Blends," Ph.D. Thesis, Department of Chemical Engineering & Materials Science, University of Minnesota, 1997. Scott, C. E., and C. W. Macosko, "Morphology Development During the Initial Stages of Polymer-Polymer Blending," Polymer, 36, 461-470 (1995). Scott, C. E. and C. W. Macosko, "Model Experiments Concerning Morphology Development During the Initial Stages of Polymer Blending," Polymer Bulletin 26, 341- 348 (1991). Sundararaj, U., C. K. Shih, and C. W. Macosko, "Evidence For Inversion of Phase Continuity During Morphology Development in Polymer Blending," Polymer Eng. and Sci., 36, 1769-1781 (1996). Sundararaj, U., and C. W. Macosko, "Drop Breakup and Coalescence in Polymer Blends: The Effects of Concentration and Compatibilization, Macromolecules, 28, 2647-2657 (1995). Sundararaj, U., Y. Dori and C. W. Macosko, "Sheet Formation in Immiscible Polymer Blends: Model Experiments on Initial Blend Morphology," Polymer, 36, 1957-1968 (1995). Sundararaj, U., C. W. Macosko, A. Nakayama, and T. Inoue, "Milligrams to Kilograms: An Evaluation of Mixers for Reactive Polymer Blending," Polym. Eng. Sci. 35, 100-114 (1995). Sundararaj, U, R. J. Rolando, H. T. Chan and C. W. Macosko, "Morphology Development in Polymer Blends," Polymer Eng. Sci. 32, 1814-1823 (1992). Utracki, L., Polymer Alloys and Blends; Hanser: New York, 1989.

Amphiphilic semi-interpenetrating polymer networks using pulverized rubber

NASA Astrophysics Data System (ADS)

Shahidi, Nima

Scrap rubber materials provide a significant challenge to either reuse or safe disposal. Every year, millions of tires are discarded to landfills in the United States, consuming a staggering amount of land space, creating a high risk for large fires, breeding mosquitoes that spread diseases, and wasting the planet's natural resources. This situation cannot be sustained. The challenge of reusing scrap rubber materials is mainly due to the crosslinked structure of vulcanized rubber that prevent them from melting and further processing for reuse. The most feasible recycling approach is believed to be a process in which the vulcanized rubber is first pulverized into a fine powder and then incorporated into new products. The production of fine rubber particles is generally accomplished through the use of a cryogenic process that is costly. Therefore, development of a cost effective technology that utilizes a large quantity of the scrap rubber materials to produce high value added materials is an essential element in maintaining a sustainable solution to rubber recycling. In this research, a cost effective pulverization process, solid state shear extrusion (SSSE), was modified and used for continuous pulverization of the rubber into fine particles. In the modified SSSE process, pulverization takes place at high compressive shear forces and a controlled temperature. Furthermore, an innovative particle modification process was developed to enhance the chemical structure and surface properties of the rubber particles for manufacturing of high value added products. Modification of rubber particles was accomplished through the polymerization of a hydrophilic monomer mixture within the intermolecular structure of the hydrophobic rubber particles. The resulting composite particles are considered as amphiphilic particulate phase semi-interpenetrating polymer networks (PPSIPNs). The modified rubber particles are water dispersible and suitable for use in a variety of aqueous media applications such as additives to waterborne emulsions. This innovative process for the first time opened up the application of rubber particles in aqueous media. The kinetics of polymerization reaction of hydrophilic monomer mixture within the rubber particles was investigated based on the assumption of partitioning of acrylic acid monomer in the hydrophobic rubber particles. The produced PPSIPNs were used as additives to waterborne emulsions and the mechanical and physical properties of the prepared coatings were examined. It was observed that the PPSIPNs could be added in high quantities with an improvement in adhesion, enhancement of the impact strength, and hardness of the coatings. This approach aims to develop environmentally benign products from scrap rubber materials.

Rheo-optical near-infrared (NIR) spectroscopy study of partially miscible polymer blend of polymethyl methacrylate (PMMA) and polyethylene glycol (PEG)

NASA Astrophysics Data System (ADS)

Shinzawa, Hideyuki; Mizukado, Junji

2018-03-01

Tensile deformations of a partially miscible blend of polymethyl methacrylate (PMMA) and polyethylene glycol (PEG) is studied by a rheo-optical characterization near-infrared (NIR) technique to probe deformation behavior during tensile deformation. Sets of NIR spectra of the polymer samples were collected by using an acousto-optic tunable filter (AOTF) NIR spectrometer coupled with a tensile testing machine as an excitation device. While deformations of the samples were readily captured as strain-dependent NIR spectra, the entire feature of the spectra was overwhelmed with the baseline fluctuation induced by the decrease in the sample thickness and subsequent change in the light scattering. Several pretreatment techniques, including multiplicative scatter collection (MSC) and null-space projection, are subjected to the NIR spectra prior to the determination of the sequential order of the spectral intensity changes by two-dimensional (2D) correlation analysis. The comparison of the MSC and null-space projection provided an interesting insight into the system, especially deformation-induced variation of light scattering observed during the tensile testing of the polymer sample. In addition, the sequential order determined with the 2D correlation spectra revealed that orientation of a specific part of PMMA chain occurs before that of the others because of the interaction between Cdbnd O group of PMMA and terminal sbnd OH group of PEG.

Controlled catalytic and thermal sequential pyrolysis and hydrolysis of mixed polymer waste streams to sequentially recover monomers or other high value products

DOEpatents

Evans, R.J.; Chum, H.L.

1994-10-25

A process of using fast pyrolysis in a carrier gas to convert a plastic waste feedstream having a mixed polymeric composition in a manner such that pyrolysis of a given polymer to its high value monomeric constituent occurs prior to pyrolysis of other plastic components therein comprising: selecting a first temperature program range to cause pyrolysis of said given polymer to its high value monomeric constituent prior to a temperature range that causes pyrolysis of other plastic components; selecting a catalyst and support for treating said feed streams with said catalyst to effect acid or base catalyzed reaction pathways to maximize yield or enhance separation of said high value monomeric constituent in said temperature program range; differentially heating said feed stream at a heat rate within the first temperature program range to provide differential pyrolysis for selective recovery of optimum quantities of the high value monomeric constituent prior to pyrolysis of other plastic components; separating the high value monomeric constituents; selecting a second higher temperature range to cause pyrolysis of a different high value monomeric constituent of said plastic waste and differentially heating the feedstream at the higher temperature program range to cause pyrolysis of the different high value monomeric constituent; and separating the different high value monomeric constituent. 83 figs.

Controlled catalytic and thermal sequential pyrolysis and hydrolysis of polymer waste comprising nylon 6 and a polyolefin or mixtures of polyolefins to sequentially recover monomers or other high value products

DOEpatents

Evans, Robert J.; Chum, Helena L.

1994-01-01

A process of using fast pyrolysis in a carrier gas to convert a plastic waste feedstream having a mixed polymeric composition in a manner such that pyrolysis of a given polymer to its high value monomeric constituent occurs prior to pyrolysis of other plastic components therein comprising: selecting a first temperature program range to cause pyrolysis of said given polymer to its high value monomeric constituent prior to a temperature range that causes pyrolysis of other plastic components; selecting a catalyst and support for treating said feed streams with said catalyst to effect acid or base catalyzed reaction pathways to maximize yield or enhance separation of said high value monomeric constituent in said temperature program range; differentially heating said feed stream at a heat rate within the first temperature program range to provide differential pyrolysis for selective recovery of optimum quantities of the high value monomeric constituent prior to pyrolysis of other plastic components; separating the high value monomeric constituents; selecting a second higher temperature range to cause pyrolysis of a different high value monomeric constituent of said plastic waste and differentially heating the feedstream at the higher temperature program range to cause pyrolysis of the different high value monomeric constituent; and separating the different high value monomeric constituent.

Controlled catalytic and thermal sequential pyrolysis and hydrolysis of mixed polymer waste streams to sequentially recover monomers or other high value products

DOEpatents

Evans, R.J.; Chum, H.L.

1994-04-05

A process is described for using fast pyrolysis in a carrier gas to convert a plastic waste feedstream having a mixed polymeric composition in a manner such that pyrolysis of a given polymer to its high value monomeric constituent occurs prior to pyrolysis of other plastic components therein comprising: selecting a first temperature program range to cause pyrolysis of said given polymer to its high value monomeric constituent prior to a temperature range that causes pyrolysis of other plastic components; selecting a catalyst and support for treating said feed streams with said catalyst to effect acid or base catalyzed reaction pathways to maximize yield or enhance separation of said high value monomeric constituent in said temperature program range; differentially heating said feed stream at a heat rate within the first temperature program range to provide differential pyrolysis for selective recovery of optimum quantities of the high value monomeric constituent prior to pyrolysis of other plastic components; separating the high value monomeric constituents, selecting a second higher temperature range to cause pyrolysis of a different high value monomeric constituent of said plastic waste and differentially heating the feedstream at the higher temperature program range to cause pyrolysis of the different high value monomeric constituent; and separating the different high value monomeric constituent. 87 figures.

Controlled catalytic and thermal sequential pyrolysis and hydrolysis of polymer waste comprising nylon 6 and a polyolefin or mixtures of polyolefins to sequentially recover monomers or other high value products

DOEpatents

Evans, R.J.; Chum, H.L.

1994-10-25

A process of using fast pyrolysis in a carrier gas to convert a plastic waste feedstream having a mixed polymeric composition in a manner such that pyrolysis of a given polymer to its high value monomeric constituent occurs prior to pyrolysis of other plastic components therein comprising: selecting a first temperature program range to cause pyrolysis of said given polymer to its high value monomeric constituent prior to a temperature range that causes pyrolysis of other plastic components; selecting a catalyst and support for treating said feed streams with said catalyst to effect acid or base catalyzed reaction pathways to maximize yield or enhance separation of said high value monomeric constituent in said temperature program range; differentially heating said feed stream at a heat rate within the first temperature program range to provide differential pyrolysis for selective recovery of optimum quantities of the high value monomeric constituent prior to pyrolysis of other plastic components; separating the high value monomeric constituents; selecting a second higher temperature range to cause pyrolysis of a different high value monomeric constituent of said plastic waste and differentially heating the feedstream at the higher temperature program range to cause pyrolysis of the different high value monomeric constituent; and separating the different high value monomeric constituent. 83 figs.

Functional Polymers and Sequential Copolymers by Phase Transfer Catalysis. Synthesis of Thermotropic Side-Chain Liquid Crystalline Polymers Containing a Poly(2,6-Dimethyl-1,4-Phenylene Oxide) Main Chain.

DTIC Science & Technology

1986-10-01

bromovalerate (Aldrich, 99%), 5-bromovaleronitrile (Aldrich, 95%), and 11-bromoundecanoic acid (Aldrich, 99%) were used without further purification. 4...atic proton’s). 71 Cm, 4 aromatic X~tons). C. Synthesis of 4- 4-oxybipheny1 butyrnc acid , 4-(4-inethoxy 4’-oxy- I hen 1 butyrnc acid , 5-(4-oxybipheny1...valeric acid , 5-(4-inethoxy-4-oxy- bi heny1 valeric acid . 11- 4-ox bipheny1 undecanoic acid and 11- 4-inethox -4 -ox biphenylundecanoic acid . The

Fluorescence Correlation Spectroscopy to Study Diffusion of Polymer Chains within Layered Hydrogen-Bonded Polymer Films

NASA Astrophysics Data System (ADS)

Pristinski, Denis; Kharlampieva, Evguenia; Sukhishvili, Svetlana

2002-03-01

Fluorescence Correlation Spectroscopy (FCS) has been used to probe molecular motions within polymer multilayers formed by hydrogen-bonding sequential self-assembly. Polyethylene glycol (PEG) molecules were end-labeled with the fluorescent tags, and self-assembled with polymethacrylic acid (PMAA) using layer-by-layer deposition. We have found that molecules included in the top adsorbed layer have significant mobility at the millisecond time scale, probably due to translational diffusion. However, their dynamics deviate from classical Brownian motion with a single diffusion time. Possible reasons for the deviation are discussed. We found that motions were significantly slowed with increasing depth within the PEG/PMAA multilayer. This phenomena occured in a narrow pH range around 4.0 in which intermolecular interactions were relatively weak.

Sequential shrink photolithography for plastic microlens arrays

NASA Astrophysics Data System (ADS)

Dyer, David; Shreim, Samir; Jayadev, Shreshta; Lew, Valerie; Botvinick, Elliot; Khine, Michelle

2011-07-01

Endeavoring to push the boundaries of microfabrication with shrinkable polymers, we have developed a sequential shrink photolithography process. We demonstrate the utility of this approach by rapidly fabricating plastic microlens arrays. First, we create a mask out of the children's toy Shrinky Dinks by simply printing dots using a standard desktop printer. Upon retraction of this pre-stressed thermoplastic sheet, the dots shrink to a fraction of their original size, which we then lithographically transfer onto photoresist-coated commodity shrink wrap film. This shrink film reduces in area by 95% when briefly heated, creating smooth convex photoresist bumps down to 30 µm. Taken together, this sequential shrink process provides a complete process to create microlenses, with an almost 99% reduction in area from the original pattern size. Finally, with a lithography molding step, we emboss these bumps into optical grade plastics such as cyclic olefin copolymer for functional microlens arrays.

Sequential shrink photolithography for plastic microlens arrays.

PubMed

Dyer, David; Shreim, Samir; Jayadev, Shreshta; Lew, Valerie; Botvinick, Elliot; Khine, Michelle

2011-07-18

Endeavoring to push the boundaries of microfabrication with shrinkable polymers, we have developed a sequential shrink photolithography process. We demonstrate the utility of this approach by rapidly fabricating plastic microlens arrays. First, we create a mask out of the children's toy Shrinky Dinks by simply printing dots using a standard desktop printer. Upon retraction of this pre-stressed thermoplastic sheet, the dots shrink to a fraction of their original size, which we then lithographically transfer onto photoresist-coated commodity shrink wrap film. This shrink film reduces in area by 95% when briefly heated, creating smooth convex photoresist bumps down to 30 µm. Taken together, this sequential shrink process provides a complete process to create microlenses, with an almost 99% reduction in area from the original pattern size. Finally, with a lithography molding step, we emboss these bumps into optical grade plastics such as cyclic olefin copolymer for functional microlens arrays.

Sequential shrink photolithography for plastic microlens arrays

PubMed Central

Dyer, David; Shreim, Samir; Jayadev, Shreshta; Lew, Valerie; Botvinick, Elliot; Khine, Michelle

2011-01-01

Endeavoring to push the boundaries of microfabrication with shrinkable polymers, we have developed a sequential shrink photolithography process. We demonstrate the utility of this approach by rapidly fabricating plastic microlens arrays. First, we create a mask out of the children’s toy Shrinky Dinks by simply printing dots using a standard desktop printer. Upon retraction of this pre-stressed thermoplastic sheet, the dots shrink to a fraction of their original size, which we then lithographically transfer onto photoresist-coated commodity shrink wrap film. This shrink film reduces in area by 95% when briefly heated, creating smooth convex photoresist bumps down to 30 µm. Taken together, this sequential shrink process provides a complete process to create microlenses, with an almost 99% reduction in area from the original pattern size. Finally, with a lithography molding step, we emboss these bumps into optical grade plastics such as cyclic olefin copolymer for functional microlens arrays. PMID:21863126

Sequential Processing for Organic Photovoltaics: Design Rules for Morphology Control by Tailored Semi-Orthogonal Solvent Blends

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

Aguirre, Jordan C.; Hawks, Steven A.; Ferreira, Amy S.

2015-03-18

Design rules are presented for significantly expanding sequential processing (SqP) into previously inaccessible polymer:fullerene systems by tailoring binary solvent blends for fullerene deposition. Starting with a base solvent that has high fullerene solubility, 2-chlorophenol (2-CP), ellipsometry-based swelling experiments are used to investigate different co-solvents for the fullerene-casting solution. By tuning the Flory-Huggins χ parameter of the 2-CP/co-solvent blend, it is possible to optimally swell the polymer of interest for fullerene interdiffusion without dissolution of the polymer underlayer. In this way solar cell power conversion efficiencies are obtained for the PTB7 (poly[(4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)(3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl)]) and PC61BM (phenyl-C61-butyric acid methyl ester) materials combination thatmore » match those of blend-cast films. Both semicrystalline (e.g., P3HT (poly(3-hexylthiophene-2,5-diyl)) and entirely amorphous (e.g., PSDTTT (poly[(4,8-di(2-butyloxy)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)-alt-(2,5-bis(4,4'-bis(2-octyl)dithieno[3,2-b:2'3'-d]silole-2,6-diyl)thiazolo[5,4-d]thiazole)]) conjugated polymers can be processed into highly efficient photovoltaic devices using the solvent-blend SqP design rules. Grazing-incidence wide-angle x-ray diffraction experiments confirm that proper choice of the fullerene casting co-solvent yields well-ordered interdispersed bulk heterojunction (BHJ) morphologies without the need for subsequent thermal annealing or the use of trace solvent additives (e.g., diiodooctane). The results open SqP to polymer/fullerene systems that are currently incompatible with traditional methods of device fabrication, and make BHJ morphology control a more tractable problem.« less

Incorporation of fused tetrathiafulvalenes (TTFs) into polythiophene architectures: varying the electroactive dominance of the TTF species in hybrid systems.

PubMed

Berridge, Rory; Skabara, Peter J; Pozo-Gonzalo, Cristina; Kanibolotsky, Alexander; Lohr, Jan; McDouall, Joseph J W; McInnes, Eric J L; Wolowska, Joanna; Winder, Christoph; Sariciftci, N Serdar; Harrington, Ross W; Clegg, William

2006-02-23

A novel polythienylenevinylene (PTV) and two new polythiophenes (PTs), featuring fused tetrathiafulvalene (TTF) units, have been prepared and characterized by ultraviolet-visible (UV-vis) and electron paramagnetic resonance (EPR) spectroelectrochemistry. All polymers undergo two sequential, reversible oxidation processes in solution. Structures in which the TTF species is directly linked to the polymer backbone (2 and 4) display redox behavior which is dictated by the fulvalene system. Once the TTF is spatially removed from the polymer chain by a nonconjugated link (polymer 3), the electroactivity of both TTF and polythiophene moieties can be detected. Computational studies confirm the delocalization of charge over both electroactive centers (TTF and PT) and the existence of a triplet dication intermediate. PTV 4 has a low band gap (1.44 eV), is soluble in common organic solvents, and is stable under ambient conditions. Organic solar cells of polymer 4:[6,6]-phenyl-C(61) butyric acid methyl ester (PCBM) have been fabricated. Under illumination, a photovoltaic effect is observed with a power conversion efficiency of 0.13% under AM1.5 solar simulated light. The onset of photocurrent at 850 nm is consistent with the onset of the pi-pi absorption band of the polymer. Remarkably, UV-vis spectroelectrochemistry of polymer 4 reveals that the conjugated polymer chain remains unchanged during the oxidation of the polymer.

Transfer-printing of active layers to achieve high quality interfaces in sequentially deposited multilayer inverted polymer solar cells fabricated in air

PubMed Central

Vohra, Varun; Anzai, Takuya; Inaba, Shusei; Porzio, William; Barba, Luisa

2016-01-01

Abstract Polymer solar cells (PSCs) are greatly influenced by both the vertical concentration gradient in the active layer and the quality of the various interfaces. To achieve vertical concentration gradients in inverted PSCs, a sequential deposition approach is necessary. However, a direct approach to sequential deposition by spin-coating results in partial dissolution of the underlying layers which decreases the control over the process and results in not well-defined interfaces. Here, we demonstrate that by using a transfer-printing process based on polydimethylsiloxane (PDMS) stamps we can obtain increased control over the thickness of the various layers while at the same time increasing the quality of the interfaces and the overall concentration gradient within the active layer of PSCs prepared in air. To optimize the process and understand the influence of various interlayers, our approach is based on surface free energy, spreading parameters and work of adhesion calculations. The key parameter presented here is the insertion of high quality hole transporting and electron transporting layers, respectively above and underneath the active layer of the inverted structure PSC which not only facilitates the transfer process but also induces the adequate vertical concentration gradient in the device to facilitate charge extraction. The resulting non-encapsulated devices (active layer prepared in air) demonstrate over 40% increase in power conversion efficiency with respect to the reference spin-coated inverted PSCs. PMID:27877901

One-pot synthesis of iniferter-bound polystyrene core nanoparticles for the controlled grafting of multilayer shells

NASA Astrophysics Data System (ADS)

Marchyk, Nataliya; Maximilien, Jacqueline; Beyazit, Selim; Haupt, Karsten; Sum Bui, Bernadette Tse

2014-02-01

A novel approach using one-pot synthesis for the production of uniform, iniferter-bound polystyrene core nanoparticles of size 30-40 nm is described. Conventional oil-in-water emulsion polymerisation of styrene and divinylbenzene, combining a hybrid initiation system (thermal and UV), triggered sequentially, was employed to form the surface-bound thiocarbamate iniferters in situ. The iniferter cores were then used as seeds for re-initiating further polymerisation by UV irradiation to produce water-compatible core-shell nanoparticles. Grafting of various shell-types is demonstrated: linear polymers of poly(N-isopropylacrylamide) brushes, crosslinked polymers bearing different surface charges and molecularly imprinted polymers. The shell thickness was readily tuned by varying the monomers' concentration and polymerisation time. Our method is straightforward and in addition, gives access to the preparation of fluorescent seeds and the possibility of grafting nanosized multiple shells. The core-shell nanoparticles were fully characterised by dynamic light scattering, transmission electron microscopy, Fourier transform infrared spectroscopy and microelemental analysis.A novel approach using one-pot synthesis for the production of uniform, iniferter-bound polystyrene core nanoparticles of size 30-40 nm is described. Conventional oil-in-water emulsion polymerisation of styrene and divinylbenzene, combining a hybrid initiation system (thermal and UV), triggered sequentially, was employed to form the surface-bound thiocarbamate iniferters in situ. The iniferter cores were then used as seeds for re-initiating further polymerisation by UV irradiation to produce water-compatible core-shell nanoparticles. Grafting of various shell-types is demonstrated: linear polymers of poly(N-isopropylacrylamide) brushes, crosslinked polymers bearing different surface charges and molecularly imprinted polymers. The shell thickness was readily tuned by varying the monomers' concentration and polymerisation time. Our method is straightforward and in addition, gives access to the preparation of fluorescent seeds and the possibility of grafting nanosized multiple shells. The core-shell nanoparticles were fully characterised by dynamic light scattering, transmission electron microscopy, Fourier transform infrared spectroscopy and microelemental analysis. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr05295h

In situ gelable interpenetrating double network hydrogel formulated from binary components: thiolated chitosan and oxidized dextran.

PubMed

Zhang, Hanwei; Qadeer, Aisha; Chen, Weiliam

2011-05-09

In situ gelable interpenetrating double-network hydrogels composed of thiolated chitosan (Chitosan-NAC) and oxidized dextran (Odex), completely devoid of potentially cytotoxic small molecule cross-linkers and that do not require complex maneuvers or catalysis, have been formulated. The interpenetrating network structure is created by Schiff base formations and disulfide bond inter-cross-linkings through exploiting the disparity of their reaction times. Compared with the autogelable thiolated chitosan hydrogels that typically require a relatively long time span for gelation to occur, the Odex/Chitosan-NAC composition solidifies rapidly and forms a well-developed 3D network in a short time span. Compared with typical hydrogels derived from natural materials, the Odex/Chitosan-NAC hydrogels are mechanically strong and resist degradation. The cytotoxicity potential of the hydrogels was determined by an in vitro viability assay using fibroblast as a model cell, and the results reveal that the hydrogels are noncytotoxic. In parallel, in vivo results from subdermal implantation in mice models demonstrate that this hydrogel is not only highly resistant to degradation but also induces very mild tissue response.

In situ Gelable Interpenetrating Double Network Hydrogel Formulated from Binary Components: Thiolated Chitosan and Oxidized Dextran

PubMed Central

Zhang, Hanwei; Qadeer, Aisha; Chen, Weiliam

2011-01-01

In situ gelable interpenetrating double network hydrogels composed of thiolated chitosan (Chitosan-NAC) and oxidized dextran (Odex), completely devoid of potentially cytotoxic small molecule crosslinkers and do not require complex maneuvers or catalysis, have been formulated. The interpenetrating network structure is created by Schiff base formations and disulfide bond inter-crosslinkings through exploiting the disparity of their reaction times. Compare to the auto-gelable thiolated chitosan hydrogels that typically require a relatively long time span for gelation to occur, the Odex/Chitosan-NAC composition solidifies rapidly and forms a well-developed three-dimensional network in a short time span. Compare to typical hydrogels derived from natural materials, the Odex/Chitosan-NAC hydrogels are mechanically strong and resist degradation. The cytotoxicity potential of the hydrogels was determined by an in vitro viability assay using fibroblast as a model cell and the results reveal that the hydrogels are non-cytotoxic. In parallel, in vivo results from subdermal implantation in mice models demonstrate that this hydrogel is not only highly resistant to degradation but also induces very mild tissue response. PMID:21410248

Silica/Polymer and Silica/Polymer/Fiber Composite Aerogels

NASA Technical Reports Server (NTRS)

Ou, Danny; Stepanian, Christopher J.; Hu, Xiangjun

2010-01-01

Aerogels that consist, variously, of neat silica/polymer alloys and silica/polymer alloy matrices reinforced with fibers have been developed as materials for flexible thermal-insulation blankets. In comparison with prior aerogel blankets, these aerogel blankets are more durable and less dusty. These blankets are also better able to resist and recover from compression . an important advantage in that maintenance of thickness is essential to maintenance of high thermal-insulation performance. These blankets are especially suitable as core materials for vacuum- insulated panels and vacuum-insulated boxes of advanced, nearly seamless design. (Inasmuch as heat leakage at seams is much greater than heat leakage elsewhere through such structures, advanced designs for high insulation performance should provide for minimization of the sizes and numbers of seams.) A silica/polymer aerogel of the present type could be characterized, somewhat more precisely, as consisting of multiply bonded, linear polymer reinforcements within a silica aerogel matrix. Thus far, several different polymethacrylates (PMAs) have been incorporated into aerogel networks to increase resistance to crushing and to improve other mechanical properties while minimally affecting thermal conductivity and density. The polymethacrylate phases are strongly linked into the silica aerogel networks in these materials. Unlike in other organic/inorganic blended aerogels, the inorganic and organic phases are chemically bonded to each other, by both covalent and hydrogen bonds. In the process for making a silica/polymer alloy aerogel, the covalent bonds are introduced by prepolymerization of the methacrylate monomer with trimethoxysilylpropylmethacrylate, which serves as a phase cross-linker in that it contains both organic and inorganic monomer functional groups and hence acts as a connector between the organic and inorganic phases. Hydrogen bonds are formed between the silanol groups of the inorganic phase and the carboxyl groups of the organic phase. The polymerization process has been adapted to create interpenetrating PMA and silica-gel networks from monomers and prevent any phase separations that could otherwise be caused by an overgrowth of either phase. Typically, the resulting PMA/silica aerogel, without or with fiber reinforcement, has a density and a thermal conductivity similar to those of pure silica aerogels. However, the PMA enhances mechanical properties. Specifically, flexural strength at rupture is increased to 102 psi (=0.7 MPa), about 50 times the flexural strength of typical pure silica aerogels. Resistance to compression is also increased: Applied pressure of 17.5 psi (=0.12 MPa) was found to reduce the thicknesses of several composite PMA/silica aerogels by only about 10 percent.

Method for polymer synthesis in a reaction well

DOEpatents

Brennan, Thomas M.

1998-01-01

A method of synthesis for building a polymer chain, oligonucleotides in particular, by sequentially adding monomer units to at least one solid support for growing and immobilizing a polymer chain thereon in a liquid reagent solution. The method includes the step of: A) depositing a liquid reagent in a reaction well (26) in contact with at least one solid support and at least one monomer unit of the polymer chain affixed to the solid support. The well (26) includes at least one orifice (74) extending into the well (26), and is of a size and dimension to form a capillary liquid seal to retain the reagent solution in the well (26) to enable polymer chain growth on the solid support. The method further includes the step of B) expelling the reagent solution from the well (26), while retaining the polymer chain therein. This is accomplished by applying a first gas pressure to the reaction well such that a pressure differential between the first gas pressure and a second gas pressure exerted on an exit (80) of the orifice (74) exceeds a predetermined amount sufficient to overcome the capillary liquid seal and expel the reagent solution from the well (26) through the orifice exit (80).

Method for polymer synthesis in a reaction well

DOEpatents

Brennan, T.M.

1998-09-29

A method of synthesis is described for building a polymer chain, oligonucleotides in particular, by sequentially adding monomer units to at least one solid support for growing and immobilizing a polymer chain thereon in a liquid reagent solution. The method includes the step of: (A) depositing a liquid reagent in a reaction well in contact with at least one solid support and at least one monomer unit of the polymer chain affixed to the solid support. The well includes at least one orifice extending into the well, and is of a size and dimension to form a capillary liquid seal to retain the reagent solution in the well to enable polymer chain growth on the solid support. The method further includes the step of (B) expelling the reagent solution from the well, while retaining the polymer chain therein. This is accomplished by applying a first gas pressure to the reaction well such that a pressure differential between the first gas pressure and a second gas pressure exerted on an exit of the orifice exceeds a predetermined amount sufficient to overcome the capillary liquid seal and expel the reagent solution from the well through the orifice exit. 9 figs.

Sieving polymer synthesis by reversible addition fragmentation chain transfer polymerization.

PubMed

Nai, Yi Heng; Jones, Roderick C; Breadmore, Michael C

2013-12-01

Replaceable sieving polymers are the fundamental component for high resolution nucleic acids separation in CE. The choice of polymer and its physical properties play significant roles in influencing separation performance. Recently, reversible addition fragmentation chain transfer (RAFT) polymerization has been shown to be a versatile polymerization technique capable of yielding well defined polymers previously unattainable by conventional free radical polymerization. In this study, a high molecular weight PDMA at 765 000 gmol-1 with a PDI of 1.55 was successfully synthesized with the use of chain transfer agent - 2-propionic acidyl butyl trithiocarbonate (PABTC) in a multi-step sequential RAFT polymerization approach. This study represents the first demonstration of RAFT polymerization for synthesizing polymers with the molecular weight range suitable for high resolution DNA separation in sieving electrophoresis. Adjustment of pH in the reaction was found to be crucial for the successful RAFT polymerization of high molecular weight polymer as the buffered condition minimizes the effect of hydrolysis and aminolysis commonly associated with trithiocarbonate chain transfer agents. The separation efficiency of PABTC-PDMA was found to have marginally superior separation performance compared to a commercial PDMA formulation, POP™-CAP, of similar molecular weight range.

Fabrication of tough epoxy with shape memory effects by UV-assisted direct-ink write printing.

PubMed

Chen, Kaijuan; Kuang, Xiao; Li, Vincent; Kang, Guozheng; Qi, H Jerry

2018-03-07

3D printing of epoxy-based shape memory polymers with high mechanical strength, excellent thermal stability and chemical resistance is highly desirable for practical applications. However, thermally cured epoxy in general is difficult to print directly. There have been limited numbers of successes in printing epoxy but they suffer from relatively poor mechanical properties. Here, we present an ultraviolet (UV)-assisted 3D printing of thermally cured epoxy composites with high tensile toughness via a two-stage curing approach. The ink containing UV curable resin and epoxy oligomer is used for UV-assisted direct-ink write (DIW)-based 3D printing followed by thermal curing of the part containing the epoxy oligomer. The UV curable resin forms a network by photo polymerization after the 1st stage of UV curing, which can maintain the printed architecture at an elevated temperature. The 2nd stage thermal curing of the epoxy oligomer yields an interpenetrating polymer network (IPN) composite with highly enhanced mechanical properties. It is found that the printed IPN epoxy composites enabled by the two-stage curing show isotropic mechanical properties and high tensile toughness. We demonstrated that the 3D-printed high-toughness epoxy composites show good shape memory properties. This UV-assisted DIW 3D printing via a two-stage curing method can broaden the application of 3D printing to fabricate thermoset materials with enhanced tensile toughness and tunable properties for high-performance and functional applications.

3D Printed Silicone-Hydrogel Scaffold with Enhanced Physicochemical Properties.

PubMed

Mohanty, Soumyaranjan; Alm, Martin; Hemmingsen, Mette; Dolatshahi-Pirouz, Alireza; Trifol, Jon; Thomsen, Peter; Dufva, Martin; Wolff, Anders; Emnéus, Jenny

2016-04-11

Scaffolds with multiple functionalities have attracted widespread attention in the field of tissue engineering due to their ability to control cell behavior through various cues, including mechanical, chemical, and electrical. Fabrication of such scaffolds from clinically approved materials is currently a huge challenge. The goal of this work was to fabricate a tissue engineering scaffold from clinically approved materials with the capability of delivering biomolecules and direct cell fate. We have used a simple 3D printing approach, that combines polymer casting with supercritical fluid technology to produce 3D interpenetrating polymer network (IPN) scaffold of silicone-poly(2-hydroxyethyl methacrylate)-co-poly(ethylene glycol) methyl ether acrylate (pHEMA-co-PEGMEA). The pHEMA-co-PEGMEA IPN materials were employed to support growth of human mesenchymal stem cells (hMSC), resulting in high cell viability and metabolic activity over a 3 weeks period. In addition, the IPN scaffolds support 3D tissue formation inside the porous scaffold with well spread cell morphology on the surface of the scaffold. As a proof of concept, sustained doxycycline (DOX) release from pHEMA-co-PEGMEA IPN was demonstrated and the biological activity of released drug from IPN was confirmed using a DOX regulated green fluorescent reporter (GFP) gene expression assay with HeLa cells. Given its unique mechanical and drug releasing characteristics, IPN scaffolds may be used for directing stem cell differentiation by releasing various chemicals from its hydrogel network.

Potassium fulvate-modified graft copolymer of acrylic acid onto cellulose as efficient chelating polymeric sorbent.

PubMed

Mohamed, Magdy F; Essawy, Hisham A; Ammar, Nabila S; Ibrahim, Hanan S

2017-01-01

Acrylic acid (AA) was graft copolymerized from cellulose (Cell) in presence of potassium fulvate (KF) in order to enhance the chemical activity of the resulting chelating polymer and the handling as well. Fourier transform infrared (FTIR) proved that KF was efficiently inserted and became a permanent part of the network structure of the sorbent in parallel during the grafting copolymerization. Scanning electron microscopy (SEM) revealed intact homogeneous structure with uniform surface. This indicates improvement of the handling, however, it was not the case for the graft copolymer of acrylic acid onto cellulose in absence of KF, which is known to be brittle and lacks mechanical integrity. Effective insertion of this co-interpenetrating agent provided more functional groups, such as OH and COOH, which improved the chelating power of the produced sorbent as found for the removal of Cu 2+ ions from its aqueous solutions (the removal efficiency reached ∼98.9%). Different models were used to express the experimental data. The results corroborated conformity of the pseudo-second order kinetic model and Langmuir isotherm model to the sorption process, which translates into dominance of the chemisorption. Regeneration of the chelating polymers under harsh conditions did not affect the efficiency of copper ions uptake up to three successive cycles. A thermodynamic investigation ensured exothermic nature of the adsorption process that became less favourable at higher temperatures. Copyright © 2016 Elsevier B.V. All rights reserved.

Self-assembly of free-standing RNA membranes

NASA Astrophysics Data System (ADS)

Han, Daehoon; Park, Yongkuk; Kim, Hyejin; Lee, Jong Bum

2014-07-01

RNA has emerged as a promising material for nanostructure and microstructure engineering. Although rare, some macroscopic RNA structures have also been constructed using lipid or polymer materials. Here, we report the first example of an enzymatically generated RNA membrane. This robust and free-standing RNA membrane has a macroscopic structure and is generated without any polymer support or complexation. Our RNA membrane is fabricated following two sequential processes, complementary rolling circle transcription and evaporation-induced self-assembly, and its structural and functional properties are rationally controlled by adjusting RNA base pairing. In this study, three types of RNA membranes are fabricated and are used to demonstrate potential applications.

Paintable band-edge liquid crystal lasers.

PubMed

Gardiner, Damian J; Morris, Stephen M; Hands, Philip J W; Mowatt, Carrie; Rutledge, Rupert; Wilkinson, Timothy D; Coles, Harry J

2011-01-31

In this paper we demonstrate photonic band-edge laser emission from emulsion-based polymer dispersed liquid crystals. The lasing medium consists of dye-doped chiral nematic droplets dispersed within a polymer matrix that spontaneously align as the film dries. Such lasers can be easily formed on single substrates with no alignment layers. The system combines the self-organizing periodic structure of chiral nematic liquid crystals with the simplicity of the emulsion procedure so as to produce a material that retains the emission characteristics of band-edge lasers yet can be readily coated. Sequential and stacked layers demonstrate the possibility of achieving simultaneous multi-wavelength laser output from glass, metallic, and flexible substrates.

Method for efficient recovery of high-purity polycarbonates from electronic waste.

PubMed

Weeden, George S; Soepriatna, Nicholas H; Wang, Nien-Hwa Linda

2015-02-17

More than one million tons of polycarbonates from waste electrical and electronic equipment are consigned to landfills at an increasing rate of 3-5% per year. Recycling the polymer waste should have a major environmental impact. Pure solvents cannot be used to selectively extract polycarbonates from mixtures of polymers with similar properties. In this study, selective mixed solvents are found using guidelines from Hansen solubility parameters, gradient polymer elution chromatography, and solubility tests. A room-temperature sequential extraction process using two mixed solvents is developed to recover polycarbonates with high yield (>95%) and a similar purity and molecular weight distribution as virgin polycarbonates. The estimated cost of recovery is less than 30% of the cost of producing virgin polycarbonates from petroleum. This method would potentially reduce raw materials from petroleum, use 84% less energy, reduce emission by 1-6 tons of CO2 per ton of polycarbonates, and reduce polymer accumulation in landfills and associated environmental hazards.

A novel surface modification technique for forming porous polymer monoliths in poly(dimethylsiloxane).

PubMed

Burke, Jeffrey M; Smela, Elisabeth

2012-03-01

A new method of surface modification is described for enabling the in situ formation of homogenous porous polymer monoliths (PPMs) within poly(dimethylsiloxane) (PDMS) microfluidic channels that uses 365 nm UV illumination for polymerization. Porous polymer monolith formation in PDMS can be challenging because PDMS readily absorbs the monomers and solvents, changing the final monolith morphology, and because PDMS absorbs oxygen, which inhibits free-radical polymerization. The new approach is based on sequentially absorbing a non-hydrogen-abstracting photoinitiator and the monomers methyl methacrylate and ethylene diacrylate within the walls of the microchannel, and then polymerizing the surface treatment polymer within the PDMS, entangled with it but not covalently bound. Four different monolith compositions were tested, all of which yielded monoliths that were securely anchored and could withstand pressures exceeding the bonding strength of PDMS (40 psi) without dislodging. One was a recipe that was optimized to give a larger average pore size, required for low back pressure. This monolith was used to concentrate and subsequently mechanical lyse B lymphocytes.

Pterygium removal using a polyethylene glycol hydrogel adherent ocular bandage.

PubMed

Hirst, Lawrence W

2013-06-01

To describe the result of using a polyethylene glycol hydrogel contact lens (ReSure; Ocular Therapeutix, Inc, Bedford, MA) as a protective bandage over denuded areas of Tenons after pterygium removal. Five sequential patients underwent pterygium removal with a conjunctival autograft and painting of bare Tenons in the area of the graft retrieval with a biodegradable polymer, and these patients were followed for 1 year for immediate postoperative pain, epithelial healing, and long-term conjunctival scarring. All patients showed prolonged persistence of the polymer for up to 8 to 10 weeks with resultant increased conjunctival inflammation and scarring with no evidence of decreased postoperative pain. This hydrogel polymer seems to cause prolonged inflammation and resultant scarring when used over extended areas of Tenons, and it has no role in reducing pain after pterygium surgery.

New nanocomposite surfaces and thermal interface materials based on mesoscopic microspheres, polymers and graphene flakes

NASA Astrophysics Data System (ADS)

Dmitriev, Alex A.; Dmitriev, Alex S.; Makarov, Petr; Mikhailova, Inna

2018-04-01

In recent years, there has been a great interest in the development and creation of new functional energy mate-rials, including for improving the energy efficiency of power equipment and for effectively removing heat from energy devices, microelectronics and optoelectronics (power micro electronics, supercapacitors, cooling of processors, servers and data centers). In this paper, the technology of obtaining new nanocomposites based on mesoscopic microspheres, polymers and graphene flakes is considered. The methods of sequential production of functional materials from graphene flakes of different volumetric concentration using epoxy polymers, as well as the addition of monodisperse microspheres are described. Data are given on the measurement of the contact angle and thermal conductivity of these nanocomposites with respect to the creation of thermal interface materials for cooling devices of electronics, optoelectronics and power engineering.

Water in polymer membranes. 4. Raman scattering from cellulose acetate films

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

Scherer, J.R.; Bailey, G.F.; Kint, S.

Raman scattering was observed from thin film optical waveguides of cellulose acetate exposed to water vapor from 0% to 100% relative humidity (RH), and from dilute solutions of water in methyl acetate. Spectra of cellulose acetate (CA398, 39.8% acetyl) at low RH and cellulose triacetate (CTA) at low and high RH are consistent with the presence of water monomers that are weakly hydrogen bonded to acetyl C=O groups. Differences between the spectra of water in CA398 and CTA at low RH are attributed to sequential hydrogen bonding involving OH groups in CA398. At high RH, CA398 and CTA (to amore » lesser extent) show bands attributed to water/water interactions that are similar to those found in sequentially hydrogen-bonded hydrates. CA398 films that are annealed at high temperatures exhibit decreased water/water interactions at high RH. Exposure of CA398 films to D/sub 2/O converts > 90% of all polymer OH groups to OD groups. This indicates that water is accessible to nearly all regions of the polymer containing OH groups. Annealing does not alter this accessibility but does reduce the total water content by roughly half, at 100% RH. Hydrogen-bonded C=O groups are associated with a band centered at 1731 cm/sup -1/ which increases in intensity with increasing water content in the film but does not shift in frequency. 38 references, 16 figures, 1 table.« less

Synthesis of wheat straw cellulose-g-poly (potassium acrylate)/PVA semi-IPNs superabsorbent resin.

PubMed

Liu, Jia; Li, Qian; Su, Yuan; Yue, Qinyan; Gao, Baoyu; Wang, Rui

2013-04-15

To better use wheat straw and minimize its negative impact on environment, a novel semi-interpenetrating polymer networks (semi-IPNs) superabsorbent resin (SAR) composed of wheat straw cellulose-g-poly (potassium acrylate) (WSC-g-PKA) network and linear polyvinyl alcohol (PVA) was prepared by polymerization in the presence of a redox initiating system. The structure and morphology of semi-IPNs SAR were characterized by means of FTIR, SEM and TGA, which confirmed that WSC and PVA participated in the graft polymerization reaction with acrylic acid (AA). The factors that can influence the water absorption of the semi-IPNs SAR were investigated and optimized, including the weight ratios of AA to WSC and PVA to WSC, the content of initiator and crosslinker, neutralization degree (ND) of AA, reaction temperature and time. The semi-IPNs SAR prepared under optimized synthesis condition gave the best water absorption of 266.82 g/g in distilled water and 34.32 g/g in 0.9 wt% NaCl solution. Copyright © 2013 Elsevier Ltd. All rights reserved.

Chemical and Topographical Modification of Polycarbonate Surfaces through Diffusion/Photocuring Processes of Hydrogel Precursors Based on Vinylpyrrolidone.

PubMed

Gallardo, Alberto; Lujan, Noelia; Reinecke, Helmut; García, Carolina; Campo, Adolfo Del; Rodriguez-Hernandez, Juan

2017-02-21

Facile procedures capable of simultaneously conferring hydrophilicity and tailored topography to surfaces of hydrophobic supports, such as polycarbonate (PC), are very attractive but rare. In this work, we describe a simple methodology to wrinkle PC surfaces after a process of (a) contacting with a photopolymerizable vinylic solution, (b) UV curing of such solutions, and (c) detachment of the formed polymer network, upon swelling in ethanol. The influence of different parameters such as contact lag time between the PC surface and the polymerizable solution, the monomer concentration and type of solvents, as well as the cross-linking degree on the formation of wrinkles, has been studied. The dimensions of the wrinkles can be tailored to some extent by altering the different parameters. Surface chemistry has been analyzed by contact angle measurements and by confocal Raman microscopy. The results are consistent with a chemical alteration of the surface and the formation of an outer hydrogel layer, which is interpenetrated into the PC structure. A mechanism of monomer diffusion and PC swelling that produces surface instabilities and wrinkling is proposed.

Fabrication of chitosan/polyacrylonitrile blend and semi-IPN hydrogel with epichlorohydrin

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

Aijaz, Muhammad Omer; Haider, Sajjad, E-mail: shaider@ksu.edu.sa; Al Mubddel, Fahad S.

2015-05-22

The present study is focused on the preparation of chitosan (CS)/polyacrylonitrile (PAN) blend and semi-interpenetrating polymer network (sIPN). Blend CS/PAN hydrogel films (HFs) were prepared by solution blending and casting technique. CS in the blend was crosslinked with epichlorohydrin (ECH) to prepare sIPN. The developed CS/PAN blend and sIPN hydrogels were characterized with Field Emission Scanning Electron Microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), Thermagravimetric analysis (TGA), and Differential Scanning Calorimeter (DSC). The result showed good miscibility between CS and PAN and crosslinking of CS in the blend. The swelling of the different blended and sIPN hydrogels samples were examinedmore » at room temperature (T{sub r}). Blend (C80/P20) sample showed highest swelling (∼2400%) and fair degree of stability (∼28% until 96 h), whereas sIPN hydrogel exhibited relatively low degree of swelling (∼244%) and high degree of aqueous (∼85 % until 96 h), and thermal (onset temperature 304°C) stabilities.« less

Physical and chemical basics of modification of poly(vinyl chloride) by means of polyisocyanate

NASA Astrophysics Data System (ADS)

Islamov, Anvar; Fakhrutdinova, Venera; Abdrakhmanova, Lyailya

2016-01-01

This research presents data relating to polyvinyl chloride (PVC) modification by means of reactive oligomer and measures technological, physical and mechanical properties of the modified composites. Polyisocyanate (PIC) has been chosen as the modifying reactive oligomer. It has been shown that insertion of the oligomer has a double effect on PVC. Primarily, PIC produces a plasticizing effect on PVC and in particular leads to an increase in thermal stability and melt flow index at the stage of processing. In addition, the molded PVC composites possess higher strength properties and lower deformability when exposed to temperature because of chemical transformations of PIC in polymer matrix and, as the result, the formation of cross-linked systems takes place. In this case, semi-interpenetrating structures are formed based on cross-linked products of PIC chemical transformations homogeneously distributed in the PVC matrix. It has been determined by means of IR-spectroscopy that the basic products of PIC curing are compounds with urea and biuret groups which leads to modifying effect on PVC especially: increase in strength, thermal and mechanical properties, and chemical resistance.

Photopolymerizable chitosan-collagen hydrogels for bone tissue engineering.

PubMed

Arakawa, Christopher; Ng, Ronald; Tan, Steven; Kim, Soyon; Wu, Benjamin; Lee, Min

2017-01-01

Photopolymerizable hydrogels derived from naturally occurring polymers have attracted significant interest in tissue-engineering applications due to their excellent biocompatibility, hydrophilic nature favourable for cell ingrowth and ability to be cured in situ through a minimally invasive procedure. In this study, we developed a composite hydrogel consisting of photocrosslinkable methacrylated glycol chitosan (MeGC) and semi-interpenetrating collagen (Col) with a riboflavin photoinitiator under blue light. The incorporation of Col in MeGC hydrogels enhanced the compressive modulus and slowed the degradation rate of the hydrogels. MeGC-Col composite hydrogels significantly enhanced cellular attachment, spreading, proliferation and osteogenic differentiation of mouse bone marrow stromal cells (BMSCs) seeded on the hydrogels compared with pure MeGC hydrogels, as observed by upregulated alkaline phosphatase (ALP) activity as well as increased mineralization. Similarly, when cells were encapsulated within hydrogels, BMSCs exhibited greater proliferation, ALP activity and mineral deposits in the presence of Col. These findings demonstrate that MeGC-Col composite hydrogels may be useful in promoting bone regeneration. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2014 John Wiley & Sons, Ltd.

Rheological properties of concentrated, nonaqueous silicon nitride suspensions

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

Bergstroem, L.

1996-12-01

The rheological properties of nonaqueous silicon nitride powder suspensions have been investigated using steady shear and viscoelastic measurements. The polymeric dispersant, Hypermer KD-3, adsorbed strongly on the powder surfaces, and colloidally stable, fluid suspensions up to a volume fraction of {Phi} = 0.50 could be prepared. The concentrated suspensions all displayed a shear thinning behavior which could be modeled using the high shear form of the Cross equation. The viscoelastic response at high concentrations was dominated by particle interactions, probably due to interpenetration of the adsorbed polymer layers, and a thickness of the adsorbed Hypermer KD-3 layer, {Delta} {approx} 10more » nm, was estimated. The volume fraction dependences of the high shear viscosity of three different silicon nitride powders were compared and the differences, analyzed by using a modified Krieger-Dougherty model, were related to effective volume effects and the physical characteristics of the powders. The significantly lower maximum volume fraction, {Phi}{sub m} = 0.47, of the SN E-10 powder was referred to the narrow particle size distribution and the possibility of an unfavorable particle morphology.« less

A Study on the Rheological and Mechanical Properties of Photo-Curable Ceramic/Polymer Composites with Different Silane Coupling Agents for SLA 3D Printing Technology.

PubMed

Song, Se Yeon; Park, Min Soo; Lee, Jung Woo; Yun, Ji Sun

2018-02-07

Silane coupling agents (SCAs) with different organofunctional groups were coated on the surfaces of Al₂O₃ ceramic particles through hydrolysis and condensation reactions, and the SCA-coated Al₂O₃ ceramic particles were dispersed in a commercial photopolymer based on interpenetrating networks (IPNs). The organofunctional groups that have high radical reactivity and are more effective in UV curing systems are usually functional groups based on acryl, such as acryloxy groups, methacrloxy groups, and acrylamide groups, and these silane coupling agents seem to improve interfacial adhesion and dispersion stability. The coating morphology and the coating thickness distribution of SCA-coated Al₂O₃ ceramic particles according to the different organofunctional groups were observed by FE-TEM. The initial dispersibility and dispersion stability of the SCA-coated Al₂O₃/High-temp composite solutions were investigated by relaxation NMR and Turbiscan. The rheological properties of the composite solutions were investigated by viscoelastic analysis and the mechanical properties of 3D-printed objects were observed with a nanoindenter.

A Study on the Rheological and Mechanical Properties of Photo-Curable Ceramic/Polymer Composites with Different Silane Coupling Agents for SLA 3D Printing Technology

PubMed Central

Song, Se Yeon; Park, Min Soo; Lee, Jung Woo; Yun, Ji Sun

2018-01-01

Silane coupling agents (SCAs) with different organofunctional groups were coated on the surfaces of Al2O3 ceramic particles through hydrolysis and condensation reactions, and the SCA-coated Al2O3 ceramic particles were dispersed in a commercial photopolymer based on interpenetrating networks (IPNs). The organofunctional groups that have high radical reactivity and are more effective in UV curing systems are usually functional groups based on acryl, such as acryloxy groups, methacrloxy groups, and acrylamide groups, and these silane coupling agents seem to improve interfacial adhesion and dispersion stability. The coating morphology and the coating thickness distribution of SCA-coated Al2O3 ceramic particles according to the different organofunctional groups were observed by FE-TEM. The initial dispersibility and dispersion stability of the SCA-coated Al2O3/High-temp composite solutions were investigated by relaxation NMR and Turbiscan. The rheological properties of the composite solutions were investigated by viscoelastic analysis and the mechanical properties of 3D-printed objects were observed with a nanoindenter. PMID:29414912

Hybrid Assembly of Different-Sized Supertetrahedral Clusters into a Unique Non-Interpenetrated Mn-In-S Open Framework with Large Cavity.

PubMed

Wang, Hongxiang; Wang, Wei; Hu, Dandan; Luo, Min; Xue, Chaozhuang; Li, Dongsheng; Wu, Tao

2018-06-04

Reported here is a unique crystalline semiconductor open-framework material built from the large-sized supertetrahedral T4 and T5 clusters with the Mn-In-S compositions. The hybrid assembly between T4 and T5 clusters by sharing terminal μ 2 -S 2- is for the first time observed among the cluster-based chalcogenide open frameworks. Such three-dimensional structure displays non-interpenetrated diamond-type topology with extra-large nonframework volume of 82%. Moreover, ion exchange, CO 2 adsorption, as well as photoluminescence properties of the title compound are also investigated.

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

Gasser, U., E-mail: urs.gasser@psi.ch; Hyatt, J. S.; Lietor-Santos, J.-J.

We study the form factor of thermoresponsive microgels based on poly(N-isopropylacrylamide) at high generalized volume fractions, ζ, where the particles must shrink or interpenetrate to fit into the available space. Small-angle neutron scattering with contrast matching techniques is used to determine the particle form factor. We find that the particle size is constant up to a volume fraction roughly between random close packing and space filling. Beyond this point, the particle size decreases with increasing particle concentration; this decrease is found to occur with little interpenetration. Noteworthily, the suspensions remain liquid-like for ζ larger than 1, emphasizing the importance ofmore » particle softness in determining suspension behavior.« less

Structure and property relations of macromolecular self-assemblies at interfaces

NASA Astrophysics Data System (ADS)

Yang, Zhihao

Hydrophilic polymer chains, poly(ethylene glycol) (PEG), are attached to glass surfaces by silylation of the silanol groups on glass surfaces with the omega-(methoxyl terminated PEG) trimethoxysilanes. These tethered polymer chains resemble the self-assembled monolayers (SAMs) of PEG, which exhibit excellent biocompatibility and provide a model system for studying the interactions of proteins with polymer surfaces. The low molecular weight PEGs tend to extend, forming a brush-like monolayer, whereas the longer polymer chains tend to interpenetrate each other, forming a mushroom-like PEG monolayer at the interface. Interactions between a plasma protein, bovine serum albumin, and the PEG-SAMs are investigated in terms of protein adsorption and diffusion on the surfaces by the technique of fluorescence recovery after photobleaching (FRAP). The diffusion and aggregation behaviors of the protein on the two monolayers are found to be quite different despite the similarities in adsorption and desorption behaviors. The results are analyzed with a hypothesis of the hydrated surface dynamics. A method of covalently bonding phospholipid molecules to silica substrates followed by loading with free phospholipids is demonstrated to form well organized and stable phospholipid self-assembled monolayers. Surfaces of such SAMs structurally mimic the aqueous sides of phospholipid bilayer membranes. The dynamics of phospholipids and an adsorbed protein, lipase, in the SAMs are probed with FRAP, in terms of lateral diffusion of both phospholipids and protein molecules. The esterase activity of lipase on the SAM surfaces is confirmed by the hydrolysis reaction of a substrate, umbelliferone stearate, showing such lipid SAMs posess biomembrane functionality in terms of interfacial activation of the membranous enzymes. Dynamics of polyethylene oxide and polypropylene oxide tri-block copolymers, PEO-PPO-PEO and PPO-PEO-PPO, at the air/water interface upon thermal stimulation is studied by surface light scattering, in terms of the dynamic surface tension changes in response to a temperature jump. The characteristic of the surface tension relaxation is found to be highly related to the molecular structure and concentration of the copolymers at the interface.

High-density interconnect substrates and device packaging using conductive composites

NASA Astrophysics Data System (ADS)

Gandhi, Pradeep; Gallagher, Catherine; Matijasevic, Goran

1998-02-01

High-end printed circuit board manufacturing technology is receiving increasing attention due to higher functionality in smaller form factors. This is evident from the industry efforts to produced reliable microvias and related trace features to pack as much circuit density as possible. Cost, density and performance requirements have prodded entry into a market that was mainly reserved for ceramic and molded packages for the last forty years. To successfully meet the demanding specifications of this market segment, a worldwide effort is underway for the development of new materials, processes and equipment. A novel base technology that is applicable to most of the major packaging and redistribution elements in an electronic module is presented.High density multilayer circuits with landless blind and buried vias can be fabricated by filling the conductor paste into photoimaged dielectrics and thermally processing it at a relatively lower temperature. Via layers are prepared directly on the inherently planarized circuit layer in an identical fashion. Because these composite materials are applied in an additive fabrication method, metal substrates can be employed for high thermal dissipation and excellent CTE control over a wide temperature range. The conductor material is based on interpenetrating polymer and metal networks that are formed in situ from metal particles and a thermosetting flux/binder. The metal network is formed when the alloy particles melt and react with adjacent high melting point metal particle. Interaction also occurs between the alloy particles and pad, lead or previous trace metallizations provided they are solderable by alloys of tin. The new alloy composition created by the interdiffusion process within the bulk material has a higher melting point than the original alloy and thus solidifies immediately upon formation. This metallurgical reaction, known as transient liquid phase sintering, is facilitated by the polymer mixture. INtegration of the polymer and metal networks is maintained by utilizing a thermosetting polymer system that cures simultaneously with the metallurgical reaction. Although similar in concept and performance to cermet inks, these compositions differ in that their process temperatures are compatible with conventional printed wiring board materials and that the polymeric binder remains to provide adhesion and fatigue resistance to the metallurgical network.

Time scale of random sequential adsorption.

PubMed

Erban, Radek; Chapman, S Jonathan

2007-04-01

A simple multiscale approach to the diffusion-driven adsorption from a solution to a solid surface is presented. The model combines two important features of the adsorption process: (i) The kinetics of the chemical reaction between adsorbing molecules and the surface and (ii) geometrical constraints on the surface made by molecules which are already adsorbed. The process (i) is modeled in a diffusion-driven context, i.e., the conditional probability of adsorbing a molecule provided that the molecule hits the surface is related to the macroscopic surface reaction rate. The geometrical constraint (ii) is modeled using random sequential adsorption (RSA), which is the sequential addition of molecules at random positions on a surface; one attempt to attach a molecule is made per one RSA simulation time step. By coupling RSA with the diffusion of molecules in the solution above the surface the RSA simulation time step is related to the real physical time. The method is illustrated on a model of chemisorption of reactive polymers to a virus surface.

Removal of heavy metals from waste streams

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

Spence, M.D.; Kozaruk, J.M.; Melvin, M.

1988-07-19

A method for removing heavy metals from effluent water is described comprising performing sequentially the following steps: (a) adding from 7-333 ppm of an anionic surfactant to the effluent water to provide coagulatable heavy metal ion; (b) adjusting the effluent water pH to within the range of 8 to 10, (c) providing from 10-200 ppm of a cationic coagulant to coagulate the heavy metal ion, (d) providing from 0.3 to 5.0 ppm of a polymeric flocculant whereby a heavy metal containing floc is formed for removal from the effluent water, and, (e) then removing the floc from the effluent water,more » wherein the anionic surfactant is sodium lauryl ether sulfate. The cationic coagulant is selected from the group consisting of diallyl dimethylammonium chloride polymer, epichlorohydrin dimethylamine polymer, ethylene amine polymer, polyaluminum chloride, and alum; and the flocculant is an acrylamide/sodium acrylate copolymer having an RSV greater than 23.« less

Growing Embossed Nanostructures of Polymer Brushes on Wet-Etched Silicon Templated via Block Copolymers

PubMed Central

Lu, Xiaobin; Yan, Qin; Ma, Yinzhou; Guo, Xin; Xiao, Shou-Jun

2016-01-01

Block copolymer nanolithography has attracted enormous interest in chip technologies, such as integrated silicon chips and biochips, due to its large-scale and mass production of uniform patterns. We further modified this technology to grow embossed nanodots, nanorods, and nanofingerprints of polymer brushes on silicon from their corresponding wet-etched nanostructures covered with pendent SiHx (X = 1–3) species. Atomic force microscopy (AFM) was used to image the topomorphologies, and multiple transmission-reflection infrared spectroscopy (MTR-IR) was used to monitor the surface molecular films in each step for the sequential stepwise reactions. In addition, two layers of polymethacrylic acid (PMAA) brush nanodots were observed, which were attributed to the circumferential convergence growth and the diffusion-limited growth of the polymer brushes. The pH response of PMAA nanodots in the same region was investigated by AFM from pH 3.0 to 9.0. PMID:26841692

Growing Embossed Nanostructures of Polymer Brushes on Wet-Etched Silicon Templated via Block Copolymers

NASA Astrophysics Data System (ADS)

Lu, Xiaobin; Yan, Qin; Ma, Yinzhou; Guo, Xin; Xiao, Shou-Jun

2016-02-01

Block copolymer nanolithography has attracted enormous interest in chip technologies, such as integrated silicon chips and biochips, due to its large-scale and mass production of uniform patterns. We further modified this technology to grow embossed nanodots, nanorods, and nanofingerprints of polymer brushes on silicon from their corresponding wet-etched nanostructures covered with pendent SiHx (X = 1-3) species. Atomic force microscopy (AFM) was used to image the topomorphologies, and multiple transmission-reflection infrared spectroscopy (MTR-IR) was used to monitor the surface molecular films in each step for the sequential stepwise reactions. In addition, two layers of polymethacrylic acid (PMAA) brush nanodots were observed, which were attributed to the circumferential convergence growth and the diffusion-limited growth of the polymer brushes. The pH response of PMAA nanodots in the same region was investigated by AFM from pH 3.0 to 9.0.

Implementation of serial amplifying fluorescent polymer arrays for enhanced chemical vapor sensing of landmines

NASA Astrophysics Data System (ADS)

Fisher, Mark E.; la Grone, Marcus; Sikes, John

2003-09-01

A sensor (known as Fido) that utilizes amplification of fluorescence quenching as the transduction mechanism for ultra-trace detection of nitroaromatic compounds associated with landmines has been described previously. Previous sensor prototypes utilized a single band of amplifying polymer deployed inside a capillary waveguide to form the sensing element of the detector. A new prototype has been developed that incorporates multiple, discrete bands of different amplifying polymers deployed in a linear array inside the capillary. Vapor-phase samples are introduced into the sensor as a sharp pulse via a gated inlet. As the vapor pulse is swept through the capillary by flow of a carrier gas, the pulse of analyte encounters the bands of polymer sequentially. If the sample contains nitroaromatic explosives, the bands of polymer will respond with a reduction in emission intensity proportional to the mass of analyte in the sample. Because the polymer bands are deployed serially, the analyte pulse does not reach the bands of polymer simultaneously. Hence, a temporal response pattern will be observed as the analyte pulse traverses the length of the capillary. In addition, the intensity of response for each band will vary, producing a ratiometric response. The temporal and ratiometric responses are characteristic of a given analyte, enhancing discrimination of target analytes from potential interferents. This should translate into a reduction in sensor false alarm rates.

Dielectric Actuation of Polymers

NASA Astrophysics Data System (ADS)

Niu, Xiaofan

Dielectric polymers are widely used in a plurality of applications, such as electrical insulation, dielectric capacitors, and electromechanical actuators. Dielectric polymers with large strain deformations under an electric field are named dielectric elastomers (DE), because of their relative low modulus, high elongation at break, and outstanding resilience. Dielectric elastomer actuators (DEA) are superior to traditional transducers as a muscle-like technology: large strains, high energy densities, high coupling efficiency, quiet operation, and light weight. One focus of this dissertation is on the design of DE materials with high performance and easy processing. UV radiation curing of reactive species is studied as a generic synthesis methodology to provide a platform for material scientists to customize their own DE materials. Oligomers/monomers, crosslinkers, and other additives are mixed and cured at appropriate ratios to control the stress-strain response, suppress electromechanical instability of the resulting polymers, and provide stable actuation strains larger than 100% and energy densities higher than 1 J/g. The processing is largely simplified in the new material system by removal of the prestretching step. Multilayer stack actuators with 11% linear strain are demonstrated in a procedure fully compatible with industrial production. A multifunctional DE derivative material, bistable electroactive polymer (BSEP), is invented enabling repeatable rigid-to-rigid deformation without bulky external structures. Bistable actuation allows the polymer actuator to have two distinct states that can support external load without device failure. Plasticizers are used to lower the glass transition temperature to 45 °C. Interpenetrating polymer network structure is established inside the BSEP to suppress electromechanical instability, providing a breakdown field of 194 MV/m and a stable bistable strain as large as 228% with a 97% strain fixity. The application of BSEP in tactile display is investigated by the prototyping of a large scale refreshable Braille display device. Braille is a critical way for the vision impaired community to learn literacy and improve life quality. Current piezoelectrics-based refreshable Braille display technologies are limited to up to 1 line of Braille text, due to the bulky size of bimorph actuators. Based on the unique actuation feature of BSEP, refreshable Braille display devices up to smartphone-size have been demonstrated by polymer sheet laminates. Dots in the devices can be individually controlled via incorporated field-driven BSEP actuators and Joule heater units. A composite material consisting of silver nanowires (AgNW) embedded in a polymer substrate is brought up as a compliant electrode candidate for BSEP application. The AgNW composite is highly conductive (Rs: 10 Ω/sq) and remains conductive at strains as high as 140% (Rs: <10 3 Ω/sq). The baseline conductivity has only small changes up to 90% strain, which makes it low enough for both field driving and stretchable Joule heating. An out-of-plane bistable area strain up to 68% under Joule heating is achieved.

Substituted amylose matrices for oral drug delivery

NASA Astrophysics Data System (ADS)

Moghadam, S. H.; Wang, H. W.; Saddar El-Leithy, E.; Chebli, C.; Cartilier, L.

2007-03-01

High amylose corn starch was used to obtain substituted amylose (SA) polymers by chemically modifying hydroxyl groups by an etherification process using 1,2-epoxypropanol. Tablets for drug-controlled release were prepared by direct compression and their release properties assessed by an in vitro dissolution test (USP XXIII no 2). The polymer swelling was characterized by measuring gravimetrically the water uptake ability of polymer tablets. SA hydrophilic matrix tablets present sequentially a burst effect, typical of hydrophilic matrices, and a near constant release, typical of reservoir systems. After the burst effect, surface pores disappear progressively by molecular association of amylose chains; this allows the creation of a polymer layer acting as a diffusion barrier and explains the peculiar behaviour of SA polymers. Several formulation parameters such as compression force, drug loading, tablet weight and insoluble diluent concentration were investigated. On the other hand, tablet thickness, scanning electron microscope analysis and mercury intrusion porosimetry showed that the high crushing strength values observed for SA tablets were due to an unusual melting process occurring during tabletting although the tablet external layer went only through densification, deformation and partial melting. In contrast, HPMC tablets did not show any traces of a melting process.

Ancillary ligand-assisted assembly of C{sub 3}-symmetric 4,4′,4″-nitrilotribenzoic acid with divalent Zn{sup 2+} ions: Syntheses, topological structures, and photoluminescence properties

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

Cui, Li-Ting; Niu, Yan-Fei; Han, Jie, E-mail: chan@ouhk.edu.hk

4,4′,4″-nitrilotribenzoic acid (H{sub 3}L), a C{sub 3}-symmetric ligand, was found to self-assemble into two polymorphs driven by intermolecular hydrogen-bonding interactions. Reactions of this ligand with Zn{sup 2+} under solvothermal conditions resulted in four new coordination polymers bearing interesting structural motifs: [Zn{sub 2}(L){sub 2}(py){sub 2}]·2(H{sub 2}NMe{sub 2}){sup +}·DMF·2H{sub 2}O (1), [Zn{sub 2}(L)(H{sub 2}L)(bipy)]·1.5H{sub 2}O·Guest (2), [Zn{sub 2}(L){sub 2}(bipy)]·2(H{sub 2}NMe{sub 2}){sup +}·2DMF (3), and [Zn{sub 3}(L){sub 2}(bpa)]·2H{sub 2}O·Guest (4) (H{sub 3}L=4,4′,4′′-nitrilotribenzoic acid, DMF=dimethylformamide, py=pyridine, bipy=4,4′-bipyridine, bpa=1,2-bis(4-pyridyl)diazene). Single-crystal structural analysis revealed that compound 1 exhibits a rare example of twofold interpenetrating anionic 3D (3,3)-net framework containing helical channels, whereas in 2, the 3Dmore » pillar-layer structure generated from bipy-pillared Zn{sub 2}(L)(H{sub 2}L) layer is further reinforced by intermolecular hydrogen bonding among pairs of free –COOH units. Compound 3 shows an interesting entangled architecture of 2D→3D parallel polycatenation consisting five-coordinated Zn{sup 2+} ions. Compound 4 displays a 3D pillar-layer framework with trimeric Zn{sub 3}(CO{sub 2}){sub 6} serving as secondary building unit (SBU). The syntheses, structures, thermal stabilities, powder X-ray diffractions and solid-state photoluminescence properties for these crystalline materials have been carried out. In addition, supramolecular assembly of H{sub 3}L under solvothermal conditions will also be addressed. - Graphical abstract: Supramolecular assembly of 4,4′,4′′-nitrilotribenzoic acid and its ligand behavior toward Zn{sup 2+} were investigated, which exhibit two polymorphs of the free acid and four metal coordination polymers bearing interesting structural motifs. - Highlights: • Two polymorphs of H{sub 3}L showing different hydrogen-bonded network were obtained. • Tune over the structure of MOFs was achieved. • 1 has a 2-fold interpenetrating anionic 3D network containing helical channels. • Structures bearing free carboxylic acid (–COOH) unit are constructed in 2. • 3 represents a rare 2D+2D→3D catenation array containing five-coordinated Zn{sup 2+}.« less

Inorganic Polymer Matrix Composite Strength Related to Interface Condition

PubMed Central

Radford, Donald W.; Grabher, Andrew; Bridge, John

2009-01-01

Resin transfer molding of an inorganic polymer binder was successfully demonstrated in the preparation of ceramic fiber reinforced engine exhaust valves. Unfortunately, in the preliminary processing trials, the resulting composite valves were too brittle for in-engine evaluation. To address this limited toughness, the effectiveness of a modified fiber-matrix interface is investigated through the use of carbon as a model material fiber coating. After sequential heat treatments composites molded from uncoated and carbon-coated fibers are compared using room temperature 3-point bend testing. Carbon-coated Nextel fiber reinforced geopolymer composites demonstrated a 50% improvement in strength, versus that of the uncoated fiber reinforced composites, after the 250 °C postcure.

Hydroxylation of organic polymer surface: method and application.

PubMed

Yang, Peng; Yang, Wantai

2014-03-26

It may be hardly believable that inert C-H bonds on a polymeric material surface could be quickly and efficiently transformed into C-OH by a simple and mild way. Thanks to the approaches developed recently, it is now possible to transform surface H atoms of a polymeric substrate into monolayer OH groups by a simple/mild photochemical reaction. Herein the method and application of this small-molecular interfacial chemistry is highlighted. The existence of hydroxyl groups on material surfaces not only determines the physical and chemical properties of materials but also provides effective reaction sites for postsynthetic sequential modification to fulfill the requirements of various applications. However, organic synthetic materials based on petroleum, especially polyolefins comprise mainly C and H atoms and thus present serious surface problems due to low surface energy and inertness in reactivity. These limitations make it challenging to perform postsynthetic surface sequential chemical derivatization toward enhanced functionalities and properties and also cause serious interfacial problems when bonding or integrating polymer substrates with natural or inorganic materials. Polymer surface hydroxylation based on direct conversion of C-H bonds on polymer surfaces is thus of significant importance for academic and practical industrial applications. Although highly active research results have reported on small-molecular C-H bond activation in solution (thus homogeneous), most of them, featuring the use of a variety of transition metals as catalysts, present a slow reaction rate, a low atom economy and an obvious environmental pollution. In sharp contrast to these conventional C-H activation strategies, the present Spotlight describes a universal confined photocatalytic oxidation (CPO) system that is able to directly convert polymer surface C-H bonds to C-OSO3(-) and, subsequently, to C-OH through a simple hydrolysis. Generally speaking, these newly implanted hydroxyl groups preserve their own reactivity toward other complementary compounds, thus creating a novel base with distinct surface properties. Thanks to this functionalized platform, a wide range of organic, inorganic and metal materials have been attached to conventional organic polymer substrates through the rational engineering of surface molecular templates from small functional groups to macromolecules. It is expected that the proposed novel CPO method and its versatile usages in advanced material applications will offer new opportunities for a variety of scientific communities, especially for those working on surface/interface modulation.

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.

Quantifying the mechanical and histological properties of thrombus analog made from human blood for the creation of synthetic thrombus for thrombectomy device testing.

PubMed

Merritt, William; Holter, Anne Marie; Beahm, Sharna; Gonzalez, Connor; Becker, Timothy A; Tabor, Aaron; Ducruet, Andrew F; Bonsmann, Laura S; Cotter, Trevor R; Frenklakh, Sergey

2018-04-25

Untreated ischemic stroke can lead to severe morbidity and death, and as such, there are numerous endovascular blood-clot removal (thrombectomy) devices approved for human use. Human thrombi types are highly variable and are typically classified in qualitative terms - 'soft/red,' 'hard/white,' or 'aged/calcified.' Quantifying human thrombus properties can accelerate the development of thrombus analogs for the study of thrombectomy outcomes, which are often inconsistent among treated patients. 'Soft'human thrombi were created from blood samples ex vivo (ie, human blood clotted in sample vials) and tested for mechanical properties using a hybrid rheometer material testing system. Synthetic thrombus materials were also mechanically tested and compared with the 'soft' human blood clots. Mechanical testing quantified the shear modulus and dynamic (elastic) modulus of volunteer human thrombus samples. This data was used to formulate a synthetic blood clot made from a composite polymer hydrogel of polyacrylamide and alginate (PAAM-Alg). The PAAM-Alg interpenetrating network of covalently and ionically cross-linked polymers had tunable elastic and shear moduli properties and shape memory characteristics. Due to its adjustable properties, PAAM-Alg can be modified to mimic various thrombi classifications. Future studies will include obtaining and quantitatively classifying patient thrombectomy samples and altering the PAAM-Alg to mimic the results for use with in vitro thrombectomy studies. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Sequestration of dyes from artificially prepared textile effluent using RSM-CCD optimized hybrid backbone based adsorbent-kinetic and equilibrium studies.

PubMed

Sukriti; Sharma, Jitender; Chadha, Amritpal Singh; Pruthi, Vaishali; Anand, Prerna; Bhatia, Jaspreet; Kaith, B S

2017-04-01

Present work reports the synthesis of semi-Interpenetrating Network Polymer (semi-IPN) using Gelatin-Gum xanthan hybrid backbone and polyvinyl alcohol in presence of l-tartaric acid and ammonium persulphate as the crosslinker-initiator system. Reaction parameters were optimized with Response Surface Methodology (RSM) in order to maximize the percent gel fraction of the synthesized sample. Polyvinyl alcohol, l-Tartaric acid, ammonium persulphate, reaction temperature, time and pH of the reaction medium were found to make an impact on the percentage gel fraction obtained. Incorporation of polyvinyl alcohol chains onto hybrid backbone and crosslinking between the different polymer chains were confirmed through techniques like FTIR, SEM-EDX and XRD. Semi-IPN was found to be very efficient in the removal of cationic dyes rhodamine-B (70%) and auramine-O (63%) from a mixture with an adsorbent dose of 700 mg, initial concentration of rhodamine-B 6 mgL -1 and auramine-O 26 mgL -1 , at an time interval of 22-25 h and 30 °C temp. Further to determine the nature of adsorption Langmuir and Freundlich adsorption isotherm models were studied and it was found that Langmuir adsorption isotherm was the best fit model for the removal of mixture of dyes. Kinetic studies for the sorption of dyes favored the reaction mechanism to occur via a pseudo second order pathway with R 2 value about 0.99. Copyright © 2017 Elsevier Ltd. All rights reserved.

Subcritical crack growth along polymer interfaces

NASA Astrophysics Data System (ADS)

Gurumurthy, Charavana Kumara

2000-10-01

The adhesion characteristics have been investigated for a polyimide (PI)/model epoxy (ME) interface that is important for microelectronic applications. The fracture toughness (G*c) of this interface has been measured using an asymmetric double cantilever beam (ADCB) technique. The G*c is low, 10-25 J/m 2, and is sensitive to the mechanical phase angle psi. A modified ADCB setup has been used to measure the subcritical crack growth velocity v due to the stress-assisted water attack (SAWA) at various relative humidities (RH) and temperatures (T) as a function of its driving force (the strain energy release rate) G*. The threshold G* decreases remarkably. Above the threshold log v rises linearly with √ G* (a hydrolysis controlled regime) but then enters a regime where the crack velocity is almost independent of √G*, i.e., v = v* (a transport controlled regime). A model for SAWA has been developed based on thermally-activated kinetics for hydrolysis of the ester covalent bonds that bridge from one side to the other of the interface. A new technique has been developed for the determination of the fatigue crack growth under thermal (T) and hydro-thermal (HT) conditions as a function of the range in the strain energy release rate (DeltaG). Under T-fatigue, the fatigue crack growth per unit temperature cycle (da/dN) increases as a power of DeltaG, i.e., a Paris law relationship holds. The HT da/dN measured is higher than da/dN under T-fatigue conditions and has been successfully modeled as a summation of two components: (a) the da/dN due to T-fatigue and (b) the da/dN due to the SAWA along the interface for a given T-cycle. A surface modification procedure that converts a thin interpenetrated by a solvent cast ME is used to strengthen ME/PI interface. The G* c increases with the interpenetration distance w. Increasing w also improves the resistance of the PI/ME interface to SAWA with the threshold G* increasing and the water transport controlled velocity (v*) decreasing.

Vertically Oriented and Interpenetrating CuSe Nanosheet Films with Open Channels for Flexible All-Solid-State Supercapacitors

DOE PAGES

Li, Lingzhi; Gong, Jiangfeng; Liu, Chunyan; ...

2017-03-22

As a p-type multifunctional semiconductor, CuSe nanostructures show great promise in optoelectronic, sensing, and photocatalytic fields. Although great progress has been achieved, controllable synthesis of CuSe nanosheets (NSs) with a desirable spacial orientation and open frameworks remains a challenge, and their use in supercapacitors (SCs) has not been explored. Herein, a highly vertically oriented and interpenetrating CuSe NS film with open channels is deposited on an Au-coated polyethylene terephthalate substrate. Such CuSe NS films exhibit high specific capacitance (209 F g–1) and can be used as a carbon black- and binder-free electrode to construct flexible, symmetric all-solid-state SCs, using polyvinylmore » alcohol–LiCl gel as the solid electrolyte. A device fabricated with such CuSe NS films exhibits high volumetric specific capacitance (30.17 mF cm–3), good cycling stability, excellent flexibility, and desirable mechanical stability. The excellent performance of such devices results from the vertically oriented and interpenetrating configuration of CuSe NS building blocks, which can increase the available surface and facilitate the diffusion of electrolyte ions. Moreover, as a prototype for application, three such solid devices in series can be used to light up a red light-emitting diode.« less

Vertically Oriented and Interpenetrating CuSe Nanosheet Films with Open Channels for Flexible All-Solid-State Supercapacitors

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

Li, Lingzhi; Gong, Jiangfeng; Liu, Chunyan

As a p-type multifunctional semiconductor, CuSe nanostructures show great promise in optoelectronic, sensing, and photocatalytic fields. Although great progress has been achieved, controllable synthesis of CuSe nanosheets (NSs) with a desirable spacial orientation and open frameworks remains a challenge, and their use in supercapacitors (SCs) has not been explored. Herein, a highly vertically oriented and interpenetrating CuSe NS film with open channels is deposited on an Au-coated polyethylene terephthalate substrate. Such CuSe NS films exhibit high specific capacitance (209 F g–1) and can be used as a carbon black- and binder-free electrode to construct flexible, symmetric all-solid-state SCs, using polyvinylmore » alcohol–LiCl gel as the solid electrolyte. A device fabricated with such CuSe NS films exhibits high volumetric specific capacitance (30.17 mF cm–3), good cycling stability, excellent flexibility, and desirable mechanical stability. The excellent performance of such devices results from the vertically oriented and interpenetrating configuration of CuSe NS building blocks, which can increase the available surface and facilitate the diffusion of electrolyte ions. Moreover, as a prototype for application, three such solid devices in series can be used to light up a red light-emitting diode.« less

Interpenetration and deflection phenomena in collisions between supersonic, magnetized, tungsten plasma flows diagnosed using high resolution optical Thomson scattering

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

Swadling, G. F.; Lebedev, S. V.; Burdiak, G.

An optical Thomson scattering diagnostic has been used to investigate collisions between supersonic, magnetized plasma flows, in particular the transition from collisionless to collisional interaction dynamics. These flows were produced using tungsten wire array z-pinches, driven by the 1.4 MA 240 ns Magpie generator at Imperial College London. Measurements of the collective-mode Thomson scattering ion-feature clearly indicate that the ablation flows are interpenetrating at 100 ns (after current start), and this interpenetration continues until at least 140 ns. The Thomson spectrum at 150 ns shows a clear change in the dynamics of the stream interactions, transitioning towards a collisional, shock-like interaction of the streamsmore » near the axis. The Thomson scattering data also provide indirect evidence of the presence of a significant toroidal magnetic field embedded in the “precursor” plasma near the axis of the array over the period 100–140 ns; these observations are in agreement with previous measurements [Swadling et al., Phys. Rev. Lett. 113, 035003 (2014)]. The Thomson scattering measurements at 150 ns suggest that this magnetic field must collapse at around the time the dense precursor column begins to form.« less

Fabrication Processes to Generate Concentration Gradients in Polymer Solar Cell Active Layers

PubMed Central

Inaba, Shusei; Vohra, Varun

2017-01-01

Polymer solar cells (PSCs) are considered as one of the most promising low-cost alternatives for renewable energy production with devices now reaching power conversion efficiencies (PCEs) above the milestone value of 10%. These enhanced performances were achieved by developing new electron-donor (ED) and electron-acceptor (EA) materials as well as finding the adequate morphologies in either bulk heterojunction or sequentially deposited active layers. In particular, producing adequate vertical concentration gradients with higher concentrations of ED and EA close to the anode and cathode, respectively, results in an improved charge collection and consequently higher photovoltaic parameters such as the fill factor. In this review, we relate processes to generate active layers with ED–EA vertical concentration gradients. After summarizing the formation of such concentration gradients in single layer active layers through processes such as annealing or additives, we will verify that sequential deposition of multilayered active layers can be an efficient approach to remarkably increase the fill factor and PCE of PSCs. In fact, applying this challenging approach to fabricate inverted architecture PSCs has the potential to generate low-cost, high efficiency and stable devices, which may revolutionize worldwide energy demand and/or help develop next generation devices such as semi-transparent photovoltaic windows. PMID:28772878

Fabrication Processes to Generate Concentration Gradients in Polymer Solar Cell Active Layers.

PubMed

Inaba, Shusei; Vohra, Varun

2017-05-09

Polymer solar cells (PSCs) are considered as one of the most promising low-cost alternatives for renewable energy production with devices now reaching power conversion efficiencies (PCEs) above the milestone value of 10%. These enhanced performances were achieved by developing new electron-donor (ED) and electron-acceptor (EA) materials as well as finding the adequate morphologies in either bulk heterojunction or sequentially deposited active layers. In particular, producing adequate vertical concentration gradients with higher concentrations of ED and EA close to the anode and cathode, respectively, results in an improved charge collection and consequently higher photovoltaic parameters such as the fill factor. In this review, we relate processes to generate active layers with ED-EA vertical concentration gradients. After summarizing the formation of such concentration gradients in single layer active layers through processes such as annealing or additives, we will verify that sequential deposition of multilayered active layers can be an efficient approach to remarkably increase the fill factor and PCE of PSCs. In fact, applying this challenging approach to fabricate inverted architecture PSCs has the potential to generate low-cost, high efficiency and stable devices, which may revolutionize worldwide energy demand and/or help develop next generation devices such as semi-transparent photovoltaic windows.

Simple triple-state polymer actuators with controllable folding characteristics

NASA Astrophysics Data System (ADS)

Chen, Shuyang; Li, Jing; Fang, Lichen; Zhu, Zeyu; Kang, Sung Hoon

2017-03-01

Driven by the interests in self-folding, there have been studies developing artificial self-folding structures at different length scales based on various polymer actuators that can realize dual-state actuation. However, their unidirectional nature limits the applicability of the actuators for a wide range of multi-state self-folding behaviors. In addition, complex fabrication and programming procedures hinder broad applications of existing polymer actuators. Moreover, few of the existing polymer actuators are able to show the self-folding behaviors with the precise control of curvature and force. To address these issues, we report an easy-to-fabricate triple-state actuator with controllable folding behaviors based on bilayer polymer composites with different glass transition temperatures. Initially, the fabricated actuator is in the flat state, and it can sequentially self-fold to angled folding states of opposite directions as it is heated up. Based on an analytical model and measured partial recovery behaviors of polymers, we can accurately control the folding characteristics (curvature and force) for the rational design. To demonstrate an application of our triple-state actuator, we have developed a self-folding transformer robot which self-folds from a two-dimensional sheet into a three-dimensional boat-like configuration and transforms from the boat shape to a car shape with the increase in the temperature applied to the actuator. Our findings offer a simple approach to generate multiple configurations from a single system by harnessing behaviors of polymers with the rational design.

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.

Gas Separation Using Organic-Vapor-Resistent Membranes In Conjunctin With Organic-Vapor-Selective Membranes

DOEpatents

Baker, Richard W.; Pinnau, Ingo; He, Zhenjie; Da Costa, Andre R.; Daniels, Ramin; Amo, Karl D.; Wijmans, Johannes G.

2003-06-03

A process for treating a gas mixture containing at least an organic compound gas or vapor and a second gas, such as natural gas, refinery off-gas or air. The process uses two sequential membrane separation steps, one using membrane selective for the organic compound over the second gas, the other selective for the second gas over the organic vapor. The second-gas-selective membranes use a selective layer made from a polymer having repeating units of a fluorinated polymer, and demonstrate good resistance to plasticization by the organic components in the gas mixture under treatment, and good recovery after exposure to liquid aromatic hydrocarbons. The membrane steps can be combined in either order.

One-Pot Automated Synthesis of Quasi Triblock Copolymers for Self-Healing Physically Crosslinked Hydrogels.

PubMed

Voorhaar, Lenny; De Meyer, Bernhard; Du Prez, Filip; Hoogenboom, Richard

2016-10-01

The preparation of physically crosslinked hydrogels from quasi ABA-triblock copolymers with a water-soluble middle block and hydrophobic end groups is reported. The hydrophilic monomer N-acryloylmorpholine is copolymerized with hydrophobic isobornyl acrylate via a one-pot sequential monomer addition through reversible addition fragmentation chain-transfer (RAFT) polymerization in an automated parallel synthesizer, allowing systematic variation of polymer chain length and hydrophobic-hydrophilic ratio. Hydrophobic interactions between the outer blocks cause them to phase-separate into larger hydrophobic domains in water, forming physical crosslinks between the polymers. The resulting hydrogels are studied using rheology and their self-healing ability after large strain damage is shown. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ordered nanoscale domains by infiltration of block copolymers

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

Darling, Seth B.; Elam, Jeffrey; Tseng, Yu-Chih

A method of preparing tunable inorganic patterned nanofeatures by infiltration of a block copolymer scaffold having a plurality of self-assembled periodic polymer microdomains. The method may be used sequential infiltration synthesis (SIS), related to atomic layer deposition (ALD). The method includes selecting a metal precursor that is configured to selectively react with the copolymer unit defining the microdomain but is substantially non-reactive with another polymer unit of the copolymer. A tunable inorganic features is selectively formed on the microdomain to form a hybrid organic/inorganic composite material of the metal precursor and a co-reactant. The organic component may be optionally removedmore » to obtain an inorganic features with patterned nanostructures defined by the configuration of the microdomain.« less

Applications of functional polymer brushes for nanoparticle uptake and prevention of protein adsorption

NASA Astrophysics Data System (ADS)

Arifuzzaman, Shafi M.

The central theme of this Ph.D. dissertation is to develop novel multifunctional polymer coatings for understanding partition of proteins and nanoparticles on polymers grafted to flat surfaces (so-called brushes). Systematic investigation of the adsorption phenomena is accomplished by utilizing surface-anchored assemblies comprising grafted polymers with variation in physical properties (i.e., length or/and grafting density) and chemical functionality. The chemical composition of the brush is tailored by either "chemical coloring" of a parent homopolymer brush with selective chemical moieties or by sequential growth of two chemically dissimilar polymer blocks. We present preparation of two types of tailor-made, surface-grafted copolymers: (1) those composed of hydrophilic and hydrophobic blocks (so-called amphiphilic polymer brushes), and (2) those comprising of anionic and cationic polymer segments (so-called polyampholyte brushes). We describe the organization of functionality in the grafted polymer brushes and the partitioning of proteins and nanoparticles using a battery of complementary analytical probes. Specifically, we address how varying the molecular weight, grafting density, and chemical composition of the brush affects adsorbtion and desorbtion of model proteins and gold nanoparticles. Our observations indicate densely-populated responsive amphiphilic polymers are very efficient in suppressing protein adsorption. In addition, we have established that the length of poly(ethylene glycol) spacers attached to a parent homopolymer brush is a key factor governing uptake of gold nanoparticles. Both grafting density and molecular weight of the coating are important in controlling the kinetics and thermodynamics of protein adsorption on surfaces. Our findings and methodologies can lead to the development of next generation environmentally friendly antifouling surfaces and will find application in medical devices, antifouling coatings and anti reflection finishes.

Structure and properties of semi-interpenetrating network hydrogel based on starch.

PubMed

Zhu, Baodong; Ma, Dongzhuo; Wang, Jian; Zhang, Shuang

2015-11-20

Starch-g-P(acrylic acid-co-acrylamide)/PVA semi-interpenetrating network (semi-IPN) hydrogels were prepared by aqueous solution polymerization method. Starch grafting copolymerization reaction, semi-IPN structure and crystal morphology were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The PVA in the form of partial crystallization distributing in the gel matrix uniformly were observed by Field emission scanning electron microscope (FESEM). The space network structure, finer microstructure and pore size in the interior of hydrogel were presented by biomicroscope. The results demonstrated that absorption ratio of water and salt generated different degree changes with the effect of PVA. In addition, the mechanical strength of hydrogel was improved. Copyright © 2015 Elsevier Ltd. All rights reserved.

Multiplexed electrokinetic sample fractionation, preconcentration and elution for proteomics.

PubMed

Hua, Yujuan; Jemere, Abebaw B; Dragoljic, Jelena; Harrison, D Jed

2013-07-07

Both 6 and 8-channel integrated microfluidic sample pretreatment devices capable of performing "in space" sample fractionation, collection, preconcentration and elution of captured analytes via sheath flow assisted electrokinetic pumping are described. Coatings and monolithic polymer beds were developed for the glass devices to provide cationic surface charge and anodal electroosmotic flow for delivery to an electrospray emitter tip. A mixed cationic ([2-(methacryloyloxy)ethyl] trimethylammonium chloride) (META) and hydrophobic butyl methacrylate-based monolithic porous polymer, photopolymerized in the 6- or 8-fractionation channels, was used to capture and preconcentrate samples. A 0.45 wt% META loaded bed generated comparable anodic electroosmotic flow to the cationic polymer PolyE-323 coated channel segments in the device. The balanced electroosmotic flow allowed stable electrokinetic sheath flow to prevent cross contamination of separated protein fractions, while reducing protein/peptide adsorption on the channel walls. Sequential elution of analytes trapped in the SPE beds revealed that the monolithic columns could be efficiently used to provide sheath flow during elution of analytes, as demonstrated for neutral carboxy SNARF (residual signal, 0.08% RSD, n = 40) and charged fluorescein (residual signal, 2.5% n = 40). Elution from monolithic columns showed reproducible performance with peak area reproducibility of ~8% (n = 6 columns) in a single sequential elution and the run-to-run reproducibility was 2.4-6.7% RSD (n = 4) for elution from the same bed. The demonstrated ability of this device design and operation to elute from multiple fractionation beds into a single exit channel for sample analysis by fluorescence or electrospray mass spectrometry is a crucial component of an integrated fractionation and assay system for proteomics.

Kinetics for the Sequential Infiltration Synthesis of Alumina in Poly(methyl methacrylate): An Infrared Spectroscopic Study

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

Biswas, Mahua; Libera, Joseph A.; Darling, Seth B.

Sequential infiltration synthesis (SIS) is a method for growing inorganic materials within polymers in an atomically controlled fashion. This technique can increase the etch resistance of optical, electron-beam, and block copolymer (BCP) lithography resists and is also a flexible strategy for nanomaterials synthesis. Despite this broad utility, the kinetics of SIS remain poorly understood, and this knowledge gap must be bridged in order to gain firm control over the growth of inorganic materials inside polymer films at a large scale. In this paper, we explore the reaction kinetics for Al 2O 3 SIS in PMMA using in situ Fourier transformmore » infrared spectroscopy. First, we establish the kinetics for saturation adsorption and desorption of trimethyl aluminum (TMA) in PMMA over a range of PMMA film thicknesses deposited on silicon substrates. These observations guide the selection of TMA dose and purge times during SIS lithography to achieve robust organic/inorganic structures. Next, we examine the effects of TMA desorption on BCP lithography by performing SIS on silicon surfaces coated with polystyrene-block-poly(methyl methacrylate) films. After etching the organic components, the substrates are examined using scanning electron microcopy to evaluate the resulting Al 2O 3 patterns. Finally, we examine the effects of temperature on Al 2O 3 SIS in PMMA to elucidate the infiltration kinetics. The insights provided by these measurements will help extend SIS lithography to larger substrate sizes for eventual commercialization and expand our knowledge of precursor-polymer interactions that will benefit the SIS of a wide range of inorganic materials in the future.« less

7Li NMR spectroscopy and ion conduction mechanism in mesoporous silica (SBA-15) composite poly(ethylene oxide) electrolyte

NASA Astrophysics Data System (ADS)

Reddy, M. Jaipal; Chu, Peter P.

A composite of mesoporous silica (SBA-15) with a polyethylene oxide (PEO) polymer electrolyte is examined for use in various electrochemical devices. Incorporation of SBA-15 in a PEO:LiClO 4 polymer electrolyte facilitates salt dissociation, enhances ion conductivity, and improves miscibility between organic and inorganic moieties. Optimized conductivity is found at 10 wt.% SBA-15 composition, above this concentration the conductivity is reduced due to aggregation of a SBA-15:Li rich phase. Heating above melt temperature of PEO allows more of the polymer segments to interact with SBA-15. This results in a greater degree of disorder upon cooling, and the ion conductivity is enhanced. A 7Li MAS NMR study reveals three types of lithium-ion coordination. Two major types of conduction mechanism can be identified: one through conventional amorphous PEO; a second via hopping in a sequential manner by replacing the nearby vacancies ('holes') on the surface (both interior and exterior) of the SBA-15 channels.

Identification of trace additives in polymer materials by attenuated total reflection Fourier transform infrared mapping coupled with multivariate curve resolution

NASA Astrophysics Data System (ADS)

Li, Qian; Tang, Yongjiao; Yan, Zhiwei; Zhang, Pudun

2017-06-01

Although multivariate curve resolution (MCR) has been applied to the analysis of Fourier transform infrared (FTIR) imaging, it is still problematic to determine the number of components. The reported methods at present tend to cause the components of low concentration missed. In this paper a new idea was proposed to resolve this problem. First, MCR calculation was repeated by increasing the number of components sequentially, then each retrieved pure spectrum of as-resulted MCR component was directly compared with a real-world pixel spectrum of the local high concentration in the corresponding MCR map. One component was affirmed only if the characteristic bands of the MCR component had been included in its pixel spectrum. This idea was applied to attenuated total reflection (ATR)/FTIR mapping for identifying the trace additives in blind polymer materials and satisfactory results were acquired. The successful demonstration of this novel approach opens up new possibilities for analyzing additives in polymer materials.

Fabrication and electro-optic characteristics of polymer-stabilized V-mode FLCD and intrinsic H-V-mode FLCD: their application to AM LCDs

NASA Astrophysics Data System (ADS)

Kobayashi, Shunsuke; Furuta, Hirokazu; Murakami, Yuji; Xu, Jun; Mochizuki, Akihiro

2003-04-01

Defect free polymer-stabilized (PS-)V-mode FLCDs and intrinsic half (H-)V-mode FLCDs have been fabricated; they exhibit high contrast ratio over 700:1 and high reliability for a temperature cycling test by using specially developed polyimide alignment materials, RN-1411 series, from Nissan Chem. Ind., and also by adopting special alignment technique such as appropriate rubbing technique, photoalignment, and ion beam irradiation techniques and also particularly developed polymer-stabilization technique. These FLCDs are shown to be useful for implementing a field sequential type full color (FS-FC) LCDs due to their fast response with the response time of τ = 100μs ~ 500μs that is 10 to 100 times faster that those of LCDs using NLCs. We have developed several prototype models of FS-FC LCDs having VGA specifications that exhibit good performance for displaying fast moving video rate images with wide color gamut.

Photoinduced Dynamics of Charge Separation: From Photosynthesis to Polymer–Fullerene Bulk Heterojunctions

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

Niklas, Jens; Beaupré, Serge; Leclerc, Mario

2015-06-18

Understanding charge separation and charge transport is crucial for improving the efficiency of organic solar cells. Their active media are based on organic molecules and polymers, serving as both light-absorbing and transport layers. The charge-transfer (CT) states play an important role, being intermediate for free carrier generation and charge recombination. Here, we use light-induced electron paramagnetic resonance spectroscopy to study the CT dynamics in blends of the polymers P3HT, PCDTBT, and PTB7 with the fullerene derivative C-60-PCBM. Time-resolved EPR measurements show strong spin-polarization patterns for all polymer-fullerene blends, confirming predominant generation of singlet CT states and partial orientation ordering nearmore » the donor-acceptor interface. These observations allow a comparison with charge separation processes in molecular donor-acceptor systems and in natural and artificial photosynthetic assemblies, and thus the elucidation of the initial steps of sequential CT in organic photovoltaic materials.« less

Tunable photonic multilayer sensors from photo-crosslinkable polymers

NASA Astrophysics Data System (ADS)

Chiappelli, Maria; Hayward, Ryan

2014-03-01

The fabrication of tunable photonic multilayer sensors from stimuli-responsive, photo-crosslinkable polymers will be described. Benzophenone is covalently incorporated as a pendent photo-crosslinker, allowing for facile preparation of multilayer films by sequential spin-coating and crosslinking processes. Copolymer chemistries and layer thicknesses are selected to provide robust multilayer sensors which can show color changes across nearly the full visible spectrum due to the specific stimulus-responsive nature of the hydrated film stack. We will describe how this approach is extended to alternative sensor designs by tailoring the thickness and chemistry of each layer independently, allowing for the preparation of sensors which depend not only on the shift in wavelength of a reflectance peak, but also on the transition between Bragg mirrors and filters. Device design is optimized by photo-patterning sensor arrays on a single substrate, providing more efficient fabrication time as well as multi-functional sensors. Finally, radiation-sensitive multilayers, designed by choosing polymers which will preferentially degrade or crosslink under ionizing radiation, will also be described.

Infrared laser dissociation of single megadalton polymer ions in a gated electrostatic ion trap: the added value of statistical analysis of individual events.

PubMed

Halim, Mohammad A; Clavier, Christian; Dagany, Xavier; Kerleroux, Michel; Dugourd, Philippe; Dunbar, Robert C; Antoine, Rodolphe

2018-05-07

In this study, we report the unimolecular dissociation mechanism of megadalton SO 3 -containing poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) polymer cations and anions with the aid of infrared multiphoton dissociation coupled to charge detection ion trap mass spectrometry. A gated electrostatic ion trap ("Benner trap") is used to store and detect single gaseous polymer ions generated by positive and negative polarity in an electrospray ionization source. The trapped ions are then fragmented due to the sequential absorption of multiple infrared photons produced from a continuous-wave CO 2 laser. Several fragmentation pathways having distinct signatures are observed. Highly charged parent ions characteristically adopt a distinctive "stair-case" pattern (assigned to the "fission" process) whereas low charge species take on a "funnel like" shape (assigned to the "evaporation" process). Also, the log-log plot of the dissociation rate constants as a function of laser intensity between PAMPS positive and negative ions is significantly different.

Effect of glass fiber surface treatments on mechanical strength of epoxy based composite materials.

PubMed

Iglesias, J G; González-Benito, J; Aznar, A J; Bravo, J; Baselga, J

2002-06-01

Sizing glass fibers with silane coupling agents enhances the adhesion and the durability of the fiber/polymer matrix interface in composite materials. There are several tests to determine the interfacial strength between a fiber and resin, but all of them present difficulties in interpreting the results and/or sample preparation. In this study, we observed the influence of different aminosilanes fiber coatings on the resistance of epoxy-based composite materials using a very easy fractographic test. In addition, we tried a new fluorescence method to get information on a molecular level precisely at the interface. Strength was taken into account from two standpoints: (i) mechanical strength and (ii) the resistance to hydrolysis of the interface in oriented glass-reinforced epoxy-based composites. Three silanes: gamma-aminopropyltriethoxysilane, gamma-Aminopropylmethyldiethoxysilane, and gamma-Aminopropyldimethylethoxysilane were used to obtain different molecular structures at the interface. It was concluded that: (i) the more accessible amine groups are, the higher the interface rigidity is; (ii) an interpenetrating network mechanism seems to be the most important for adhesion and therefore to the interfacial strength; and (iii) the higher the degree of crosslinking in the silane coupling layer is, the higher the hydrolytic damage rate is.

Preparation of wheat straw based superabsorbent resins and their applications as adsorbents for ammonium and phosphate removal.

PubMed

Liu, Jia; Su, Yuan; Li, Qian; Yue, Qinyan; Gao, Baoyu

2013-09-01

A novel wheat straw cellulose-g-poly (potassium acrylate)/polyvinyl alcohol (WSC-g-PKA/PVA) semi-interpenetrating polymer networks (semi-IPNs) superabsorbent resin (SAR) was prepared by graft copolymerization. The structure and performance of the WSC-g-PKA/PVA semi-IPNs SAR was studied and compared with those of wheat straw cellulose-g-poly (potassium acrylate) (WSC-g-PKA) SAR. The effects of various experimental parameters such as solution pH, concentration, contact time and ion strength on NH4(+) and PO4(3-) removal from solutions were investigated. Equilibrium isotherm data of adsorption of both NH4(+) and PO4(3-) were well fitted to the Freundlich model. Kinetic analysis showed that the pseudo-second-order kinetic model was more suitable for describing the whole adsorption process of NH4(+) and PO4(3-) on SARs. Overall, WSC-g-PKA/PVA semi-IPNs SAR showed better properties in comparison with WSC-g-PKA SAR and it could be considered as one efficient material for the removal and recovery of nitrogen and phosphorus with the agronomic reuse as a fertilizer. Copyright © 2013 Elsevier Ltd. All rights reserved.

Angle selective backscattered electron contrast in the low-voltage scanning electron microscope: Simulation and experiment for polymers.

PubMed

Wan, Q; Masters, R C; Lidzey, D; Abrams, K J; Dapor, M; Plenderleith, R A; Rimmer, S; Claeyssens, F; Rodenburg, C

2016-12-01

Recently developed detectors can deliver high resolution and high contrast images of nanostructured carbon based materials in low voltage scanning electron microscopes (LVSEM) with beam deceleration. Monte Carlo Simulations are also used to predict under which exact imaging conditions purely compositional contrast can be obtained and optimised. This allows the prediction of the electron signal intensity in angle selective conditions for back-scattered electron (BSE) imaging in LVSEM and compares it to experimental signals. Angle selective detection with a concentric back scattered (CBS) detector is considered in the model in the absence and presence of a deceleration field, respectively. The validity of the model prediction for both cases was tested experimentally for amorphous C and Cu and applied to complex nanostructured carbon based materials, namely a Poly(N-isopropylacrylamide)/Poly(ethylene glycol) Diacrylate (PNIPAM/PEGDA) semi-interpenetration network (IPN) and a Poly(3-hexylthiophene-2,5-diyl) (P3HT) film, to map nano-scale composition and crystallinity distribution by avoiding experimental imaging conditions that lead to a mixed topographical and compositional contrast. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

The effect of matrix composition of 3D constructs on embryonic stem cell differentiation.

PubMed

Battista, Sabrina; Guarnieri, Daniela; Borselli, Cristina; Zeppetelli, Stefania; Borzacchiello, Assunta; Mayol, Laura; Gerbasio, Diego; Keene, Douglas R; Ambrosio, Luigi; Netti, Paolo A

2005-11-01

The use of embryonic stem (ES) cells as unlimited cell source in tissue engineering has ignited the hope of regenerating any kind of tissue in vitro. However, the role of the material in control and guidance of their development and commitment into complex and viable three-dimensional (3D) tissues is still poorly understood. In this work, we investigate the role of material composition and structure on promoting ES cells growth and differentiation, by culturing mouse ES cell-derived embryoid bodies (EBs) in various semi-interpenetrating polymer networks (SIPNs), made of collagen, fibronectin (FN) and laminin (LM). We show that both composition and strength of the supportive matrix play an important role in EBs development. High collagen concentrations inhibit EBs cavitation and hence the following EBs differentiation, by inhibiting apoptosis. The presence of FN in 3D collagen constructs strongly stimulates endothelial cell differentiation and vascularization. Conversely, LM increases the ability of ES cells to differentiate into beating cardiomyocytes. Our data suggest that matrix composition has an important role in EBs development and that it is possible to influence stem cell differentiation toward preferential pattern, by modulating the physical and biochemical properties of the scaffold.

Facile modification of electrospun fibrous structures with antifouling zwitterionic hydrogels.

PubMed

Xu, Tong; Yang, Jing; Zhang, Jiamin; Zhu, Yingnan; Li, Qingsi; Pan, Chao; Zhang, Lei

2017-12-28

Electrospinning technology can easily produce different shaped fibrous structures, making them highly valuable to various biomedical applications. However, surface contamination of biomolecules, cells, or blood has emerged as a significant challenge to the success of electrospun devices, especially artificial blood vessels, catheters and wound dressings etc. Many efforts have been made to resist the surface non-specific biomolecules or cells adsorption, but most of them require complex pre-treatment processes, hard-to-remove metal catalysts or rigorous reaction conditions. In addition, the stability of antifouling coatings, especially in complex conditions, is still a major concern. In this work, inspired by the interpenetrating polymer network and reinforced concrete structure, an efficient and facile strategy for modifying hydrophobic electrospun meshes and tubes with antifouling zwitterionic hydrogels has been introduced. The resulting products could efficiently resist the adhesion of proteins, cells, or even fresh whole blood. Meanwhile, they could maintain the shapes and mechanical strength of the original electrospun structures. Furthermore, the hydrogel structures could retain stable in a physiological condition for at least 3 months. This paper provided a general antifouling and hydrophilicity surface modification strategy for various fibrous structures, and could be of great value for many biomedical applications where antifouling properties are critical.

Aromatic organic contaminant removal from an aqueous environment by p(4-VP)-based materials.

PubMed

Sahiner, Nurettin; Ozay, Ozgur; Aktas, Nahit

2011-10-01

p(4-vinylpyridine) (p(4-VP)) hydrogels were prepared in bulk (macro, 5 × 6 mm) and in nanosizes (370 nm) dimensions. The prepared hydrogels were used to remove organic aromatic contaminates such as 4-nitrophenol (4-NP), 2-nitrophenol (2-NP), phenol (Ph) and nitrobenzene (NB) from an aqueous environment. Important parameters affecting the absorption phenomena, such as the initial concentration of the organic species and the absorbent, absorption rate, absorption capacity, pH and the temperature of the medium, were evaluated for both hydrogel sizes. The absorption capacity of bulk and microgels were found to be 4-NP>2-NP>Ph>NB. Furthermore, p(4-VP) microgels were embedded in poly(acrylamide) (p(AAm)) bulk hydrogel as a microgel-hydrogel interpenetrating polymer network and proved to be very practical in overcoming the difficulty of using the microgels in real applications. Moreover, it was demonstrated that separately prepared magnetic ferrite particles inserted inside p(4-VP) microgels during synthesis allowed for trouble-free removal of p(4-VP)-magnetic composite microgels from the aqueous environment by an externally applied magnetic field upon completion of their task. Copyright © 2011 Elsevier Ltd. All rights reserved.

A Numerical Study on the Effect of Facesheet-Core Disbonds on the Buckling Load of Curved Honeycomb Sandwich Panels

NASA Technical Reports Server (NTRS)

Pineda, Evan J.; Myers, David E.; Bednarcyk, Brett A.; Krivanek, Thomas M.

2015-01-01

A numerical study on the effect of facesheet-core disbonds on the post-buckling response of curved honeycomb sandwich panels is presented herein. This work was conducted as part of the development of a damage tolerance approach for the next-generation Space Launch System heavy lift vehicle payload fairing. As such, the study utilized full-scale fairing barrel segments as the structure of interest. The panels were composed of carbon fiber reinforced polymer facesheets and aluminum honeycomb core. The panels were analyzed numerically using the finite element method. Facesheet and core nodes in a predetermined circular region were detached to simulate a disbond induced via low-speed impact between the outer mold line facesheet and honeycomb core. Surface-to-surface contact in the disbonded region was invoked to prevent interpenetration of the facesheet and core elements. The diameter of this disbonded region was varied and the effect of the size of the disbond on the post-buckling response was observed. A significant change in the slope of the edge load-deflection response was used to determine the onset of global buckling and corresponding buckling load.

Novel pH-sensitive IPNs of polyacrylamide-g-gum ghatti and sodium alginate for gastro-protective drug delivery.

PubMed

Boppana, Rashmi; Krishna Mohan, G; Nayak, Usha; Mutalik, Srinivas; Sa, Biswanath; Kulkarni, Raghavendra V

2015-04-01

This article reports the development of pH-sensitive interpenetrating polymer network (IPN) microbeads using polyacrylamide-grafted-gum ghatti (PAAm-g-GG) and sodium alginate (SA) for gastro-protective controlled delivery of ketoprofen. We have synthesized PAAm-grafted-GG copolymer under microwave irradiation using cerric ammonium nitrate as reaction initiator; further, the PAAm-g-GG was converted to pH-sensitive copolymer through alkaline hydrolysis. Sophisticated instrumentation techniques were used to characterize PAAm-g-GG. The IPN microbeads of PAAm-g-GG and SA, pre-loaded with ketoprofen were prepared by dual crosslinking using Ca(2+) ions and glutaraldehyde (GA). The IPN microbeads demonstrated excellent pH-sensitive behavior as noted in the pulsatile swelling test and scanning electron microscopy. IPN microbeads also showed larger amount of drug release in buffer solution of pH 7.4 as compared to drug release in solution of pH 1.2. The in vivo pharmacokinetic, pharmacodynamic and stomach histopathology studies conducted on wistar rats confirmed the pH-sensitive controlled release of ketoprofen; IPN microbeads retarded the drug release in stomach resulting in reduced adverse effects of ketoprofen. Copyright © 2015 Elsevier B.V. All rights reserved.

A Multifluid Numerical Algorithm for Interpenetrating Plasma Dynamics

NASA Astrophysics Data System (ADS)

Ghosh, Debojyoti; Kavouklis, Christos; Berger, Richard; Chapman, Thomas; Hittinger, Jeffrey

2017-10-01

Interpenetrating plasmas occur in situations including inertial confinement fusion experiments, where plasmas ablate off the hohlraum and capsule surfaces and interact with each other, and in high-energy density physics experiments that involve the collision of plasma streams ablating off discs irradiated by laser beams. Single-fluid, multi-species hydrodynamic models are not well-suited to study this interaction because they cannot support more than a single fluid velocity; this results in unphysical solutions. Though kinetic models yield accurate solutions for multi-fluid interactions, they are prohibitively expensive for at-scale three-dimensional (3D) simulations. In this study, we propose a multifluid approach where the compressible fluid equations are solved for each ion species and the electrons. Electrostatic forces and inter-species friction and thermal equilibration couple the species. A high-order finite-volume algorithm with explicit time integration is used to solve on a 3D Cartesian domain, and a high-order Poisson solver is used to compute the electrostatic potential. We present preliminary results for the interpenetration of two plasma streams in vacuum and in the presence of a gas fill. This work was performed under the auspices of the U.S. DOE by Lawrence Livermore National Laboratory under Contract No. DE-AC52- 07NA27344 and funded by the LDRD Program at LLNL under project tracking code 17-ERD-081.

Nontoxic, Hydrophilic Cationic Polymers-Identified as Class of Antimicrobial Polymers.

PubMed

Strassburg, Arne; Kracke, Frauke; Wenners, Julia; Jemeljanova, Anna; Kuepper, Jannis; Petersen, Hanne; Tiller, Joerg C

2015-12-01

Amphiphilic polycations are an alternative to biocides but also toxic to mammalian cells. Antimicrobially active hydrophilic polycations based on 1,4-dibromo-2-butene and tetramethyl-1,3-propanediamine named PBI are not hemotoxic for porcine red blood cells with a hemocytotoxicity (HC50) of more than 40,000 μg · mL(-1). They are quickly killing bacterial cells at their MIC (minimal inhibitory concentration). The highest found selectivity HC50 /MIC is more than 20,000 for S. epidermidis. Investigations on sequentially prepared PBIs with defined molecular weight Mn and tailored end groups revealed that there is a dependence of antimicrobial activity and selectivity on Mn and nature of the end groups. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Application of organic IR788-loaded semi-interpenetrating network dyes for photoacoustic imaging

NASA Astrophysics Data System (ADS)

Phuc Nguyen, Van; Kim, Hyejin; Kang, Mingyeong; Kwak, Minseok; Kang, Hyun Wook

2017-07-01

In this study, we present the feasibility of a biocompatible Lumogen® IR788-loaded polymeric nanoparticle (NP) as a novel photoabsorbing agent for photoacoustic (PA) imaging. The NP was fabricated through a semi-interpenetrating network (sIPN) within the core of F127 resulting in IR788-sIPN formation. To evaluate the PA sensitivity of the material, tubing phantoms were injected with various concentrations of IR788-sIPN, and H1975 lung-tumor-bearing mice were intratumorally injected with IR788-sIPN. Compared with the background, the PA contrast was enhanced up to 80 and 40% in the phantom and in vivo experiments, respectively. IR788-sIPN can be a feasible IR-absorbing material for early cancer detection.

Navier-Stokes relaxation to sinh-Poisson states at finite Reynolds numbers

NASA Technical Reports Server (NTRS)

Montgomery, David; Shan, Xiaowen; Matthaeus, William H.

1993-01-01

A mathematical framework is proposed in which it seems possible to justify the computationally-observed relaxation of a two-dimensional Navier-Stokes fluid to a 'most probable', or maximum entropy, state. The relaxation occurs at large but finite Reynolds numbers, and involves substantial decay of higher-order ideal invariants such as enstrophy. A two-fluid formulation, involving interpenetrating positive and negative vorticity fluxes (continuous and square integrable) is developed, and is shown to be intimately related to the passive scalar decay problem. Increasing interpenetration of the two fluids corresponds to the decay of vorticity flux due to viscosity. It is demonstrated numerically that, in two dimensions, passive scalars decay rapidly, relative to mean-square vorticity (enstrophy). This observation provides a basis for assigning initial data to the two-fluid field variables.

Numerical Simulations of As-Extruded Mg Matrix Composites Interpenetrated by Metal Reinforcement

NASA Astrophysics Data System (ADS)

Y Wang, H.; Wang, S. R.; Yang, X. F.; Li, P.

2017-12-01

The interpenetrating magnesium composites reinforced by three-dimensional braided stainless steel wire reinforcement were fabricated and investigated. The extrusion processes of the composites in different conditions were carried out and simulated by finite element method using the DEFORM-3D software. The results show that the matrix and reinforcement of the composites form a good interfacial bonding and the grains were refined by extrusion and the influence of reinforcement, which are in accordance with the enhanced strength and degraded plasticity. The combined quality between the matrix and reinforcement can be strengthened in extrusion chamber where occurred large strain and suffered intense stress, and the effective stress of the material increases continuously with the increase in extrusion ratio and the decrease in extrusion speed until it reaches a stable value.

Simplified charge separation energetics in a two-dimensional model for polymer-based photovoltaic cells.

PubMed

Sylvester-Hvid, Kristian O; Ratner, Mark A

2005-01-13

An extension of our two-dimensional working model for photovoltaic behavior in binary polymer and/or molecular photoactive blends is presented. The objective is to provide a more-realistic description of the charge generation and charge separation processes in the blend system. This is achieved by assigning an energy to each of the possible occupation states, describing the system according to a simple energy model for exciton and geminate electron-hole pair configurations. The energy model takes as primary input the ionization potential, electron affinity and optical gap of the components of the blend. The underlying photovoltaic model considers a nanoscopic subvolume of a photoactive blend and represents its p- and n-type domain morphology, in terms of a two-dimensional network of donor and acceptor sites. The nearest-neighbor hopping of charge carriers in the illuminated system is described in terms of transitions between different occupation states. The equations governing the dynamics of these states are cast into a linear master equation, which can be solved for arbitrary two-dimensional donor-acceptor networks, assuming stationary conditions. The implications of incorporating the energy model into the photovoltaic model are illustrated by simulations of the short circuit current versus thickness of the photoactive blend layer for different choices of energy parameters and donor-acceptor topology. The results suggest the existence of an optimal thickness of the photoactive film in bulk heterojunctions, based on kinetic considerations alone, and that this optimal thickness is very sensitive to the choice of energy parameters. The results also indicate space-charge limiting effects for interpenetrating donor-acceptor networks with characteristic domain sizes in the nanometer range and high driving force for the photoinduced electron transfer across the donor-acceptor internal interface.

Green Approach To Synthesize Crystalline Nanoscale ZnII-Coordination Polymers: Cell Growth Inhibition and Immunofluorescence Study.

PubMed

Mukherjee, Somali; Ganguly, Sumi; Manna, Krishnendu; Mondal, Sanchaita; Mahapatra, Supratim; Das, Debasis

2018-04-02

Five new coordination polymers (CPs) namely, [{Zn(μ 2 -H 2 O) 0.5 (5N 3 -IPA)(2,2'-bpe)}] ∞ (1), [{Zn(μ 2 -H 2 O) 0.5 (5N 3 -IPA)(1,10-phen)}] ∞ (2), [{Zn(5N 3 -IPA)(1,2-bpe)}] ∞ (3), [{Zn(5N 3 -IPA)(1,2-bpey)}] ∞ (4), and [{Zn(H 2 O)(5N 3 -IPA)(4,4'-tme)}(H 2 O) 0.5 ] ∞ (5) (5N 3 -H 2 IPA = 5-azidoisophthalic acid, 2,2'-bpe= 2,2'-bipyridine, 1,10-phen = 1,10-phenanthroline, 1,2-bpe = 1,2-bis(4-pyridyl)ethane, 1,2-bpey = 1,2-bis(4-pyridyl)ethylene, 4,4'-tme = 4,4'-trimethylenedipyridine), have been synthesized based on a mixed ligand approach adopting a solvothermal technique. Depending upon the intrinsic structural flexibility of the bis-pyridyl coligands, interesting structural topologies have also been observed in the resulting CPs: Sra SrAl2 type topology for 3 and a 3-fold interpenetrated dmp topology for 4. A green hand grinding technique has been implemented to reduce the particle size of the CPs to generate nanoscale CPs (NCPs). SEM studies of NCPs reveal the formation of square and spherical particles for NCP 1 and 2, respectively, and nano rod for NCP 3, 4, and 5. Remarkably, when scaled down to nano range all the NCPs retain their crystalline nature. The cytotoxic activity of the NCPs (1-5) has been studied using human colorectal carcinoma cells (HCT 116). Significant cell death is observed for NCP 2, which is further corroborated by cell growth inhibition study. The observed cell death is likely to be due to mitochondrial-assisted apoptosis as is evident from immunofluorescence study.

Design and construction of diverse structures of coordination polymers: Photocatalytic properties

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

Wu, Yu, E-mail: wuyuhlj@163.com; Institute of Functional Materials, Sichuan University of Science & Engineering, Zigong 643000; Lu, Lu

2017-01-15

The reaction of Cu(NO{sub 3}){sub 2}·3H{sub 2}O/Ni(NO{sub 3}){sub 2}·6H{sub 2}O with 4′-(4-(3,5-dicarboxylphenoxy)phenyl)-4,2′:6′,4′′-terpyridine (H{sub 2}dbp) gave [Cu{sub 0.5}(Hdbp)]{sub n} (1) and [Ni(dbp)(H{sub 2}O)]{sub n} (2), while the reactions of Co(NO{sub 3}){sub 2}·6H{sub 2}O with H{sub 2}dbp in the presence of 4,4′-bipy and 2,2′-bpy generated [Co(dbp)(4,4′-bipy)]{sub n} (3) and ([Co(dbp)(2,2′-bipy)]{sub n}·H{sub 2}O) (4), respectively (4,4′-bipy=4.4′-pyridine and 2,2′-bipy=2,2′-bipyridine). X-Ray single-crystal analyses reveal that 1 contains a 1D double chain. 2 possesses a 3D architecture with (4.6{sup 2}0.8{sup 3}){sub 2} topology that is interpenetrated with each other to form a 2-fold network. In 3, the 2D [Co(dbp)]n sheets are pillared by 4,4′-bpy to formmore » a 3D framework with 1D open channel. Compound 4 consists of a 1D ladder-like chain. The results showed that the structural diversity of the coordination polymers resulted from the different geometries of metal ions and effect of assistant ligands. Furthermore, the photocatalytic properties of 1–4 for degradation of the methyl violet (MV) have been examined. - Graphical abstract: The photocatalytic activity and selectivity of complexes 1–4 prove that they may be good and stable photocatalysts for degradation of organic dyes.« less

Mechanically robust silver coatings prepared by electroless plating on thermoplastic polyurethane

NASA Astrophysics Data System (ADS)

Vasconcelos, B.; Vediappan, K.; Oliveira, J. C.; Fonseca, C.

2018-06-01

A simple and low-cost surface functionalization method is proposed to activate a thermoplastic polyurethane (TPU) for the electroless deposition of a silver coating with excellent adhesion and low resistivity. The TPU surface functionalization was performed in solution and consisted in forming a physical interpenetrating network at the TPU surface, involving TPU and polyvinylpyrrolidone (PVP), a polymer displaying a strong affinity for metals. The presence of PVP on the TPU surface and its stability in aqueous solution were assessed by ATR-FTIR and contact angle measurements as a function of the PVP concentration and treatment time. A modified Tollens solution was used to grow a silver film on the TPU substrate, by using the electroless plating method. Compact silver films with an average thickness of 12.5 μm and a resistivity of 8.57 mΩ·cm were obtained for a 24 h plating time. The adhesion strength of the silver film proved to be higher than 8.5 N/cm. The resistance to fatigue of the silver films was studied by performing series of compression/stretching tests (150 cycles). It was concluded that the films kept low resistance values, although displaying a higher sensitivity to compression than to stretching. Furthermore, the films keep a good conductivity for strains up to 400%. The excellent electrical and mechanical properties of the films make them suitable candidates for the coating of multipin dry bioelectrodes. Owing to the high affinity of many metals for PVP, this activation technique has the potential to be extended to the deposition of other metals and other polymers as well, provided a suitable solvent is used.

Syntheses, crystal structures, and properties of four coordination polymers based on mixed multi-N donor and polycarboxylate ligands

NASA Astrophysics Data System (ADS)

Chen, Shui-Sheng; Guo, Xing-Zhe; Zhao, Yue; Li, Wei-Dong

2018-02-01

Four new coordination polymers [Ni2(HL1)2(L1)3(BTC)2]·6H2O (1), [Ni2(L1)3(HBTC)2]·4H2O (2), [Cd2(L2)(BTC)(H2O)3]·2H2O (3) and [Cd2(HL2)(BTCA)] (4) were synthesized by reactions of nickel(II)/ cadmium(II) salts with rigid ligands of 1,4-di(1H-imidazol-4-yl)benzene (L1), 1,3-di(1-imidazolyl)-5-(4H-tetrazol-5-yl)benzene (HL2) and polycarboxylic acids of 1,3,5-benzenetricarboxylic acid (H3BTC), 1,2,4,5-benzenetetracarboxylic acid (H4BTCA), respectively. The structures of the complexes were determined by single crystal X-ray diffraction analysis. The complex 1 is one-dimensional (1D) chain while 2 is a (4, 4)-connected two-dimensional (2D) layered structure with 2D → 2D parallel interpenetration. Complex 3 is a rare tetranodal (3,4)-connected three-dimensional (3D) CrVTiSc architecture with Point (Schläfli) symbol of (4·82)(4·84·10)(42·82·102)(83), and compound 4 has the 2D network with (4,4) topology based on the [Cd2(COO)4] SBUs. The weak interactions such as hydrogen bonds and π···π stacking contribute to stabilize crystal structure and extend the low-dimensional entities into high-dimensional frameworks. The UV-vis absorption spectra of 1 - 4 are discussed. Moreover, the photo luminescent properties of 3 and 4 and gas sorption property of 2 have been investigated.

Poly[[sesqui[mu2-1,4-bis(imidazol-1-ylmethyl)benzene-kappa(2)N:N'](carbonato-kappa(2)O,O')copper(II)] 1,4-bis(imidazol-1-ylmethyl)benzene hemisolvate pentahydrate].

PubMed

Dai, Yu-Mei; Tang, En; Huang, Jin-Feng; Yang, Qiu-Yan

2008-10-01

The asymmetric unit of the title compound, {[Cu(CO(3))(C(14)H(14)N(4))(1.5)] x 0.5 C(14)H(14)N(4) x 5 H(2)O}(n), contains one Cu(II) cation in a slightly distorted square-pyramidal coordination environment, one CO(3)(2-) anion, one full and two half 1,4-bis(imidazol-1-ylmethyl)benzene (bix) ligands, one half-molecule of which is uncoordinated, and five uncoordinated water molecules. One of the coordinated bix ligands and the uncoordinated bix molecule are situated about centers of symmetry, located at the centers of the benzene rings. The coordinated bix ligands link the copper(II) ions into a [Cu(bix)(1.5)](n) molecular ladder. These molecular ladders do not form interpenetrated ladders but are arranged in an ABAB parallel terrace, i.e. with the ladders arranged one above another, with sequence A translated with respect to B by 8 A. To best of our knowledge, this arrangement has not been observed in any of the molecular ladder frameworks synthesized to date. The coordination environment of the Cu(II) atom is completed by two O atoms of the CO(3)(2-) anion. The framework is further strengthened by extensive O-H...O and O-H...N hydrogen bonds involving the water molecules, the O atoms of the CO(3)(2-) anion and the N atoms of the bix ligands. This study describes the first example of a molecular ladder coordination polymer based on bix and therefore demonstrates further the usefulness of bix as a versatile multidentate ligand for constructing coordination polymers with interesting architectures.

LaRC-RP41: A Tough, High-Performance Composite Matrix

NASA Technical Reports Server (NTRS)

Pater, Ruth H.; Johnston, Norman J.; Smith, Ricky E.; Snoha, John J.; Gautreaux, Carol R.; Reddy, Rakasi M.

1991-01-01

New polymer exhibits increased toughness and resistance to microcracking. Cross-linking PMR-15 and linear LaRC-TPI combined to provide sequential semi-2-IPN designated as LaRC-RP41. Synthesized from PMR-15 imide prepolymer undergoing cross-linking in immediate presence of LaRC-TPI polyamic acid, also undergoing simultaneous imidization and linear chain extension. Potentially high-temperature matrix resin, adhesive, and molding resin. Applications include automobiles, electronics, aircraft, and aerospace structures.

Dual-Color Fluorescence Imaging of Magnetic Nanoparticles in Live Cancer Cells Using Conjugated Polymer Probes

PubMed Central

Sun, Minjie; Sun, Bin; Liu, Yun; Shen, Qun-Dong; Jiang, Shaojun

2016-01-01

Rapid growth in biological applications of nanomaterials brings about pressing needs for exploring nanomaterial-cell interactions. Cationic blue-emissive and anionic green-emissive conjugated polymers are applied as dual-color fluorescence probes to the surface of negatively charged magnetic nanoparticles through sequentially electrostatic adsorption. These conjugated polymers have large extinction coefficients and high fluorescence quantum yield (82% for PFN and 62% for ThPFS). Thereby, one can visualize trace amount (2.7 μg/mL) of fluorescence-labeled nanoparticles within cancer cells by confocal laser scanning microscopy. Fluorescence labeling by the conjugated polymers is also validated for quantitative determination of the internalized nanoparticles in each individual cell by flow cytometry analysis. Extensive overlap of blue and green fluorescence signals in the cytoplasm indicates that both conjugated polymer probes tightly bind to the surface of the nanoparticles during cellular internalization. The highly charged and fluorescence-labeled nanoparticles non-specifically bind to the cell membranes, followed by cellular uptake through endocytosis. The nanoparticles form aggregates inside endosomes, which yields a punctuated staining pattern. Cellular internalization of the nanoparticles is dependent on the dosage and time. Uptake efficiency can be enhanced three-fold by application of an external magnetic field. The nanoparticles are low cytotoxicity and suitable for simultaneously noninvasive fluorescence and magnetic resonance imaging application. PMID:26931282

Segregated Methods for Two-Fluid Models

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

Prosperetti, Andrea; Sundaresan, Sankaran; Pannala, Sreekanth

2007-01-01

The previous chapter, with its direct simulation of the fluid flow and a modeling approach to the particle phase, may be seen as a transition between the methods for a fully resolved simulation described in the first part of this book and those for a coarse grained description based on the averaging approach described in chapter ??. We now turn to the latter, which in practice are the only methods able to deal with the complex flows encountered in most situations of practical interest such as fluidized beds, pipelines, energy generation, sediment transport, and others. This chapter and the nextmore » one are devoted to numerical methods for so-called two-fluid models in which the phases are treated as inter-penetrating continua describing, e.g., a liquid and a gas, or a fluid and a suspended solid phase. These models can be extended to deal with more than two continua and, then, the denomination multi-fluid models might be more appropriate. For example, the commercial code OLGA (Bendiksen et al. 1991), widely used in the oil industry, recognizes three phases, all treated as interpenetrating continua: a continuous liquid, a gas, and a disperse liquid phase present as drops suspended in the gas phase. The more recent PeTra (Petroleum Transport, Larsen et al. 1997) also describes three phases, gas, oil, and water. Recent approaches to the description of complex boiling flows recognize four inter-penetrating phases: a liquid phase present both as a continuum and as a dispersion of droplets, and a gas/vapor phase also present as a continuum and a dispersion of bubbles. Methods for these multi-fluid models are based on those developed for the two-fluid model to which we limit ourselves. In principle, one could simply take the model equations, discretize them, and solve them by a method suitable for non-linear problems, e.g. Newton-Raphson iteration. In practice, the computational cost of such a frontal attack is nearly always prohibitive in terms of storage requirement and execution time. It is therefore necessary to devise different, less direct strategies. Two principal classes of algorithms have been developed for this purpose. The first one, described in this chapter, consists of algorithms derived from the pressure based schemes widely used in single-phase flow, such as SIMPLE and its variations (see e.g. Patankar 1980). In this approach, the model equations are solved sequentially and, therefore, these methods are often referred to as segregated algorithms to distinguish them from a second class of methods, object of the next chapter, in which a coupled or semi-coupled time-marching solution strategy is adopted. Broadly speaking, the first class of methods is suitable for relatively slow transients, such as fluidized beds, or phenomena with a long duration, such as flow in pipelines. The methods in the second group have been designed to deal principally with fast transients, such as those hypothesized in nuclear reactor safety. Since in segregated solvers the equations are solved one by one, it is possible to add equations to the mathematical model - to describe e.g. turbulence - at a later stage after the development of the initial code without major modifications of the algorithm.« less

Fibrillar Organic Phases And Their Roles In Rigid Biological Composites

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

Arey, Bruce W.; Park, John J.; Mayer, George

2015-06-01

This study focused on determining the presence of organic phases in the siliceous components of rigid marine composites ("glass" sponge spicules), and thereby to clarify how those composites dissipate significant mechanical energy. Through the use of imaging by helium ion microscopy in the examination of the spicules, the organic phase that is present between the layers of hydrated silica was also detected within the silica cylinders of the composite, indicating the existence therein of a network, scaffolding, or other pattern that has not yet been determined. It was concluded that the presence of an interpenetrating network of some kind, andmore » tenacious fibrillar interfaces are responsible for the large energy dissipation in these siliceous composites by viscoelastic processes. This discovery means that future mechanics analyses of such composites, extending to large deformations must consider such interpenetrating phases.« less

A three-dimensional interpenetrating electrode of reduced graphene oxide for selective detection of dopamine.

PubMed

Yu, Xiaowen; Sheng, Kaixuan; Shi, Gaoquan

2014-09-21

Electrochemical detection of dopamine plays an important role in medical diagnosis. In this paper, we report a three-dimensional (3D) interpenetrating graphene electrode fabricated by electrochemical reduction of graphene oxide for selective detection of dopamine. This electrochemically reduced graphene oxide (ErGO) electrode was used directly without further functionalization or blending with other functional materials. This electrode can efficiently lower the oxidation potential of ascorbic acid; thus, it is able to selectively detect dopamine in the presence of ascorbic acid and uric acid. The ErGO-based biosensor exhibited a linear response towards dopamine in the concentration range of 0.1-10 μM with a low detection limit of 0.1 μM. Furthermore, this electrode has good reproducibility and environmental stability, and can be used to analyse real samples.

CFA-7: an interpenetrated metal-organic framework of the MFU-4 family.

PubMed

Schmieder, Phillip; Grzywa, Maciej; Denysenko, Dmytro; Hambach, Manuel; Volkmer, Dirk

2015-08-07

The novel interpenetrated metal-organic framework CFA-7 (Coordination Framework Augsburg University-7), [Zn5Cl4(tqpt)3], has been synthesized containing the organic linker {H2-tqpt = 6,6,14,14-tetramethyl-6,14-dihydroquinoxalino[2,3-b]phenazinebistriazole}. Reaction of H2-tqpt and anhydrous ZnCl2 in N,N-dimethylformamide (DMF) yields CFA-7 as pseudo-cubic crystals. CFA-7 serves as precursor for the synthesis of isostructural frameworks with redox-active metal centers, which is demonstrated by postsynthetic metal exchange of Zn(2+) by different M(2+) (M = Co, Ni, Cu) ions. The novel framework is robust upon solvent removal and has been structurally characterized by single-crystal X-ray diffraction, TGA and IR spectroscopy, as well as gas sorption (Ar, CO2 and H2).

Interpenetrating Triphase Cobalt-Based Nanocomposites as Efficient Bifunctional Oxygen Electrocatalysts for Long-Lasting Rechargeable Zn–Air Batteries

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

Jiang, Yi; Deng, Ya-Ping; Fu, Jing

Rational construction of atomic-scale interfaces in multiphase nanocomposites is an intriguing and challenging approach to developing advanced catalysts for both oxygen reduction (ORR) and evolution reactions (OER). In this paper, a hybrid of interpenetrating metallic Co and spinel Co 3O 4 “Janus” nanoparticles stitched in porous graphitized shells (Co/Co 3O 4@PGS) is synthesized via ionic exchange and redox between Co 2+ and 2D metal–organic-framework nanosheets. This strategy is proven to effectively establish highways for the transfer of electrons and reactants within the hybrid through interfacial engineering. Specifically, the phase interpenetration of mixed Co species and encapsulating porous graphitized shells providesmore » an optimal charge/mass transport environment. Furthermore, the defect-rich interfaces act as atomic-traps to achieve exceptional adsorption capability for oxygen reactants. Finally, robust coupling between Co and N through intimate covalent bonds prohibits the detachment of nanoparticles. As a result, Co/Co 3O 4@PGS outperforms state-of-the-art noble-metal catalysts with a positive half-wave potential of 0.89 V for ORR and a low potential of 1.58 V at 10 mA cm -2 for OER. Finally, in a practical demonstration, ultrastable cyclability with a record lifetime of over 800 h at 10 mA cm -2 is achieved by Zn–air batteries with Co/Co 3O 4@PGS within the rechargeable air electrode.« less

Molecular weight dependence of LB morphology of poly(n-hexyl isocyanate) (PHIC).

PubMed

Morioka, Takako; Shibata, Osamu; Kawaguchi, Masami

2010-12-07

The morphologies of Langmuir-Blodgett (LB) films of two fractionated poly(n-hexyl isocyanate) (PHIC) and those of their binary mixtures were observed by AFM, together with those of an unfractionated PHIC. The low molecular weight PHIC formed random packing of bundles consisting of rigid rods, while the high molecular weight PHIC formed random packing of bundles consisting of hairy rods. Bundle interpenetration was observed only for the latter in the semidilute regime. In the bilayer region, the area occupied by the PHIC bundles in the upper layer was obviously smaller for the high molecular weight PHIC than for the low molecular weight PHIC, suggesting that the bundles of high molecular weight PHIC more easily interpenetrate than those of low molecular weight PHIC. For the blended films composed of both low and high molecular weight PHICs, the characteristic morphologies of the respective PHIC samples were no longer present. Moreover, the morphologies of the blended films appeared to resemble each other at any molar fraction owing to the ideal miscibility of the low molecular weight and high molecular weight PHICs. The morphologies of the blended films were also similar to that of the unfractionated PHIC film in the dilute regime. In the semidilute regime, the blended films became rounded owing to an increase in bundles interpenetration between PHICs as compared to that in the dilute regime, whereas the morphology of unfractionated PHIC films remained unchanged as compared to that in the dilute regime.

Interpenetrating Triphase Cobalt-Based Nanocomposites as Efficient Bifunctional Oxygen Electrocatalysts for Long-Lasting Rechargeable Zn–Air Batteries

DOE PAGES

Jiang, Yi; Deng, Ya-Ping; Fu, Jing; ...

2018-01-31

Rational construction of atomic-scale interfaces in multiphase nanocomposites is an intriguing and challenging approach to developing advanced catalysts for both oxygen reduction (ORR) and evolution reactions (OER). In this paper, a hybrid of interpenetrating metallic Co and spinel Co 3O 4 “Janus” nanoparticles stitched in porous graphitized shells (Co/Co 3O 4@PGS) is synthesized via ionic exchange and redox between Co 2+ and 2D metal–organic-framework nanosheets. This strategy is proven to effectively establish highways for the transfer of electrons and reactants within the hybrid through interfacial engineering. Specifically, the phase interpenetration of mixed Co species and encapsulating porous graphitized shells providesmore » an optimal charge/mass transport environment. Furthermore, the defect-rich interfaces act as atomic-traps to achieve exceptional adsorption capability for oxygen reactants. Finally, robust coupling between Co and N through intimate covalent bonds prohibits the detachment of nanoparticles. As a result, Co/Co 3O 4@PGS outperforms state-of-the-art noble-metal catalysts with a positive half-wave potential of 0.89 V for ORR and a low potential of 1.58 V at 10 mA cm -2 for OER. Finally, in a practical demonstration, ultrastable cyclability with a record lifetime of over 800 h at 10 mA cm -2 is achieved by Zn–air batteries with Co/Co 3O 4@PGS within the rechargeable air electrode.« less

Silk sericin/polyacrylamide in situ forming hydrogels for dermal reconstruction.

PubMed

Kundu, Banani; Kundu, Subhas C

2012-10-01

In situ forming tissue sealants are advantageous due to ease in application, complete coverage of defect site and assured comfort levels to patients. The interconnected three-dimensional hydrophilic networks perfectly manage typical dermal wounds by suitably scaffolding skin fibroblast, diffusing the nutrients, therapeutics and exudates while still maintaining an adequately moist environment. We evaluate the cell homing ability of semi-interpenetrating non-mulberry tropical tasar silk sericin/polyacrylamide hydrophilic network with a keen understanding of its network characteristics and correlation of protein concentration with the performance as cell scaffold. Interconnectivity of porous networks observed through scanning electron micrograph revealed pore sizes ranging from 23 to 52 μm. The enhanced β-sheet content with the increasing sericin concentration in far red spectroscopy study supported their corresponding improved compressive strength. These semi-interpenetrating networks were found to possess a maximum fluid uptake of 112% of its weight, hence preventing the accumulation of exudates at the wound area. The present systems appear to possess characteristics like rapid gelation (~5min) at 37 °C, 98% porosity enabling the migration of fibroblasts during healing (observed through confocal and scanning electron micrographs), cell adhesion together with the absence of any cyto-toxic effect suggesting its potential as in situ tissue sealants. The compressive strength up to 61 kPa ensured ease in handling even when wet. The results prove the suitability to use non-mulberry tasar cocoon silk sericin/polyacrylamide semi-interpenetrating network as a reconstructive dermal sealant. Copyright © 2012 Elsevier Ltd. All rights reserved.

Secondary ligand-directed assembly of Co(II) coordination polymers based on a pyridine carboxylate ligand

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

Cao, Ke-Li; Zhang, Yi-Ping; Cai, Yi-Ni

2014-07-01

To investigate the influence of hydrogen bonds and secondary ligands on the structures and properties of the resulting frameworks, five new Co(II) compounds have been synthesized by the reactions of Co(II) salts and 3,5-bis(pyridin-4-ylmethoxy)benzoic acid (HL) with four rationally selected dicarboxylic acid ligands. Without secondary ligand, we got one compound [CoL{sub 2}(H{sub 2}O){sub 2}]{sub n}·2nH{sub 2}O (1), which possesses a 1D chain structure. In the presence of ancillary ligands, namely, 1,3-adamantanedicarboxylic acid (H{sub 2}adbc), terephthalic acid (H{sub 2}tpa), thiophene-2,5-dicarboxylic acid (H{sub 2}tdc) and 1,4-benzenedithioacetic acid (H{sub 2}bdtc), four 3D structures [Co{sub 2}L{sub 2}(adbc)]{sub n}·nH{sub 2}O (2), [Co{sub 2}L{sub 2}(tpa)]{sub n}more » (3), [Co{sub 2}L{sub 2}(tdc)]{sub n} (4), [Co{sub 2}L{sub 2}(bdtc)(H{sub 2}O)]{sub n} (5) were obtained, respectively. It can be observed from the architectures of 1–5 that hydrogen bonds and secondary ligands both have great effects on the spatial connective fashions, resulting in the formation of various dimensional compounds. The XRPD, TGA data of title polymers and the magnetic properties for 2 and 5 have also been investigated. - Graphical abstract: The structural differences show that the ancillary ligands have great effects on the spatial connective fashions, resulting in the formation of various dimensional compounds. - Highlights: • Five new Co(II) coordination polymers have been synthesized by solvothermal reactions based on 3,5-bis(pyridin-4-ylmethoxy)benzoic acid (HL). • The long-flexible ligand (HL) is a good candidate to produce interpenetrating architectures. • The secondary dicarboxylic acid ligands play important roles in the spatial connective fashions and the formation of various dimensional compounds. • The magnetism studies show that both 2 and 5 exhibit antiferromagnetic interactions.« less

Creation of high-refractive-index amorphous titanium oxide thin films from low-fractal-dimension polymeric precursors synthesized by a sol-gel technique with a hydrazine monohydrochloride catalyst.

PubMed

Shimizu, Wataru; Nakamura, Satoshi; Sato, Takaaki; Murakami, Yasushi

2012-08-21

Amorphous titanium dioxide (TiO(2)) thin films exhibiting high refractive indices (n ≈ 2.1) and high transparency were fabricated by spin-coating titanium oxide liquid precursors having a weakly branched polymeric structure. The precursor solution was prepared from titanium tetra-n-butoxide (TTBO) via the catalytic sol-gel process with hydrazine monohydrochloride used as a salt catalyst, which serves as a conjugate acid-base pair catalyst. Our unique catalytic sol-gel technique accelerated the overall polycondensation reaction of partially hydrolyzed alkoxides, which facilitated the formation of liner polymer-like titanium oxide aggregates having a low fractal dimension of ca. (5)/(3), known as a characteristic of the so-called "expanded polymer chain". Such linear polymeric features are essential to the production of highly dense amorphous TiO(2) thin films; mutual interpenetration of the linear polymeric aggregates avoided the creation of void space that is often generated by the densification of high-fractal-dimension (particle-like) aggregates produced in a conventional sol-gel process. The mesh size of the titanium oxide polymers can be tuned either by water concentration or the reaction time, and the smaller mesh size in the liquid precursor led to a higher n value of the solid thin film, thanks to its higher local electron density. The reaction that required no addition of organic ligand to stabilize titanium alkoxides was advantageous to overcoming issues from organic residues such as coloration. The dense amorphous film structure suppressed light scattering loss owing to its extremely smooth surface and the absence of inhomogeneous grains or particles. Furthermore, the fabrication can be accomplished at a low heating temperature of <80 °C. Indeed, we successfully obtained a transparent film with a high refractive index of n = 2.064 (at λ = 633 nm) on a low-heat-resistance plastic, poly(methyl methacrylate), at 60 °C. The result offers an efficient route to high-refractive-index amorphous TiO(2) films as well as base materials for a wider range of applications.

Preparation and Electrocatalytic Activity of Gold Nanoparticles Immobilized on the Surface of 4-Mercaptobenzoyl-Functionalized Multiwalled Carbon Nanotubes

DTIC Science & Technology

2010-12-20

thiolate -Au bonds,30 and so GNP/MB-MWCNT hybrids were synthesized using a modified literature procedure.31 The SEM images show sequential...4 The electrocatalytic stability of GNP/MB-MWCNT supposes to be originated from the formation of stable thiolate -Au bonds that prevent aggregation of...Moon, K.-S.; Wong, C. P. Carbon 2007, 45, 655–661. (19) Sandler, J.; Shaffer, M. S. P.; Prasse, T.; Bauhofer, W.; Schulte, K.; Windle, A. H. Polymer

Self-assembly of mesoscopically ordered chromatic polydiacetylene/silica nanocomposites

NASA Technical Reports Server (NTRS)

Lu, Y.; Yang, Y.; Sellinger, A.; Lu, M.; Huang, J.; Fan, H.; Haddad, R.; Lopez, G.; Burns, A. R.; Sasaki, D. Y.;

Simple diagnosis of HbA1c using the dual-plasmonic platform integrated with LSPR and SERS

NASA Astrophysics Data System (ADS)

Heo, Nam Su; Kwak, Cheol Hwan; Lee, Hoomin; Kim, Dongjoo; Lee, Sunmook; Kim, Gi-bum; Kwon, Soonjo; Kim, Woo Sik; Huh, Yun Suk

2017-07-01

A plasmonic active chip was designed with a transparent polymer film self-assembled with gold nanoparticles (AuNPs). In this study, we demonstrated the feasibility and sensitivity of biosensors by employing a plasmonic resonance technique. AuNPs are widely used as biosensing probes because they facilitate stable immobilization of biomolecules. Transparent polymer film facilitated measurement of changes in absorbance via transmitted light and analysis of Raman scattering via scattered light. The cysteine rich protein G and anti-HbA1c were sequentially conjugated to self-assembled AuNPs on the transparent polymer film to detect a target protein. HbA1c, which is used as an indicator for diabetes diagnosis, was selected for target protein detection. We confirmed the linearly increased absorbance values with increasing HbA1c level (3.19-14.0%) by LSPR detection. We also verified the linear increase in SERS intensity as the concentration of anti-Hb increased from 10 ng mL-1 to 1 μg mL-1 by analyzing the SERS spectra of Cy3 labeled anti-Hb added substrates.

Sequence-Independent Cloning and Post-Translational Modification of Repetitive Protein Polymers through Sortase and Sfp-Mediated Enzymatic Ligation.

PubMed

Ott, Wolfgang; Nicolaus, Thomas; Gaub, Hermann E; Nash, Michael A

2016-04-11

Repetitive protein-based polymers are important for many applications in biotechnology and biomaterials development. Here we describe the sequential additive ligation of highly repetitive DNA sequences, their assembly into genes encoding protein-polymers with precisely tunable lengths and compositions, and their end-specific post-translational modification with organic dyes and fluorescent protein domains. Our new Golden Gate-based cloning approach relies on incorporation of only type IIS BsaI restriction enzyme recognition sites using PCR, which allowed us to install ybbR-peptide tags, Sortase c-tags, and cysteine residues onto either end of the repetitive gene polymers without leaving residual cloning scars. The assembled genes were expressed in Escherichia coli and purified using inverse transition cycling (ITC). Characterization by cloud point spectrophotometry, and denaturing polyacrylamide gel electrophoresis with fluorescence detection confirmed successful phosphopantetheinyl transferase (Sfp)-mediated post-translational N-terminal labeling of the protein-polymers with a coenzyme A-647 dye (CoA-647) and simultaneous sortase-mediated C-terminal labeling with a GFP domain containing an N-terminal GG-motif in a one-pot reaction. In a further demonstration, we installed an N-terminal cysteine residue into an elastin-like polypeptide (ELP) that was subsequently conjugated to a single chain poly(ethylene glycol)-maleimide (PEG-maleimide) synthetic polymer, noticeably shifting the ELP cloud point. The ability to straightforwardly assemble repetitive DNA sequences encoding ELPs of precisely tunable length and to post-translationally modify them specifically at the N- and C- termini provides a versatile platform for the design and production of multifunctional smart protein-polymeric materials.

Heterometallic mixed-valence copper(I,II) cyanides that were tuned by using the chelate effect: discovery of famous Cairo pentagonal tiling and unprecedented (3,4)-connected {8(3)}2{8(6)} topological 3D net.

PubMed

Qin, Ying-Lian; Yao, Ru-Xin; Wu, Guo-Xing; Liu, Min-Min; Zhang, Xian-Ming

2013-07-01

By using environmentally friendly [Ni(CN)4](2-) as a cyanide source, three new heterometallic cyano-bridged mixed-valence Cu(I)/Cu(II) coordination polymers with three different electronic configurations (d(8)-d(10)), that is, [Cu2Ni(CN)5(H2O)3] (1), [Cu2Ni(CN)5(pn)H2O] (2), and [Cu3Ni(CN)6(pn)2] (3, pn = 1,2-propane diamine) have been synthesized by gradually increasing the amount of pn. Compound 1, which was hydrothermally synthesized in the absence of pn ligand, exhibits the famous 2D Cairo pentagonal tiling, in which the Cu(I), Cu(II), and Ni(II) atoms act as trigonal, T-shaped, and square-planar nodes, respectively. Notably, there are three water molecules located at the meridianal positions of the octahedrally coordinated Cu(II) atom in compound 1. A similar reaction, except for the addition of a small amount of pn, generated a similar Cairo pentagonal tiling layer in which two of the water molecules that were located at the meridianal positions of the octahedrally coordinated Cu(II) atom were replaced by a chelating pn group. Another similar hydrothermal reaction, with the addition of a larger amount of pn, yielded compound 3, which showed a related two-fold-interpenetrated (3,4)-connected 3D framework with an unprecedented {8(3)}2{8(6)} topology in which the Cu(II) atom was chelated by two pn groups. These structural changes between compounds 1-3 can be explained by the chelating effect of the pn group. The replacement of two meridianally coordinated water molecules on the octahedral Cu(II) atom in compound 1 by a pn group gives compound 2, which shows similar Cairo tiling, and a further increase in the amount of pn results in the formation of the [Cu(NC)2(pn)2] unit and the two-fold-interpenetrated 3D framework of compound 3. The mixed-valence properties of compounds 1, 2, and 3 were confirmed by variable-temperature magnetic-susceptibility measurements. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Protection of Polymers from the Space Environment by Atomic Layer Deposition

NASA Astrophysics Data System (ADS)

Lindholm, Ned F.; Zhang, Jianming; Minton, Timothy K.; O'Patchen, Jennifer; George, Steven M.; Groner, Markus D.

2009-01-01

Polymers in space may be subjected to a barrage of incident atoms, photons, and/or ions. For example, oxygen atoms can etch and oxidize these materials. Photons may act either alone or in combination with oxygen atoms to degrade polymers and paints and thus limit their usefulness. Colors fade under the intense vacuum ultraviolet (VUV) solar radiation. Ions can lead to the build-up of static charge on polymers. Atomic layer deposition (ALD) techniques can provide coatings that could mitigate many challenges for polymers in space. ALD is a gas-phase technique based on two sequential, self-limiting surface reactions, and it can deposit very uniform, conformal, and pinhole-free films with atomic layer control. We have studied the efficacy of various ALD coatings to protect Kapton® polyimide, FEP Teflon®, and poly(methyl methacrylate) films from atomic-oxygen and VUV attack. Atomic-oxygen and VUV studies were conducted with the use of a laser-breakdown source for hyperthermal O atoms and a D2 lamp as a source of VUV light. These studies used a quartz crystal microbalance (QCM) to monitor mass loss in situ, as well as surface profilometry and scanning electron microscopy to study the surface recession and morphology changes ex situ. Al2O3 ALD coatings applied to polyimide and FEP Teflon® films protected the underlying substrates from O-atom attack, and ZnO coatings protected the poly(methyl methacrylate) substrate from VUV-induced damage.

Automated solid-phase extraction of phenolic acids using layered double hydroxide-alumina-polymer disks.

PubMed

Ghani, Milad; Palomino Cabello, Carlos; Saraji, Mohammad; Manuel Estela, Jose; Cerdà, Víctor; Turnes Palomino, Gemma; Maya, Fernando

2018-01-26

The application of layered double hydroxide-Al 2 O 3 -polymer mixed-matrix disks for solid-phase extraction is reported for the first time. Al 2 O 3 is embedded in a polymer matrix followed by an in situ metal-exchange process to obtain a layered double hydroxide-Al 2 O 3 -polymer mixed-matrix disk with excellent flow-through properties. The extraction performance of the prepared disks is evaluated as a proof of concept for the automated extraction using sequential injection analysis of organic acids (p-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid, gallic acid) following an anion-exchange mechanism. After the solid-phase extraction, phenolic acids were quantified by reversed-phase high-performance liquid chromatography with diode-array detection using a core-shell silica-C18 stationary phase and isocratic elution (acetonitrile/0.5% acetic acid in pure water, 5:95, v/v). High sensitivity and reproducibility were obtained with limits of detection in the range of 0.12-0.25 μg/L (sample volume, 4 mL), and relative standard deviations between 2.9 and 3.4% (10 μg/L, n = 6). Enrichment factors of 34-39 were obtained. Layered double hydroxide-Al 2 O 3 -polymer mixed-matrix disks had an average lifetime of 50 extractions. Analyte recoveries ranged from 93 to 96% for grape juice and nonalcoholic beer samples. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrostatic assembly of binary nanoparticle superlattices using protein cages

NASA Astrophysics Data System (ADS)

Kostiainen, Mauri A.; Hiekkataipale, Panu; Laiho, Ari; Lemieux, Vincent; Seitsonen, Jani; Ruokolainen, Janne; Ceci, Pierpaolo

2013-01-01

Binary nanoparticle superlattices are periodic nanostructures with lattice constants much shorter than the wavelength of light and could be used to prepare multifunctional metamaterials. Such superlattices are typically made from synthetic nanoparticles, and although biohybrid structures have been developed, incorporating biological building blocks into binary nanoparticle superlattices remains challenging. Protein-based nanocages provide a complex yet monodisperse and geometrically well-defined hollow cage that can be used to encapsulate different materials. Such protein cages have been used to program the self-assembly of encapsulated materials to form free-standing crystals and superlattices at interfaces or in solution. Here, we show that electrostatically patchy protein cages--cowpea chlorotic mottle virus and ferritin cages--can be used to direct the self-assembly of three-dimensional binary superlattices. The negatively charged cages can encapsulate RNA or superparamagnetic iron oxide nanoparticles, and the superlattices are formed through tunable electrostatic interactions with positively charged gold nanoparticles. Gold nanoparticles and viruses form an AB8fcc crystal structure that is not isostructural with any known atomic or molecular crystal structure and has previously been observed only with large colloidal polymer particles. Gold nanoparticles and empty or nanoparticle-loaded ferritin cages form an interpenetrating simple cubic AB structure (isostructural with CsCl). We also show that these magnetic assemblies provide contrast enhancement in magnetic resonance imaging.

Property-based design: optimization and characterization of polyvinyl alcohol (PVA) hydrogel and PVA-matrix composite for artificial cornea.

PubMed

Jiang, Hong; Zuo, Yi; Zhang, Li; Li, Jidong; Zhang, Aiming; Li, Yubao; Yang, Xiaochao

2014-03-01

Each approach for artificial cornea design is toward the same goal: to develop a material that best mimics the important properties of natural cornea. Accordingly, the selection and optimization of corneal substitute should be based on their physicochemical properties. In this study, three types of polyvinyl alcohol (PVA) hydrogels with different polymerization degree (PVA1799, PVA2499 and PVA2699) were prepared by freeze-thawing techniques. After characterization in terms of transparency, water content, water contact angle, mechanical property, root-mean-square roughness and protein adsorption behavior, the optimized PVA2499 hydrogel with similar properties of natural cornea was selected as a matrix material for artificial cornea. Based on this, a biomimetic artificial cornea was fabricated with core-and-skirt structure: a transparent PVA hydrogel core, surrounding by a ringed PVA-matrix composite skirt that composed of graphite, Fe-doped nano hydroxyapatite (n-Fe-HA) and PVA hydrogel. Different ratio of graphite/n-Fe-HA can tune the skirt color from dark brown to light brown, which well simulates the iris color of Oriental eyes. Moreover, morphologic and mechanical examination showed that an integrated core-and-skirt artificial cornea was formed from an interpenetrating polymer network, no phase separation appeared on the interface between the core and the skirt.

In vitro characterization of peptide-modified p(AAm-co-EG/AAc) IPN-coated titanium implants.

PubMed

Barber, Thomas A; Gamble, Lara J; Castner, David G; Healy, Kevin E

2006-07-01

Interpenetrating polymer networks (IPNs) of poly(acrylamide-co-ethylene glycol/acrylic acid) [p(AAm-co-EG/AAc)] functionalized with an -Arg-Gly-Asp- containing peptide derived from rat bone sialoprotein [bsp-RGD(15)] were grafted to titanium implants in an effort to modulate osteoblast behavior in vitro. Surface characterization data were consistent with the presence of an IPN, and ligand density measurements established that the range of peptide density on the modified implants spanned three orders of magnitude (0.01-20 pmol/cm2). In vitro biological characterization of the modified implants employing the primary rat calvarial osteoblast (RCO) model resulted in the identification of a critical ligand density (0.01

Glucose-sensitive silicone hydrogel contact lens toward tear glucose monitoring.

PubMed

Badugu, Ramachandram; Reece, Edward Albert; Lakowicz, Joseph R

2018-05-01

Accurate and reliable monitoring of blood glucose is needed for the treatment of diabetes, which has many challenges, including lack of patient compliance. Measuring tear glucose is an alternative to traditional finger-stick tests used to track blood sugar levels, but glucose sensing using tears has yet to be achieved. We report a methodology for possible tear glucose monitoring using glucose-sensitive silicone hydrogel (SiHG) contact lenses, the primary type of lenses available in today's market. Initially, we assessed the interpenetrating polymer network, with nearly pure silicone and water regions, existing in the SiHGs using a polarity-sensitive probe Prodan. We then synthesized a glucose-sensitive fluorophore Quin-C18 with a hydrophobic side chain for localization of probe at the interfacial region. Using our glucose-sensing contact lens, we were able to measure varying concentrations of glucose in an in-vitro system. The Quin-C18 strongly bound to the lenses with insignificant leaching even after multiple rinses. The lenses displayed a similar response to glucose after three months of storage in water. This study demonstrates that it may be possible to develop a contact lens for continuous glucose monitoring in the near term, using our concept of fluorophore binding at the silicone-water interface. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

An Effective Design of Electrically Conducting Thin-Film Composite (TFC) Membranes for Bio and Organic Fouling Control in Forward Osmosis (FO).

PubMed

Liu, Qing; Qiu, Guanglei; Zhou, Zhengzhong; Li, Jingguo; Amy, Gary Lee; Xie, Jianping; Lee, Jim Yang

2016-10-04

The organic foulants and bacteria in secondary wastewater treatment can seriously impair the membrane performance in a water treatment plant. The embedded electrode approach using an externally applied potential to repel organic foulants and inhibit bacterial adhesion can effectively reduce the frequency of membrane replacement. Electrode embedment in membranes is often carried out by dispensing a conductor (e.g., carbon nanotubes, or CNTs) in the membrane substrate, which gives rise to two problems: the leaching-out of the conductor and a percolation-limited membrane conductivity that results in an added energy cost. This study presents a facile method for the embedment of a continuous electrode in thin-film composite (TFC) forward osmosis (FO) membranes. Specifically, a conducting porous carbon paper is used as the understructure for the formation of a membrane substrate by the classical phase inversion process. The carbon paper and the membrane substrate polymer form an interpenetrating structure with good stability and low electrical resistance (only about 1Ω/□). The membrane-electrode assembly was deployed as the cathode of an electrochemical cell, and showed good resistance to organic and microbial fouling with the imposition of a 2.0 V DC voltage. The carbon paper-based FO TFC membranes also possess good mechanical stability for practical use.

Two luminescent d10 metal coordination polymers assembled from a semirigid terpyridyl carboxylate ligand with high selective detecting of Cu2+, Cr2O72- and acetone

NASA Astrophysics Data System (ADS)

Yuan, Fei; Wang, Ting-Ting; Hu, Huai-Ming; Li, Chuan-Ti; Zhou, Chun-Sheng; Wang, Xiaofang; Xue, Ganglin

2017-07-01

Using a carboxylic oligopyridine ligand, 4‧-(4-carboxyphenyl)-4,2‧:6‧,4″- terpyridine (Hcptpy), and imidazole-4,5-dicarboxylic acid (H3idc), two metal(II)-cptpy compounds formulated as [Zn2(cptpy)4]n·nH2O (1), [Zn2(cptpy)2(Hidc)(H2O)2]n·nH2O (2) have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Compound 1 shows a 2D +2D →3D supramolecular framework structure generated by two-fold interpenetrating 3-connected 2D framework (2D+2D→2D) with the sql topological net and the Schläfli symbol of {44·62}. Compound 2 displays a 1D ladder chain structure. The luminescent properties of 1 and the ones immersed in various kinds of organic compounds and nitrate@DMF solutions have been investigated. Importantly, 1 shows highly selective and sensitive response to acetone and Cu2+ through luminescence quenching effects, making it a promising luminescent sensor for acetone molecule and Cu2+. Meaningwhile, compound 2 shows highly selective sensitivity for Cr2O72-.

Nanoscale confinement effects on the relaxation dynamics in networks of diglycidyl ether of bisphenol-A and low-molecular-weight poly(ethylene oxide).

PubMed

Kalogeras, Ioannis M; Stathopoulos, Andreas; Vassilikou-Dova, Aglaia; Brostow, Witold

2007-03-22

Thermoplastic poly(ethylene oxide) (PEO) (Mw(PEO) approximately 4000) has been used to prepare thermosetting nanocomposites incorporating diglycidyl ether of bisphenol A (DGEBA) epoxy oligomer. Blends with various PEO/DGEBA weight ratios were cured using stoichiometric portions of 4,4'-diaminodiphenylmethane. The resulting semi-interpenetrating polymer networks were studied by several techniques. Nanoscale confinement effects, thermal (glass transition, melting and crystallization temperatures) and structural features of our materials are similar to those for networks with much higher Mw(PEO) and different curing agents; however, the polyether crystallization onset occurs in our case at a lower PEO concentration; shorter PEO chains organize themselves more easily into crystalline domains. Very low estimates of the k parameter of the Gordon-Taylor equation, used to fit the compositional dependences of the dielectric and calorimetric glass transition temperatures, and a strong plasticization of the motion of the glyceryl segments (beta-relaxation) in the epoxy resin were observed. These illustrate an intensified weakening in the strength of the intermolecular interactions in the modified networks, as compared to the high strength of the self-association of hydroxyls in the neat resin. The significance of hydrogen-bonding interactions between the components for obtaining structurally homogeneous thermoset-i-thermoplastic networks is discussed.

Post-Buckling Analysis of Curved Honeycomb Sandwich Panels Containing Interfacial Disbonds

NASA Technical Reports Server (NTRS)

Pineda, Evan J.; Bednarcyk, Brett A.; Krivanek, Thomas K.

2016-01-01

A numerical study on the effect of facesheet-core disbonds on the post-buckling response of curved honeycomb sandwich panels is presented herein. This work was conducted as part of the development of a damage tolerance plan for the next-generation Space Launch System heavy lift launch vehicle payload fairing. As such, the study utilized full-scale fairing barrel segments as the structure of interest. The panels were composed of carbon fiber reinforced polymer facesheets and aluminum honeycomb core. The panels were analyzed numerically using the finite element method incorporating geometric nonlinearity. In a predetermined circular region, facesheet and core nodes were detached to simulate a disbond, between the outer mold line facesheet and honeycomb core, induced via low-speed impact. Surface-to-surface contact in the disbonded region was invoked to prevent interpenetration of the facesheet and core elements and obtain realistic stresses in the core. The diameter of this disbonded region was varied and the effect of the size of the disbond on the post-buckling response was observed. Significant changes in the slope of the edge load-deflection response were used to determine the onset of global buckling and corresponding buckling load. Finally, several studies were conducted to determine the sensitivity of the numerical predictions to refinement in the finite element mesh.

Enhanced fill factor of tandem organic solar cells incorporating a diketopyrrolopyrrole-based low-bandgap polymer and optimized interlayer.

PubMed

Wang, Dong Hwan; Kyaw, Aung Ko Ko; Park, Jong Hyeok

2015-01-01

We demonstrate that reproducible results can be obtained from tandem solar cells based on the wide-bandgap poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2',1',3'-benzothiadiazole] (PCDTBT) and the diketopyrrolopyrrole (DPP)-based narrow bandgap polymer (DT-PDPP2T-TT) with a decyltetradecyl (DT) and an electron-rich 2,5-di-2-thienylthieno[3,2-b]thiophene (2T-TT) group fabricated using an optimized interlayer (ZnO NPs/ph-n-PEDOT:PSS) [NPs: nanoparticles; ph-n: pH-neutral PEDOT: poly(3,4-ethylenedioxythiophene); PSS: polystyrene sulfonate]. The tandem cells are fabricated by applying a simple process without thermal annealing. The ZnO NP interlayer operates well when the ZnO NPs are dispersed in 2-methoxyethanol, as no precipitation and chemical reactions occur. In addition to the ZnO NP film, we used neutral PEDOT:PSS as a second interlayer which is not affect to the sequential deposited bulk heterojunction (BHJ) active layer of acidification. The power conversion efficiency (PCE) of a tandem device reaches 7.4 % (open-circuit voltage VOC =1.53 V, short-circuit current density JSC =7.3 mA cm(-2) , and fill factor FF=67 %). Furthermore, FF is increased to up to 71 % when another promising large bandgap (bandgap ∼1.94 eV) polymer (PBnDT-FTAZ) is used. The surface of each layer with nanoscale morphology (BHJ1/ZnO NPs film/ph-n-PEDOT:PSS/BHJ2) was examined by means of AFM analysis during sequential processing. The combination of these factors, efficient DPP-based narrow bandgap material and optimized interlayer, leads to the high FF (average approaches 70 %) and reproducibly operating tandem BHJ solar cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Directing the phase behavior of polyelectrolyte complexes using chiral patterned peptides

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

Pacalin, Naomi M.; Leon, Lorraine; Tirrell, Matthew

Polyelectrolyte complexes (PECs) have a broad range of promising applications as soft materials due to their self-assembly and diversity of structure and chemical composition. Peptide polymer PECs are highly biocompatible and biodegradable, making them particularly useful for encapsulation of food additives and flavors, micellar drug delivery, medical and underwater adhesives, fetal membrane patches, and scaffolds for cell growth in tissue engineering. While parameters affecting PEC formation and stability in regards to charge effects are well researched, little is known about the effects of van der Waals interactions, hydrogen bonding, and secondary structure in these materials. Peptide chirality provides a uniquemore » opportunity to manipulate PEC phase to modulate the amount of solid-like (precipitate) or liquid-like (coacervate) character by influencing hydrogen bonding interactions among peptide chains. In previous work, we showed that chiral peptides form solid complexes, while complexes with even one racemic peptide were fluid. This raised the interesting question of how long a homochiral sequence must be to result in solid phase formation. In this work, we designed chiral patterned peptides of polyglutamic acid and polylysine ranging from 50 to 90% L-chiral residues with increasing numbers of sequential L-chiral residues before a chirality change. These polymers were mixed together to form PECs. We observed that 8 or more sequential L-chiral residues are necessary to achieve both the appearance of a precipitate phase and sustained beta-sheets in the complex, as determined by optical imaging and FTIR Spectroscopy. Less homochiral content results in formation of a coacervate phase. Thus, we show that chiral sequence can be used to control the phase transition of PECs. Understanding how to manipulate PEC phase using chiral sequence as presented here may enable tuning of the material properties to achieve the desired mechanical strength for coatings and polymer brushes, or the most effective molecular release kinetics for drug delivery applications, for example.« less

Directing the phase behavior of polyelectrolyte complexes using chiral patterned peptides

NASA Astrophysics Data System (ADS)

Pacalin, Naomi M.; Leon, Lorraine; Tirrell, Matthew

2016-10-01

Polyelectrolyte complexes (PECs) have a broad range of promising applications as soft materials due to their self-assembly and diversity of structure and chemical composition. Peptide polymer PECs are highly biocompatible and biodegradable, making them particularly useful for encapsulation of food additives and flavors, micellar drug delivery, medical and underwater adhesives, fetal membrane patches, and scaffolds for cell growth in tissue engineering. While parameters affecting PEC formation and stability in regards to charge effects are well researched, little is known about the effects of van der Waals interactions, hydrogen bonding, and secondary structure in these materials. Peptide chirality provides a unique opportunity to manipulate PEC phase to modulate the amount of solid-like (precipitate) or liquid-like (coacervate) character by influencing hydrogen bonding interactions among peptide chains. In previous work, we showed that chiral peptides form solid complexes, while complexes with even one racemic peptide were fluid. This raised the interesting question of how long a homochiral sequence must be to result in solid phase formation. In this work, we designed chiral patterned peptides of polyglutamic acid and polylysine ranging from 50 to 90% L-chiral residues with increasing numbers of sequential L-chiral residues before a chirality change. These polymers were mixed together to form PECs. We observed that 8 or more sequential L-chiral residues are necessary to achieve both the appearance of a precipitate phase and sustained β-sheets in the complex, as determined by optical imaging and FTIR Spectroscopy. Less homochiral content results in formation of a coacervate phase. Thus, we show that chiral sequence can be used to control the phase transition of PECs. Understanding how to manipulate PEC phase using chiral sequence as presented here may enable tuning of the material properties to achieve the desired mechanical strength for coatings and polymer brushes, or the most effective molecular release kinetics for drug delivery applications, for example.

Battery structures, self-organizing structures, and related methods

DOEpatents

Chiang, Yet-Ming; Moorehead, William Douglas

2013-11-19

An energy storage device includes a first electrode comprising a first material and a second electrode comprising a second material, at least a portion of the first and second materials forming an interpenetrating network when dispersed in an electrolyte, the electrolyte, the first material and the second material are selected so that the first and second materials exert a repelling forve on each other when combined. An electrochemical device, includes a first electrode in electrical communication with a first current collector; a second electrode in electrical communication with a second current collector; and an ionicaily conductive medium in ionic contact with said first and second electrodes, wherein at least a portion of the first and second electrodes form an interpenetrating network and wherein at least one of the first and second electrodes comprises an electrode structure providing two or more pathways to its current collector.

Battery Structures, self-organizing structures, and related methods

DOEpatents

Chiang, Yet-Ming; Moorehead, William Douglas

2013-11-12

An energy storage device includes a first electrode comprising a first material and a second electrode comprising a second material, at least a portion of the first and second materials forming an interpenetrating network when dispersed in an electrolyte, the electrolyte, the first material and the second material are selected so that the first and second materials exert a repelling force on each other when combined. An electrochemical device, includes a first electrode in electrical communication with a first current collector; a second electrode in electrical communication with a second current collector; and an ionically conductive medium in ionic contact with said first and second electrodes, wherein at least a portion of the first and second electrodes form an interpenetrating network and wherein at least one of the first and second electrodes comprises an electrode structure providing two or more pathways to its current collector.

Battery structures, self-organizing structures and related methods

DOEpatents

Chiang, Yet-Ming [Framingham, MA; Moorehead, William Douglas [Virginia Beach, VA

2012-06-26

An energy storage device includes a first electrode comprising a first material and a second electrode comprising a second material, at least a portion of the first and second materials forming an interpenetrating network when dispersed in an electrolyte, the electrolyte, the first material and the second material are selected so that the first and second materials exert a repelling force on each other when combined. An electrochemical device, includes a first electrode in electrical communication with a first current collector; a second electrode in electrical communication with a second current collector; and an ionically conductive medium in ionic contact with said first and second electrodes, wherein at least a portion of the first and second electrodes form an interpenetrating network and wherein at least one of the first and second electrodes comprises an electrode structure providing two or more pathways to its current collector.

Unique Chiral Interpenetrating d-f Heterometallic MOFs as Luminescent Sensors.

PubMed

Wu, Zhi-Lei; Dong, Jie; Ni, Wei-Yan; Zhang, Bo-Wen; Cui, Jian-Zhong; Zhao, Bin

2015-06-01

One novel three-dimensional (3D) 3d-4f metal-organic framework (MOF), [TbZn(L)(CO3)2(H2O)]n (1) [HL = 4'-(4-carboxyphenyl)-2,2':6',2″-terpyridine], has been successfully synthesized and structurally characterized. Structural analysis shows that compound 1 features a unique chiral interpenetrating 3D framework for the first time. The resulting crystals of 1 are composed of enantiomers 1a (P41) and 1b (P43), as was clearly confirmed by the crystal structure and the corresponding circular dichroism (CD) analyses of eight randomly selected crystals. The investigations on CD spectra based on every single crystal clearly assigned the Cotton effect signals. The powder X-ray diffraction measurement of 1 after being immersed in common solvents reveals that 1 possess excellent solvent stability. Furthermore, luminescent studies imply that 1 displays highly selective luminescent sensing of aldehydes, such as formol, acetaldehyde, and propanal.

Series of chiral interpenetrating 3d-4f heterometallic MOFs: Luminescent sensors and magnetic properties

NASA Astrophysics Data System (ADS)

Zhang, Xiaolei; Chen, Chen; Liu, Xiaoli; Gao, Peng; Hu, Ming

2017-09-01

Series of chiral 3d-4f heterometallic MOFs based on a multidentate terpyridyl carboxylic acid ligand have been synthesized under the solvothermal conditions, namely, [LnZnL(CO3)2(H2O)]n (Ln = Eu (1), Gd (2), Dy (3), Ho (4), Er (5), Tm (6), Yb (7), Lu (8)) (HL = 4‧-(4-carboxyphenyl)-2,2‧:6‧,2″-terpyridine). Compounds 1-8 were structurally characterized by the elemental analyses, infrared spectra, and single crystal X-ray diffractions. Compounds 1-8 exhibit the chiral interpenetrating 3D frameworks. Interestingly, 1 can serve as the luminescent sensor to detect nitrobenzene molecules with high sensitivity. The investigations on CD spectra of single crystals clearly assigned the Cotton effect, indicating that there exist two chiral enantiomers of 1-8 in the course of crystallization. The magnetic properties of 2 and 7 were exploited, respectively.

Battery structures, self-organizing structures and related methods

DOEpatents

Chiang, Yet Ming [Framingham, MA; Moorehead, William Douglas [Virginia Beach, VA; Gozdz, Antoni S [Marlborough, MA; Holman, Richard K [Belmont, MA; Loxley, Andrew [Somerville, MA; Riley, Jr., Gilbert N.; Viola, Michael S [Burlington, MA

2009-08-25

An energy storage device includes a first electrode comprising a first material and a second electrode comprising a second material, at least a portion of the first and second materials forming an interpenetrating network when dispersed in an electrolyte, the electrolyte, the first material and the second material are selected so that the first and second materials exert a repelling force on each other when combined. An electrochemical device, includes a first electrode in electrical communication with a first current collector; a second electrode in electrical communication with a second current collector; and an ionically conductive medium in ionic contact with said first and second electrodes, wherein at least a portion of the first and second electrodes form an interpenetrating network and wherein at least one of the first and second electrodes comprises an electrode structure providing two or more pathways to its current collector.

Battery structures, self-organizing structures and related methods

DOEpatents

Chiang, Yet-Ming [Framingham, MA; Moorehead, William D [Virginia Beach, VA; Gozdz, Antoni S [Marlborough, MA; Holman, Richard K [Belmont, MA; Loxley, Andrew L [Roslindale, MA; Riley, Jr., Gilbert N.; Viola, Michael S [Burlington, MA

2012-05-01

An energy storage device includes a first electrode comprising a first material and a second electrode comprising a second material, at least a portion of the first and second materials forming an interpenetrating network when dispersed in an electrolyte, the electrolyte, the first material and the second material are selected so that the first and second materials exert a repelling force on each other when combined. An electrochemical device, includes a first electrode in electrical communication with a first current collector; a second electrode in electrical communication with a second current collector; and an ionically conductive medium in ionic contact with said first and second electrodes, wherein at least a portion of the first and second electrodes form an interpenetrating network and wherein at least one of the first and second electrodes comprises an electrode structure providing two or more pathways to its current collector.

Battery structures, self-organizing structures and related methods

DOEpatents

Chiang, Yet-Ming [Framingham, MA; Moorehead, William D [Virginia Beach, VA; Gozdz, Antoni S [Marlborough, MA; Holman, Richard K [Belmont, MA; Loxley, Andrew L [Roslindale, MA; Riley, Jr., Gilbert N.; Viola, Michael S [Burlington, MA

2011-08-02

An energy storage device includes a first electrode comprising a first material and a second electrode comprising a second material, at least a portion of the first and second materials forming an interpenetrating network when dispersed in an electrolyte, the electrolyte, the first material and the second material are selected so that the first and second materials exert a repelling force on each other when combined. An electrochemical device, includes a first electrode in electrical communication with a first current collector; a second electrode in electrical communication with a second current collector; and an ionically conductive medium in ionic contact with said first and second electrodes, wherein at least a portion of the first and second electrodes form an interpenetrating network and wherein at least one of the first and second electrodes comprises an electrode structure providing two or more pathways to its current collector.

Partially Interpenetrated NbO Topology Metal–Organic Framework Exhibiting Selective Gas Adsorption

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

Verma, Gaurav; Kumar, Sanjay; Pham, Tony

2017-03-29

We report on the first partially interpenetrated metal–organic framework (MOF) with NbO topology for its ability to separate methane from carbon dioxide and permanently sequester the greenhouse gas CO2. The MOF, Cu2(pbpta) (H4pbpta = 4,4',4'',4'''-(1,4-phenylenbis(pyridine-4,2-6-triyl))-tetrabenzoic acid), crystallizes in the monoclinic C2/m space group and has a 2537 m2/g Brunauer, Emmett and Teller surface area with an 1.06 cm3/g pore volume. The MOF exhibits selective adsorption of CO2 over CH4 as well as that of C2H6 and C2H4 over CH4. Cu2(pbpta) additionally shows excellent catalytic efficacy for the cycloaddition reaction of CO2 with epoxides to produce industrially important cyclic carbonates usingmore » solvent-free conditions.« less

Compressed glassy carbon: An ultrastrong and elastic interpenetrating graphene network

PubMed Central

Hu, Meng; He, Julong; Zhao, Zhisheng; Strobel, Timothy A.; Hu, Wentao; Yu, Dongli; Sun, Hao; Liu, Lingyu; Li, Zihe; Ma, Mengdong; Kono, Yoshio; Shu, Jinfu; Mao, Ho-kwang; Fei, Yingwei; Shen, Guoyin; Wang, Yanbin; Juhl, Stephen J.; Huang, Jian Yu; Liu, Zhongyuan; Xu, Bo; Tian, Yongjun

2017-01-01

Carbon’s unique ability to have both sp2 and sp3 bonding states gives rise to a range of physical attributes, including excellent mechanical and electrical properties. We show that a series of lightweight, ultrastrong, hard, elastic, and conductive carbons are recovered after compressing sp2-hybridized glassy carbon at various temperatures. Compression induces the local buckling of graphene sheets through sp3 nodes to form interpenetrating graphene networks with long-range disorder and short-range order on the nanometer scale. The compressed glassy carbons have extraordinary specific compressive strengths—more than two times that of commonly used ceramics—and simultaneously exhibit robust elastic recovery in response to local deformations. This type of carbon is an optimal ultralight, ultrastrong material for a wide range of multifunctional applications, and the synthesis methodology demonstrates potential to access entirely new metastable materials with exceptional properties. PMID:28630918

High-volume-fraction Cu/Al2O3-SiC hybrid interpenetrating phase composite

NASA Astrophysics Data System (ADS)

Saidi, Hesam; Roudini, Ghodratollah; Afarani, Mahdi Shafiee

2015-10-01

Metal matrix particulate interpenetrating phase composites are a class of composites materials with three-dimensional internal connections of matrix and reinforcements. This kind of microstructure affects the mechanical and physical properties of the composites. In this study, Al2O3-SiC hybrid preforms were produced by polyurethane foams removal (replica method) within mean pore size of 30 pores per inch (ppi), and sintering at 1200 °C. Subsequently, the molten copper was infiltrated into the preforms by squeeze casting method. The microstructure, density, porosity, bending strength and thermal shock resistance of the preforms were investigated. Then, the composites microstructure and compressive strength were studied. The results showed that with SiC concentration increasing, the density, flexural strength and thermal shock resistance of the preforms were improved. Also the composites compressive strengths were changed with variation of SiC concentration.

Magnetic field advection in two interpenetrating plasma streams

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

Ryutov, D. D.; Kugland, N. L.; Levy, M. C.

2013-03-15

Laser-generated colliding plasma streams can serve as a test-bed for the study of various astrophysical phenomena and the general physics of self-organization. For streams of a sufficiently high kinetic energy, collisions between the ions of one stream with the ions of the other stream are negligible, and the streams can penetrate through each other. On the other hand, the intra-stream collisions for high-Mach-number flows can still be very frequent, so that each stream can be described hydrodynamically. This paper presents an analytical study of the effects that these interpenetrating streams have on large-scale magnetic fields either introduced by external coilsmore » or generated in the plasma near the laser targets. Specifically, a problem of the frozen-in constraint is assessed and paradoxical features of the field advection in this system are revealed. A possibility of using this system for studies of magnetic reconnection is mentioned.« less

Preparation and Electrochemical Characterization of Mesoporous Polyaniline-Silica Nanocomposites as an Electrode Material for Pseudocapacitors

PubMed Central

Zu, Lei; Cui, Xiuguo; Jiang, Yanhua; Hu, Zhongkai; Lian, Huiqin; Liu, Yang; Jin, Yushun; Li, Yan; Wang, Xiaodong

2015-01-01

Mesoporous polyaniline-silica nanocomposites with a full interpenetrating structure for pseudocapacitors were synthesized via the vapor phase approach. The morphology and structure of the nanocomposites were deeply investigated by scanning electron microscopy, infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis and nitrogen adsorption-desorption tests. The results present that the mesoporous nanocomposites possess a uniform particle morphology and full interpenetrating structure, leading to a continuous conductive polyaniline network with a large specific surface area. The electrochemical performances of the nanocomposites were tested in a mixed solution of sulfuric acid and potassium iodide. With the merits of a large specific surface area and suitable pore size distribution, the nanocomposite showed a large specific capacitance (1702.68 farad (F)/g) due to its higher utilization of the active material. This amazing value is almost three-times larger than that of bulk polyaniline when the same mass of active material was used. PMID:28788006

Calculation of Thomson scattering spectral fits for interpenetrating flows

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

Swadling, G. F., E-mail: george.swadling@imperial.ac.uk; Lebedev, S. V., E-mail: george.swadling@imperial.ac.uk; Burdiak, G. C.

2014-12-15

Collective mode optical Thomson scattering has been used to investigate the interactions of radially convergent ablation flows in Tungsten wire arrays. These experiments were carried out at the Magpie pulsed power facility at Imperial College, London. Analysis of the scattered spectra has provided direct evidence of ablation stream interpenetration on the array axis, and has also revealed a previously unobserved axial deflection of the ablation streams towards the anode as they approach the axis. It is has been suggested that this deflection is caused by the presence of a static magnetic field, advected with the ablation streams, stagnated and accruedmore » around the axis. Analysis of the Thomson scattering spectra involved the calculation and fitting of the multi-component, non-relativistic, Maxwellian spectral density function S (k, ω). The method used to calculate the fits of the data are discussed in detail.« less

Experimental characterization of a transition from collisionless to collisional interaction between head-on-merging supersonic plasma jets

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

Moser, Auna L., E-mail: mosera@fusion.gat.com; Hsu, Scott C., E-mail: scotthsu@lanl.gov

We present results from experiments on the head-on merging of two supersonic plasma jets in an initially collisionless regime for the counter-streaming ions. The plasma jets are of either an argon/impurity or hydrogen/impurity mixture and are produced by pulsed-power-driven railguns. Based on time- and space-resolved fast-imaging, multi-chord interferometry, and survey-spectroscopy measurements of the overlapping region between the merging jets, we observe that the jets initially interpenetrate, consistent with calculated inter-jet ion collision lengths, which are long. As the jets interpenetrate, a rising mean-charge state causes a rapid decrease in the inter-jet ion collision length. Finally, the interaction becomes collisional andmore » the jets stagnate, eventually producing structures consistent with collisional shocks. These experimental observations can aid in the validation of plasma collisionality and ionization models for plasmas with complex equations of state.« less

Intercalation of Coordinatively Unsaturated Fe(III) Ion within Interpenetrated Metal-Organic Framework MOF-5.

PubMed

Holmberg, Rebecca J; Burns, Thomas; Greer, Samuel M; Kobera, Libor; Stoian, Sebastian A; Korobkov, Ilia; Hill, Stephen; Bryce, David L; Woo, Tom K; Murugesu, Muralee

2016-06-01

Coordinatively unsaturated Fe(III) metal sites were successfully incorporated into the iconic MOF-5 framework. This new structure, Fe(III) -iMOF-5, is the first example of an interpenetrated MOF linked through intercalated metal ions. Structural characterization was performed with single-crystal and powder XRD, followed by extensive analysis by spectroscopic methods and solid-state NMR, which reveals the paramagnetic ion through its interaction with the framework. EPR and Mössbauer spectroscopy confirmed that the intercalated ions were indeed Fe(III) , whereas DFT calculations were employed to ascertain the unique pentacoordinate architecture around the Fe(III) ion. Interestingly, this is also the first crystallographic evidence of pentacoordinate Zn(II) within the MOF-5 SBU. This new MOF structure displays the potential for metal-site addition as a framework connector, thus creating further opportunity for the innovative development of new MOF materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Use of sequential infiltration synthesis to improve the pattern transfer of PS-b-PLA DSA (Conference Presentation)

NASA Astrophysics Data System (ADS)

Evangelio Araujo, Laura; Fernández-Regúlez, Marta; Chevalier, Xavier; Nicolet, Célia; Cayrefourcq, Ian; Navarro, Christophe; Fleury, Guillaume; Pérez-Murano, Francesc

2017-03-01

Directed self-assembly of block copolymers is considered one of the candidates to fulfill the requirements of the next technological nodes [1,2]. Polymer domains are aligned by using a chemical and/or a topographical pre-pattern in which preferential surfaces to one of the two blocks or neutral wetting areas are created. In particular, polystyrene-block-polymetylmethacrylate (PS-b-PMMA) has been extensively studied during the last years showing strong capabilities to define periodic nanostructures. However, the relatively low Flory-Huggins parameter and, the resulting low segregation strength of PS-b-PMMA systems, limit their achievable resolution to around 11 nm [3]. The application of block copolymer on sub-10 nm technologies requires the development of the new block copolymer generation known as high- block copolymers. Additionally, an important requirement for their integration on the lithography roadmap is the capability of selectively remove one of the two blocks. The etch contrast between the two domains is typically low due to their organic chemistry. In this sense, selective sequential infiltration synthesis by ALD into one of the blocks can be used in order to incorporate an inorganic material. The formed organic/inorganic blend sustains better the plasma etching to remove the non-infiltrated organic block. In this contribution, we show the use of high- polystyrene-b-polylactide acid (PS-b-PLA) lamellar block copolymer for line/space applications. PS-b-PLA has a larger Flory-Huggins parameter (=0.218 at room temperature[4]) compared with PS-b-PMMA, allowing the size reduction of the self-assembled domains. The method to control the orientation of the polymer domains is similar to the one typically used for PS-b-PMMA. Chemical contrast and the subsequent alignment of the polymer domains are achieved by the definition of a chemical pre-pattern on a random copolymer PS-r-PMMA (48% of PS) (figure 1). The polymer brush is grafted on the substrate and then locally modified by the combination of e-beam lithography and soft oxygen plasma. Afterwards, the PS-b-PLA block copolymer is spin-coated and thermally annealed on the chemically pre-patterned substrate. A chemical contrast is observed between the modified and unmodified stripes. While, the lamellar domains are oriented perpendicular to the substrate on unmodified areas, PLA domains are strongly attracted to the O2 modified surfaces inducing a parallel orientation to the substrate. Additionally, the wetting behavior of the polymer domains is also studied through the difference of surface free energy between the substrate and each polymer block. The energy estimated by the Younǵs equation [Δγ =γSA -γSB= γAB·cos(ØAB)], where γSA and γSB are the interface tensions between homo-polymers A and B with the substrate, and ØAB is the contact angle between A and B homo-polymers which is obtained in de-wetting experiments. Finally, sequential infiltration synthesis is used to selectively infiltrate alumina (Al3O2) on PLA domains (figure 2). A selective infiltration is achieved because the precursor molecules react with the carbonyl (C=O) groups that are only present in the PLA block. After five cycles of SIS, the SIS modified PLA domains become more resistant to O2 plasma etching than PS enabling the PS etching without using other kind of hard-masks. The research leading to these results received funding from the European Union's Seventh Framework Program FP7/2007-2013, under the project CoLiSA and the European Nanoelectronics Initiative Advisory Council under the project PLACYD (ENIAC-2013-2). L. Evangelio acknowledges MECD for the PhD contract FPU13/03746 [1] R. Ruiz, H. Kang, F. A. Detcheverry, E. Dobisz, D. S. Kercher, T. R. Albrecht, J. J. de Pablo, P. F. Nealey, Science 321 (2008) 936-939. [2] M. Fernández-Regúlez, L, Evangelio, M. Lorenzoni, J. Fraxedas, F. Perez-Murano, ACS Appl. Mater. Interfaces 6 (2014) 21596-21602. [3] L. Wan, R. Ruiz, H. Gao, K. C. Patel, T. R. Albrecht, J. Yin, J. Kim, Y. Cao, G. Lin, ACS Nano 9 (2015) 7506-7514 [4] A. S. Zalusky, R. Olayo-Valles , J. H. Wolf , M. A. Hillmyer, J. Am. Chem. Soc. 124 (2002) 12761-12773

Multilayer white lighting polymer light-emitting diodes

NASA Astrophysics Data System (ADS)

Gong, Xiong; Wang, Shu; Heeger, Alan J.

2006-08-01

Organic and polymer light-emitting diodes (OLEDs/PLEDs) that emit white light are of interest and potential importance for use in active matrix displays (with color filters) and because they might eventually be used for solid-state lighting. In such applications, large-area devices and low-cost of manufacturing will be major issues. We demonstrated that high performance multilayer white emitting PLEDs can be fabricated by using a blend of luminescent semiconducting polymers and organometallic complexes as the emission layer, and water-soluble (or ethanol-soluble) polymers/small molecules (for example, PVK-SO 3Li) as the hole injection/transport layer (HIL/HTL) and water-soluble (or ethanol-soluble) polymers/small molecules (for example, t-Bu-PBD-SO 3Na) as the electron injection/transport layer (EIL/HTL). Each layer is spin-cast sequentially from solutions. Illumination quality light is obtained with stable Commission Internationale d'Eclairage coordinates, stable color temperatures, and stable high color rendering indices, all close to those of "pure" white. The multilayer white-emitting PLEDs exhibit luminous efficiency of 21 cd/A, power efficiency of 6 lm/W at a current density of 23 mA/cm2 with luminance of 5.5 x 10 4 cd/m2 at 16 V. By using water-soluble (ethanol-soluble) polymers/small molecules as HIL/HTL and polymers/small molecules as EIL/ETL, the interfacial mixing problem is solved (the emissive polymer layer is soluble in organic solvents, but not in water/ ethanol). As a result, this device architecture and process technology can potentially be used for printing large-area multiplayer light sources and for other applications in "plastic" electronics. More important, the promise of producing large areas of high quality white light with low-cost manufacturing technology makes the white multilayer white-emitting PLEDs attractive for the development of solid state light sources.

Challenges in Laser Sintering of Melt-Processable Thermoset Imide Resin

NASA Technical Reports Server (NTRS)

Chuang, Kathy C.; Gornet, Timothy; Koerner, Hilmar

2016-01-01

Polymer Laser Sintering (LS) is an additive manufacturing technique that builds 3D models layer by layer using a laser to selectively melt cross sections in powdered polymeric materials, following sequential slices of the CAD model. LS generally uses thermoplastic polymeric powders, such as polyamides (i.e. Nylon), and the resultant 3D objects are often weaker in their strength compared to traditionally processed materials, due to the lack of polymer inter-chain connection in the z-direction. The objective of this project is to investigate the possibility of printing a melt-processable RTM370 imide resin powder terminated with reactive phenylethynyl groups by LS, followed by a postcure in order to promote additional crosslinking to achieve higher temperature (250-300 C) capability. A preliminary study to build tensile specimens by LS and the corresponding DSC and rheology study of RTM370 during LS process is presented.

Challenges in Laser Sintering of Thermoset Imide Resin

NASA Technical Reports Server (NTRS)

Chuang, Kathy C.; Gornet, Timothy; Koerner, Hilmar

2016-01-01

Polymer Laser Sintering (LS) is an additive manufacturing technique that builds 3D models layer by layer using a laser to selectively melt cross sections in powdered polymeric materials, following sequential slices of the CAD model. LS generally uses thermoplastic polymeric powders, such as polyamides (i.e. Nylon), and the resultant 3D objects are often weaker in their strength compared to traditionally processed materials, due to the lack of polymer inter-chain connection in the z-direction. The objective of this project is to investigate the possibility of printing a melt-processable RTM370 imide resin powder terminated with reactive phenylethynyl groups by LS, followed by a postcure in order to promote additional crosslinking to achieve higher temperature (250-300 C) capability. A preliminary study to build tensile specimens by LS and the corresponding DSC and rheology study of RTM370 during LS process is presented.

Statistics of lattice animals

NASA Astrophysics Data System (ADS)

Hsu, Hsiao-Ping; Nadler, Walder; Grassberger, Peter

2005-07-01

The scaling behavior of randomly branched polymers in a good solvent is studied in two to nine dimensions, modeled by lattice animals on simple hypercubic lattices. For the simulations, we use a biased sequential sampling algorithm with re-sampling, similar to the pruned-enriched Rosenbluth method (PERM) used extensively for linear polymers. We obtain high statistics of animals with up to several thousand sites in all dimension 2⩽d⩽9. The partition sum (number of different animals) and gyration radii are estimated. In all dimensions we verify the Parisi-Sourlas prediction, and we verify all exactly known critical exponents in dimensions 2, 3, 4, and ⩾8. In addition, we present the hitherto most precise estimates for growth constants in d⩾3. For clusters with one site attached to an attractive surface, we verify the superuniversality of the cross-over exponent at the adsorption transition predicted by Janssen and Lyssy.

Nanospace-Mediated Self-Organization of Nanoparticles in Flexible Porous Polymer Templates.

PubMed

Kuroda, Yoshiyuki; Muto, Itaru; Shimojima, Atsushi; Wada, Hiroaki; Kuroda, Kazuyuki

2017-09-12

Self-organization is a fundamental process for the construction of complex hierarchically ordered nanostructures, which are widespread in biological systems. However, precise control of size, shape, and surface properties is required for self-organization of nanoparticles. Here, we demonstrate a novel self-organization phenomenon mediated by flexible nanospaces in templates. Inorganic nanoparticles (e.g., silica, zirconia, and titania) are deposited in porous polymer thin films with randomly distributed pores on the surface, leaving a partially filled nanospace in each pore. Heating at temperatures beyond the glass transition temperature of the template leads to self-organization of the inorganic nanoparticles into one-dimensional chainlike networks. The self-organization is mediated by the deformation and fusion of the residual nanospaces, and it can be rationally controlled by sequential heat treatments. These results show that a nanospace, defined by the nonexistence of matter, interacts indirectly with matter and can be used as a component of self-organization systems.

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

Fuel cell water transport

DOEpatents

Vanderborgh, Nicholas E.; Hedstrom, James C.

1990-01-01

The moisture content and temperature of hydrogen and oxygen gases is regulated throughout traverse of the gases in a fuel cell incorporating a solid polymer membrane. At least one of the gases traverses a first flow field adjacent the solid polymer membrane, where chemical reactions occur to generate an electrical current. A second flow field is located sequential with the first flow field and incorporates a membrane for effective water transport. A control fluid is then circulated adjacent the second membrane on the face opposite the fuel cell gas wherein moisture is either transported from the control fluid to humidify a fuel gas, e.g., hydrogen, or to the control fluid to prevent excess water buildup in the oxidizer gas, e.g., oxygen. Evaporation of water into the control gas and the control gas temperature act to control the fuel cell gas temperatures throughout the traverse of the fuel cell by the gases.

Synthesis and Properties of Poly(l-lactide)-b-poly (l-phenylalanine) Hybrid Copolymers

PubMed Central

Planellas, Marc; Puiggalí, Jordi

2014-01-01

Hybrid materials constituted by peptides and synthetic polymers have nowadays a great interest since they can combine the properties and functions of each constitutive block, being also possible to modify the final characteristics by using different topologies. Poly(l-lactide-b-l-phenylalanine) copolymers with various block lengths were synthesized by sequential ring-opening polymerization of l-lactide and the N-carboxyanhydride of l-phenylalanine. The resulting block copolymers were characterized by NMR spectrometry, IR spectroscopy, gel permeation chromatography, MALDI-TOF and UV-vis, revealing the successful incorporation of the polyphenylalanine (PPhe) peptide into the previously formed poly(l-lactide) (PLLA) polymer chain. X-ray diffraction and DSC data also suggested that the copolymers were phase-separated in domains containing either crystalline PLLA or PPhe phases. A peculiar thermal behavior was also found by thermogravimetric analysis when polyphenylalanine blocks were incorporated into polylactide. PMID:25075980

Synthesis and properties of poly(L-lactide)-b-poly (L-phenylalanine) hybrid copolymers.

PubMed

Planellas, Marc; Puiggalí, Jordi

2014-07-29

Hybrid materials constituted by peptides and synthetic polymers have nowadays a great interest since they can combine the properties and functions of each constitutive block, being also possible to modify the final characteristics by using different topologies. Poly(l-lactide-b-l-phenylalanine) copolymers with various block lengths were synthesized by sequential ring-opening polymerization of l-lactide and the N-carboxyanhydride of l-phenylalanine. The resulting block copolymers were characterized by NMR spectrometry, IR spectroscopy, gel permeation chromatography, MALDI-TOF and UV-vis, revealing the successful incorporation of the polyphenylalanine (PPhe) peptide into the previously formed poly(l-lactide) (PLLA) polymer chain. X-ray diffraction and DSC data also suggested that the copolymers were phase-separated in domains containing either crystalline PLLA or PPhe phases. A peculiar thermal behavior was also found by thermogravimetric analysis when polyphenylalanine blocks were incorporated into polylactide.

Space environmental effects on polymeric materials

NASA Technical Reports Server (NTRS)

Kiefer, Richard L.; Orwoll, Robert A.

1987-01-01

Polymeric materials that may be exposed on spacecraft to the hostile environment beyond Earth's atmosphere were subjected to atomic oxygen, electron bombardment, and ultraviolet radiation in terrestrial experiments. Evidence is presented for the utility of an inexpensive asher for determining the relative susceptibility of organic polymers to atomic oxygen. Kapton, Ultem, P1700 polysulfone, and m-CBB/BIS-A (a specially formulated polymer prepared at NASA Langley) all eroded at high rates, just as was observed in shuttle experiments. Films of Ultem, P1700 polysulfone, and m-CBB/BIS-A were irradiated with 85 keV electrons. The UV/VIS absorbance of Ultem was found to decay with time after irradiation, indicating free radical decay. The tensile properties of Ultem began to change only after it had been exposed to 100 Mrads. The effects of dose rate, temperature, and simultaneous vs. sequential electron and UV irradiation were also studied.

Photo-crosslinkable polymers for fabrication of photonic multilayer sensors

NASA Astrophysics Data System (ADS)

Chiappelli, Maria; Hayward, Ryan C.

2013-03-01

We have used photo-crosslinkable polymers to fabricate photonic multilayer sensors. Benzophenone is utilized as a covalently incorporated pendent photo-crosslinker, providing a convenient means of fabricating multilayer films by sequential spin-coating and crosslinking processes. Colorimetric temperature sensors were designed from thermally-responsive, low-refractive index poly(N-isopropylacrylamide) (PNIPAM) and high-refractive index poly(para-methyl styrene) (P pMS). Copolymer chemistries and layer thicknesses were selected to provide robust multilayer sensors which show color changes across nearly the full visible spectrum due to changes in temperature of the hydrated film stack. We have characterized the uniformity and interfacial broadening within the multilayers, the kinetics of swelling and de-swelling, and the reversibility over multiple hydration/dehydration cycles. We also describe how the approach can be extended to alternative sensor designs through the ability to tailor each layer independently, as well as to additional stimuli by selecting alternative copolymer chemistries.

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

Thermally responsive polymer systems for self-healing, reversible adhesion and shape memory applications

NASA Astrophysics Data System (ADS)

Luo, Xiaofan

Responsive polymers are "smart" materials that are capable of performing prescribed, dynamic functions under an applied stimulus. In this dissertation, we explore several novel design strategies to develop thermally responsive polymers and polymer composites for self-healing, reversible adhesion and shape memory applications. In the first case described in Chapters 2 and 3, a thermally triggered self-healing material was prepared by blending a high-temperature epoxy resin with a thermoplastic polymer, poly(epsilon-caprolactone) (PCL). The initially miscible system undergoes polymerization induced phase separation (PIPS) during the curing of epoxy and yields a variety of compositionally dependent morphologies. At a particular PCL loading, the cured blend displays a "bricks-and-mortar" morphology in which epoxy exists as interconnected spheres ("bricks") within a continuous PCL matrix ("mortar"). A heat induced "bleeding" phenomenon was observed in the form of spontaneous wetting of all free surfaces by the molten PCL, and is attributed to the volumetric thermal expansion of PCL above its melting point in excess of epoxy brick expansion, which we term differential expansive bleeding (DEB). This DEB is capable of healing damage such as cracks. In controlled self-healing experiments, heating of a cracked specimen led to PCL bleeding from the bulk that yields a liquid layer bridging the crack gap. Upon cooling, a "scar" composed of PCL crystals was formed at the site of the crack, restoring a significant portion of mechanical strength. We further utilized DEB to enable strong and thermally-reversible adhesion of the material to itself and to metallic substrates, without any requirement for macroscopic softening or flow. After that, Chapters 4--6 present a novel composite strategy for the design and fabrication of shape memory polymer composites. The basic approach involves physically combining two or more functional components into an interpenetrating fiber/matrix structure, allowing them to function in a synergistic fashion yet remain physically separated. This latter aspect is critical since it enables the control of overall composite properties and functions by separately tuning each component. Utilizing the intrinsic versatility of this approach, composites with novel properties and functions (in addition to "regular" shape memory) have been developed, including (1) shape memory elastomeric composites (SMECs; Chapter 4), (2) triple-shape polymeric composites (TSPCs; Chapter 5), and (3) electrically conductive nanocomposites (Chapter 6). Then in Chapter 7, by combining the success in both thermoplastic based self-healing and shape memory polymer composites, we demonstrate a thermally triggered self-healing coating. This coating features a unique "shape memory assisted self-healing" mechanism in which crack closure (via shape memory) and crack re-bonding (via melting and diffusion of the thermoplastic healing agent) are achieved simultaneously upon a single heating step, leading to both structural and functional (corrosion resistance) recovery. Finally, Chapter 8 presents for the first time the preparation of functionally graded shape memory polymers (SMPs) that, unlike conventional SMPs, have a range of glass transition temperatures that are spatially graded. This was achieved using a temperature gradient curing method that imposes different vitrification limits at different positions along the gradient. The resulting material is capable of responding to a wide range of thermal triggers and a good candidate for low-cost, material based temperature sensors. All the aforementioned materials and methods show great potential for practical applications due to their high performance, low cost and broad applicability. Some recommendations for future research and development are given in Chapter 9.

Controlled delivery of paclitaxel from stent coatings using poly(hydroxystyrene-b-isobutylene-b-hydroxystyrene) and its acetylated derivative.

PubMed

Sipos, Laszlo; Som, Abhijit; Faust, Rudolf; Richard, Robert; Schwarz, Marlene; Ranade, Shrirang; Boden, Mark; Chan, Ken

2005-01-01

A poly(styrene-b-isobutylene-b-styrene) (SIBS) triblock polymer is employed as the polymer drug carrier for the TAXUS Express2 Paclitaxel-Eluting Coronary Stent system (Boston Scientific Corp.). It has been shown that the release of paclitaxel (PTx) from SIBS can be modulated by modification of either drug-loading ratio or altering the triblock morphology by blending. In the present work, results toward achieving release modulation of PTx by chemical modification of the styrenic portion (using hydroxystyrene or its acetylated version) of the SIBS polymer system are reported. The synthesis of the precursor poly[(p-tert-butyldimethylsilyloxystyrene)]-b-isobutylene-b-[(p-tert-butyldimethylsilyloxystyrene] triblock copolymers was accomplished by living sequential block copolymerization of isobutylene (IB) and p-(tert-butyldimethylsiloxy)styrene (TBDMS) utilizing the capping-tuning technique in a one-pot procedure in methylcyclohexane/CH3Cl at -80 degrees C. This procedure involved the living cationic polymerization of IB with the 5-tert-butyl-1,3-bis(1-chloro-1-methylethyl)benzene/TiCl4 initiating system and capping of living difunctional polyisobutylene (PIB) chain ends with 1,1-ditolylethylene (DTE) followed by addition of titanium(IV) isopropoxide (Ti(OIp)4) to lower the Lewis acidity before the introduction of TBDMS. Deprotection of the product with tetrabutylammonium fluoride yielded poly(hydroxystyrene-b-isobutylene-b-hydroxystyrene), which was quantitatively acetylated to obtain the acetylated derivative. The hydroxystyrene and acetoxystyrene triblock copolymers have acceptable mechanical properties for use as drug delivery coatings for coronary stent applications. It was concluded that the hydrophilic nature of the endblocks and polarity effects on the drug/polymer miscibility lead to enhanced release of PTx from these polymers. The drug-polymer miscibility was confirmed by differential scanning calorimetry and atomic force microscopy evaluations.

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

Kennemur, Justin G.; Bates, Frank S.; Hillmyer, Marc A.

Synthesis of poly(methyl ethacrylate), (PMEA), in tetrahydrofuran at -78 °C using anionic polymerization techniques results in high molar mass (>30 kg mol-1), low dispersity (1.3), and high conversion (>81%). The molar masses of a series of samples are consistent with values anticipated by the monomer-to-initiator ratio and conversion. These results represent a significant improvement to earlier reported attempts to prepare PMEA using anionic methods. Successful diblock polymerization of polystyrene-block-PMEA, (PS-PMEA), and poly(4-tert-butylstyrene)-block-PMEA, (PtBS-PMEA), is achieved through sequential anionic polymerization techniques with dispersities as low as 1.06 and segment molar fractions close to those targeted. Broad principal scattering peaks observed bymore » small-angle X-ray scattering (SAXS) for symmetric PS-PMEA at relatively high molar mass (39 kg mol-1) suggests an effective interaction parameter (χeff) that is smaller than for PS-block-poly(methyl methacrylate). On the other hand, PtBS-PMEA block polymers form a well-ordered morphology based on SAXS measurements and is attributable to the more hydrophobic PtBS segment. These results confirm the viability of PMEA as a new constituent in the expanding suite of polymers suitable for preparing nanostructured block polymers.« less

Mechanistic Understanding of Tungsten Oxide In-Plane Nanostructure Growth via Sequential Infiltration Synthesis

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

Kim, Jae Jin; Suh, Hyo Seon; Zhou, Chun

Tungsten oxide (WO3-x) nanostructures with hexagonal in-plane arrangements were fabricated by sequential infiltration synthesis (SIS), using the selective interaction of gas phase precursors with functional groups in one domain of a block copolymer (BCP) self-assembled template. Such structures are highly desirable for various practical applications and as model systems for fundamental studies. The nanostructures were characterized by cross-sectional scanning electron microscopy, grazing-incidence small/wide-angle X-ray scattering (GISAXS/GIWAXS), and X-ray absorption near edge structure (XANES) measurements at each stage during the SIS process and subsequent thermal treatments, to provide a comprehensive picture of their evolution in morphology, crystallography and electronic structure. Inmore » particular, we discuss the critical role of SIS Al2O3 seeds toward modifying the chemical affinity and free volume in a polymer for subsequent infiltration of gas phase precursors. The insights into SIS growth obtained from this study are valuable to the design and fabrication of a wide range of targeted nanostructures.« less

Sequential lignin depolymerization by combination of biocatalytic and formic acid/formate treatment steps.

PubMed

Gasser, Christoph A; Čvančarová, Monika; Ammann, Erik M; Schäffer, Andreas; Shahgaldian, Patrick; Corvini, Philippe F-X

2017-03-01

Lignin, a complex three-dimensional amorphous polymer, is considered to be a potential natural renewable resource for the production of low-molecular-weight aromatic compounds. In the present study, a novel sequential lignin treatment method consisting of a biocatalytic oxidation step followed by a formic acid-induced lignin depolymerization step was developed and optimized using response surface methodology. The biocatalytic step employed a laccase mediator system using the redox mediator 1-hydroxybenzotriazole. Laccases were immobilized on superparamagnetic nanoparticles using a sorption-assisted surface conjugation method allowing easy separation and reuse of the biocatalysts after treatment. Under optimized conditions, as much as 45 wt% of lignin could be solubilized either in aqueous solution after the first treatment or in ethyl acetate after the second (chemical) treatment. The solubilized products were found to be mainly low-molecular-weight aromatic monomers and oligomers. The process might be used for the production of low-molecular-weight soluble aromatic products that can be purified and/or upgraded applying further downstream processes.

Development of enantioselective chemiluminescence flow- and sequential-injection immunoassays for alpha-amino acids.

PubMed

Silvaieh, Hossein; Schmid, Martin G; Hofstetter, Oliver; Schurig, Volker; Gübitz, Gerald

2002-01-01

The development of an enantioselective flow-through chemiluminescence immunosensor for amino acids is described. The approach is based on a competitive assay using enantioselective antibodies. Two different instrumental approaches, a flow-injection (FIA) and a sequential-injection system (SIA), are used. Compared to the flow-injection technique, the sequential injection-mode showed better repeatability. Both systems use an immunoreactor consisting of a flow cell packed with immobilized haptens. The haptens (4-amino-L- or D-phenylalanine) are immobilized onto a hydroxysuccinimide-activated polymer (Affi-prep 10) via a tyramine spacer. Stereoselective antibodies, raised against 4-amino-L- or D-phenylalanine, are labeled with an acridinium ester. Stereoselective inhibition of binding of the acridinum-labeled antibodies to the immobilized hapten by amino acids takes place. Chiral recognition was observed not only for the hapten molecule but also for a series of different amino acids. One assay cycle including regeneration takes 6:30 min in the FIA mode and 4:40 min in the SIA mode. Using D-phenylalanine as a sample, the detection limit was found to be 6.13 pmol/ml (1.01 ng/ml) for the flow-injection immunoassay (FIIA) and 1.76 pmol/ml (0.29 ng/ml ) for the sequential-injection immunoassay (SIIA) which can be lowered to 0.22 pmol/ml (0.036 ng/ml) or 0.064 pmol/ml (0.01 ng/ml) by using a stopped flow system. The intra-assay repeatability was found to be about 5% RSD and the inter-assay repeatability below 6% (within 3 days).

Viscoelastic Properties of Alkoxy Silane-Epoxy Interpenetrating Networks

DTIC Science & Technology

2003-11-01

Owens Corning Fiberglass for supply of the epoxy film former emulsion used in the model silane formulation. The authors also wish to acknowledge the...inclusion filled composite µm- powderproperties 4 triblock copolymer surfactant. The Owens Corning Company generously provided the film former emulsion

Novel Imprinted Polymer for the Preconcentration of Cadmium with Determination by Inductively Coupled Plasma Mass Spectrometry

PubMed Central

Yilmaz, Vedat; Yilmaz, Hayriye; Arslan, Zikri; Leszczynski, Jerzy

2016-01-01

A novel Cd(II)-imprinted polymer was prepared with chemical immobilization approach by using N-methacryloyl-L-histidine as a vinylated chelating agent for on-line solid phase extraction of Cd(II) for determination by inductively coupled plasma mass spectrometry. Cd(II)-monomer complex was synthesized and copolymerized via bulk polymerization method in the presence of ethyleneglycoldimethacrylate cross-linker. The resulting polymer was leached with 1.0 mol L−1 HNO3 to generate the cavities in the polymer for Cd(II) ions. The experimental conditions, including load pH, solution flow rate, and eluent concentration for effective sorption of Cd(II) were optimized using a minicolumn of the imprinted polymer. A volume of 5.0 mL sample 5 μg L−1 Cd(II) solution at pH 6.5 was loaded onto the column at 2.0 mL min−1 by using a sequential injection system (FIALab 3200) followed by elution with 1.0 mL of 0.75 mol L−1 HNO3. The relative selectivity coefficients of the imprinted polymer for Cd(II) were 38.5, 3.5, 3.0, 2.5 and 6.0 in the presence of Cu(II), Ni(II), Zn(II), Co(II) and Pb(II), respectively. Computational calculations revealed that the selectivity of the imprinted polymer was mediated by the stability of Cd(II)-N-methacryloyl-L-histidine complex which was far more stable than those of commonly used monomers, such as 4-vinyl pyridine, methacrylic acid and vinylimidazole. The detection limit (3s) and relative standard deviation (%) were found to be 0.004 μg L−1 and 3.2%, respectively. The method was validated by analysis of seawater certified reference material (CASS-4) and successfully applied to the determination of Cd(II) in coastal seawater and estuarine water samples. PMID:28239183

Hierarchically Flower-like N-Doped Porous Carbon Materials Derived from an Explosive 3-Fold Interpenetrating Diamondoid Copper Metal-Organic Framework for a Supercapacitor.

PubMed

Li, Zuo-Xi; Zou, Kang-Yu; Zhang, Xue; Han, Tong; Yang, Ying

2016-07-05

A peculiar copper metal-organic framework (Cu-MOF) was synthesized by a self-assembly method, which presents a 3-fold interpenetrating diamondoid net based on the square-planar Cu(II) node. Although it exhibits a high degree of interpenetration, the Cu-MOF still exhibits a one-dimensional channel, which provides a template for constructing porous materials through the "precursor" strategy. Furthermore, the explosive ClO4(-) ion, which resided in the channel, could induce the quick decomposition of organic ingredients and release a huge amount of gas, which is beneficial for the porosity of postsynthetic materials. Significantly, we first utilize this explosive MOF to prepare a series of Cu@C composites through the calcination-thermolysis method at different temperatures, which contain copper particles exhibiting various shapes and combinations with the carbon substrate. Considering the hole-forming effect of copper particles, Cu@C composites were etched by HCl to afford a sequence of hierarchically flower-like N-doped porous carbon materials (NPCs), which retain the original morphology of the Cu-MOF. Interestingly, NPC-900, originating from the calcination of the Cu-MOF at 900 °C, exhibits a more regular flower-like morphology, the largest specific surface area, abundant porosities, and multiple nitrogen functionalities. The remarkable specific capacitances are 138 F g(-1) at 5 mV s(-1) and 149 F g(-1) at 0.5 A g(-1) for the NPC-900 electrode in a 6 M potassium hydroxide aqueous solution. Moreover, the retention of capacitance remains 86.8% (125 F g(-1)) at 1 A g(-1) over 2000 cycles, which displays good chemical stability. These findings suggest that NPC-900 can be applied as a suitable electrode for a supercapacitor.

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

Bisht, Kamal Kumar; Rachuri, Yadagiri; Academy of Scientific and Innovative Research

Four ternary coordination polymers (CPs) namely, ([Ni(SDB)(BITMB)(H{sub 2}O)]·H{sub 2}O){sub n} (CP1), ([Cd(SDB)(BITMB) (H{sub 2}O)]·(THF)(H{sub 2}O)){sub n} (CP2), ([Zn{sub 2}(SDB){sub 2}(BITMB)]·(THF){sub 2}){sub n} (CP3) and ([Co{sub 2}(SDB){sub 2}(BITMB)]·(Dioxane){sub 3}){sub n} (CP4) composed of angular dicarboxylate SDB (4,4'-sulfonyldibenzoate) and N-donor BITMB (1,3-bis(imidazol-1-ylmethyl)-2,4,6-trimethyl benzene) have been synthesized by solvothermal reactions and characterized by single crystal X-ray diffraction and other physico-chemical techniques. CP1 possesses one-dimensional ribbon type metal–organic motifs glued together by H-bonds and π⋯π interactions, whereas CP2–CP4, exhibit non-interpenetrated sql networks supported by weak supramolecular interactions. Structural diversity of these CPs can be attributed to the coordination geometry adopted by the metal nodes,more » versatile coordination modes of SDB and conformational flexibility of BITMB. Solid state luminescence properties of CP1–CP4 were explored. Photocatalytic performance of all CPs for the decomposition of metanil yellow by dilute hydrogen peroxide in the presence of visible light was also investigated. 25–83% dye removal from aqueous solutions in the presence of CP1–CP4 was observed. - Graphical abstract: Four new ternary transition metal CPs have been hydrothermally prepared and their structural aspects as well as photocatalytic activity for decolourization of metanil yellow (MY) dye have been investigated. - Highlights: • Four ternary coordination polymers containing Ni, Cd, Zn and Co center are prepared. • Crystal structure and thermal stability of all four CPs has been described. • PL and diffuse reflectance spectra of synthesized CPs have also been examined. • Band gap values suggest semiconducting behavior of prepared CPs. • Photocatalytic activity of CPs for oxidative degradation of metanil yellow is studied.« less

Sociological and Communication-Theoretical Perspectives on the Commercialization of the Sciences

ERIC Educational Resources Information Center

Leydesdorff, Loet

2013-01-01

Both self-organization and organization are important for the further development of the sciences: the two dynamics condition and enable each other. Commercial and public considerations can interact and "interpenetrate" in historical organization; different codes of communication are then "recombined". However,…

Space-filling polyhedral sorbents

DOEpatents

Haaland, Peter

2016-06-21

Solid sorbents, systems, and methods for pumping, storage, and purification of gases are disclosed. They derive from the dynamics of porous and free convection for specific gas/sorbent combinations and use space filling polyhedral microliths with facial aplanarities to produce sorbent arrays with interpenetrating interstitial manifolds of voids.

Keratin sponge/hydrogel II, active agent delivery

USDA-ARS?s Scientific Manuscript database

Keratin sponge/hydrogels from oxidation and reduction hydrolysis of fine and coarse wool fibers were formed to behave as cationic hydrogels to swell and release active agents in the specific region of the gastro-intestinal (GI) tract. Their porous, interpenetrating networks (IPN) were effective for...

Effect of sub-Tg annealing on CuZr and AlSm glasses: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Sun, Yang; Zhang, Feng; Zhang, Yue; Ye, Zhuo; Mendelev, Mikhail; Wang, Cai-Zhuang; Ho, Kai-Ming

Cu65Zr35 and Al90Sm10 glasses, which represent strong and marginal binary metallic glass formers, respectively, were developed with a sub-Tg annealing method using Molecular Dynamics simulations. The short-range order (SRO) in both systems was characterized based on the concept of ``crystal gene'' that we established recently. Furthermore, we found that while the local clusters representing the dominant short-range order form an ever-more pronounced interpenetrating network with slower cooling rates in Cu65Zr35 glasses, the interpenetration of SRO in Al90Sm10 glasses only shows a weak dependence on the cooling rate. This clear difference in the connectivity of the SRO, which can characterize the medium-range order (MRO), could contribute to the different glass forming abilities of both systems. Work at Ames Laboratory was supported by the U.S. Department of Energy, Basic Energy Sciences, Materials Science and Engineering Division, under Contract No. DE-AC02-07CH11358.

Collisionless shock experiments with lasers and observation of Weibel instabilities

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

Park, H.-S., E-mail: park1@llnl.gov; Huntington, C. M.; Fiuza, F.

2015-05-15

Astrophysical collisionless shocks are common in the universe, occurring in supernova remnants, gamma ray bursts, and protostellar jets. They appear in colliding plasma flows when the mean free path for ion-ion collisions is much larger than the system size. It is believed that such shocks could be mediated via the electromagnetic Weibel instability in astrophysical environments without pre-existing magnetic fields. Here, we present laboratory experiments using high-power lasers and investigate the dynamics of high-Mach-number collisionless shock formation in two interpenetrating plasma streams. Our recent proton-probe experiments on Omega show the characteristic filamentary structures of the Weibel instability that are electromagneticmore » in nature with an inferred magnetization level as high as ∼1% [C. M. Huntington et al., “Observation of magnetic field generation via the weibel instability in interpenetrating plasma flows,” Nat. Phys. 11, 173–176 (2015)]. These results imply that electromagnetic instabilities are significant in the interaction of astrophysical conditions.« less

Experimental characterization of a transition from collisionless to collisional interaction between head-on-merging supersonic plasma jets a)

DOE PAGES

Moser, Auna L.; Hsu, Scott C.

2015-05-01

We present results from experiments on the head-on merging of two supersonic plasma jets in an initially collisionless regime for the counter-streaming ions [A. L. Moser & S. C. Hsu, Phys. Plasmas, submitted (2014)]. The plasma jets are of either an argon/impurity or hydrogen/impurity mixture and are produced by pulsed-power-driven railguns. Based on time- and space-resolved fast-imaging, multi-chord interferometry, and survey-spectroscopy measurements of the overlapping region between the merging jets, we observe that the jets initially interpenetrate, consistent with calculated inter-jet ion collision lengths, which are long. As the jets interpenetrate, a rising mean-charge state causes a rapid decrease inmore » the inter-jet ion collision length. Finally, the interaction becomes collisional and the jets stagnate, eventually producing structures consistent with collisional shocks. These experimental observations can aid in the validation of plasma collisionality and ionization models for plasmas with complex equations of state.« less

Experimental Evidence of Kinetic Effects in Indirect-Drive Inertial Confinement Fusion Hohlraums

NASA Astrophysics Data System (ADS)

Shan, L. Q.; Cai, H. B.; Zhang, W. S.; Tang, Q.; Zhang, F.; Song, Z. F.; Bi, B.; Ge, F. J.; Chen, J. B.; Liu, D. X.; Wang, W. W.; Yang, Z. H.; Qi, W.; Tian, C.; Yuan, Z. Q.; Zhang, B.; Yang, L.; Jiao, J. L.; Cui, B.; Zhou, W. M.; Cao, L. F.; Zhou, C. T.; Gu, Y. Q.; Zhang, B. H.; Zhu, S. P.; He, X. T.

2018-05-01

We present the first experimental evidence supported by simulations of kinetic effects launched in the interpenetration layer between the laser-driven hohlraum plasma bubbles and the corona plasma of the compressed pellet at the Shenguang-III prototype laser facility. Solid plastic capsules were coated with carbon-deuterium layers; as the implosion neutron yield is quenched, DD fusion yield from the corona plasma provides a direct measure of the kinetic effects inside the hohlraum. An anomalous large energy spread of the DD neutron signal (˜282 keV ) and anomalous scaling of the neutron yield with the thickness of the carbon-deuterium layers cannot be explained by the hydrodynamic mechanisms. Instead, these results can be attributed to kinetic shocks that arise in the hohlraum-wall-ablator interpenetration region, which result in efficient acceleration of the deuterons (˜28.8 J , 0.45% of the total input laser energy). These studies provide novel insight into the interactions and dynamics of a vacuum hohlraum and near-vacuum hohlraum.

Gel characteristics and microstructure of fish myofibrillar protein/cassava starch composites.

PubMed

Fan, Mingcong; Hu, Ting; Zhao, Siming; Xiong, Shanbai; Xie, Jing; Huang, Qilin

2017-03-01

The changes in fish myofibrillar protein/cassava starch composites in the starch fraction range from 0 to 1, with their total content maintained at 60mg/mL, were investigated in terms of textural properties, rheological behaviours, morphology, spatial distribution and protein molecular structure. The results revealed that the starch fraction of 0.5 was a critical point for the conversion of the protein matrix to starch matrix and conversion of the gel from elastic to weak. Moreover, the protein-starch synergistic effect on the storage modulus was strongest at fractions of 0.5 and 0.6, due to the formation of a semi-interpenetrating network, with more amylose from the melted starch granules interpenetrated with the protein molecules, and the absorption of water by the starch granules to concentrate the protein matrix. Additionally, no covalent interaction between the protein and starch occurred with increasing starch fraction, thus having no significant influence on the protein secondary structure. Copyright © 2016 Elsevier Ltd. All rights reserved.

Reflectance of vegetation, soil, and water

NASA Technical Reports Server (NTRS)

Wiegand, C. L. (Principal Investigator)

1973-01-01

The author has identified the following significant results. A ratio of MSS channels 5 and 7 (5/7) and 5 to 6 (5/6) signals resulted in a correct recognition of 86.9% of the members of representative crop and soil conditions, compared with recognitions of 60.0, 64.1, 74.1, and 81.4% for channels 4, 5, 6, and 7 taken individually. Based on this result a satellite channel ratio procedure has been developed that enhances line printer gray maps for more efficient experimental test site location in the CCT data. Because independent estimates are not available to judge acreage estmates derived from ERTS-1 data against, except for a few crops, an interpenetrating sample constituting 3.5% of the county is ground truthed periodically. The crop of land uses and their acreages, respectively, as estimated from the interpenetrating samples, are: cotton, 129, 714; sorghum, 182,783; mixed citrus, 53,954; oranges, 16,929; grapefruit, 13,863; rangeland, 137,845; and, improved pastures, 57.169.

Kinetic instability of electrostatic ion cyclotron waves in inter-penetrating plasmas

NASA Astrophysics Data System (ADS)

Bashir, M. F.; Ilie, R.; Murtaza, G.

2018-05-01

The Electrostatic Ion Cyclotron (EIC) instability that includes the effect of wave-particle interaction is studied owing to the free energy source through the flowing velocity of the inter-penetrating plasmas. It is shown that the origin of this current-less instability is different from the classical current driven EIC instability. The threshold conditions applicable to a wide range of plasma parameters and the estimate of the growth rate are determined as a function of the normalized flowing velocity ( u0/vt f e ), the temperature ( Tf/Ts ) and the density ratios ( nf 0/ns 0 ) of flowing component to static one. The EIC instability is driven by either flowing electrons or flowing ions, depending upon the different Doppler shifted frequency domains. It is found that the growth rate for electron-driven instability is higher than the ion-driven one. However, in both cases, the denser (hotter) is the flowing plasma, the lesser (greater) is the growth rate. The possible applications related to the terrestrial solar plasma environment are also discussed.

Highly water-absorbing silk yarn with interpenetrating network via in situ polymerization.

PubMed

Lee, Ka I; Wang, Xiaowen; Guo, Xia; Yung, Ka-Fu; Fei, Bin

2017-02-01

Silk was modified via in situ polymerization of two monomers acrylamide and sodium acrylate by swelling in an effective LiBr dissolution system. Swelling of natural silks in LiBr solutions of low concentration was clearly observed under optical microscope, and their conformational changes were revealed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Dissolution tests and FTIR spectra of these modified silks suggested the presence of interpenetrating network of polyacrylamide and poly(sodium acrylate) in the silk yarns. These modified silks exhibited superior water absorption to that of raw silk and greatly improved mechanical properties in both dry and wet states. These novel modified silks also showed low cytotoxicity towards skin keratinocytes, having potential applications in biomedical textiles. This modification method by in situ polymerization after swelling in LiBr provides a new route to highly enhance the properties and performance of silk for various applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Guar gum based biodegradable, antibacterial and electrically conductive hydrogels.

PubMed

Kaith, Balbir S; Sharma, Reena; Kalia, Susheel

2015-04-01

Guar gum-polyacrylic acid-polyaniline based biodegradable electrically conductive interpenetrating network (IPN) structures were prepared through a two-step aqueous polymerization. Hexamine and ammonium persulfate (APS) were used as a cross linker-initiator system to crosslink the poly(AA) chains on Guar gum (Ggum) backbone. Optimum reaction conditions for maximum percentage swelling (7470.23%) were time (min) = 60; vacuum (mmHg) = 450; pH = 7.0; solvent (mL) = 27.5; [APS] (mol L(-1)) = 0.306 × 10(-1); [AA] (mol L(-1)) = 0.291 × 10(-3) and [hexamine] (mol L(-1))=0.356 × 10(-1). The semi-interpenetrating networks (semi-IPNs) were converted into IPNs through impregnation of polyaniline chains under acidic and neutral conditions. Fourier transform infra-red spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) techniques were used to characterize the semi-IPNs and IPNs. Synthesized semi-IPNs and IPNs were further evaluated for moisture retention in different soils, antibacterial and biodegradation behavior. Copyright © 2015 Elsevier B.V. All rights reserved.

Design of interpenetrated network MWCNT/poly(1,5-DAN) on interdigital electrode: toward NO2 gas sensing.

PubMed

Nguyen, Dzung Tuan; Nguyen, My Thanh; Ho, Giang Truong; Nguyen, Toan Ngoc; Reisberg, S; Piro, B; Pham, M C

2013-10-15

In this paper, poly(1,5-diaminonaphthalene) was interpenetrated into the network made of multiwalled carbon nanotubes (MWCNT) on platinum interdigital electrode (IDE) by electro-polymerization of 1,5-diaminonaphthalene (1,5-DAN). The electro-polymerization process of 1,5-DAN on MWCNT was controlled by scanning the cyclic voltage at 50 mV s(-1) scan rate between -0.1 V and +0.95 V vs. saturated calomel electrode (SCE). The results of voltammetric responses and Raman spectroscopy represented that the films MWCNT/poly(1,5-DAN) were successfully created by this polymerization process. The films MWCNT/poly(1,5-DAN) were investigated for gas-sensing to NO2 at low concentration level. The gas-sensing results showed that the response-recovery times were long and strongly affected by thickness of the film MWCNT/poly(1,5-DAN). Nevertheless, these films represented auspicious results for gas sensors operating at room temperature. Copyright © 2013 Elsevier B.V. All rights reserved.

Experimental characterization of a transition from collisionless to collisional interaction between head-on-merging supersonic plasma jets a)

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

Moser, Auna L.; Hsu, Scott C.

We present results from experiments on the head-on merging of two supersonic plasma jets in an initially collisionless regime for the counter-streaming ions [A. L. Moser & S. C. Hsu, Phys. Plasmas, submitted (2014)]. The plasma jets are of either an argon/impurity or hydrogen/impurity mixture and are produced by pulsed-power-driven railguns. Based on time- and space-resolved fast-imaging, multi-chord interferometry, and survey-spectroscopy measurements of the overlapping region between the merging jets, we observe that the jets initially interpenetrate, consistent with calculated inter-jet ion collision lengths, which are long. As the jets interpenetrate, a rising mean-charge state causes a rapid decrease inmore » the inter-jet ion collision length. Finally, the interaction becomes collisional and the jets stagnate, eventually producing structures consistent with collisional shocks. These experimental observations can aid in the validation of plasma collisionality and ionization models for plasmas with complex equations of state.« less

Biaxially mechanical tuning of 2-D reversible and irreversible surface topologies through simultaneous and sequential wrinkling.

PubMed

Yin, Jie; Yagüe, Jose Luis; Boyce, Mary C; Gleason, Karen K

2014-02-26

Controlled buckling is a facile means of structuring surfaces. The resulting ordered wrinkling topologies provide surface properties and features desired for multifunctional applications. Here, we study the biaxially dynamic tuning of two-dimensional wrinkled micropatterns under cyclic mechanical stretching/releasing/restretching simultaneously or sequentially. A biaxially prestretched PDMS substrate is coated with a stiff polymer deposited by initiated chemical vapor deposition (iCVD). Applying a mechanical release/restretch cycle in two directions loaded simultaneously or sequentially to the wrinkled system results in a variety of dynamic and tunable wrinkled geometries, the evolution of which is investigated using in situ optical profilometry, numerical simulations, and theoretical modeling. Results show that restretching ordered herringbone micropatterns, created through sequential release of biaxial prestrain, leads to reversible and repeatable surface topography. The initial flat surface and the same wrinkled herringbone pattern are obtained alternatively after cyclic release/restretch processes, owing to the highly ordered structure leaving no avenue for trapping irregular topological regions during cycling as further evidenced by the uniformity of strains distributions and negligible residual strain. Conversely, restretching disordered labyrinth micropatterns created through simultaneous release shows an irreversible surface topology whether after sequential or simultaneous restretching due to creation of irregular surface topologies with regions of highly concentrated strain upon formation of the labyrinth which then lead to residual strains and trapped topologies upon cycling; furthermore, these trapped topologies depend upon the subsequent strain histories as well as the cycle. The disordered labyrinth pattern varies after each cyclic release/restretch process, presenting residual shallow patterns instead of achieving a flat state. The ability to dynamically tune the highly ordered herringbone patterning through mechanical stretching or other actuation makes these wrinkles excellent candidates for tunable multifunctional surfaces properties such as reflectivity, friction, anisotropic liquid flow or boundary layer control.

Silver(I) coordination polymers assembled from flexible cyclotriphosphazene ligand: structures, topologies and investigation of the counteranion effects.

PubMed

Davarcı, Derya; Gür, Rüştü; Beşli, Serap; Şenkuytu, Elif; Zorlu, Yunus

2016-06-01

The reactions of a flexible ligand hexakis(3-pyridyloxy)cyclotriphosphazene (HPCP) with a variety of silver(I) salts (AgX; X = NO3(-), PF6(-), ClO4(-), CH3PhSO3(-), BF4(-) and CF3SO3(-)) afforded six silver(I) coordination polymers, namely {[Ag2(HPCP)]·(NO3)2·H2O}n (1), {[Ag2(HPCP)(CH3CN)]·(PF6)2}n (2), {[Ag2(HPCP)(CH3CN)]·(ClO4)2}n (3), [Ag3(HPCP)(CH3PhSO3)3]n (4), [Ag2(HPCP)(CH3CN)(BF4)2]n (5) and {[Ag(HPCP)]·(CF3SO3)}n (6). All of the isolated crystalline compounds were structurally determined by X-ray crystallography. Changing the counteranions in the reactions, which were conducted under similar conditions of M/L ratio (1:1), temperature and solvent, resulted in structures with different types of topologies. In complexes (1)-(6), the ligand HPCP shows different coordination modes with Ag(I) ions giving two-dimensional layered structures and three-dimensional frameworks with different topologies. Complex (1) displays a new three-dimensional framework adopting a (3,3,6)-connected 3-nodal net with point symbol {4.6(2)}2{4(2).6(10).8(3)}. Complexes (2) and (3) are isomorphous and have a two-dimensional layered structure showing the same 3,6L60 topology with point symbol {4.2(6)}2{4(8).6(6).8}. Complex (4) is a two-dimensional structure incorporating short Ag...Ag argentophilic interactions and has a uninodal 4-connected sql/Shubnikov tetragonal plane net with {4(4).6(2)} topology. Complex (5) exhibits a novel three-dimensional framework and more suprisingly contains twofold interpenetrated honeycomb-like networks, in which the single net has a trinodal (2,3,5)-connected 3-nodal net with point symbol {6(3).8(6).12}{6(3)}{8}. Complex (6) crystallizes in a trigonal crystal system with the space group R\\bar 3 and possesses a three-dimensional polymeric structure showing a binodal (4,6)-connected fsh net with the point symbol (4(3).6(3))2.(4(6).6(6).8(3)). The effect of the counteranions on the formation of coordination polymers is discussed in this study.

In-situ immobilization of quantum dots in polysaccharide-based nanogels for integration of optical pH-sensing, tumor cell imaging, and drug delivery.

PubMed

Wu, Weitai; Aiello, Michael; Zhou, Ting; Berliner, Alexandra; Banerjee, Probal; Zhou, Shuiqin

2010-04-01

We report a class of polysaccharide-based hybrid nanogels that can integrate the functional building blocks for optical pH-sensing, cancer cell imaging, and controlled drug release into a single nanoparticle system, which can offer broad opportunities for combined diagnosis and therapy. The hybrid nanogels were prepared by in-situ immobilization of CdSe quantum dots (QDs) in the interior of the pH and temperature dual responsive hydroxypropylcellulose-poly(acrylic acid) (HPC-PAA) semi-interpenetrating polymer networks. The-OH groups of the HPC chains are designed to sequester the precursor Cd(2+) ions into the nanogels as well as stabilize the in-situ formed CdSe QDs. The pH-sensitive PAA network chains are designed to induce a pH-responsive volume phase transition of the hybrid nanogels. The developed HPC-PAA-CdSe hybrid nanogels combine a strong trap emission at 741nm for sensing physicochemical environment in a pH dependent manner and a visible excitonic emission at 592nm for mouse melanoma B16F10 cell imaging. The hybrid nanogels also provide excellent stability as a drug carrier, which cannot only provide a high drug loading capacity for a model anticancer drug temozolomide, but also offer a pH-triggered sustained-release of the drug molecules in the gel network. Copyright 2010 Elsevier Ltd. All rights reserved.

Characterization of photochemical-cured acrylates with calorimetric methods

NASA Astrophysics Data System (ADS)

Strehmel, Bernd; Anwand, Dirk; Wetzel, Henrik

1994-05-01

Radical polymerization kinetics of different kinds of diacrylates was investigated in linear polymers (binders) by using an isoperibolic calorimeter. For all experiments benzoin compounds were added as photoinitiator. The ester between acrylic acid and bisphenol-A-diglycidylether (DDGDA) and hexamethylenediacrylate were used as monomers. Both compounds have a high limiting conversion and a large polymerization rate in the binders investigated. Additionally, three kinds of termination reaction were observed: first order, second order, and primary radical termination. The last reaction was mainly found in the case of using the hexamethylenediacrylate monomer. The materials were investigated by DSC to determine the phase behavior. Both monomers form one phase with the binder (polymethylmethacrylate, PMMA). In contrast, a phase separation was observed between the crosslinked hexamethylenediacrylate and PMMA. Formations of semi- interpenetrating networks were found in the case of crosslinked DDGDA and PMMA. The glass transition temperatures were determined at different polymerization degrees also. The obtained results indicate that most of the network formation occurred in the glassy state. Fluorescence probe technique was applied to study changes in the mobility during network formation. The fluorescence probe crystal violet (CV) was used because this compound shows a strong free volume-dependent fluorescence. It was found that in the glassy state, where most of networks were formed, a large variation of the molecular mobility was observed during irradiation of the photopolymers. This result was in agreement with the observations during DSC experiments.

Teaching Religion and Material Culture

ERIC Educational Resources Information Center

Carp, Richard M.

2007-01-01

Because religions discipline and interpret bodies; create and define sacred spaces; generate, adore and study images in all media; regulate the intake of food; structure temporal experience; and in general interpenetrate and are permeated by the cultural landscapes in which they exist, religious studies must engage material religion and religious…

Accurate masking technology for high-resolution powder blasting

NASA Astrophysics Data System (ADS)

Pawlowski, Anne-Gabrielle; Sayah, Abdeljalil; Gijs, Martin A. M.

2005-07-01

We have combined eroding 10 µm diameter Al2O3 particles with a new masking technology to realize the smallest and most accurate possible structures by powder blasting. Our masking technology is based on the sequential combination of two polymers:(i) the brittle epoxy resin SU8 for its photosensitivity and (ii) the elastic and thermocurable poly-dimethylsiloxane for its large erosion resistance. We have micropatterned various types of structures with a minimum width of 20 µm for test structures with an aspect ratio of 1, and 50 µm for test structures with an aspect ratio of 2.

Multi-Scale Responses of Liquid Crystals Triggered by Interfacial Assemblies of Cleavable Homopolymers.

PubMed

Kim, Young-Ki; Huang, Yuran; Tsuei, Michael; Wang, Xin; Gianneschi, Nathan C; Abbott, Nicholas L

2018-04-22

Liquid crystals (LCs) offer the basis of stimuli-responsive materials that can amplify targeted molecular events into macroscopic outputs. However, general and versatile design principles are needed to realize the full potential of these materials. To this end, we report the synthesis of two homopolymers with mesogenic side chains that can be cleaved upon exposure to either H 2 O 2 (polymer P1) or UV light (polymer P2). Optical measurements reveal that the polymers dissolve in bulk LC and spontaneously assemble at nematic LC-aqueous interfaces to impose a perpendicular orientation on the LCs. Subsequent addition of H 2 O 2 to the aqueous phase or exposure of the LC to UV was shown to trigger a surface-driven ordering transition to a planar orientation and an accompanying macroscopic optical output. Differences in the dynamics of the response to each stimulus are consistent with sequential processing of P1 at the LC-aqueous interface (H 2 O 2 ) and simultaneous transformation of P2 within the LC (UV). The versatility of the approach is demonstrated by creating stimuli-responsive LCs as films or microdroplets, and by dissolving mixtures of P1 and P2 into LCs to create LC materials that respond to two stimuli. Overall, our results validate a simple and generalizable approach to the rational design of polymers that can be used to program stimuli-responsiveness into LC materials. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mass-manufacturable polymer microfluidic device for dual fiber optical trapping.

PubMed

De Coster, Diane; Ottevaere, Heidi; Vervaeke, Michael; Van Erps, Jürgen; Callewaert, Manly; Wuytens, Pieter; Simpson, Stephen H; Hanna, Simon; De Malsche, Wim; Thienpont, Hugo

2015-11-30

We present a microfluidic chip in Polymethyl methacrylate (PMMA) for optical trapping of particles in an 80µm wide microchannel using two counterpropagating single-mode beams. The trapping fibers are separated from the sample fluid by 70µm thick polymer walls. We calculate the optical forces that act on particles flowing in the microchannel using wave optics in combination with non-sequential ray-tracing and further mathematical processing. Our results are compared with a theoretical model and the Mie theory. We use a novel fabrication process that consists of a premilling step and ultraprecision diamond tooling for the manufacturing of the molds and double-sided hot embossing for replication, resulting in a robust microfluidic chip for optical trapping. In a proof-of-concept demonstration, we show the trapping capabilities of the hot embossed chip by trapping spherical beads with a diameter of 6µm, 8µm and 10µm and use the power spectrum analysis of the trapped particle displacements to characterize the trap strength.

Co-Pt core-shell nanostructured catalyst prepared by selective chemical vapor pulse deposition of Pt on Co as a cathode in polymer electrolyte fuel cells

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

Seo, Sang-Joon; Chung, Ho-Kyoon; Yoo, Ji-Beom

2014-01-15

A new type of PtCo/C catalyst for use as a cathode in polymer electrolyte fuel cells was prepared by selective chemical vapor pulse deposition (CVPD) of Pt on the surface of Co. The activity of the prepared catalyst for oxygen reduction was higher than that of a catalyst prepared by sequential impregnation (IMP) with the two metallic components. This catalytic activity difference occurs because the former catalyst has smaller Pt crystallites that produce stronger Pt-Co interactions and have a larger Pt surface area. Consequently, the CVPD catalyst has a great number of Co particles that are in close contact withmore » the added Pt. The Pt surface was also electronically modified by interactions with Co, which were stronger in the CVPD catalyst than in the IMP catalyst, as indicated by X-ray diffraction, X-ray photoemission spectroscopy, and cyclic voltammetry measurements of the catalysts.« less

Magnetically responsive smart nanoparticles for cancer treatment with a combination of magnetic hyperthermia and remote-control drug release.

PubMed

Hayashi, Koichiro; Nakamura, Michihiro; Miki, Hirokazu; Ozaki, Shuji; Abe, Masahiro; Matsumoto, Toshio; Sakamoto, Wataru; Yogo, Toshinobu; Ishimura, Kazunori

2014-01-01

We report the synthesis of smart nanoparticles (NPs) that generate heat in response to an alternating current magnetic field (ACMF) and that sequentially release an anticancer drug (doxorubicin, DOX). We further study the in vivo therapeutic efficacy of the combination of magnetic hyperthermia (MHT) and chemotherapy using the smart NPs for the treatment of multiple myeloma. The smart NPs are composed of a polymer with a glass-transition temperature (T g) of 44°C, which contains clustered Fe3O4 NPs and DOX. The clustered Fe3O4 NPs produce heat when the ACMF is applied and rise above 44°C, which softens the polymer phase and leads to the release of DOX. The combination of MHT and chemotherapy using the smart NPs destroys cancer cells in the entire tumor and achieves a complete cure in one treatment without the recurrence of malignancy. Furthermore, the smart NPs have no significant toxicity.

Upconversion-Triggered Charge Separation in Polymer Semiconductors.

PubMed

Jang, Yu Jin; Kim, Eunah; Ahn, Seonghyeon; Chung, Kyungwha; Kim, Jihyeon; Kim, Heejun; Wang, Huan; Lee, Jiseok; Kim, Dong-Wook; Kim, Dong Ha

2017-01-19

Upconversion is a unique optical property that is driven by a sequential photon pumping and generation of higher energy photons in a consecutive manner. The efficiency improvement in photovoltaic devices can be achieved when upconverters are integrated since upconverters contribute to the generation of extra photons. Despite numerous experimental studies confirming the relationship, fundamental explanations for a real contribution of upconversion to photovoltaic efficiency are still in demand. In this respect, we suggest a new approach to visualize the upconversion event in terms of surface photovoltage (SPV) by virtue of Kelvin probe force microscopy (KPFM). One of the most conventional polymer semiconductors, poly(3-hexyl thiophene) (P3HT), is employed as a sensitizer to generate charge carriers by upconverted light. KPFM measurements reveal that the light upconversion enabled the formation of charge carriers in P3HT, resulting in large SPV of -54.9 mV. It confirms that the energy transfer from upconverters to P3HT can positively impact the device performance in organic solar cells (OSCs).

Multifunctional polymer-capped mesoporous silica nanoparticles for pH-responsive targeted drug delivery.

PubMed

Niedermayer, Stefan; Weiss, Veronika; Herrmann, Annika; Schmidt, Alexandra; Datz, Stefan; Müller, Katharina; Wagner, Ernst; Bein, Thomas; Bräuchle, Christoph

2015-05-07

A highly stable modular platform, based on the sequential covalent attachment of different functionalities to the surface of core-shell mesoporous silica nanoparticles (MSNs) for targeted drug delivery is presented. A reversible pH-responsive cap system based on covalently attached poly(2-vinylpyridine) (PVP) was developed as drug release mechanism. Our platform offers (i) tuneable interactions and release kinetics with the cargo drug in the mesopores based on chemically orthogonal core-shell design, (ii) an extremely robust and reversible closure and release mechanism based on endosomal acidification of the covalently attached PVP polymer block, (iii) high colloidal stability due to a covalently coupled PEG shell, and (iv) the ability to covalently attach a wide variety of dyes, targeting ligands and other functionalities at the outer periphery of the PEG shell. The functionality of the system was demonstrated in several cell studies, showing pH-triggered release in the endosome, light-triggered endosomal escape with an on-board photosensitizer, and efficient folic acid-based cell targeting.

Combining hydrothermal pretreatment with enzymes de-pectinates and exposes the innermost xyloglucan-rich hemicellulose layers of wine grape pomace.

PubMed

Zietsman, Anscha J J; Moore, John P; Fangel, Jonatan U; Willats, William G T; Vivier, Melané A

2017-10-01

Chardonnay grape pomace was treated with pressurized heat followed by enzymatic hydrolysis, with commercial or pure enzymes, in buffered conditions. The pomace was unfermented as commonly found for white winemaking wastes and treatments aimed to simulate biovalorization processing. Cell wall profiling techniques showed that the pretreatment led to depectination of the outer layers thereby exposing xylan polymers and increasing the extractability of arabinans, galactans, arabinogalactan proteins and mannans. This higher extractability is believed to be linked with partial degradation and opening-up of cell wall networks. Pectinase-rich enzyme preparations were presumably able to access the inner rhamnogalacturonan I dominant coating layers due to the hydrothermal pretreatment. Patterns of epitope abundance and the sequential release of cell wall polymers with specific combinations of enzymes led to a working model of the hitherto, poorly understood innermost xyloglucan-rich hemicellulose layers of unfermented grape pomace. Copyright © 2017 Elsevier Ltd. All rights reserved.

Controlled fragmentation of multimaterial fibres and films via polymer cold-drawing.

PubMed

Shabahang, Soroush; Tao, Guangming; Kaufman, Joshua J; Qiao, Yangyang; Wei, Lei; Bouchenot, Thomas; Gordon, Ali P; Fink, Yoel; Bai, Yuanli; Hoy, Robert S; Abouraddy, Ayman F

2016-06-23

Polymer cold-drawing is a process in which tensile stress reduces the diameter of a drawn fibre (or thickness of a drawn film) and orients the polymeric chains. Cold-drawing has long been used in industrial applications, including the production of flexible fibres with high tensile strength such as polyester and nylon. However, cold-drawing of a composite structure has been less studied. Here we show that in a multimaterial fibre composed of a brittle core embedded in a ductile polymer cladding, cold-drawing results in a surprising phenomenon: controllable and sequential fragmentation of the core to produce uniformly sized rods along metres of fibre, rather than the expected random or chaotic fragmentation. These embedded structures arise from mechanical-geometric instabilities associated with 'neck' propagation. Embedded, structured multimaterial threads with complex transverse geometry are thus fragmented into a periodic train of rods held stationary in the polymer cladding. These rods can then be easily extracted via selective dissolution of the cladding, or can self-heal by thermal restoration to re-form the brittle thread. Our method is also applicable to composites with flat rather than cylindrical geometries, in which case cold-drawing leads to the break-up of an embedded or coated brittle film into narrow parallel strips that are aligned normally to the drawing axis. A range of materials was explored to establish the universality of this effect, including silicon, germanium, gold, glasses, silk, polystyrene, biodegradable polymers and ice. We observe, and verify through nonlinear finite-element simulations, a linear relationship between the smallest transverse scale and the longitudinal break-up period. These results may lead to the development of dynamical and thermoreversible camouflaging via a nanoscale Venetian-blind effect, and the fabrication of large-area structured surfaces that facilitate high-sensitivity bio-detection.