Phase Behavior and Conductivity of Phosphonated Block Copolymers Containing Ionic Liquids

NASA Astrophysics Data System (ADS)

Jung, Ha Young; Kim, Sung Yeon; Park, Moon Jeong

2015-03-01

As the focus on proton exchange fuel cells continues to escalate in the era of alternative energy systems, the rational design of sulfonated polymers has emerged as a key technique for enhancing device efficiency. While the sulfonic acid group guarantees high proton conductivity of membranes under humidified conditions, the growing need for high temperature operation has discouraged their practical uses in fuel cells. In this respect, phosphonated polymers have drawn intensive attention in recent years owing to their self-dissociation ability. In this study, we have synthesized a set of phosphonated block copolymers, poly(styrenephosphonate-methylbutylene) (PSP- b - PMB), by varying phosphonation level (PL). A wide variety of self-assembled morphologies, i.e., disordered, lamellar, hexagonally perforated lamellae and hexagonally packed cylindrical phases, were observed with PL. Remarkably, upon comparing the morphology of PSP- b-PMB and that of sulfonated analog, we found distinctly dissimilar domain sizes at the same molecular weight and composition. A range of ionic liquids (ILs) were incorporated into the PSP- b-PMB block copolymers and their ion transport properties were examined. It has been revealed that the degree of confinement of ionic phases (domain size) impacts the ion mobility and proton dissociation efficiency of IL-containing polymers.

New Polytetrahydrofuran Graft Copolymers.

DTIC Science & Technology

1979-03-15

chioroprene) , chiorobutyl - ~~~~~ rubber , bromobutyl rubber , chlorinated EPDM , chlorinated poly(buta— diene) and chlorinated butadiene styrene copolymer...bromobutyl rubber , which after dehalogenation is unstable with respect to conjugated dienes, the yields of graft copolymer are low. With poly(chloroprerte

Phase Behavior of Neat Triblock Copolymers and Copolymer/Homopolymer Blends Near Network Phase Windows

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

M Tureau; L Rong; B Hsiao

The phase behavior of poly(isoprene-b-styrene-b-methyl methacrylate) (ISM) copolymers near the styrene-rich network phase window was examined through the use of neat triblock copolymers and copolymer/homopolymer blends. Both end-block and middle-block blending protocols were employed using poly(isoprene) (PI), poly(methyl methacrylate) (PMMA), and poly(styrene) (PS) homopolymers. Blended specimens exhibited phase transformations to well-ordered nanostructures (at homopolymer loadings up to 26 vol % of the total blend volume). Morphological consistency between neat and blended specimens was established at various locations in the ISM phase space. Copolymer/homopolymer blending permitted the refinement of lamellar, hexagonally packed cylinder, and disordered melt phase boundaries as well asmore » the identification of double gyroid (Q{sup 230}), alternating gyroid (Q{sup 214}), and orthorhombic (O{sup 70}) network regimes. Additionally, the experimental phase diagram exhibited similar trends to those found in a theoretical ABC triblock copolymer phase diagram with symmetric interactions and statistical segments lengths generated by Tyler et al.« less

Block copolymer based composition and morphology control in nanostructured hybrid materials for energy conversion and storage: solar cells, batteries, and fuel cells.

PubMed

Orilall, M Christopher; Wiesner, Ulrich

2011-02-01

The development of energy conversion and storage devices is at the forefront of research geared towards a sustainable future. However, there are numerous issues that prevent the widespread use of these technologies including cost, performance and durability. These limitations can be directly related to the materials used. In particular, the design and fabrication of nanostructured hybrid materials is expected to provide breakthroughs for the advancement of these technologies. This tutorial review will highlight block copolymers as an emerging and powerful yet affordable tool to structure-direct such nanomaterials with precise control over structural dimensions, composition and spatial arrangement of materials in composites. After providing an introduction to materials design and current limitations, the review will highlight some of the most recent examples of block copolymer structure-directed nanomaterials for photovoltaics, batteries and fuel cells. In each case insights are provided into the various underlying fundamental chemical, thermodynamic and kinetic formation principles enabling general and relatively inexpensive wet-polymer chemistry methodologies for the efficient creation of multiscale functional materials. Examples include nanostructured ceramics, ceramic-carbon composites, ceramic-carbon-metal composites and metals with morphologies ranging from hexagonally arranged cylinders to three-dimensional bi-continuous cubic networks. The review ends with an outlook towards the synthesis of multicomponent and hierarchical multifunctional hybrid materials with different nano-architectures from self-assembly of higher order blocked macromolecules which may ultimately pave the way for the further development of energy conversion and storage devices.

Molecular Interaction Control in Diblock Copolymer Blends and Multiblock Copolymers with Opposite Phase Behaviors

NASA Astrophysics Data System (ADS)

Cho, Junhan

2014-03-01

Here we show how to control molecular interactions via mixing AB and AC diblock copolymers, where one copolymer exhibits upper order-disorder transition and the other does lower disorder-order transition. Linear ABC triblock copolymers possessing both barotropic and baroplastic pairs are also taken into account. A recently developed random-phase approximation (RPA) theory and the self-consistent field theory (SCFT) for general compressible mixtures are used to analyze stability criteria and morphologies for the given systems. It is demonstrated that the copolymer systems can yield a variety of phase behaviors in their temperature and pressure dependence upon proper mixing conditions and compositions, which is caused by the delicate force fields generated in the systems. We acknowledge the financial support from National Research Foundation of Korea and Center for Photofunctional Energy Materials.

Bicomponent Block Copolymers Derived from One or More Random Copolymers as an Alternative Route to Controllable Phase Behavior

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

Ashraf, Arman R.; Ryan, Justin J.; Satkowski, Michael M.

Block copolymers have been extensively studied due to their ability to spontaneously self-organize into a wide variety of morphologies that are valuable in energy-, medical- and conservation-related (nano)technologies. While the phase behavior of bicomponent diblock and triblock copolymers is conventionally governed by temperature and individual block masses, we demonstrate that their phase behavior can alternatively be controlled through the use of blocks with random monomer sequencing. Block random copolymers (BRCs), i.e., diblock copolymers wherein one or both blocks is a random copolymer comprised of A and B repeat units, have been synthesized, and their phase behavior, expressed in terms ofmore » the order-disorder transition (ODT), has been investigated. Our results establish that, depending on the block composition contrast and molecular weight, BRCs can microphase-separate. We also report that the predicted ODT can be generated at relatively constant molecular weight and temperature with these new soft materials. This sequence-controlled synthetic strategy is extended to thermoplastic elastomeric triblock copolymers differing in chemistry and possessing a random-copolymer midblock.« less

Morphology and Proton Transport in Humidified Phosphonated Peptoid Block Copolymers

DOE PAGES

Sun, Jing; Jiang, Xi; Siegmund, Aaron; ...

2016-04-04

Polymers that conduct protons in the hydrated state are of crucial importance in a wide variety of clean energy applications such as hydrogen fuel cells and artificial photosynthesis. Phosphonated and sulfonated polymers are known to conduct protons at low water content. In this study, we report on the synthesis phosphonated peptoid diblock copolymers, poly-N-(2-ethyl)hexylglycine-block-poly-N-phosphonomethylglycine (pNeh-b-pNpm), with volume fractions of pNpm (Φ Npm) values ranging from 0.13 to 0.44 and dispersity (¯D) ≤ 1.0003. The morphologies of the dry block copolypeptoids were determined by transmission electron microscopy and in both the dry and hydrated states by synchrotron small-angle X-ray scattering. Drymore » samples with Φ Npm > 0.13 exhibited a lamellar morphology. Upon hydration, the lowest molecular weight sample transitioned to a hexagonally packed cylinder morphology, while the others maintained their dry morphologies. Water uptake of all of the ordered samples was 8.1 ± 1.1 water molecules per phosphonate group. In spite of this, the proton conductivity of the ordered pNeh-b-pNpm copolymers ranged from 0.002 to 0.008 S/cm. Finally, we demonstrate that proton conductivity is maximized in high molecular weight, symmetric pNeh-b-pNpm copolymers.« less

Microphase separation in random multiblock copolymers

NASA Astrophysics Data System (ADS)

Govorun, E. N.; Chertovich, A. V.

2017-01-01

Microphase separation in random multiblock copolymers is studied with the mean-field theory assuming that long blocks of a copolymer are strongly segregated, whereas short blocks are able to penetrate into "alien" domains and exchange between the domains and interfacial layer. A bidisperse copolymer with blocks of only two sizes (long and short) is considered as a model of multiblock copolymers with high polydispersity in the block size. Short blocks of the copolymer play an important role in the microphase separation. First, their penetration into the "alien" domains leads to the formation of joint long blocks in their own domains. Second, short blocks localized at the interface considerably change the interfacial tension. The possibility of penetration of short blocks into the "alien" domains is controlled by the product χ Nsh (χ is the Flory-Huggins interaction parameter and Nsh is the short block length). At not very large χ Nsh , the domain size is larger than that for a regular copolymer consisting of the same long blocks as in the considered random copolymer. At a fixed mean block size, the domain size grows with an increase in the block size dispersity, the rate of the growth being dependent of the more detailed parameters of the block size distribution.

Polybenzimidazole block copolymers for fuel cell: synthesis and studies of block length effects on nanophase separation, mechanical properties, and proton conductivity of PEM.

PubMed

Maity, Sudhangshu; Jana, Tushar

2014-05-14

A series of meta-polybenzimidazole-block-para-polybenzimidazole (m-PBI-b-p-PBI), segmented block copolymers of PBI, were synthesized with various structural motifs and block lengths by condensing the diamine terminated meta-PBI (m-PBI-Am) and acid terminated para-PBI (p-PBI-Ac) oligomers. NMR studies and existence of two distinct glass transition temperatures (Tg), obtained from dynamical mechanical analysis (DMA) results, unequivocally confirmed the formation of block copolymer structure through the current polymerization methodology. Appropriate and careful selection of oligomers chain length enabled us to tailor the block length of block copolymers and also to make varieties of structural motifs. Increasingly distinct Tg peaks with higher block length of segmented block structure attributed the decrease in phase mixing between the meta-PBI and para-PBI blocks, which in turn resulted into nanophase segregated domains. The proton conductivities of proton exchange membrane (PEM) developed from phosphoric acid (PA) doped block copolymer membranes were found to be increasing substantially with increasing block length of copolymers even though PA loading of these membranes did not alter appreciably with varying block length. For example when molecular weight (Mn) of blocks were increased from 1000 to 5500 then the proton conductivities at 160 °C of resulting copolymers increased from 0.05 to 0.11 S/cm. Higher block length induced nanophase separation between the blocks by creating less morphological barrier within the block which facilitated the movement of the proton in the block and hence resulting higher proton conductivity of the PEM. The structural varieties also influenced the phase separation and proton conductivity. In comparison to meta-para random copolymers reported earlier, the current meta-para segmented block copolymers were found to be more suitable for PBI-based PEM.

Rapid self-assembly of block copolymers to photonic crystals

DOEpatents

Xia, Yan; Sveinbjornsson, Benjamin R; Grubbs, Robert H; Weitekamp, Raymond; Miyake, Garret M; Atwater, Harry A; Piunova, Victoria; Daeffler, Christopher Scot; Hong, Sung Woo; Gu, Weiyin; Russell, Thomas P.

2016-07-05

The invention provides a class of copolymers having useful properties, including brush block copolymers, wedge-type block copolymers and hybrid wedge and polymer block copolymers. In an embodiment, for example, block copolymers of the invention incorporate chemically different blocks comprising polymer size chain groups and/or wedge groups that significantly inhibit chain entanglement, thereby enhancing molecular self-assembly processes for generating a range of supramolecular structures, such as periodic nanostructures and microstructures. The present invention also provides useful methods of making and using copolymers, including block copolymers.

Lignin poly(lactic acid) copolymers

DOEpatents

Olsson, Johan Vilhelm; Chung, Yi-Lin; Li, Russell Jingxian; Waymouth, Robert; Sattely, Elizabeth; Billington, Sarah; Frank, Curtis W.

2017-02-14

Provided herein are graft co-polymers of lignin and poly(lactic acid) (lignin-g-PLA copolymer), thermoset and thermoplastic polymers including them, methods of preparing these polymers, and articles of manufacture including such polymers.

21 CFR 175.210 - Acrylate ester copolymer coating.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Acrylate ester copolymer coating. 175.210 Section... COATINGS Substances for Use as Components of Coatings § 175.210 Acrylate ester copolymer coating. Acrylate...) The acrylate ester copolymer is a fully polymerized copolymer of ethyl acrylate, methyl methacrylate...

Multidimensional chromatographic techniques for hydrophilic copolymers II. Analysis of poly(ethylene glycol)-poly(vinyl acetate) graft copolymers.

PubMed

Knecht, Daniela; Rittig, Frank; Lange, Ronald F M; Pasch, Harald

2006-10-13

A large variety of hydrophilic copolymers is applied in different fields of chemical industry including bio, pharma and pharmaceutical applications. For example, poly(ethylene glycol)-poly(vinyl alcohol) graft copolymers that are used as tablet coatings are responsible for the controlled release of the active compounds. These copolymers are produced by grafting of vinyl acetate onto polyethylene glycol (PEG) and subsequent hydrolysis of the poly(ethylene glycol)-poly(vinyl acetate) graft copolymers. The poly(ethylene glycol)-poly(vinyl acetate) copolymers are distributed with regard to molar mass and chemical composition. In addition, they frequently contain the homopolymers polyethylene glycol and polyvinyl acetate. The comprehensive analysis of such complex systems requires hyphenated analytical techniques, including two-dimensional liquid chromatography and combined LC and nuclear magnetic resonance spectroscopy. The development and application of these techniques are discussed in the present paper.

Polyether-polyester graft copolymer

NASA Technical Reports Server (NTRS)

Bell, Vernon L. (Inventor)

1987-01-01

Described is a polyether graft polymer having improved solvent resistance and crystalline thermally reversible crosslinks. The copolymer is prepared by a novel process of anionic copolymerization. These polymers exhibit good solvent resistance and are well suited for aircraft parts. Previous aromatic polyethers, also known as polyphenylene oxides, have certain deficiencies which detract from their usefulness. These commercial polymers are often soluble in common solvents including the halocarbon and aromatic hydrocarbon types of paint thinners and removers. This limitation prevents the use of these polyethers in structural articles requiring frequent painting. In addition, the most popular commercially available polyether is a very high melting plastic. This makes it considerably more difficult to fabricate finished parts from this material. These problems are solved by providing an aromatic polyether graft copolymer with improved solvent resistance and crystalline thermally reversible crosslinks. The graft copolymer is formed by converting the carboxyl groups of a carboxylated polyphenylene oxide polymer to ionic carbonyl groups in a suitable solvent, reacting pivalolactone with the dissolved polymer, and adding acid to the solution to produce the graft copolymer.

Polyether/Polyester Graft Copolymers

NASA Technical Reports Server (NTRS)

Bell, Vernon L., Jr.; Wakelyn, N.; Stoakley, D. M.; Proctor, K. M.

1986-01-01

Higher solvent resistance achieved along with lower melting temperature. New technique provides method of preparing copolymers with polypivalolactone segments grafted onto poly (2,6-dimethyl-phenylene oxide) backbone. Process makes strong materials with improved solvent resistance and crystalline, thermally-reversible crosslinks. Resulting graft copolymers easier to fabricate into useful articles, including thin films, sheets, fibers, foams, laminates, and moldings.

High temperature polymers for proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Einsla, Brian Russel

Novel proton exchange membranes (PEMs) were investigated that show potential for operating at higher temperatures in both direct methanol (DMFC) and H 2/air PEM fuel cells. The need for thermally stable polymers immediately suggests the possibility of heterocyclic polymers bearing appropriate ion conducting sites. Accordingly, monomers and random disulfonated poly(arylene ether) copolymers containing either naphthalimide, benzoxazole or benzimidazole moieties were synthesized via direct copolymerization. The ion exchange capacity (IEC) was varied by simply changing the ratio of disulfonated monomer to nonsulfonated monomer in the copolymerization step. Water uptake and proton conductivity of cast membranes increased with IEC. The water uptake of these heterocyclic copolymers was lower than that of comparable disulfonated poly(arylene ether) systems, which is a desirable improvement for PEMs. Membrane electrode assemblies were prepared and the initial fuel cell performance of the disulfonated polyimide and polybenzoxazole (PBO) copolymers was very promising at 80°C compared to the state-of-the-art PEM (NafionRTM); nevertheless these membranes became brittle under operating conditions. Several series of poly(arylene ether)s based on disodium-3,3'-disulfonate-4,4 '-dichlorodiphenylsulfone (S-DCDPS) and a benzimidazole-containing bisphenol were synthesized and afforded copolymers with enhanced stability. Selected properties of these membranes were compared to separately prepared miscible blends of disulfonated poly(arylene ether sulfone) copolymers and polybenzimidazole (PBI). Complexation of the sulfonic acid groups with the PBI structure reduced water swelling and proton conductivity. The enhanced proton conductivity of NafionRTM membranes has been proposed to be due to the aggregation of the highly acidic side-chain sulfonic acid sites to form ion channels. A series of side-chain sulfonated poly(arylene ether sulfone) copolymers based on methoxyhydroquinone was

Directed self assembly of block copolymers using chemical patterns with sidewall guiding lines, backfilled with random copolymer brushes.

PubMed

Pandav, Gunja; Durand, William J; Ellison, Christopher J; Willson, C Grant; Ganesan, Venkat

2015-12-21

Recently, alignment of block copolymer domains has been achieved using a topographically patterned substrate with a sidewall preferential to one of the blocks. This strategy has been suggested as an option to overcome the patterning resolution challenges facing chemoepitaxy strategies, which utilize chemical stripes with a width of about half the period of block copolymer to orient the equilibrium morphologies. In this work, single chain in mean field simulation methodology was used to study the self assembly of symmetric block copolymers on topographically patterned substrates with sidewall interactions. Random copolymer brushes grafted to the background region (space between patterns) were modeled explicitly. The effects of changes in pattern width, film thicknesses and strength of sidewall interaction on the resulting morphologies were examined and the conditions which led to perpendicular morphologies required for lithographic applications were identified. A number of density multiplication schemes were studied in order to gauge the efficiency with which the sidewall pattern can guide the self assembly of block copolymers. The results indicate that such a patterning technique can potentially utilize pattern widths of the order of one-two times the period of block copolymer and still be able to guide ordering of the block copolymer domains up to 8X density multiplication.

Method of forming oriented block copolymer line patterns, block copolymer line patterns formed thereby, and their use to form patterned articles

DOEpatents

Russell, Thomas P.; Hong, Sung Woo; Lee, Doug Hyun; Park, Soojin; Xu, Ting

2015-10-13

A block copolymer film having a line pattern with a high degree of long-range order is formed by a method that includes forming a block copolymer film on a substrate surface with parallel facets, and annealing the block copolymer film to form an annealed block copolymer film having linear microdomains parallel to the substrate surface and orthogonal to the parallel facets of the substrate. The line-patterned block copolymer films are useful for the fabrication of magnetic storage media, polarizing devices, and arrays of nanowires.

Method of forming oriented block copolymer line patterns, block copolymer line patterns formed thereby, and their use to form patterned articles

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

Russell, Thomas P.; Hong, Sung Woo; Lee, Dong Hyun

A block copolymer film having a line pattern with a high degree of long-range order is formed by a method that includes forming a block copolymer film on a substrate surface with parallel facets, and annealing the block copolymer film to form an annealed block copolymer film having linear microdomains parallel to the substrate surface and orthogonal to the parallel facets of the substrate. The line-patterned block copolymer films are useful for the fabrication of magnetic storage media, polarizing devices, and arrays of nanowires.

Block copolymer lithography of rhodium nanoparticles for high temperature electrocatalysis.

PubMed

Boyd, David A; Hao, Yong; Li, Changyi; Goodwin, David G; Haile, Sossina M

2013-06-25

We present a method for forming ordered rhodium nanostructures on a solid support. The approach makes use of a block copolymer to create and assemble rhodium chloride nanoparticles from solution onto a surface; subsequent plasma and thermal processing are employed to remove the polymer and fully convert the nanostructures to metallic rhodium. Films cast from a solution of the triblock copolymer poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) dissolved in toluene with rhodium(III) chloride hydrate were capable of producing a monolayer of rhodium nanoparticles of uniform size and interparticle spacing. The nanostructures were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. The electrocatalytic performance of the nanoparticles was investigated with AC impedance spectroscopy. We observed that the addition of the particles to a model solid oxide fuel cell anode provided up to a 14-fold improvement in the anode activity as evidenced by a decrease in the AC impedance resistance. Examination of the anode after electrochemical measurement revealed that the basic morphology and distribution of the particles were preserved.

Biodegradable copolymers carrying cell-adhesion peptide sequences.

PubMed

Proks, Vladimír; Machová, Lud'ka; Popelka, Stepán; Rypácek, Frantisek

2003-01-01

Amphiphilic block copolymers are used to create bioactive surfaces on biodegradable polymer scaffolds for tissue engineering. Cell-selective biomaterials can be prepared using copolymers containing peptide sequences derived from extracellular-matrix proteins (ECM). Here we discuss alternative ways for preparation of amphiphilic block copolymers composed of hydrophobic polylactide (PLA) and hydrophilic poly(ethylene oxide) (PEO) blocks with cell-adhesion peptide sequences. Copolymers PLA-b-PEO were prepared by a living polymerisation of lactide in dioxane with tin(II)2-ethylhexanoate as a catalyst. The following approaches for incorporation of peptides into copolymers were elaborated. (a) First, a side-chain protected Gly-Arg-Gly-Asp-Ser-Gly (GRGDSG) peptide was prepared by solid-phase peptide synthesis (SPPS) and then coupled with delta-hydroxy-Z-amino-PEO in solution. In the second step, the PLA block was grafted to it via a controlled polymerisation of lactide initiated by the hydroxy end-groups of PEO in the side-chain-protected GRGDSG-PEO. Deprotection of the peptide yielded a GRGDSG-b-PEO-b-PLA copolymer, with the peptide attached through its C-end. (b) A protected GRGDSG peptide was built up on a polymer resin and coupled with Z-carboxy-PEO using a solid-phase approach. After cleavage of the delta-hydroxy-PEO-GRGDSG copolymer from the resin, polymerisation of lactide followed by deprotection of the peptide yielded a PLA-b-PEO-b-GRGDSG block copolymer, in which the peptide is linked through its N-terminus.

Advanced Materials for PEM-Based Fuel Cell Systems

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

James E. McGrath; Donald G. Baird; Michael von Spakovsky

2005-10-26

Proton exchange membrane fuel cells (PEMFCs) are quickly becoming attractive alternative energy sources for transportation, stationary power, and small electronics due to the increasing cost and environmental hazards of traditional fossil fuels. Two main classes of PEMFCs include hydrogen/air or hydrogen/oxygen fuel cells and direct methanol fuel cells (DMFCs). The current benchmark membrane for both types of PEMFCs is Nafion, a perfluorinated sulfonated copolymer made by DuPont. Nafion copolymers exhibit good thermal and chemical stability, as well as very high proton conductivity under hydrated conditions at temperatures below 80 degrees C. However, application of these membranes is limited due tomore » their high methanol permeability and loss of conductivity at high temperatures and low relative humidities. These deficiencies have led to the search for improved materials for proton exchange membranes. Potential PEMs should have good thermal, hydrolytic, and oxidative stability, high proton conductivity, selective permeability, and mechanical durability over long periods of time. Poly(arylene ether)s, polyimides, polybenzimidazoles, and polyphenylenes are among the most widely investigated candidates for PEMs. Poly(arylene ether)s are a promising class of proton exchange membranes due to their excellent thermal and chemical stability and high glass transition temperatures. High proton conductivity can be achieved through post-sulfonation of poly(arylene ether) materials, but this most often results in very high water sorption or even water solubility. Our research has shown that directly polymerized poly(arylene ether) copolymers show important advantages over traditional post-sulfonated systems and also address the concerns with Nafion membranes. These properties were evaluated and correlated with morphology, structure-property relationships, and states of water in the membranes. Further improvements in properties were achieved through incorporation of

Imide/arylene ether block copolymers

NASA Technical Reports Server (NTRS)

Jensen, B. J.; Hergenrother, P. M.; Bass, R. G.

1991-01-01

Two series of imide/arylene either block copolymers were prepared using an arylene ether block and either an amorphous or semi-crystalline imide block. The resulting copolymers were characterized and selected physical and mechanical properties were determined. These results, as well as comparisons to the homopolymer properties, are discussed.

Compatibility Assessment of Fuel System Infrastructure Plastics with Bio-oil and Diesel Fuel

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

Kass, Michael D.; Janke, Christopher James; Connatser, Raynella M.

We report that bio-oil derived via fast pyrolysis is being developed as a renewable fuel option for petroleum distillates. The compatibility of neat bio-oil with 18 plastic types was evaluated using neat diesel fuel as the baseline. The plastic materials included polyphenylene sulfide (PPS), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyoxymethylene (POM), POM copolymer, high density polyethylene (HDPE), polybutylene terephthalate (PBT), polypropylene (PP), polyethylene terephthalate glycol (PETG), polythiourea (PTU), four nylon grades, and four thermosetting resins. Specimens of each material were immersed in the test fuels for a period of 16 weeks to achieve full saturation. Except formore » PP and HDPE, the plastic materials underwent higher volume expansion in bio-oil than in the baseline diesel (which was negligible in most cases). This volume increase corresponds to the higher polarity of the bio-oil. PPS, PET, and PTFE were unaffected by bio-oil exposure, but modest swelling (between 2 and 5%) occurred for the two acetals (POM and POM copolymer), Nylon-12, PBT, PETG, and the four resin grades. More moderate swelling (8–15%) was noted for Nylon-6, Nylon-6/6, and Nylon-11, and excessive swell (>40%) occurred for PTU. The nonpolar nature of PP and HDPE matches that of diesel, leading to higher solubility (swell) in this fuel type. Finally, the relatively low volume expansion following exposure indicates that many of the existing infrastructure plastics (excluding PTU) should be suitable for use with bio-oil.« less

40 CFR 721.10519 - Perfluoroalkyl acrylate copolymer (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... as perfluoroalkyl acrylate copolymer (PMN P-11-63) is subject to reporting under this section for the... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Perfluoroalkyl acrylate copolymer... Specific Chemical Substances § 721.10519 Perfluoroalkyl acrylate copolymer (generic). (a) Chemical...

40 CFR 721.10519 - Perfluoroalkyl acrylate copolymer (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... as perfluoroalkyl acrylate copolymer (PMN P-11-63) is subject to reporting under this section for the... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Perfluoroalkyl acrylate copolymer... Specific Chemical Substances § 721.10519 Perfluoroalkyl acrylate copolymer (generic). (a) Chemical...

Self-assembly of model graft copolymers of agarose and weak polyelectrolyte-based amphiphilic diblock copolymers: controlled drug release and degradation.

PubMed

Muppalla, Ravikumar; Jewrajka, Suresh K; Prasad, Kamalesh

2013-06-01

Polysaccharide-based copolymers are promising biomaterials due to their biocompatibility and biodegradability. For potential biomedical applications the copolymer as a whole and all the degraded species must be biocompatible and easily removable from the system. In this regards, new model pH-responsive seaweed agarose (Agr) grafted with weak polyelectrolyte-based well-defined amphiphilic block copolymers ca. poly[(methyl methacrylate)-b-(2-dimethylamino)ethyl methacrylate)] (PMMA-b-PDMA) were designed and synthesized to study the self-assembly, degradation, and in vitro hydrophobic/hydrophilic drug release behavior. The graft copolymer solutions display extremely low critical micelle concentration (CMC) and form pH responsive stable micelles. The degradation study of the graft copolymer reveals that the entire degraded components are well soluble/dispersible in water due to formation of mixed micelles. The micelles are also strongly adsorbed on the mica surface owing to electrostatic interaction. One application of the graft copolymer micelles is that it can entrap both hydrophilic and poorly water soluble hydrophobic drugs effectively and exhibit slow release kinetics. The release kinetics of both the hydrophilic and poorly water soluble hydrophobic drugs change with pH as well as with the composition of the graft copolymer. Copyright © 2012 Wiley Periodicals, Inc.

21 CFR 172.775 - Methacrylic acid-divinylbenzene copolymer.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Methacrylic acid-divinylbenzene copolymer. 172.775... HUMAN CONSUMPTION Other Specific Usage Additives § 172.775 Methacrylic acid-divinylbenzene copolymer. Methacrylic acid-divinylbenzene copolymer may be safely used in food in accordance with the following...

21 CFR 172.775 - Methacrylic acid-divinylbenzene copolymer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Methacrylic acid-divinylbenzene copolymer. 172.775... HUMAN CONSUMPTION Other Specific Usage Additives § 172.775 Methacrylic acid-divinylbenzene copolymer. Methacrylic acid-divinylbenzene copolymer may be safely used in food in accordance with the following...

21 CFR 177.1211 - Cross-linked polyacrylate copolymers.

Code of Federal Regulations, 2011 CFR

2011-04-01

... polyacrylate copolymers consist of: (1) The grafted copolymer of cross-linked sodium polyacrylate identified as... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Cross-linked polyacrylate copolymers. 177.1211... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1211 Cross-linked polyacrylate...

21 CFR 177.1211 - Cross-linked polyacrylate copolymers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... polyacrylate copolymers consist of: (1) The grafted copolymer of cross-linked sodium polyacrylate identified as... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Cross-linked polyacrylate copolymers. 177.1211... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1211 Cross-linked polyacrylate...

21 CFR 177.1060 - n-Alkylglutarimide/acrylic copolymers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true n-Alkylglutarimide/acrylic copolymers. 177.1060... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1060 n-Alkylglutarimide/acrylic copolymers. n-Alkylglutarimide/acrylic copolymers identified in this section may be safely used as articles...

21 CFR 177.1320 - Ethylene-ethyl acrylate copolymers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-ethyl acrylate copolymers. 177.1320... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1320 Ethylene-ethyl acrylate copolymers. Ethylene-ethyl acrylate copolymers may be safely used to produce packaging materials, containers...

Light-emitting block copolymers composition, process and use

DOEpatents

Ferraris, John P.; Gutierrez, Jose J.

2006-11-14

Generally, and in one form, the present invention is a composition of light-emitting block copolymer. In another form, the present invention is a process producing a light-emitting block copolymers that intends polymerizing a first di(halo-methyl) aromatic monomer compound in the presence of an anionic initiator and a base to form a polymer and contacting a second di(halo-methyl) aromatic monomer compound with the polymer to form a homopolymer or block copolymer wherein the block copolymer is a diblock, triblock, or star polymer. In yet another form, the present invention is an electroluminescent device comprising a light-emitting block copolymer, wherein the electroluminescent device is to be used in the manufacturing of optical and electrical devices.

Block Copolymers: Synthesis and Applications in Nanotechnology

NASA Astrophysics Data System (ADS)

Lou, Qin

This study is focused on the synthesis and study of (block) copolymers using reversible deactivation radical polymerizations (RDRPs), including atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization. In particular, two primary areas of study are undertaken: (1) a proof-of-concept application of lithographic block copolymers, and (2) the mechanistic study of the deposition of titania into block copolymer templates for the production of well-ordered titania nanostructures. Block copolymers have the ability to undergo microphase separation, with an average size of each microphase ranging from tens to hundreds of nanometers. As such, block copolymers have been widely considered for nanotechnological applications over the past two decades. The development of materials for various nanotechnologies has become an increasingly studied area as improvements in many applications, such as those found in the semiconductor and photovoltaic industries are constantly being sought. Significant growth in developments of new synthetic methods ( i.e. RDRPs) has allowed the production of block copolymers with molecular (and sometimes atomic) definition. In turn, this has greatly expanded the use of block copolymers in nanotechnology. Herein, we describe the synthesis of statistical and block copolymers of 193 nm photolithography methacrylate and acrylate resist monomers with norbornyl and adamantyl moieties using RAFT polymerization.. For these resist (block) copolymers, the phase separation behaviors were examined by atomic force microscopy (AFM). End groups were removed from the polymers to avoid complications during the photolithography since RAFT end groups absorb visible light. Poly(glycidyl methacrylate-block-polystyrene) (PGMA-b-PS) was synthesize by ATRP and demonstrated that this block copolymer acts as both a lithographic UV (365 nm) photoresist and a self-assembly material. The PGMA segments can undergo cationic

21 CFR 177.1350 - Ethylene-vinyl acetate copolymers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-vinyl acetate copolymers. 177.1350 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1350 Ethylene-vinyl acetate copolymers. Ethylene-vinyl acetate copolymers may be safely used as articles or components of articles...

21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-acrylic acid copolymers. 177.1310 Section... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1310 Ethylene-acrylic acid copolymers. The ethylene-acrylic acid copolymers identified in paragraph (a) of this section may be safely...

21 CFR 177.1312 - Ethylene-carbon monoxide copolymers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-carbon monoxide copolymers. 177.1312... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1312 Ethylene-carbon monoxide copolymers. The ethylene-carbon monoxide copolymers identified in paragraph (a) of this section may be safely...

Counteranion-Mediated Intrinsic Healing of Poly(ionic liquid) Copolymers.

PubMed

Guo, Panlong; Zhang, Houyu; Liu, Xiaokong; Sun, Junqi

2018-01-17

Fabrication of self-healing/healable materials using reversible interactions that are governed by their inherent chemical features is highly desirable because it avoids the introduction of extra groups that may present negative effects on their functions. The present study exploits the inherently featured electrostatic interactions of the ion pairs in polymeric ionic liquids (PILs) as the driving force to fabricate healable PIL copolymers. The healable PIL copolymers are fabricated through the copolymerization of the IL monomers with ethyl acrylate followed by the replacement of Br - counteranions with bulkier ones such as bis(trifluoromethanesulfonyl)imide (TFSI - ). Without modifying the chemical structures of the PIL moieties, the healing performance of the as-prepared PIL copolymers can be effectively mediated by their counteranions. The PIL copolymers that do not possess healability when paired with Br - counteranions become healable after exchanging the Br - counteranions with larger-sized ones (e.g., TFSI - ). The PIL copolymers paired with bulky counteranions exhibit enhanced chain mobility and highly reversible ion-pair interactions, which facilitate the healing process. The PIL copolymers paired with TFSI - anions can completely heal the damage/cut upon heating at 55 °C for 7.5 h. Meanwhile, the counteranions with larger sizes not only benefit the healing performance of the PIL copolymers but also enhance their ion conductivity. The ion conductivity of the PIL copolymers paired with TFSI - is an order of magnitude higher than that of the PIL copolymers paired with Br - . Therefore, the as-prepared healable PIL copolymers are potentially useful as solid electrolytes in PIL-based energy devices to improve their safety and reliability.

Melt structure and self-nucleation of ethylene copolymers

NASA Astrophysics Data System (ADS)

Alamo, Rufina G.

A strong memory effect of crystallization has been observed in melts of random ethylene copolymers well above the equilibrium melting temperature. These studies have been carried out by DSC, x-ray, TEM and optical microscopy on a large number of model, narrow, and broad copolymers with different comonomer types and contents. Melt memory is correlated with self-seeds that increase the crystallization rate of ethylene copolymers. The seeds are associated with molten ethylene sequences from the initial crystals that remain in close proximity and lower the nucleation barrier. Diffusion of all sequences to a randomized melt state is a slow process, restricted by topological chain constraints (loops, knots, and other entanglements) that build in the intercrystalline region during crystallization. Self-seeds dissolve above a critical melt temperature that demarcates homogeneity of the copolymer melt. There is a critical threshold level of crystallinity to observe the effect of melt memory on crystallization rate, thus supporting the correlation between melt memory and the change in melt structure during copolymer crystallization. Unlike binary blends, commercial ethylene-1-alkene copolymers with a range in inter-chain comonomer composition between 1 and about 15 mol % display an inversion of the crystallization rate in a range of melt temperatures where narrow copolymers show a continuous acceleration of the rate. With decreasing the initial melt temperature, broadly distributed copolymers show enhanced crystallization followed by a decrease of crystallization rate. The inversion demarcates the onset of liquid-liquid phase separation (LLPS) and a reduction of self-nuclei due to the strong thermodynamic drive for molecular segregation inside the binodal. The strong effect of melt memory on crystallization rate can be used to identify liquid-liquid phase separation in broadly distributed copolymers, and offers strategies to control the state of copolymer melts in ways of

Hemocompatibility evaluation in vitro of methoxy polyethyleneglycol-polycaprolactone copolymer solutions.

PubMed

Hu, Qian; Zhang, Yi; Wang, Changyong; Xu, Jiake; Wu, Jianping; Liu, Zonghua; Xue, Wei

2016-03-01

Amphiphilic block copolymer methoxy polyethyleneglycol-polycaprolactone (mPEG-PCL) has attracted interest in the biomedical field, due to its water solubility and biodegradability. Nevertheless, the blood safety of mPEG-PCL copolymers has not been investigated in detail. Because mPEG-PCL copolymers introduced in vivo would inevitably interact with blood tissue, an investigation of possible interactions of mPEG-PCL with key blood components is crucial. We studied the effects of two mPEG-PCL copolymer solutions on blood coagulation, the morphology and lysis of human red blood cells (RBCs), the structure of plasma fibrinogen, complement activation, and platelet aggregation. We found that higher concentrations of the mPEG-PCL copolymers impaired blood clotting, and the copolymers had little impact on the morphology or lysis of RBCs. From the spectroscopy results, the copolymers affected the local microstructure of fibrinogen. The copolymers significantly activated the complement system in a concentration-dependent way. At higher concentrations, the copolymers impaired platelet aggregation, which may have been mediated by an inhibition of the arachidonic acid pathway. These findings provide important information that may be useful for the molecular design and biomedical applications of mPEG-PCL copolymers. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 802-812, 2016. © 2016 Wiley Periodicals, Inc.

Amphiphilic block copolymer membrane for vanadium redox flow battery

NASA Astrophysics Data System (ADS)

Wang, Fei; Sylvia, James M.; Jacob, Monsy M.; Peramunage, Dharmasena

2013-11-01

An amphiphilic block copolymer comprised of hydrophobic polyaryletherketone (PAEK) and hydrophilic sulfonated polyaryletherketone (SPAEK) blocks has been synthesized and characterized. A membrane prepared from the block copolymer is used as the separator in a single cell vanadium redox flow battery (VRB). The proton conductivity, mechanical property, VO2+ permeability and single VRB cell performance of this block copolymer membrane are investigated and compared to Nafion™ 117. The block copolymer membrane showed significantly improved vanadium ion selectivity, higher mechanical strength and lower conductivity than Nafion™ 117. The VRB containing the block copolymer membrane exhibits higher coulombic efficiency and similar energy efficiency compared to a VRB using Nafion™ 117. The better vanadium ion selectivity of the block copolymer membrane has led to a much smaller capacity loss during 50 charge-discharge cycles for the VRB.

Periodic nanostructures from self assembled wedge-type block-copolymers

DOEpatents

Xia, Yan; Sveinbjornsson, Benjamin R.; Grubbs, Robert H.; Weitekamp, Raymond; Miyake, Garret M.; Piunova, Victoria; Daeffler, Christopher Scot

2015-06-02

The invention provides a class of wedge-type block copolymers having a plurality of chemically different blocks, at least a portion of which incorporates a wedge group-containing block providing useful properties. For example, use of one or more wedge group-containing blocks in some block copolymers of the invention significantly inhibits chain entanglement and, thus, the present block copolymers materials provide a class of polymer materials capable of efficient molecular self-assembly to generate a range of structures, such as periodic nanostructures and microstructures. Materials of the present invention include copolymers having one or more wedge group-containing blocks, and optionally for some applications copolymers also incorporating one or more polymer side group-containing blocks. The present invention also provides useful methods of making and using wedge-type block copolymers.

Injectable biodegradable temperature-responsive PLGA-PEG-PLGA copolymers: synthesis and effect of copolymer composition on the drug release from the copolymer-based hydrogels.

PubMed

Qiao, Mingxi; Chen, Dawei; Ma, Xichen; Liu, Yanjun

2005-04-27

Injectable biodegradable temperature-responsive poly(DL-lactide-co-glycolide-b-ethylene glycol-b-DL-lactide-co-glycolide) (PLGA-PEG-PLGA) triblock copolymers with DL-lactide/glycolide molar ratio ranging from 6/1 to 15/l were synthesized from monomers of DL-lactide, glycolide and polyethylene glycol and characterized by 1H NMR. The resulting copolymers are soluble in water to form free flowing fluid at room temperature but become hydrogels at body temperature. The hydrophobicity of the copolymer increased with the increasing of DL-lactide/glycolide molar ratio. In vitro dissolution studies with two different hydrophobic drugs (5-fluorouracil and indomethacin) were performed to study the effect of DL-lactide/glycolide molar ratio on drug release and to elucidate drug release mechanism. The release mechanism for hydrophilic 5-fluorouracil was diffusion-controlled, while hydrophobic indomethacin showed an biphasic profile comprising of an initial diffusion-controlled stage followed by the hydrogel erosion-dominated stage. The effect of DL-lactide/glycolide molar ratio on drug release seemed to be dependent on the drug release mechanism. It has less effect on the drug release during the diffusion-controlled stage, but significantly affected drug release during the hydrogel erosion-controlled stage. Compared with ReGel system, the synthesized copolymers showed a higher gelation temperature and longer period of drug release. The copolymers can solubilize the hydrophobic indomethacin and the solubility (13.7 mg/ml) was increased 3425-fold compared to that in water (4 microg/ml, 25 degrees C). Two methods of physical mixing method and solvent evaporation method were used for drug solubilization and the latter method showed higher solubilization efficiency.

Oxygen plasma resistant phosphine oxide containing imide/arylene copolymers

NASA Technical Reports Server (NTRS)

Jensen, Brian J.

1993-01-01

A series of oxygen plasma resistant imide/arylene ether copolymers were prepared by reacting anhydride-terminated poly(amide acids) and amine-terminated polyarylene ethers containing phosphine oxide units. Inherent viscosities for these copolymers ranged from 0.42 to 0.80 dL/g. After curing, the resulting copolymers had glass transition temperatures ranging from 224 C to 228 C. Solution cast films of the block copolymers were tough and flexible with tensile strength, tensile moduli, and elongation at break up to 16.1 ksi, 439 ksi, and 23 percent, respectively at 25 C and 9.1 ksi, 308 ksi and 97 percent, respectively at 150 C. The copolymers show a significant improvement in resistance to oxygen plasma when compared to the commercial polyimide Kapton. The imide/arylene ether copolymers containing phosphine oxide units are suitable as coatings, films, adhesives, and composite matrices.

Block Copolymer Membranes for Biofuel Purification

NASA Astrophysics Data System (ADS)

Evren Ozcam, Ali; Balsara, Nitash

2012-02-01

Purification of biofuels such as ethanol is a matter of considerable concern as they are produced in complex multicomponent fermentation broths. Our objective is to design pervaporation membranes for concentrating ethanol from dilute aqueous mixtures. Polystyrene-b-polydimethylsiloxane-b-polystyrene block copolymers were synthesized by anionic polymerization. The polydimethylsiloxane domains provide ethanol-transporting pathways, while the polystyrene domains provide structural integrity for the membrane. The morphology of the membranes is governed by the composition of the block copolymer while the size of the domains is governed by the molecular weight of the block copolymer. Pervaporation data as a function of these two parameters will be presented.

40 CFR 721.10213 - Polyether polyester copolymer phosphate (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Polyether polyester copolymer... Specific Chemical Substances § 721.10213 Polyether polyester copolymer phosphate (generic). (a) Chemical... as polyether polyester copolymer phosphate (PMN P-09-253) is subject to reporting under this section...

40 CFR 721.336 - Perfluoroalkylethyl acrylate copolymer (generic name).

Code of Federal Regulations, 2011 CFR

2011-07-01

... as a perfluoroalkylethyl acrylate copolymer (PMN P-94-241) is subject to reporting under this section... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Perfluoroalkylethyl acrylate copolymer... Specific Chemical Substances § 721.336 Perfluoroalkylethyl acrylate copolymer (generic name). (a) Chemical...

40 CFR 721.336 - Perfluoroalkylethyl acrylate copolymer (generic name).

Code of Federal Regulations, 2013 CFR

2013-07-01

... as a perfluoroalkylethyl acrylate copolymer (PMN P-94-241) is subject to reporting under this section... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Perfluoroalkylethyl acrylate copolymer... Specific Chemical Substances § 721.336 Perfluoroalkylethyl acrylate copolymer (generic name). (a) Chemical...

40 CFR 721.336 - Perfluoroalkylethyl acrylate copolymer (generic name).

Code of Federal Regulations, 2014 CFR

2014-07-01

... as a perfluoroalkylethyl acrylate copolymer (PMN P-94-241) is subject to reporting under this section... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Perfluoroalkylethyl acrylate copolymer... Specific Chemical Substances § 721.336 Perfluoroalkylethyl acrylate copolymer (generic name). (a) Chemical...

40 CFR 721.336 - Perfluoroalkylethyl acrylate copolymer (generic name).

Code of Federal Regulations, 2012 CFR

2012-07-01

... as a perfluoroalkylethyl acrylate copolymer (PMN P-94-241) is subject to reporting under this section... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Perfluoroalkylethyl acrylate copolymer... Specific Chemical Substances § 721.336 Perfluoroalkylethyl acrylate copolymer (generic name). (a) Chemical...

Injectible bodily prosthetics employing methacrylic copolymer gels

DOEpatents

Mallapragada, Surya K.; Anderson, Brian C.

2007-02-27

The present invention provides novel block copolymers as structural supplements for injectible bodily prosthetics employed in medical or cosmetic procedures. The invention also includes the use of such block copolymers as nucleus pulposus replacement materials for the treatment of degenerative disc disorders and spinal injuries. The copolymers are constructed by polymerization of a tertiary amine methacrylate with either a (poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) polymer, such as the commercially available Pluronic.RTM. polymers, or a poly(ethylene glycol) methyl ether polymer.

Reversible geling co-polymer and method of making

DOEpatents

Gutowska, Anna

2005-12-27

The present invention is a thereapeutic agent carrier having a thermally reversible gel or geling copolymer that is a linear random copolymer of an [meth-]acrylamide derivative and a hydrophilic comonomer, wherein the linear random copolymer is in the form of a plurality of linear chains having a plurality of molecular weights greater than or equal to a minimum geling molecular weight cutoff and a therapeutic agent.

Copolymers For Capillary Gel Electrophoresis

DOEpatents

Liu, Changsheng; Li, Qingbo

2005-08-09

This invention relates to an electrophoresis separation medium having a gel matrix of at least one random, linear copolymer comprising a primary comonomer and at least one secondary comonomer, wherein the comonomers are randomly distributed along the copolymer chain. The primary comonomer is an acrylamide or an acrylamide derivative that provides the primary physical, chemical, and sieving properties of the gel matrix. The at least one secondary comonomer imparts an inherent physical, chemical, or sieving property to the copolymer chain. The primary and secondary comonomers are present in a ratio sufficient to induce desired properties that optimize electrophoresis performance. The invention also relates to a method of separating a mixture of biological molecules using this gel matrix, a method of preparing the novel electrophoresis separation medium, and a capillary tube filled with the electrophoresis separation medium.

Dimensionally Stable Ether-Containing Polyimide Copolymers

NASA Technical Reports Server (NTRS)

Fay, Catharine C. (Inventor); St.Clair, Anne K. (Inventor)

1999-01-01

Novel polyimide copolymers containing ether linkages were prepared by the reaction of an equimolar amount of dianhydride and a combination of diamines. The polyimide copolymers described herein possess the unique features of low moisture uptake, dimensional stability, good mechanical properties, and moderate glass transition temperatures. These materials have potential application as encapsulants and interlayer dielectrics.

Advanced Materials for PEM-Based Fuel Cell Systems

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

James E. McGrath

2005-10-26

Proton exchange membrane fuel cells (PEMFCs) are quickly becoming attractive alternative energy sources for transportation, stationary power, and small electronics due to the increasing cost and environmental hazards of traditional fossil fuels. Two main classes of PEMFCs include hydrogen/air or hydrogen/oxygen fuel cells and direct methanol fuel cells (DMFCs). The current benchmark membrane for both types of PEMFCs is Nafion, a perfluorinated sulfonated copolymer made by DuPont. Nafion copolymers exhibit good thermal and chemical stability, as well as very high proton conductivity under hydrated conditions at temperatures below 80 °C. However, application of these membranes is limited due to theirmore » high methanol permeability and loss of conductivity at high temperatures and low relative humidities. These deficiencies have led to the search for improved materials for proton exchange membranes. Potential PEMs should have good thermal, hydrolytic, and oxidative stability, high proton conductivity, selective permeability, and mechanical durability over long periods of time. Poly(arylene ether)s, polyimides, polybenzimidazoles, and polyphenylenes are among the most widely investigated candidates for PEMs. Poly(arylene ether)s are a promising class of proton exchange membranes due to their excellent thermal and chemical stability and high glass transition temperatures. High proton conductivity can be achieved through post-sulfonation of poly(arylene ether) materials, but this most often results in very high water sorption or even water solubility. Our research has shown that directly polymerized poly(arylene ether) copolymers show important advantages over traditional post-sulfonated systems and also address the concerns with Nafion membranes. These properties were evaluated and correlated with morphology, structure-property relationships

21 CFR 177.1340 - Ethylene-methyl acrylate copolymer resins.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-methyl acrylate copolymer resins. 177.1340... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1340 Ethylene-methyl acrylate copolymer resins. Ethylene-methyl acrylate copolymer resins may be safely used as articles or components of...

Highly Conductive Anion Exchange Block Copolymers

DTIC Science & Technology

We are developing a comprehensive fundamental understanding of the interplay between transport and morphology in newly synthesized hydroxide...conducting block copolymers. We are synthesizing hydroxide conducting block copolymers of various (1) morphology types, (2) ionic concentrations, and (3...ionic domain sizes. We are carefully characterizing the morphology and transport properties using both conventional and new advanced in situ techniques

pH-sensitive methacrylic copolymers and the production thereof

DOEpatents

Mallapragada, Surya K.; Anderson, Brian C.; Bloom, Paul D.; Sheares Ashby, Valerie V.

2006-02-14

The present invention provides novel multi-functional methacrylic copolymers that exhibit cationic pH-sensitive behavior as well as good water solubility under acidic conditions. The copolymers are constructed from tertiary amine methacrylates and poly(ethylene glycol) containing methacrylates. The copolymers are useful as gene vectors, pharmaceutical carriers, and in protein separation applications.

pH-sensitive methacrylic copolymers and the production thereof

DOEpatents

Mallapragada, Surya K.; Anderson, Brian C.; Bloom, Paul D.; Sheares Ashby, Valerie V.

2007-01-09

The present invention provides novel multi-functional methacrylic copolymers that exhibit cationic pH-sensitive behavior as well as good water solubility under acidic conditions. The copolymers are constructed from tertiary amine methacrylates and poly(ethylene glycol) containing methacrylates. The copolymers are useful as gene vectors, pharmaceutical carriers, and in protein separation applications.

21 CFR 177.1960 - Vinyl chloride-hexene-1 copolymers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Vinyl chloride-hexene-1 copolymers. 177.1960... Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1960 Vinyl chloride-hexene-1 copolymers. The vinyl chloride-hexene-1 copolymers identified in paragraph (a) of this section or as...

Ion Transport in Nanostructured Block Copolymer/Ionic Liquid Membranes

NASA Astrophysics Data System (ADS)

Hoarfrost, Megan Lane

Incorporating an ionic liquid into one block copolymer microphase provides a platform for combining the outstanding electrochemical properties of ionic liquids with a number of favorable attributes provided by block copolymers. In particular, block copolymers thermodynamically self-assemble into well-ordered nanostructures, which can be engineered to provide a durable mechanical scaffold and template the ionic liquid into continuous ion-conducting nanochannels. Understanding how the addition of an ionic liquid affects the thermodynamic self-assembly of block copolymers, and how the confinement of ionic liquids to block copolymer nanodomains affects their ion-conducting properties is essential for predictable structure-property control. The lyotropic phase behavior of block copolymer/ionic liquid mixtures is shown to be reminiscent of mixtures of block copolymers with selective molecular solvents. A variety of ordered microstructures corresponding to lamellae, hexagonally close-packed cylinders, body-centered cubic, and face-centered cubic oriented micelles are observed in a model system composed of mixtures of imidazolium bis(trifluoromethylsulfonyl)imide ([Im][TFSI]) and poly(styrene- b-2-vinyl pyridine) (PS-b-P2VP). In contrast to block copolymer/molecular solvent mixtures, the interfacial area occupied by each PS-b-P2VP chain decreases upon the addition of [Im][TFSI], indicating a considerable increase in the effective segregation strength of the PS-b-P2VP copolymer with ionic liquid addition. The relationship between membrane structure and ionic conductivity is illuminated through the development of scaling relationships that describe the ionic conductivity of block copolymer/ionic liquid mixtures as a function of membrane composition and temperature. It is shown that the dominant variable influencing conductivity is the overall volume fraction of ionic liquid in the mixture, which means there

Efficient encapsulation of proteins with random copolymers.

PubMed

Nguyen, Trung Dac; Qiao, Baofu; Olvera de la Cruz, Monica

2018-06-12

Membraneless organelles are aggregates of disordered proteins that form spontaneously to promote specific cellular functions in vivo. The possibility of synthesizing membraneless organelles out of cells will therefore enable fabrication of protein-based materials with functions inherent to biological matter. Since random copolymers contain various compositions and sequences of solvophobic and solvophilic groups, they are expected to function in nonbiological media similarly to a set of disordered proteins in membraneless organelles. Interestingly, the internal environment of these organelles has been noted to behave more like an organic solvent than like water. Therefore, an adsorbed layer of random copolymers that mimics the function of disordered proteins could, in principle, protect and enhance the proteins' enzymatic activity even in organic solvents, which are ideal when the products and/or the reactants have limited solubility in aqueous media. Here, we demonstrate via multiscale simulations that random copolymers efficiently incorporate proteins into different solvents with the potential to optimize their enzymatic activity. We investigate the key factors that govern the ability of random copolymers to encapsulate proteins, including the adsorption energy, copolymer average composition, and solvent selectivity. The adsorbed polymer chains have remarkably similar sequences, indicating that the proteins are able to select certain sequences that best reduce their exposure to the solvent. We also find that the protein surface coverage decreases when the fluctuation in the average distance between the protein adsorption sites increases. The results herein set the stage for computational design of random copolymers for stabilizing and delivering proteins across multiple media.

Method for making block siloxane copolymers

DOEpatents

Butler, Nora; Jessop, Edward S.; Kolb, John R.

1982-01-01

A method for synthesizing block polysiloxane copolymers. Diorganoscyclosiloxanes and an end-blocking compound are interacted in the presence of a ring opening polymerization catalyst, producing a blocked prepolymer. The prepolymer is then interacted with a silanediol, resulting in condensation polymerization of the prepolymers. A second end-blocking compound is subsequently introduced to end-cap the polymers and copolymers formed from the condensation polymerization.

Nanopatterned articles produced using reconstructed block copolymer films

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

Russell, Thomas P.; Park, Soojin; Wang;, Jia-Yu

Nanopatterned surfaces are prepared by a method that includes forming a block copolymer film on a substrate, annealing and surface reconstructing the block copolymer film to create an array of cylindrical voids, depositing a metal on the surface-reconstructed block copolymer film, and heating the metal-coated block copolymer film to redistribute at least some of the metal into the cylindrical voids. When very thin metal layers and low heating temperatures are used, metal nanodots can be formed. When thicker metal layers and higher heating temperatures are used, the resulting metal structure includes nanoring-shaped voids. The nanopatterned surfaces can be transferred tomore » the underlying substrates via etching, or used to prepare nanodot- or nanoring-decorated substrate surfaces.« less

Microbial Cometabolism and Polyhydroxyalkanoate Co-polymers.

PubMed

Ray, Subhasree; Kalia, Vipin Chandra

2017-03-01

Polyhydroxyalkanoate (PHAs) are natural, biodegradable biopolymers, which can be produced from renewable materials. PHAs have potential to replace petroleum derived plastics. Quite a few bacteria can produce PHA under nutritional stress. They generally produce homopolymers of butyrate i.e., polyhydroxybutyrate (PHB), as a storage material. The biochemical characteristics of PHB such as brittleness, low strength, low elasticity, etc. make these unsuitable for commercial applications. Co-polymers of PHA, have high commercial value as they overcome the limitations of PHBs. Co-polymers can be produced by supplementing the feed with volatile fatty acids or through hydrolysates of different biowastes. In this review, we have listed the potential bacterial candidates and the substrates, which can be co-metabolized to produce PHA co-polymers.

Iodinated glycidyl methacrylate copolymer as a radiopaque material for biomedical applications.

PubMed

Dawlee, S; Jayabalan, M

2013-07-01

Polymeric biomaterial was synthesized by copolymerizing 50:50 mol% of monomers, glycidyl methacrylate and methyl methacrylate. Iodine atoms were then grafted to the epoxide groups of glycidyl methacrylate units, rendering the copolymer radiopaque. The percentage weight of iodine in the present copolymer was found to be as high as 23%. The iodinated copolymer showed higher glass transition temperature and thermal stability in comparison with unmodified polymer. Radiographic analysis showed that the copolymer possessed excellent radiopacity. The iodinated copolymer was cytocompatible to L929 mouse fibroblast cells. The in vivo toxicological evaluation by intracutaneous reactivity test of the copolymer extracts has revealed that the material was nontoxic. Subcutaneous implantation of iodinated copolymer in rats has shown that the material was well tolerated. Upon explantation and histological examination, no hemorrhage, infection or necrosis was observed. The samples were found to be surrounded by a vascularized capsule consisting of connective tissue cells. The results indicate that the iodinated copolymer is biocompatible and may have suitable applications as implantable materials.

Controlling block copolymer phase behavior using ionic surfactant

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

Ray, D.; Aswal, V. K.

2016-05-23

The phase behavior of poly(ethylene oxide)-poly(propylene oxide-poly(ethylene oxide) PEO-PPO-PEO triblock copolymer [P85 (EO{sub 26}PO{sub 39}EO{sub 26})] in presence of anionic surfactant sodium dodecyl sulfate (SDS) in aqueous solution as a function of temperature has been studied using dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The measurements have been carried out for fixed concentrations (1 wt%) of block copolymer and surfactants. Each of the individual components (block copolymer and surfactant) and the nanoparticle–surfactant mixed system have been examined at varying temperature. The block copolymer P85 forms spherical micelles at room temperature whereas shows sphere-to-rod like micelle transition at highermore » temperatures. On the other hand, SDS surfactant forms ellipsoidal micelles over a wide temperature range. Interestingly, it is found that phase behavior of mixed micellar system (P85 + SDS) as a function of temperature is drastically different from that of P85, giving the control over the temperature-dependent phase behavior of block copolymers.« less

Morphological studies on block copolymer modified PA 6 blends

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

Poindl, M., E-mail: marcus.poindl@ikt.uni-stuttgart.de, E-mail: christian.bonten@ikt.uni-stuttgart.de; Bonten, C., E-mail: marcus.poindl@ikt.uni-stuttgart.de, E-mail: christian.bonten@ikt.uni-stuttgart.de

Recent studies show that compounding polyamide 6 (PA 6) with a PA 6 polyether block copolymers made by reaction injection molding (RIM) or continuous anionic polymerization in a reactive extrusion process (REX) result in blends with high impact strength and high stiffness compared to conventional rubber blends. In this paper, different high impact PA 6 blends were prepared using a twin screw extruder. The different impact modifiers were an ethylene propylene copolymer, a PA PA 6 polyether block copolymer made by reaction injection molding and one made by reactive extrusion. To ensure good particle matrix bonding, the ethylene propylene copolymermore » was grafted with maleic anhydride (EPR-g-MA). Due to the molecular structure of the two block copolymers, a coupling agent was not necessary. The block copolymers are semi-crystalline and partially cross-linked in contrast to commonly used amorphous rubbers which are usually uncured. The combination of different analysis methods like atomic force microscopy (AFM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) gave a detailed view in the structure of the blends. Due to the partial cross-linking, the particles of the block copolymers in the blends are not spherical like the ones of ethylene propylene copolymer. The differences in molecular structure, miscibility and grafting of the impact modifiers result in different mechanical properties and different blend morphologies.« less

Arbitrary lattice symmetries via block copolymer nanomeshes

PubMed Central

Majewski, Pawel W.; Rahman, Atikur; Black, Charles T.; Yager, Kevin G.

2015-01-01

Self-assembly of block copolymers is a powerful motif for spontaneously forming well-defined nanostructures over macroscopic areas. Yet, the inherent energy minimization criteria of self-assembly give rise to a limited library of structures; diblock copolymers naturally form spheres on a cubic lattice, hexagonally packed cylinders and alternating lamellae. Here, we demonstrate multicomponent nanomeshes with any desired lattice symmetry. We exploit photothermal annealing to rapidly order and align block copolymer phases over macroscopic areas, combined with conversion of the self-assembled organic phase into inorganic replicas. Repeated photothermal processing independently aligns successive layers, providing full control of the size, symmetry and composition of the nanoscale unit cell. We construct a variety of symmetries, most of which are not natively formed by block copolymers, including squares, rhombuses, rectangles and triangles. In fact, we demonstrate all possible two-dimensional Bravais lattices. Finally, we elucidate the influence of nanostructure on the electrical and optical properties of nanomeshes. PMID:26100566

21 CFR 177.1060 - n-Alkylglutarimide/acrylic copolymers.

Code of Federal Regulations, 2011 CFR

2011-04-01

.../acrylic copolymers are copolymers obtained by reaction of substances permitted by § 177.1010(a) (1), (2... solvent or solvents characterizing the type of food and under the conditions of time and temperature...

Method for making block siloxane copolymers

DOEpatents

Butler, N.L.; Jessop, E.S.; Kolb, J.R.

1981-02-25

A method for synthesizing block polysiloxane copolymers is disclosed. Diorganoscyclosiloxanes and an end-blocking compound are interacted in the presence of a ring opening polymerization catalyst, producing a blocked prepolymer. The prepolymer is then interacted with a silanediol, resulting in condensation polymerization of the prepolymers. A second end-blocking compound is subsequently introduced to end-cap the polymers and copolymers formed from the condensation polymerization.

Tribological Behavior of Aqueous Copolymer Lubricant in Mixed Lubrication Regime.

PubMed

Ta, Thi D; Tieu, A Kiet; Zhu, Hongtao; Zhu, Qiang; Kosasih, Prabouno B; Zhang, Jie; Deng, Guanyu

2016-03-02

Although a number of experiments have been attempted to investigate the lubrication of aqueous copolymer lubricant, which is applied widely in metalworking operations, a comprehensive theoretical investigation at atomistic level is still lacking. This study addresses the influence of loading pressure and copolymer concentration on the structural properties and tribological performance of aqueous copolymer solution of poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) (PPO-PEO-PPO) at mixed lubrication using a molecular dynamic (MD) simulation. An effective interfacial potential, which has been derived from density functional theory (DFT) calculations, was employed for the interactions between the fluid's molecules and iron surface. The simulation results have indicated that the triblock copolymer is physisorption on iron surface. Under confinement by iron surfaces, the copolymer molecules form lamellar structure in aqueous solution and behave differently from its bulk state. The lubrication performance of aqueous copolymer lubricant increases with concentration, but the friction reduction is insignificant at high loading pressure. Additionally, the plastic deformation of asperity is dependent on both copolymer concentration and loading pressure, and the wear behavior shows a linear dependence of friction force on the number of transferred atoms between contacting asperities.

Polyamide copolymers having 2,5-furan dicarboxamide units

DOEpatents

Chisholm, Bret Ja; Samanta, Satyabrata

2017-09-19

Polyamide copolymers, and methods of making and using polyamide copolymers, having 2,5-furan dicarboxamide units are disclosed herein. Such polymers can be useful for engineering thermoplastics having advantageous physical and/or chemical properties.

HPMA copolymers: Origins, early developments, present, and future☆

PubMed Central

Kopeček, Jindřich; Kopečková, Pavla

2010-01-01

The overview covers the discovery of N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers, initial studies on their synthesis, evaluation of biological properties, and explorations of their potential as carriers of biologically active compounds in general and anticancer drugs in particular. The focus is on the research in the authors’ laboratory – the development of macromolecular therapeutics for the treatment of cancer and musculoskeletal diseases. In addition, the evaluation of HPMA (co)polymers as building blocks of mod and new biomaterials is presented: the utilization of semitelechelic poly(HPMA) and HPMA copolymers for the modification of biomaterial and protein surfaces and the design of hybrid block and graft HPMA copolymers that self-assemble into smart hydrogels. Finally, suggestions for the design of second-generation macromolecular therapeutics are portrayed. PMID:19919846

Dynamic photoinduced realignment processes in photoresponsive block copolymer films: effects of the chain length and block copolymer architecture.

PubMed

Sano, Masami; Shan, Feng; Hara, Mitsuo; Nagano, Shusaku; Shinohara, Yuya; Amemiya, Yoshiyuki; Seki, Takahiro

2015-08-07

A series of block copolymers composed of an amorphous poly(butyl methacrylate) (PBMA) block connected with an azobenzene (Az)-containing liquid crystalline (PAz) block were synthesized by changing the chain length and polymer architecture. With these block copolymer films, the dynamic realignment process of microphase separated (MPS) cylinder arrays of PBMA in the PAz matrix induced by irradiation with linearly polarized light was studied by UV-visible absorption spectroscopy, and time-resolved grazing incidence small angle X-ray scattering (GI-SAXS) measurements using a synchrotron beam. Unexpectedly, the change in the chain length hardly affected the realignment rate. In contrast, the architecture of the AB-type diblock or the ABA-type triblock essentially altered the realignment feature. The strongly cooperative motion with an induction period before realignment was characteristic only for the diblock copolymer series, and the LPL-induced alignment change immediately started for triblock copolymers and the PAz homopolymer. Additionally, a marked acceleration in the photoinduced dynamic motions was unveiled in comparison with a thermal randomization process.

21 CFR 177.1020 - Acrylonitrile/butadiene/sty-rene co-polymer.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Acrylonitrile/butadiene/sty-rene co-polymer. 177... SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances.../butadiene/sty-rene co-polymer. Acrylonitrile/butadiene/styrene copolymer identified in this section may be...

21 CFR 177.1020 - Acrylonitrile/butadiene/sty-rene co-polymer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Acrylonitrile/butadiene/sty-rene co-polymer. 177... SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances.../butadiene/sty-rene co-polymer. Acrylonitrile/butadiene/styrene copolymer identified in this section may be...

21 CFR 177.1020 - Acrylonitrile/butadiene/sty-rene co-polymer.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Acrylonitrile/butadiene/sty-rene co-polymer. 177... SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances.../butadiene/sty-rene co-polymer. Acrylonitrile/butadiene/styrene copolymer identified in this section may be...

21 CFR 177.1020 - Acrylonitrile/butadiene/sty-rene co-polymer.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Acrylonitrile/butadiene/sty-rene co-polymer. 177... SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances.../butadiene/sty-rene co-polymer. Acrylonitrile/butadiene/styrene copolymer identified in this section may be...

Fabrication routes for one-dimensional nanostructures via block copolymers

NASA Astrophysics Data System (ADS)

Tharmavaram, Maithri; Rawtani, Deepak; Pandey, Gaurav

2017-05-01

Nanotechnology is the field which deals with fabrication of materials with dimensions in the nanometer range by manipulating atoms and molecules. Various synthesis routes exist for the one, two and three dimensional nanostructures. Recent advancements in nanotechnology have enabled the usage of block copolymers for the synthesis of such nanostructures. Block copolymers are versatile polymers with unique properties and come in many types and shapes. Their properties are highly dependent on the blocks of the copolymers, thus allowing easy tunability of its properties. This review briefly focusses on the use of block copolymers for synthesizing one-dimensional nanostructures especially nanowires, nanorods, nanoribbons and nanofibers. Template based, lithographic, and solution based approaches are common approaches in the synthesis of nanowires, nanorods, nanoribbons, and nanofibers. Synthesis of metal, metal oxides, metal oxalates, polymer, and graphene one dimensional nanostructures using block copolymers have been discussed as well.

Self-assembly of block copolymers on topographically patterned polymeric substrates

DOEpatents

Russell, Thomas P.; Park, Soojin; Lee, Dong Hyun; Xu, Ting

2016-05-10

Highly-ordered block copolymer films are prepared by a method that includes forming a polymeric replica of a topographically patterned crystalline surface, forming a block copolymer film on the topographically patterned surface of the polymeric replica, and annealing the block copolymer film. The resulting structures can be used in a variety of different applications, including the fabrication of high density data storage media. The ability to use flexible polymers to form the polymeric replica facilitates industrial-scale processes utilizing the highly-ordered block copolymer films.

Poly(ortho-phenylenediamine-co-aniline) based copolymer with improved capacitance

NASA Astrophysics Data System (ADS)

Olmedo-Martínez, Jorge L.; Farías-Mancilla, Bárbara I.; Vega-Rios, Alejandro; Zaragoza-Contreras, E. Armando

2017-10-01

A poly(ortho-phenylenediamine-co-aniline) copolymer is synthesized via the oxidative route, using a 1:1 M ratio of aniline to ortho-phenylenediamine (oPDA) and ammonium persulfate as the oxidizing agent. Infrared spectroscopy indicates that the copolymer contains the functional groups typically present in polyaniline and poly(ortho-phenylenediamine); whereas UV-vis-NIR spectroscopy shows that the copolymer adopts a phenazine-type structure. Cyclic voltammetry evidences the copolymer synthesis, as a redox peak at -65 mV, different from those exhibited by polyaniline (160 mV and 600 mV) or poly(o-phenylenediamine) (-240 mV) is observed. Finally, electrochemical impedance spectroscopy and the charge/discharge test provide support to propose the copolymer application in electrodes for supercapacitors.

21 CFR 177.1570 - Poly-1-butene resins and butene/ethylene copolymers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Poly-1-butene resins and butene/ethylene copolymers... resins and butene/ethylene copolymers. The poly-1-butene resins and butene/ethylene copolymers identified... the catalytic polymerization of 1-butene liquid monomer. Butene/ethylene copolymers are produced by...

Communication: Molecular-level insights into asymmetric triblock copolymers: Network and phase development

NASA Astrophysics Data System (ADS)

Tallury, Syamal S.; Mineart, Kenneth P.; Woloszczuk, Sebastian; Williams, David N.; Thompson, Russell B.; Pasquinelli, Melissa A.; Banaszak, Michal; Spontak, Richard J.

2014-09-01

Molecularly asymmetric triblock copolymers progressively grown from a parent diblock copolymer can be used to elucidate the phase and property transformation from diblock to network-forming triblock copolymer. In this study, we use several theoretical formalisms and simulation methods to examine the molecular-level characteristics accompanying this transformation, and show that reported macroscopic-level transitions correspond to the onset of an equilibrium network. Midblock conformational fractions and copolymer morphologies are provided as functions of copolymer composition and temperature.

Co-polymer Films for Sensors

NASA Technical Reports Server (NTRS)

Ryan, Margaret A. (Inventor); Jewell, April D. (Inventor); Taylor, Charles (Inventor); Yen, Shiao-Pin S. (Inventor); Kisor, Adam (Inventor); Manatt, Kenneth S. (Inventor); Blanco, Mario (Inventor); Goddard, William A. (Inventor); Homer, Margie L. (Inventor); Shevade, Abhijit V. (Inventor)

2012-01-01

Embodiments include a sensor comprising a co-polymer, the co-polymer comprising a first monomer and a second monomer. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is polystyrene and the second monomer is poly-2-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium benzylamine chloride. Other embodiments are described and claimed.

Co-polymer films for sensors

NASA Technical Reports Server (NTRS)

Ryan, Margaret A. (Inventor); Homer, Margie L. (Inventor); Yen, Shiao-Pin S. (Inventor); Kisor, Adam (Inventor); Jewell, April D. (Inventor); Shevade, Abhijit V. (Inventor); Manatt, Kenneth S. (Inventor); Taylor, Charles (Inventor); Blanco, Mario (Inventor); Goddard, William A. (Inventor)

2010-01-01

Embodiments include a sensor comprising a co-polymer, the co-polymer comprising a first monomer and a second monomer. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is polystyrene and the second monomer is poly-2-vinyl pyridinium propylamine chloride. For some embodiments, the first monomer is poly-4-vinyl pyridine, and the second monomer is poly-4-vinyl pyridinium benzylamine chloride. Other embodiments are described and claimed.

21 CFR 177.1360 - Ethylene-vinyl acetate-vinyl alcohol copolymers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-vinyl acetate-vinyl alcohol copolymers... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1360 Ethylene-vinyl acetate-vinyl alcohol copolymers. Ethylene-vinyl acetate-vinyl alcohol copolymers (CAS Reg. No. 26221-27-2...

Nanopatterned articles produced using surface-reconstructed block copolymer films

DOEpatents

Russell, Thomas P.; Park, Soojin; Wang, Jia-Yu; Kim, Bokyung

2016-06-07

Nanopatterned surfaces are prepared by a method that includes forming a block copolymer film on a substrate, annealing and surface reconstructing the block copolymer film to create an array of cylindrical voids, depositing a metal on the surface-reconstructed block copolymer film, and heating the metal-coated block copolymer film to redistribute at least some of the metal into the cylindrical voids. When very thin metal layers and low heating temperatures are used, metal nanodots can be formed. When thicker metal layers and higher heating temperatures are used, the resulting metal structure includes nanoring-shaped voids. The nanopatterned surfaces can be transferred to the underlying substrates via etching, or used to prepare nanodot- or nanoring-decorated substrate surfaces.

40 CFR 721.10527 - Perfluoroalkylethyl methacrylate copolymer (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... as perfluoroalkylethyl methacrylate copolymer (PMN P-11-646) is subject to reporting under this... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Perfluoroalkylethyl methacrylate... Specific Chemical Substances § 721.10527 Perfluoroalkylethyl methacrylate copolymer (generic). (a) Chemical...

40 CFR 721.10527 - Perfluoroalkylethyl methacrylate copolymer (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... as perfluoroalkylethyl methacrylate copolymer (PMN P-11-646) is subject to reporting under this... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Perfluoroalkylethyl methacrylate... Specific Chemical Substances § 721.10527 Perfluoroalkylethyl methacrylate copolymer (generic). (a) Chemical...

40 CFR 721.10619 - Perfluoroalkylethyl methacrylate copolymer (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... as perfluoroalkylethyl methacrylate copolymer (PMN P-11-653) is subject to reporting under this... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Perfluoroalkylethyl methacrylate... Specific Chemical Substances § 721.10619 Perfluoroalkylethyl methacrylate copolymer (generic). (a) Chemical...

40 CFR 721.10619 - Perfluoroalkylethyl methacrylate copolymer (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... as perfluoroalkylethyl methacrylate copolymer (PMN P-11-653) is subject to reporting under this... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Perfluoroalkylethyl methacrylate... Specific Chemical Substances § 721.10619 Perfluoroalkylethyl methacrylate copolymer (generic). (a) Chemical...

Sorption of Aromatic Compounds with Copolymer Sorbent Materials Containing β-Cyclodextrin.

PubMed

Wilson, Lee D; Mohamed, Mohamed H; Berhaut, Christopher L

2011-08-29

Urethane copolymer sorbent materials that incorporate β-cyclodextrin (CD) have been prepared and their sorption properties with chlorinated aromatic compounds (i.e., pentachlorophenol, 2,4-dichlorophenol and 2,4-dichlorophenoxy acetic acid) have been evaluated. The sorption properties of granular activated carbon (GAC) were similarly compared in aqueous solution at variable pH conditions. The sorbents displayed variable BET surface areas as follows: MDI-X copolymers (< 10¹ m²/g), CDI-X copolymers (< 10¹ m²/g), and granular activated carbon (GAC ~10³ m²/g). The sorption capacities for the copolymers sorbents are listed in descending order, as follows: GAC > CDI-3 copolymer ≈ MDI-3 copolymer. The sorption capacity for the aromatic adsorbates with each sorbent are listed in descending order, as follows: 2,4-dichlorophenol > 2,4-dichlorophenoxy acetic acid > pentachlorophenol. In general, the differences in the sorption properties of the copolymer sorbents with the chlorinated organics were related to the following factors: (i) surface area of the sorbent; (ii) CD content and accessibility; and (iii) and the chemical nature of the sorbent material.

Sorption of Aromatic Compounds with Copolymer Sorbent Materials Containing β-Cyclodextrin

PubMed Central

Wilson, Lee D.; Mohamed, Mohamed H.; Berhaut, Christopher L.

2011-01-01

Urethane copolymer sorbent materials that incorporate β-cyclodextrin (CD) have been prepared and their sorption properties with chlorinated aromatic compounds (i.e., pentachlorophenol, 2,4-dichlorophenol and 2,4-dichlorophenoxy acetic acid) have been evaluated. The sorption properties of granular activated carbon (GAC) were similarly compared in aqueous solution at variable pH conditions. The sorbents displayed variable BET surface areas as follows: MDI-X copolymers (< 101 m2/g), CDI-X copolymers (< 101 m2/g), and granular activated carbon (GAC ~103 m2/g). The sorption capacities for the copolymers sorbents are listed in descending order, as follows: GAC > CDI-3 copolymer ≈ MDI-3 copolymer. The sorption capacity for the aromatic adsorbates with each sorbent are listed in descending order, as follows: 2,4-dichlorophenol > 2,4-dichlorophenoxy acetic acid > pentachlorophenol. In general, the differences in the sorption properties of the copolymer sorbents with the chlorinated organics were related to the following factors: (i) surface area of the sorbent; (ii) CD content and accessibility; and (iii) and the chemical nature of the sorbent material. PMID:28824156

Branched Rod-Coil Polyimide-Poly(Alkylene Oxide) Copolymers and Electrolyte Compositions

NASA Technical Reports Server (NTRS)

Meador, Maryann B. (Inventor); Tigelaar, Dean M. (Inventor)

2014-01-01

Crosslinked polyimide-poly(alkylene oxide) copolymers capable of holding large volumes of liquid while maintaining good dimensional stability. Copolymers are derived at ambient temperatures from amine endcapped amic-acid oligomers subsequently imidized in solution at increased temperatures, followed by reaction with trifunctional compounds in the presence of various additives. Films of these copolymers hold over four times their weight at room temperature of liquids such as ionic liquids (RTIL) and/or carbonate solvents. These rod-coil polyimide copolymers are used to prepare polymeric electrolytes by adding to the copolymers various amounts of compounds such as ionic liquids (RTIL), lithium trifluoromethane-sulfonimide (LiTFSi) or other lithium salts, and alumina.

21 CFR 177.1480 - Nitrile rubber modified acrylonitrile-methyl acrylate copolymers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Nitrile rubber modified acrylonitrile-methyl... Nitrile rubber modified acrylonitrile-methyl acrylate copolymers. Nitrile rubber modified acrylonitrile... rubber modified acrylonitrile-methyl acrylate copolymers consist of basic copolymers produced by the...

Water-soluble graft copolymers of starch-acrylamide and uses therefor

DOEpatents

Butler, George B.; Hogen-Esch, Thieo E.; Meister, John J.; Pledger, Jr., Huey

1983-08-23

Graft copolymers having starch as the central chain with grafted side chains of acrylamide or acrylamide-acrylic acid, and a process for preparation of such copolymers in the presence of Ce.sup.+4 or other redox initiators. These copolymers are employed in preparing highly viscous aqueous solutions that are particularly useful in oil recovery from subterranean wells.

Microbial production of polyhydroxyalkanoate block copolymer by recombinant Pseudomonas putida.

PubMed

Li, Shi Yan; Dong, Cui Ling; Wang, Shen Yu; Ye, Hai Mu; Chen, Guo-Qiang

2011-04-01

Polyhydroxyalkanoate (PHA) synthesis genes phaPCJ(Ac) cloned from Aeromonas caviae were transformed into Pseudomonas putida KTOY06ΔC, a mutant of P. putida KT2442, resulting in the ability of the recombinant P. putida KTOY06ΔC (phaPCJ(A.c)) to produce a short-chain-length and medium-chain-length PHA block copolymer consisting of poly-3-hydroxybutyrate (PHB) as one block and random copolymer of 3-hydroxyvalerate (3HV) and 3-hydroxyheptanoate (3HHp) as another block. The novel block polymer was studied by differential scanning calorimetry (DSC), nuclear magnetic resonance, and rheology measurements. DSC studies showed the polymer to possess two glass transition temperatures (T(g)), one melting temperature (T(m)) and one cool crystallization temperature (T(c)). Rheology studies clearly indicated a polymer chain re-arrangement in the copolymer; these studies confirmed the polymer to be a block copolymer, with over 70 mol% homopolymer (PHB) of 3-hydroxybutyrate (3HB) as one block and around 30 mol% random copolymers of 3HV and 3HHp as the second block. The block copolymer was shown to have the highest tensile strength and Young's modulus compared with a random copolymer with similar ratio and a blend of homopolymers PHB and PHVHHp with similar ratio. Compared with other commercially available PHA including PHB, PHBV, PHBHHx, and P3HB4HB, the short-chain- and medium-chain-length block copolymer PHB-b-PHVHHp showed differences in terms of mechanical properties and should draw more attentions from the PHA research community. © Springer-Verlag 2010

Laccase-mediated synthesis of lignin-core hyperbranched copolymers

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

Cannatelli, Mark D.; Ragauskas, Arthur J.

Lignin, one of the major chemical constituents of woody biomass, is the second most abundant biopolymer found in nature. The pulp and paper industry has long produced lignin on the scale of millions of tons annually as a by-product of the pulping process, and the dawn of cellulosic ethanol production has further contributed to this amount. Historically, lignin has been perceived as a waste material and burned as a fuel for the pulping process. But, recent research has been geared toward developing cost-effective technologies to convert lignin into valuable commodities. Attributing to the polyphenolic structure of lignin, enzymatic modification ofmore » its surface using laccases (benzenediol:oxygen oxidoreductases, EC 1.10.3.2) has demonstrated to be highly successful. The current study aims at developing lignin-core hyperbranched copolymers via the laccase-assisted copolymerization of kraft lignin with methylhydroquinone and a trithiol. Based on the physical properties of the resulting material, it is likely that crosslinking reactions have taken place during the drying process to produce a copolymeric network rather than discrete hyperbranched copolymers, with NMR data providing evidence of covalent bonding between monomers. A preliminary thermal analysis data reveals that the copolymeric material possesses a moderate glass transition temperature and exhibits good thermostability, thus may have potential application as a lignin-based thermoplastic. Scanning electron microscopy images confirm the smooth, glossy surface of the material and that it is densely packed. Our results are a sustainable, ecofriendly, economic method to create an exciting novel biomaterial from a renewable feedstock while further enhancing lignin valorization.« less

Laccase-mediated synthesis of lignin-core hyperbranched copolymers

DOE PAGES

Cannatelli, Mark D.; Ragauskas, Arthur J.

2017-06-06

Lignin, one of the major chemical constituents of woody biomass, is the second most abundant biopolymer found in nature. The pulp and paper industry has long produced lignin on the scale of millions of tons annually as a by-product of the pulping process, and the dawn of cellulosic ethanol production has further contributed to this amount. Historically, lignin has been perceived as a waste material and burned as a fuel for the pulping process. But, recent research has been geared toward developing cost-effective technologies to convert lignin into valuable commodities. Attributing to the polyphenolic structure of lignin, enzymatic modification ofmore » its surface using laccases (benzenediol:oxygen oxidoreductases, EC 1.10.3.2) has demonstrated to be highly successful. The current study aims at developing lignin-core hyperbranched copolymers via the laccase-assisted copolymerization of kraft lignin with methylhydroquinone and a trithiol. Based on the physical properties of the resulting material, it is likely that crosslinking reactions have taken place during the drying process to produce a copolymeric network rather than discrete hyperbranched copolymers, with NMR data providing evidence of covalent bonding between monomers. A preliminary thermal analysis data reveals that the copolymeric material possesses a moderate glass transition temperature and exhibits good thermostability, thus may have potential application as a lignin-based thermoplastic. Scanning electron microscopy images confirm the smooth, glossy surface of the material and that it is densely packed. Our results are a sustainable, ecofriendly, economic method to create an exciting novel biomaterial from a renewable feedstock while further enhancing lignin valorization.« less

Laccase-mediated synthesis of lignin-core hyperbranched copolymers.

PubMed

Cannatelli, Mark D; Ragauskas, Arthur J

2017-08-01

Lignin, one of the major chemical constituents of woody biomass, is the second most abundant biopolymer found in nature. The pulp and paper industry has long produced lignin on the scale of millions of tons annually as a by-product of the pulping process, and the dawn of cellulosic ethanol production has further contributed to this amount. Historically, lignin has been perceived as a waste material and burned as a fuel for the pulping process. However, recent research has been geared toward developing cost-effective technologies to convert lignin into valuable commodities. Attributing to the polyphenolic structure of lignin, enzymatic modification of its surface using laccases (benzenediol:oxygen oxidoreductases, EC 1.10.3.2) has demonstrated to be highly successful. The current study aims at developing lignin-core hyperbranched copolymers via the laccase-assisted copolymerization of kraft lignin with methylhydroquinone and a trithiol. Based on the physical properties of the resulting material, it is likely that crosslinking reactions have taken place during the drying process to produce a copolymeric network rather than discrete hyperbranched copolymers, with NMR data providing evidence of covalent bonding between monomers. Preliminary thermal analysis data reveals that the copolymeric material possesses a moderate glass transition temperature and exhibits good thermostability, thus may have potential application as a lignin-based thermoplastic. Scanning electron microscopy images confirm the smooth, glossy surface of the material and that it is densely packed. The presented results are a sustainable, ecofriendly, economic method to create an exciting novel biomaterial from a renewable feedstock while further enhancing lignin valorization.

Inhomogeneity of block copolymers at the interface of an immiscible polymer blend

NASA Astrophysics Data System (ADS)

Ryu, Ji Ho; Kim, YongJoo; Lee, Won Bo

2018-04-01

We present the effects of structure and stiffness of block copolymers on the interfacial properties of an immiscible homopolymer blend. Diblock and two-arm grafted copolymers with variation in stiffness are modeled using coarse-grained molecular dynamics to compare the compatibilization efficiency, i.e., reduction of interfacial tension. Overall, grafted copolymers are located more compactly at the interface and show better compatibilization efficiency than diblock copolymers. In addition, an increase in the stiffness for one of the blocks of the diblock copolymers causes unusual inhomogeneous interfacial coverage due to bundle formation. However, an increase in the stiffness for one of blocks of the grafted copolymers prevents the bundle formation due to the branched chain. As a result, homogeneous interfacial coverage of homopolymer blends is realized with significant reduction of interfacial tension which makes grafted copolymer a better candidate for the compatibilizer of immiscible homopolymer blend.

Mesoporous Polymer Frameworks from End-Reactive Bottlebrush Copolymers

DOE PAGES

Altay, Esra; Nykypanchuk, Dmytro; Rzayev, Javid

2017-08-07

Reticulated nanoporous materials generated by versatile molecular framework approaches are limited to pore dimensions on the scale of the utilized rigid molecular building blocks (<5 nm). The inherent flexibility of linear polymers precludes their utilization as long framework connectors for the extension of this strategy to larger length scales. We report a method for the fabrication of mesoporous frameworks by using bottlebrush copolymers with reactive end blocks serving as rigid macromolecular interconnectors with directional reactivity. End-reactive bottlebrush copolymers with pendant alkene functionalities were synthesized by a combination of controlled radical polymerization and polymer modification protocols. Ru-catalyzed cross-metathesis cross-linking of bottlebrushmore » copolymers with two reactive end blocks resulted in the formation of polymer frameworks where isolated cross-linked domains were interconnected with bottlebrush copolymer bridges. The resulting materials were characterized by a continuous network pore structure with average pore sizes of 9–50 nm, conveniently tunable by the length of the utilized bottlebrush copolymer building blocks. As a result, the materials fabrication strategy described in this work expands the length scale of molecular framework materials and provides access to mesoporous polymers with a molecularly tunable reticulated pore structure without the need for templating, sacrificial component etching, or supercritical fluid drying.« less

Defining donor and acceptor strength in conjugated copolymers

NASA Astrophysics Data System (ADS)

Hedström, Svante; Wang, Ergang; Persson, Petter

2017-03-01

The progress in efficiency of organic photovoltaic devices is largely driven by the development of new donor-acceptor (D-A) copolymers. The number of possible D-A combinations escalates rapidly with the ever-increasing number of donor and acceptor units, and the design process often involves a trial-and-error approach. We here present a computationally efficient methodology for the prediction of optical and electronic properties of D-A copolymers based on density functional theory calculations of donor- and acceptor-only homopolymers. Ten donors and eight acceptors are studied, as well as all of their 80 D-A copolymer combinations, showing absorption energies of 1.3-2.3 eV, and absorption strengths varying by up to a factor of 2.5. Focus lies on exhibited trends in frontier orbital energies, optical band gaps, and absorption intensities, as well as their relation to the molecular structure. Based on the results, we define the concept of donor and acceptor strength, and calculate this quantity for all investigated units. The light-harvesting capabilities of the 80 D-A copolymers were also assessed. This gives a valuable theoretical guideline to the design of D-A copolymers with the potential to reduce the synthesis efforts in the development of new polymers.

Slip-spring model of entangled rod-coil block copolymers

NASA Astrophysics Data System (ADS)

Wang, Muzhou; Likhtman, Alexei E.; Olsen, Bradley D.

2015-03-01

Understanding the dynamics of rod-coil block copolymers is important for optimal design of functional nanostructured materials for organic electronics and biomaterials. Recently, we proposed a reptation theory of entangled rod-coil block copolymers, predicting the relaxation mechanisms of activated reptation and arm retraction that slow rod-coil dynamics relative to coil and rod homopolymers, respectively. In this work, we introduce a coarse-grained slip-spring model of rod-coil block copolymers to further explore these mechanisms. First, parameters of the coarse-grained model are tuned to match previous molecular dynamics simulation results for coils, rods, and block copolymers. For activated reptation, rod-coil copolymers are shown to disfavor configurations where the rod occupies curved portions of the entanglement tube of randomly varying curvature created by the coil ends. The effect of these barriers on diffusion is quantitatively captured by considering one-dimensional motion along an entanglement tube with a rough free energy potential. Finally, we analyze the crossover between the two mechanisms. The resulting dynamics from both mechanisms acting in combination is faster than from each one individually.

Stabilizing Various Bicontinuous Morphologies via Polydispersity of Diblock Copolymers

NASA Astrophysics Data System (ADS)

Lai, Chi To; Shi, An-Chang

Diblock copolymers are macromolecules composed of two chemically distinct homopolymers covalently bound end-to-end. The ability to self-assembly into a wide variety of ordered periodic structures, as means of minimizing the free energy, is their most well-studied property. There are many factors affecting the observed equilibrium morphology, one of which is polydispersity. The phase behaviour of polydispersed diblock copolymers is more rich, and diverse when compared to their monodispersed counterpart. The rich behaviour of polydispersed diblock copolymers provides an opportunity to engineer novel morphologies which are not available in monodispersed systems. Using the self-consistent field theory (SCFT), we explore the possibility of exploiting polydispersity of diblock copolymers in binary mixtures to stabilize the various bicontinuous phases, such as the double-diamond morphology. Specifically, solutions of the SCFT equations corresponding to different bicontinuous phases are obtained numerically for binary mixtures of diblock copolymers. The relative stability of the different ordered phases is examined by comparing their free energy. From the study, we determine optimal sets of parameters that stabilize the double-diamond or other exotic morphologies.

Water-soluble graft copolymers of starch-acrylamide and uses therefor

DOEpatents

Butler, G.B.; Hogen-Esch, T.E.; Meister, J.J.; Pledger, H. Jr.

1983-08-23

Graft copolymers having starch as the central chain with grafted side chains of acrylamide or acrylamide-acrylic acid, and a process for preparation of such copolymers in the presence of Ce[sup +4] or other redox initiators are disclosed. These copolymers are employed in preparing highly viscous aqueous solutions that are particularly useful in oil recovery from subterranean wells. 2 figs.

Tailoring charge density and hydrogen bonding of imidazolium copolymers for efficient gene delivery.

PubMed

Allen, Michael H; Green, Matthew D; Getaneh, Hiwote K; Miller, Kevin M; Long, Timothy E

2011-06-13

Conventional free radical polymerization with subsequent postpolymerization modification afforded imidazolium copolymers with controlled charge density and side chain hydroxyl number. Novel imidazolium-containing copolymers where each permanent cation contained one or two adjacent hydroxyls allowed precise structure-transfection efficiency studies. The degree of polymerization was identical for all copolymers to eliminate the influence of molecular weight on transfection efficiency. DNA binding, cytotoxicity, and in vitro gene transfection in African green monkey COS-7 cells revealed structure-property-transfection relationships for the copolymers. DNA gel shift assays indicated that higher charge densities and hydroxyl concentrations increased DNA binding. As the charge density of the copolymers increased, toxicity of the copolymers also increased; however, as hydroxyl concentration increased, cytotoxicity remained constant. Changing both charge density and hydroxyl levels in a systematic fashion revealed a dramatic influence on transfection efficiency. Dynamic light scattering of the polyplexes, which were composed of copolymer concentrations required for the highest luciferase expression, showed an intermediate DNA-copolymer binding affinity. Our studies supported the conclusion that cationic copolymer binding affinity significantly impacts overall transfection efficiency of DNA delivery vehicles, and the incorporation of hydroxyl sites offers a less toxic and effective alternative to more conventional highly charged copolymers.

40 CFR 721.10419 - Tetrafluoroethylene chlorotrifluoroethylene copolymer (generic) (P-11-561).

Code of Federal Regulations, 2013 CFR

2013-07-01

... chlorotrifluoroethylene copolymer (generic) (P-11-561). 721.10419 Section 721.10419 Protection of Environment... chlorotrifluoroethylene copolymer (generic) (P-11-561). (a) Chemical substance and significant new uses subject to... copolymer (PMN P-11-561) is subject to reporting under this section for the significant new uses described...

40 CFR 721.10419 - Tetrafluoroethylene chlorotrifluoroethylene copolymer (generic) (P-11-561).

Code of Federal Regulations, 2012 CFR

2012-07-01

... chlorotrifluoroethylene copolymer (generic) (P-11-561). 721.10419 Section 721.10419 Protection of Environment... chlorotrifluoroethylene copolymer (generic) (P-11-561). (a) Chemical substance and significant new uses subject to... copolymer (PMN P-11-561) is subject to reporting under this section for the significant new uses described...

40 CFR 721.10419 - Tetrafluoroethylene chlorotrifluoroethylene copolymer (generic) (P-11-561).

Code of Federal Regulations, 2014 CFR

2014-07-01

... chlorotrifluoroethylene copolymer (generic) (P-11-561). 721.10419 Section 721.10419 Protection of Environment... chlorotrifluoroethylene copolymer (generic) (P-11-561). (a) Chemical substance and significant new uses subject to... copolymer (PMN P-11-561) is subject to reporting under this section for the significant new uses described...

Influence of Chirality in Ordered Block Copolymer Phases

NASA Astrophysics Data System (ADS)

Prasad, Ishan; Grason, Gregory

2015-03-01

Block copolymers are known to assemble into rich spectrum of ordered phases, with many complex phases driven by asymmetry in copolymer architecture. Despite decades of study, the influence of intrinsic chirality on equilibrium mesophase assembly of block copolymers is not well understood and largely unexplored. Self-consistent field theory has played a major role in prediction of physical properties of polymeric systems. Only recently, a polar orientational self-consistent field (oSCF) approach was adopted to model chiral BCP having a thermodynamic preference for cholesteric ordering in chiral segments. We implement oSCF theory for chiral nematic copolymers, where segment orientations are characterized by quadrupolar chiral interactions, and focus our study on the thermodynamic stability of bi-continuous network morphologies, and the transfer of molecular chirality to mesoscale chirality of networks. Unique photonic properties observed in butterfly wings have been attributed to presence of chiral single-gyroid networks, this has made it an attractive target for chiral metamaterial design.

Patchy micelles based on coassembly of block copolymer chains and block copolymer brushes on silica particles.

PubMed

Zhu, Shuzhe; Li, Zhan-Wei; Zhao, Hanying

2015-04-14

Patchy particles are a type of colloidal particles with one or more well-defined patches on the surfaces. The patchy particles with multiple compositions and functionalities have found wide applications from the fundamental studies to practical uses. In this research patchy micelles with thiol groups in the patches were prepared based on coassembly of free block copolymer chains and block copolymer brushes on silica particles. Thiol-terminated and cyanoisopropyl-capped polystyrene-block-poly(N-isopropylacrylamide) block copolymers (PS-b-PNIPAM-SH and PS-b-PNIPAM-CIP) were synthesized by reversible addition-fragmentation chain transfer polymerization and chemical modifications. Pyridyl disulfide-functionalized silica particles (SiO2-SS-Py) were prepared by four-step surface chemical reactions. PS-b-PNIPAM brushes on silica particles were prepared by thiol-disulfide exchange reaction between PS-b-PNIPAM-SH and SiO2-SS-Py. Surface micelles on silica particles were prepared by coassembly of PS-b-PNIPAM-CIP and block copolymer brushes. Upon cleavage of the surface micelles from silica particles, patchy micelles with thiol groups in the patches were obtained. Dynamic light scattering, transmission electron microscopy, and zeta-potential measurements demonstrate the preparation of patchy micelles. Gold nanoparticles can be anchored onto the patchy micelles through S-Au bonds, and asymmetric hybrid structures are formed. The thiol groups can be oxidized to disulfides, which results in directional assembly of the patchy micelles. The self-assembly behavior of the patchy micelles was studied experimentally and by computer simulation.

Responsive Copolymers for Enhanced Petroleum Recovery

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

McCormick, C.; Hester, R.

The objectives of this work was to: synthesize responsive copolymer systems; characterize molecular structure and solution behavior; measure rheological properties of aqueous fluids in fixed geometry flow profiles; and to tailor final polymer compositions for in situ rheology control under simulated conditions. This report focuses on the synthesis and characterization of novel stimuli responsive copolymers, the investigation of dilute polymer solutions in extensional flow and the design of a rheometer capable of measuring very dilute aqueous polymer solutions at low torque.

Synthesis and Characterization of Stimuli Responsive Block Copolymers, Self-Assembly Behavior and Applications

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

Determan, Michael Duane

The central theme of this thesis work is to develop new block copolymer materials for biomedical applications. While there are many reports of stimuli-responsive amphiphilic [19-21] and crosslinked hydrogel materials [22], the development of an in situ gel forming, pH responsive pentablock copolymer is a novel contribution to the field, Figure 1.1 is a sketch of an ABCBA pentablock copolymer. The A blocks are cationic tertiary amine methacrylates blocked to a central Pluronic F127 triblock copolymer. In addition to the prerequisite synthetic and macromolecular characterization of these new materials, the self-assembled supramolecular structures formed by the pentablock were experimentally evaluated.more » This synthesis and characterization process serves to elucidate the important structure property relationships of these novel materials, The pH and temperature responsive behavior of the pentablock copolymer were explored especially with consideration towards injectable drug delivery applications. Future synthesis work will focus on enhancing and tuning the cell specific targeting of DNA/pentablock copolymer polyplexes. The specific goals of this research are: (1) Develop a synthetic route for gel forming pentablock block copolymers with pH and temperature sensitive properties. Synthesis of these novel copolymers is accomplished with ATRP, yielding low polydispersity and control of the block copolymer architecture. Well defined macromolecular characteristics are required to tailor the phase behavior of these materials. (2) Characterize relationship between the size and shape of pentablock copolymer micelles and gel structure and the pH and temperature of the copolymer solutions with SAXS, SANS and CryoTEM. (3) Evaluate the temperature and pH induced phase separation and macroscopic self-assembly phenomenon of the pentablock copolymer. (4) Utilize the knowledge gained from first three goals to design and formulate drug delivery formulations based on the multi

21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

Code of Federal Regulations, 2011 CFR

2011-04-01

... this section are not applicable to ethylene-acrylic acid copolymers used in food-packaging adhesives... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ethylene-acrylic acid copolymers. 177.1310 Section 177.1310 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

Code of Federal Regulations, 2013 CFR

2013-04-01

... this section are not applicable to ethylene-acrylic acid copolymers used in food-packaging adhesives... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ethylene-acrylic acid copolymers. 177.1310 Section 177.1310 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

Code of Federal Regulations, 2012 CFR

2012-04-01

... this section are not applicable to ethylene-acrylic acid copolymers used in food-packaging adhesives... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ethylene-acrylic acid copolymers. 177.1310 Section 177.1310 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

Imide/arylene ether copolymers with pendent trifluoromethyl groups

NASA Technical Reports Server (NTRS)

Jensen, Brian J.; Havens, Stephen J.

1992-01-01

A series of imide/arylene ether block copolymers were prepared using an arylene ether block containing a hexafluoroisopropylidene group and an imide block containing a hexafluoroisopropylidene and a trifluoromethyl group in the polymer backbone. The copolymers were characterized and mechanical properties were determined and compared to the homopolymers.

Highly Stable, Anion Conductive, Comb-Shaped Copolymers for Alkaline Fuel Cells

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

Li, NW; Leng, YJ; Hickner, MA

2013-07-10

To produce an anion-conductive and durable polymer electrolyte for alkaline fuel cell applications, a series of quaternized poly(2,6-dimethyl phenylene oxide)s containing long alkyl side chains pendant to the nitrogen-centered cation were synthesized using a Menshutkin reaction to form comb-shaped structures. The pendant alkyl chains were responsible for the development of highly conductive ionic domains, as confirmed by small-angle X-ray scattering (SAXS). The comb-shaped polymers having one alkyl side chain showed higher hydroxide conductivities than those with benzyltrimethyl ammonium moieties or structures with more than one alkyl side chain per cationic site. The highest conductivity was observed for comb-shaped polymers withmore » benzyldimethylhexadecyl ammonium cations. The chemical stabilities of the comb-shaped membranes were evaluated under severe, accelerated-aging conditions, and degradation was observed by measuring IEC and ion conductivity changes during aging. The comb-shaped membranes retained their high ion conductivity in 1 M NaOH at 80 degrees C for 2000 h. These cationic polymers were employed as ionomers in catalyst layers for alkaline fuel cells. The results indicated that the C-16 alkyl side chain ionomer had a slightly better initial performance, despite its low IEC value, but very poor durability in the fuel cell. In contrast, 90% of the initial performance was retained for the alkaline fuel cell with electrodes containing the C-6 side chain after 60 h of fuel cell operation.« less

Phase behavior of model ABC triblock copolymers

NASA Astrophysics Data System (ADS)

Chatterjee, Joon

The phase behavior of poly(isoprene-b-styrene- b-ethylene oxide) (ISO), a model ABC triblock copolymer has been studied. This class of materials exhibit self-assembly, forming a large array of ordered morphologies at length scales of 5-100 nm. The formation of stable three-dimensionally continuous network morphologies is of special interest in this study. Since these nanostructures considerably impact the material properties, fundamental knowledge for designing ABC systems have high technological importance for realizing applications in the areas of nanofabrication, nanoporous media, separation membranes, drug delivery and high surface area catalysts. A comprehensive framework was developed to describe the phase behavior of the ISO triblock copolymers at weak to intermediate segregation strengths spanning a wide range of composition. Phases were characterized through a combination of characterization techniques, including small angle x-ray scattering, dynamic mechanical spectroscopy, transmission electron microscopy, and birefringence measurements. Combined with previous investigations on ISO, six different stable ordered state symmetries have been identified: lamellae (LAM), Fddd orthorhombic network (O70), double gyroid (Q230), alternating gyroid (Q214), hexagonal (HEX), and body-centered cubic (BCC). The phase map was found to be somewhat asymmetric around the fI = fO isopleth. This work provides a guide for theoretical studies and gives insight into the intricate effects of various parameters on the self-assembly of ABC triblock copolymers. Experimental SAXS data evaluated with a simple scattering intensity model show that local mixing varies continuously across the phase map between states of two- and three-domain segregation. Strategies of blending homopolymers with ISO triblock copolymer were employed for studying the swelling properties of a lamellar state. Results demonstrate that lamellar domains swell or shrink depending upon the type of homopolymer that

Non-immunogenic, hydrophilic/cationic block copolymers and uses thereof

DOEpatents

Scales, Charles W.; Huang, Faqing; McCormick, Charles L.

2010-05-18

The present invention provides novel non-immunogenic, hydrophilic/cationic block copolymers comprising a neutral-hydrophilic polymer and a cationic polymer, wherein both polymers have well-defined chain-end functionality. A representative example of such a block copolymer comprises poly(N-(2-hydroxypropyl)methacrylamide) (PHPMA) and poly(N-[3-(dimethylamino)propyl]methacrylamide) (PDMAPMA). Also provided is a synthesis method thereof in aqueous media via reversible addition fragmentation chain transfer (RAFT) polymerization. Further provided are uses of these block copolymers as drug delivery vehicles and protection agents.

21 CFR 177.1310 - Ethylene-acrylic acid copolymers.

Code of Federal Regulations, 2014 CFR

2014-04-01

... applicable to ethylene-acrylic acid copolymers used in food-packaging adhesives complying with § 175.105 of... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Ethylene-acrylic acid copolymers. 177.1310 Section 177.1310 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

Chlorine resistant desalination membranes based on directly sulfonated poly(arylene ether sulfone) copolymers

DOEpatents

McGrath, James E [Blacksburg, VA; Park, Ho Bum [Austin, TX; Freeman, Benny D [Austin, TX

2011-10-04

The present invention provides a membrane, kit, and method of making a hydrophilic-hydrophobic random copolymer membrane. The hydrophilic-hydrophobic random copolymer membrane includes a hydrophilic-hydrophobic random copolymer. The hydrophilic-hydrophobic random copolymer includes one or more hydrophilic monomers having a sulfonated polyarylsulfone monomer and a second monomer and one or more hydrophobic monomers having a non-sulfonated third monomer and a fourth monomer. The sulfonated polyarylsulfone monomer introduces a sulfonate into the hydrophilic-hydrophobic random copolymer prior to polymerization.

Electrically conductive doped block copolymer of polyacetylene and polyisoprene

DOEpatents

Aldissi, Mahmoud

1985-01-01

An electrically conductive block copolymer of polyisoprene and polyacetyl and a method of making the same are disclosed. The polymer is prepared by first polymerizing isoprene with n-butyllithium in a toluene solution to form an active isoprenyllithium polymer. The active polymer is reacted with an equimolar amount of titanium butoxide and subsequently exposed to gaseous acetylene. A block copolymer of polyisoprene and polyacetylene is formed. The copolymer is soluble in common solvents and may be doped with I.sub.2 to give it an electrical conductivity in the metallic regime.

Morphologies of precise polyethylene-based acid copolymers and ionomers

NASA Astrophysics Data System (ADS)

Buitrago, C. Francisco

Acid copolymers and ionomers are polymers that contain a small fraction of covalently bound acidic or ionic groups, respectively. For the specific case of polyethylene (PE), acid and ionic pendants enhance many of the physical properties such as toughness, adhesion and rheological properties. These improved properties result from microphase separated aggregates of the polar pendants in the non-polar PE matrix. Despite the widespread industrial use of these materials, rigorous chemical structure---morphology---property relationships remain elusive due to the inevitable structural heterogeneities in the historically-available acid copolymers and ionomers. Recently, precise acid copolymers and ionomers were successfully synthesized by acyclic diene metathesis (ADMET) polymerization. These precise materials are linear, high molecular weight PEs with pendant acid or ionic functional groups separated by a precisely controlled number of carbon atoms. The morphologies of nine precise acid copolymers and eleven precise ionomers were investigated by X-ray scattering, solid-state 13C nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). For comparison, the morphologies of linear PEs with pseudo-random placement of the pendant groups were also studied. Previous studies of precise copolymers with acrylic acid (AA) found that the microstructural precision produces a new morphology in which PE crystals drive the acid aggregates into layers perpendicular to the chain axes and presumably at the interface between crystalline and amorphous phases. In this dissertation, a second new morphology for acid copolymers is identified in which the aggregates arrange on cubic lattices. The fist report of a cubic morphology was observed at room and elevated temperatures for a copolymer functionalized with two phosphonic acid (PA) groups on every 21st carbon atom. The cubic lattice has been identified as face-centered cubic (FCC). Overall, three morphology types have been

Block coordination copolymers

DOEpatents

Koh, Kyoung Moo; Wong-Foy, Antek G; Matzger, Adam J; Benin, Annabelle I; Willis, Richard R

2014-11-11

The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

Block coordination copolymers

DOEpatents

Koh, Kyoung Moo; Wong-Foy, Antek G.; Matzger, Adam J.; Benin, Annabelle I.; Willis, Richard R.

2012-12-04

The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

Block coordination copolymers

DOEpatents

Koh, Kyoung Moo; Wong-Foy, Antek G; Matzger, Adam J; Benin, Annabelle I; Willis, Richard R

2012-11-13

The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

Thermodynamics of strain-induced crystallization of random copolymers.

PubMed

Nie, Yijing; Gao, Huanhuan; Wu, Yixian; Hu, Wenbing

2014-01-14

Industrial semi-crystalline polymers contain various kinds of sequence defects, which behave like non-crystallizable comonomer units on random copolymers. We performed dynamic Monte Carlo simulations of strain-induced crystallization of random copolymers with various contents of comonomers at high temperatures. We observed that the onset strains of crystallization shift up with the increase of comonomer contents and temperatures. The behaviors can be predicted well by a combination of Flory's theories on the melting-point shifting-down of random copolymers and on the melting-point shifting-up of strain-induced crystallization. Our thermodynamic results are fundamentally important for us to understand the rubber strain-hardening, the plastic molding, the film stretching as well as the fiber spinning.

Copolymer-in-oil phantom materials for elastography.

PubMed

Oudry, J; Bastard, C; Miette, V; Willinger, R; Sandrin, L

2009-07-01

Phantoms that mimic mechanical and acoustic properties of soft biological tissues are essential to elasticity imaging investigation and to elastography device characterization. Several materials including agar/gelatin, polyvinyl alcohol and polyacrylamide gels have been used successfully in the past to produce tissue phantoms, as reported in the literature. However, it is difficult to find a phantom material with a wide range of stiffness, good stability over time and high resistance to rupture. We aim at developing and testing a new copolymer-in-oil phantom material for elastography. The phantom is composed of a mixture of copolymer, mineral oil and additives for acoustic scattering. The mechanical properties of phantoms were evaluated with a mechanical test instrument and an ultrasound-based elastography technique. The acoustic properties were investigated using a through-transmission water-substituting method. We showed that copolymer-in-oil phantoms are stable over time. Their mechanical and acoustic properties mimic those of most soft tissues: the Young's modulus ranges from 2.2-150 kPa, the attenuation coefficient from 0.4-4.0 dB.cm(-1) and the ultrasound speed from 1420-1464 m/s. Their density is equal to 0.90 +/- 0.04 g/cm3. The results suggest that copolymer-in-oil phantoms are attractive materials for elastography.

Crafting threads of diblock copolymer micelles via flow-enabled self-assembly.

PubMed

Li, Bo; Han, Wei; Jiang, Beibei; Lin, Zhiqun

2014-03-25

Hierarchically assembled amphiphilic diblock copolymer micelles were exquisitely crafted over large areas by capitalizing on two concurrent self-assembling processes at different length scales, namely, the periodic threads composed of a monolayer or a bilayer of diblock copolymer micelles precisely positioned by flow-enabled self-assembly (FESA) on the microscopic scale and the self-assembly of amphiphilic diblock copolymer micelles into ordered arrays within an individual thread on the nanometer scale. A minimum spacing between two adjacent threads λmin was observed. A model was proposed to rationalize the relationship between the thread width and λmin. Such FESA of diblock copolymer micelles is remarkably controllable and easy to implement. It opens up possibilities for lithography-free positioning and patterning of diblock copolymer micelles for various applications in template fabrication of periodic inorganic nanostructures, nanoelectronics, optoelectronics, magnetic devices, and biotechnology.

Non-native three-dimensional block copolymer morphologies

DOE PAGES

Rahman, Atikur; Majewski, Pawel W.; Doerk, Gregory; ...

2016-12-22

Self-assembly is a powerful paradigm, wherein molecules spontaneously form ordered phases exhibiting well-defined nanoscale periodicity and shapes. However, the inherent energy-minimization aspect of self-assembly yields a very limited set of morphologies, such as lamellae or hexagonally packed cylinders. Here, we show how soft self-assembling materials—block copolymer thin films—can be manipulated to form a diverse library of previously unreported morphologies. In this iterative assembly process, each polymer layer acts as both a structural component of the final morphology and a template for directing the order of subsequent layers. Specifically, block copolymer films are immobilized on surfaces, and template successive layers throughmore » subtle surface topography. As a result, this strategy generates an enormous variety of three-dimensional morphologies that are absent in the native block copolymer phase diagram.« less

Non-native three-dimensional block copolymer morphologies

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

Rahman, Atikur; Majewski, Pawel W.; Doerk, Gregory

Self-assembly is a powerful paradigm, wherein molecules spontaneously form ordered phases exhibiting well-defined nanoscale periodicity and shapes. However, the inherent energy-minimization aspect of self-assembly yields a very limited set of morphologies, such as lamellae or hexagonally packed cylinders. Here, we show how soft self-assembling materials—block copolymer thin films—can be manipulated to form a diverse library of previously unreported morphologies. In this iterative assembly process, each polymer layer acts as both a structural component of the final morphology and a template for directing the order of subsequent layers. Specifically, block copolymer films are immobilized on surfaces, and template successive layers throughmore » subtle surface topography. As a result, this strategy generates an enormous variety of three-dimensional morphologies that are absent in the native block copolymer phase diagram.« less

Synthesis and Characterization of Itaconic Anhydride and Stearyl Methacrylate Copolymers

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

Shang, S.; Huang, S; Weiss, R

The free-radical copolymerization and the properties of comb-like copolymers derived from renewable resources, itaconic anhydride (ITA) and stearyl methacrylate (SM), are described. The ITA-SM copolymers were nearly random with a slight alternating tendency. The copolymers exhibited a nanophase-separated morphology, with the stearate side-chains forming a bilayer, semi-crystalline structure. The melting point (Tm) of the side-chains and the crystallinity decreased with increasing ITA concentration. The crystalline side-chains suppressed molecular motion of the main chain, so that a glass transition temperature (Tg) was not resolved unless the ITA concentration was sufficiently high so that Tg > Tm. The softening point and modulusmore » of the copolymers increased with the increasing ITA concentration, but the thermal stability decreased.« less

Interaction chromatography for characterization and large-scale fractionation of chemically heterogeneous copolymers

NASA Astrophysics Data System (ADS)

Han, Junwon

The remarkable development of polymer synthesis techniques to make complex polymers with controlled chain architectures has inevitably demanded the advancement of polymer characterization tools to analyze the molecular dispersity in polymeric materials beyond size exclusion chromatography (SEC). In particular, man-made synthetic copolymers that consist of more than one monomer type are disperse mixtures of polymer chains that have distributions in terms of both chemical heterogeneity and chain length (molar mass). While the molecular weight distribution has been quite reliably estimated by the SEC, it is still challenging to properly characterize the chemical composition distribution in the copolymers. Here, I have developed and applied adsorption-based interaction chromatography (IC) techniques as a promising tool to characterize and fractionate polystyrene-based block, random and branched copolymers in terms of their chemical heterogeneity. The first part of this thesis is focused on the adsorption-desorption based purification of PS-b-PMMA diblock copolymers using nanoporous silica. The liquid chromatography analysis and large scale purification are discussed for the PS-b-PMMA block copolymers that have been synthesized by sequential anionic polymerization. SEC and IC are compared to critically analyze the contents of PS homopolymers in the as-synthesized block copolymers. In addition, I have developed an IC technique to provide faster and more reliable information on the chemical heterogeneity in the as-synthesized block copolymers. Finally, a large scale (multi-gram) separation technique is developed to obtain "homopolymer-free" block copolymers via a simple chromatographic filtration technique. By taking advantage of the large specific surface area of nanoporous silica (≈300m 2/g), large scale purification of neat PS-b-PMMA has successfully been achieved by controlling adsorption and desorption of the block copolymers on the silica gel surface using a

Temperature-dependent optical properties of gold nanoparticles coated with a charged diblock copolymer and an uncharged triblock copolymer.

PubMed

Volden, Sondre; Kjøniksen, Anna-Lena; Zhu, Kaizheng; Genzer, Jan; Nyström, Bo; Glomm, Wilhelm R

2010-02-23

We demonstrate that the optical properties of gold nanoparticles can be used to detect and follow stimuli-induced changes in adsorbed macromolecules. Specifically, we investigate thermal response of anionic diblock and uncharged triblock copolymers based on poly(N-isopropylacrylamide) (PNIPAAM) blocks adsorbed onto gold nanoparticles and planar gold surfaces in a temperature range between 25 and 60 degrees C. By employing a palette of analytical probes, including UV-visible spectroscopy, dynamic light scattering, fluorescence, and quartz crystal microbalance with dissipation monitoring, we establish that while the anionic copolymer forms monolayers at both low and high temperature, the neutral copolymer adsorbs as a monolayer at low temperatures and forms multilayers above the cloud point (T(C)). Raising the temperature above T(C) severely affects the optical properties of the gold particle/polymer composites, expelling associated water and altering the immediate surroundings of the gold nanoparticles. This effect, stronger for the uncharged polymer, is related to the amount of polymer adsorbed on the surface, where a denser shell influences the surface plasmon band to a greater degree. This is corroborated with light scattering experiments, which reveal that flocculation of the neutral polymer-coated particles occurs at high temperatures. The flocculation behavior of the neutral copolymer on planar gold surfaces results in multilayer formation. The observed effects are discussed within the framework of the Mie-Drude theory.

Responsive copolymers for enhanced petroleum recovery. Second annual report

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

McCormick, C.; Hester, R.

The authors describe second year efforts in synthesis, characterization, and rheology to develop polymers with significantly improved efficiency in mobility control and conformance. These advanced polymer systems would maintain high viscosities or behave as virtual gels under low shear conditions and at elevated electrolyte concentrations. At high fluid shear rates, associates would deaggregate yielding low viscosity solutions, reducing problems of shear degradation or face plugging during injection. Polymeric surfactants were also developed with potential for use in higher salt, higher temperature reservoirs for mobilization of entrapped oil. Chapters include: Ampholytic terpolymers of acrylamide with sodium 3-acrylamido-3-methylbutanoate and 2-acrylamido-2-methylpropanetrimethylammonium chloride; Hydrophilicmore » sulfobetaine copolymers of acrylamide and 3-(2-acrylamido-methylpropane-dimethylammonio)-1-propanesulfonate; Copolymerization of maleic anhydride and N-vinylformamide; Reactivity ratio of N-vinylformamide with acrylamide, sodium acrylate, and n-butyl acrylate; Effect of the distribution of the hydrophobic cationic monomer dimethyldodecyl(2-acrylamidoethyl)ammonium bromide on the solution behavior of associating acrylamide copolymers; Effect of surfactants on the solution properties of amphipathic copolymers of acrylamide and N,N-dimethyl-N-dodecyl-N-(2-acrylamidoethyl)ammonium bromide; Associative interactions and photophysical behavior of amphiphilic terpolymers prepared by modification of maleic anhydride/ethyl vinyl ether copolymers; Copolymer compositions of high-molecular-weight functional acrylamido water-soluble polymers using direct-polarization magic-angle spinning {sup 13}C NMR; Use of factorial experimental design in static and dynamic light scattering characterization of water soluble polymers; and Porous medium elongational rheometer studies of NaAMB/AM copolymer solutions.« less

Heat Capacity of Spider Silk-like Block Copolymers

PubMed Central

Huang, Wenwen; Krishnaji, Sreevidhya; Hu, Xiao; Kaplan, David; Cebe, Peggy

2012-01-01

We synthesized and characterized a new family of di-block copolymers based on the amino acid sequences of Nephila clavipes major ampulate dragline spider silk, having the form HABn and HBAn (n=1–3), comprising an alanine-rich hydrophobic block, A, a glycine-rich hydrophilic block, B, and a histidine tag, H. The reversing heat capacities, Cp(T), for temperatures below and above the glass transition, Tg, were measured by temperature modulated differential scanning calorimetry. For the solid state, we then calculated the heat capacities of our novel block copolymers based on the vibrational motions of the constituent poly(amino acid)s, whose heat capacities are known or can be estimated from the ATHAS Data Bank. For the liquid state, the heat capacity was estimated by using the rotational and translational motions in the polymer chain. Excellent agreement was found between the measured and calculated values of the heat capacity, showing that this method can serve as a standard by which to assess the Cp for other biologically inspired block copolymers. The fraction of beta sheet crystallinity of spider silk block copolymers was also determined by using the predicted Cp, and was verified by wide angle X-ray diffraction and Fourier transform infrared spectroscopy. The glass transition temperatures of spider silk block copolymer were fitted by Kwei’s equation and the results indicate that attractive interaction exists between the A-block and B-block. PMID:23869111

Block copolymer battery separator

DOEpatents

Wong, David; Balsara, Nitash Pervez

2016-04-26

The invention herein described is the use of a block copolymer/homopolymer blend for creating nanoporous materials for transport applications. Specifically, this is demonstrated by using the block copolymer poly(styrene-block-ethylene-block-styrene) (SES) and blending it with homopolymer polystyrene (PS). After blending the polymers, a film is cast, and the film is submerged in tetrahydrofuran, which removes the PS. This creates a nanoporous polymer film, whereby the holes are lined with PS. Control of morphology of the system is achieved by manipulating the amount of PS added and the relative size of the PS added. The porous nature of these films was demonstrated by measuring the ionic conductivity in a traditional battery electrolyte, 1M LiPF.sub.6 in EC/DEC (1:1 v/v) using AC impedance spectroscopy and comparing these results to commercially available battery separators.

Electric-Field-Induced Alignment of Block Copolymer/Nanoparticle Blends

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

Liedel, Clemens; Schindler, Kerstin; Pavan, Mariela J.

External electric fi elds readily align birefringent block-copolymer mesophases. In this study the effect of gold nanoparticles on the electric-fi eld-induced alignment of a lamellae-forming polystyrene- block -poly(2-vinylpyridine) copolymer is assessed. Nanoparticles are homogeneously dispersed in the styrenic phase and promote the quantitative alignment of lamellar domains by substantially lowering the critical field strength above which alignment proceeds. The results suggest that the electric-fi eldassisted alignment of nanostructured block copolymer/nanoparticle composites may offer a simple way to greatly mitigate structural and orientational defects of such fi lms under benign experimental conditions.

Highly conductive side chain block copolymer anion exchange membranes.

PubMed

Wang, Lizhu; Hickner, Michael A

2016-06-28

Block copolymers based on poly(styrene) having pendent trimethyl styrenylbutyl ammonium (with four carbon ring-ionic group alkyl linkers) or benzyltrimethyl ammonium groups with a methylene bridge between the ring and ionic group were synthesized by reversible addition-fragmentation radical (RAFT) polymerization as anion exchange membranes (AEMs). The C4 side chain polymer showed a 17% increase in Cl(-) conductivity of 33.7 mS cm(-1) compared to the benzyltrimethyl ammonium sample (28.9 mS cm(-1)) under the same conditions (IEC = 3.20 meq. g(-1), hydration number, λ = ∼7.0, cast from DMF/1-propanol (v/v = 3 : 1), relative humidity = 95%). As confirmed by small angle X-ray scattering (SAXS), the side chain block copolymers with tethered ammonium cations showed well-defined lamellar morphologies and a significant reduction in interdomain spacing compared to benzyltrimethyl ammonium containing block copolymers. The chemical stabilities of the block copolymers were evaluated under severe, accelerated conditions, and degradation was observed by (1)H NMR. The block copolymer with C4 side chain trimethyl styrenylbutyl ammonium motifs displayed slightly improved stability compared to that of a benzyltrimethyl ammonium-based AEM at 80 °C in 1 M NaOD aqueous solution for 30 days.

Rheological Design of Sustainable Block Copolymers

NASA Astrophysics Data System (ADS)

Mannion, Alexander M.

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

Molecular Design of Sulfonated Triblock Copolymer Permselective Membranes

DTIC Science & Technology

2008-07-03

factors governing sorption and permeability ofphosphoorganic agents in PEM made of sulfonated triblock copolymers of styrene and lower olefins by means...membrane morphology at environmental conditions, and the membrane sorption and transport properties with respect to water and nerve gas simulant...and chemical factors governing sorption and permeability of phosphoorganic agents in PEM made of sulfonated triblock copolymers of styrene and lower

Physical Aging Studies of Styrene-Butadiene and Carbonate-Siloxane Block Copolymers

DTIC Science & Technology

1979-11-19

Carbonate-Siloxane Block Copolymers, ,-- by Martin Tant Garth . D D C Prepared for Publication r - r-on n[? in the JAN Journal of Applied Polymer Science B...revereie ifI nocesy and Identify by black mumibo,) Polymer glasses Non equilibrium glasses Stress relaxation Block copolymers 20. AOSTRACT (Continwaon...copolymers in material applications. -2- Introduction The physical aging phenomenon in glassy polymers has drawn considerable interest within the

Resonant soft x-ray GISAXS on block copolymer films

NASA Astrophysics Data System (ADS)

Wang, Cheng; Araki, T.; Watts, B.; Ade, H.; Hexemer, A.; Park, S.; Russell, T. P.; Schlotter, W. F.; Stein, G. E.; Tang, C.; Kramer, E. J.

2008-03-01

Ordered block copolymer thin films may have important applications in modern device fabrication. Current characterization methods such as conventional GISAXS have fixed electron density contrast that can be overwhelmed by surface scattering. However, soft x-rays have longer wavelength, energy dependent contrast and tunable penetration, making resonant GISAXS a very promising tool for probing nanostructured polymer thin films. Our preliminary investigation was performed using PS-b-P2VP block copolymer films on beam-line 5-2 SSRL, and beam-line 6.3.2 at ALS, LBNL. The contrast/sensitivity of the scattering pattern varies significantly with photon energy close to the C K-edge (˜290 eV). Also, higher order peaks are readily observed, indicating hexagonal packing structure in the sample. Comparing to the hard x-ray GISAXS data of the same system, it is clear that resonant GISAXS has richer data and better resolution. Beyond the results on the A-B diblock copolymers, results on ABC block copolymers are especially interesting.

ABC triblock copolymer vesicles with mesh-like morphology.

PubMed

Zhao, Wei; Chen, Dian; Hu, Yunxia; Grason, Gregory M; Russell, Thomas P

2011-01-25

Polymer vesicles made from poly(isoprene-b-styrene-b-2-vinyl pyridine) (PI-b-PS-b-P2VP) triblock copolymer confined within the nanopores of an anodic aluminum oxide (AAO) membrane are studied. It was found that these vesicles have well-defined, nanoscopic size, and complex microphase-separated hydrophobic membranes, comprised of the PS and PI blocks, while the coronas are formed by the P2VP block. Vesicle formation was tracked using both transmission and scanning electron microscopy. A mesh-like morphology formed in the membrane at a well-defined composition of the three blocks that can be tuned by changing the copolymer composition. The nanoscale confinement, copolymer composition, and subtle molecular interactions contribute to the generation of these vesicles with such unusual morphologies.

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

Let there be light: photo-cross-linked block copolymer nanoparticles.

PubMed

Roy, Debashish; Sumerlin, Brent S

2014-01-01

Polymeric nanoparticles are prepared by selectively cross-linking a photo-sensitive dimethylmaleimide-containing block of a diblock copolymer via UV irradiation. A well-defined photo-cross-linkable block copolymer is prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization of a dimethylmaleimide-functional acrylamido monomer containing photoreactive pendant groups with a poly(N,N-dimethylacrylamide) (PDMA) macro-chain transfer agent. The resulting amphiphilic block copolymers form micelles in water with a hydrophilic PDMA shell and a hydrophobic photo-cross-linkable dimethylmaleimide-containing core. UV irradiation results in photodimerization of the dimethylmaleimide groups within the micelle cores to yield core-cross-linked aggregates. Alternatively, UV irradiation of homogeneous solutions of the block copolymer in a non-selective solvent leads to in situ nanoparticle formation. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of nanoparticles on the compatibility of PEO-PMMA block copolymers.

PubMed

Mu, Dan; Li, Jian-Quan; Li, Wei-Dong; Wang, Song

2011-12-01

The compatibility of six kinds of designed poly(ethylene oxide)-block-poly(methyl methacrylate) (PEO-b-PMMA) copolymers was studied at 270, 298 and 400 K via mesoscopic modeling. The values of the order parameters depended on both the structures of the block copolymers and the simulation temperature, while the values of the order parameters of the long chains were higher than those of the short ones; temperature had a more obvious effect on long chains than on the short ones. Plain copolymers doped with poly(ethylene oxide) (PEO) or poly(methyl methacrylate) (PMMA) homopolymer showed different order parameter values. When a triblock copolymer had the same component at both ends and was doped with one of its component polymers as a homopolymer (such as A5B6A5 doped with B6 or A5 homopolymer), the value of its order parameter depended on the simulation temperature. The highest order parameter values were observed for A5B6A5 doped with B6 at 400 K and for A5B6A5 doped with A5 at 270 K. A study of copolymers doped with nanoparticles showed that the mesoscopic phase was influenced by not only the properties of the nanoparticles, such as the size and density, but also the compositions of the copolymers. Increasing the size of the nanoparticles used as a dopant had the most significant effect on the phase morphologies of the copolymers.

Ultraviolet absorbing copolymers

DOEpatents

Gupta, Amitava; Yavrouian, Andre H.

1982-01-01

Photostable and weather stable absorping copolymers have been prepared from acrylic esters such as methyl methacrylate containing 0.1 to 5% of an 2-hydroxy-allyl benzophenone, preferably the 4,4' dimethoxy derivative thereof. The pendant benzophenone chromophores protect the acrylic backbone and when photoexcited do not degrade the ester side chain, nor abstract hydrogen from the backbone.

Effect of Temperature on Electrical Conductivity of Guaiacol-Guanidine Hydrochloride-Formaldehyde Copolymer Resin

NASA Astrophysics Data System (ADS)

Kukade, S. D.; Bawankar, S. V.

2018-02-01

The purpose of the present paper is to report temperature dependence of electrical conductivity on Guaiacol-guanidine hydrochloride-formaldehyde copolymer resin. By using a microwave irradiation technique, various ratios of copolymer resin were synthesized from the reacting monomers, i.e., guaiacol, guanidine hydrochloride and formaldehyde. The characterization of the copolymer resins has been fulfilled by spectral methods viz. ultraviolet visible (UV visible), infrared and proton nuclear magnetic spectroscopy (1H-NMR). The solid state direct current electrical conductivity of synthesized copolymer resins has been measured as a function of temperature. The electrical conductivity values of all the copolymers have been found in the range of a semiconductor.

Responsive copolymers for enhanced petroleum recovery. Annual report

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

McCormick, C.; Hester, R.

1994-08-01

A coordinated research program involving synthesis, characterization, and rheology has been undertaken to develop advanced polymer system which should be significantly more efficient than polymers presently used for mobility control and conformance. Unlike the relatively inefficient, traditional EOR polymers, these advanced polymer systems possess microstructural features responsive to temperature, electrolyte concentration, and shear conditions. Contents of this report include the following chapters. (1) First annual report responsive copolymers for enhanced oil recovery. (2) Copolymers of acrylamide and sodium 3-acrylamido-3-methylbutanoate. (3) Terpolymers of NaAMB, Am, and n-decylacrylamide. (4) Synthesis and characterization of electrolyte responsive terpolymers of acrylamide, N-(4-butyl)phenylacrylamide, and sodium acrylate,more » sodium-2-acrylamido-2-methylpropanesulphonate or sodium-3-acrylamido-3-methylbutanoate. (5) Synthesis and solution properties of associative acrylamido copolymers with pyrensulfonamide fluorescence labels. (6) Photophysical studies of the solution behavior of associative pyrenesulfonamide-labeled polyacrylamides. (7) Ampholytic copolymers of sodium 2-(acrylamido)-2-methylpropanesulfonate with [2-(acrylamido)-2-methypropyl]trimethylammonium chloride. (8) Ampholytic terpolymers of acrylamide with sodium 2-acrylamido-2-methylpropanesulphoante and 2-acrylamido-2-methylpropanetrimethyl-ammonium chloride and (9) Polymer solution extensional behavior in porous media.« less

Molecular architecture of electroactive and biodegradable copolymers composed of polylactide and carboxyl-capped aniline trimer.

PubMed

Guo, Baolin; Finne-Wistrand, Anna; Albertsson, Ann-Christine

2010-04-12

Two-, four-, and six-armed branched copolymers with electroactive and biodegradable properties were synthesized by coupling reactions between poly(l-lactides) (PLLAs) with different architecture and carboxyl-capped aniline trimer (CCAT). The aniline oligomer CCAT was prepared from amino-capped aniline trimer and succinic anhydride. FT-IR, NMR, and SEC analyses confirmed the structure of the branched copolymers. UV-vis spectra and cyclic voltammetry of CCAT and copolymer solution showed good electroactive properties, similar to those of polyaniline. The water contact angle of the PLLAs was the highest, followed by the undoped copolymer and the doped copolymers. The values of doped four-armed copolymers were 54-63 degrees . Thermal properties of the polymers were studied by DSC and TGA. The copolymers had better thermal stability than the pure PLLAs, and the T(g) between 48-58 degrees C and T(m) between 146-177 degrees C of the copolymers were lower than those of the pure PLLA counterparts. This kind of electroactive and biodegradable copolymer has a great potential for applications in cardiovascular or neuronal tissue engineering.

Biophysical Characterization of Copolymer-Protected Gene Vectors (COPROGs)

PubMed Central

Hönig, Daniel; DeRouchey, Jason; Jungmann, Ralf; Koch, Christian; Plank, Christian; Rädler, Joachim O.

2010-01-01

A copolymer-protected gene vector (COPROG) is a three component gene delivery system consisting of a preformed DNA and branched polyethylenimine (bPEI) complex subsequently modified by the addition of a copolymer (P6YE5C) incorporating both poly(ethylene glycol) (PEG) and anionic peptides. Using fluorescence correlation spectroscopy (FCS) and atomic force microscopy (AFM), we characterized and compared the self-assembly of bPEI/DNA particles and COPROG complexes. In low salt buffer, both bPEI/DNA and COPROG formulations form stable nanoparticles with hydrodynamic radii between 60–120 nm. COPROG particles, as compared to bPEI/DNA, show greatly improved particle stability to both physiological salt as well as low pH conditions. Binding stoichiometry of the three-component COPROG system was investigated by dual-color fluorescence cross-correlation spectroscopy (FCCS). It was found that a significant fraction of P6YE5C copolymer aggregates with excess bPEI forming bPEI/P6YE5C “ghost complexes” with no DNA inside. The ratio of ghost particles to COPROG complexes is about 4:1. In addition we find a large fraction of excess P6YE5C copolymer, which remains unbound in solution. We observe a 2–4 fold enhanced reporter gene expression with COPROG formulations at various equivalents as compared to bPEI-DNA alone. We believe that both complex stabilization as well as the capture of excess bPEI into ghost particles induced by the copolymer is responsible for the improvement in gene expression. PMID:20672861

Method of producing nanopatterned articles using surface-reconstructed block copolymer films

DOEpatents

Russell, Thomas P; Park, Soojin; Wang, Jia-Yu; Kim, Bokyung

2013-08-27

Nanopatterned surfaces are prepared by a method that includes forming a block copolymer film on a substrate, annealing and surface reconstructing the block copolymer film to create an array of cylindrical voids, depositing a metal on the surface-reconstructed block copolymer film, and heating the metal-coated block copolymer film to redistribute at least some of the metal into the cylindrical voids. When very thin metal layers and low heating temperatures are used, metal nanodots can be formed. When thicker metal layers and higher heating temperatures are used, the resulting metal structure includes nanoring-shaped voids. The nanopatterned surfaces can be transferred to the underlying substrates via etching, or used to prepare nanodot- or nanoring-decorated substrate surfaces.

21 CFR 177.1340 - Ethylene-methyl acrylate copolymer resins.

Code of Federal Regulations, 2011 CFR

2011-04-01

... ethylene-methyl acrylate copolymer resins used in food-packaging adhesives complying with § 175.105 of this... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Ethylene-methyl acrylate copolymer resins. 177.1340 Section 177.1340 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN...

21 CFR 177.1340 - Ethylene-methyl acrylate copolymer resins.

Code of Federal Regulations, 2013 CFR

2013-04-01

... ethylene-methyl acrylate copolymer resins used in food-packaging adhesives complying with § 175.105 of this... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Ethylene-methyl acrylate copolymer resins. 177.1340 Section 177.1340 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN...

21 CFR 177.1340 - Ethylene-methyl acrylate copolymer resins.

Code of Federal Regulations, 2012 CFR

2012-04-01

... ethylene-methyl acrylate copolymer resins used in food-packaging adhesives complying with § 175.105 of this... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Ethylene-methyl acrylate copolymer resins. 177.1340 Section 177.1340 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN...

New thiol-responsive mono-cleavable block copolymer micelles labeled with single disulfides.

PubMed

Sourkohi, Behnoush Khorsand; Schmidt, Rolf; Oh, Jung Kwon

2011-10-18

Thiol-responsive symmetric triblock copolymers having single disulfide linkages in the middle blocks (called mono-cleavable block copolymers, ss-ABP(2)) were synthesized by atom transfer radical polymerization in the presence of a disulfide-labeled difunctional Br-initiator. These brush-like triblock copolymers consist of a hydrophobic polyacrylate block having pendent oligo(propylene oxide) and a hydrophilic polymethacrylate block having pendent oligo(ethylene oxide). Gel permeation chromatography and (1)H NMR results confirmed the synthesis of well-defined mono-cleavable block copolymers and revealed that polymerizations were well controlled. Because of amphiphilic nature, these copolymers self-assembled to form colloidally stable micelles above critical micellar concentration of 0.032 mg · mL(-1). In response to reductive reactions, disulfides in thiol-responsive micelles were cleaved. Atomic force microscopy and dynamic light scattering analysis suggested that the cleavage of disulfides caused dissociation of micelles to smaller-sized assembled structures in water. Moreover, in a biomedical perspective, the mono-cleavable block copolymer micelles are not cytotoxic and thus biocompatible. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-oscillating AB diblock copolymer developed by post modification strategy

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

Ueki, Takeshi, E-mail: ueki@cross.t.u-tokyo.ac.jp, E-mail: ryo@cross.t.u-tokyo.ac.jp; Onoda, Michika; Tamate, Ryota

We prepared AB diblock copolymer composed of hydrophilic poly(ethylene oxide) segment and self-oscillating polymer segment. In the latter segment, ruthenium tris(2,2′-bipyridine) (Ru(bpy){sub 3}), a catalyst of the Belousov-Zhabotinsky reaction, is introduced into the polymer architecture based on N-isopropylacrylamide (NIPAAm). The Ru(bpy){sub 3} was introduced into the polymer segment by two methods; (i) direct random copolymerization (DP) of NIPAAm and Ru(bpy){sub 3} vinyl monomer and (ii) post modification (PM) of Ru(bpy){sub 3} with random copolymer of NIPAAm and N-3-aminopropylmethacrylamide. For both the diblock copolymers, a bistable temperature region (the temperature range; ΔT{sub m}), where the block copolymer self-assembles into micelle atmore » reduced Ru(bpy){sub 3}{sup 2+} state whereas it breaks-up into individual polymer chain at oxidized Ru(bpy){sub 3}{sup 3+} state, monotonically extends as the composition of the Ru(bpy){sub 3} increases. The ΔT{sub m} of the block copolymer prepared by PM is larger than that by DP. The difference in ΔT{sub m} is rationalized from the statistical analysis of the arrangement of the Ru(bpy){sub 3} moiety along the self-oscillating segments. By using the PM method, the well-defined AB diblock copolymer having ΔT{sub m} (ca. 25 °C) large enough to cause stable self-oscillation can be prepared. The periodic structural transition of the diblock copolymer in a dilute solution ([Polymer] = 0.1 wt. %) is closely investigated in terms of the time-resolved dynamic light scattering technique at constant temperature in the bistable region. A macroscopic viscosity oscillation of a concentrated polymer solution (15 wt. %) coupled with the periodic microphase separation is also demonstrated.« less

Rapid Ordering in "Wet Brush" Block Copolymer/Homopolymer Ternary Blends.

PubMed

Doerk, Gregory S; Yager, Kevin G

2017-12-26

The ubiquitous presence of thermodynamically unfavored but kinetically trapped topological defects in nanopatterns formed via self-assembly of block copolymer thin films may prevent their use for many envisioned applications. Here, we demonstrate that lamellae patterns formed by symmetric polystyrene-block-poly(methyl methacrylate) diblock copolymers self-assemble and order extremely rapidly when the diblock copolymers are blended with low molecular weight homopolymers of the constituent blocks. Being in the "wet brush" regime, the homopolymers uniformly distribute within their respective self-assembled microdomains, preventing increases in domain widths. An order-of-magnitude increase in topological grain size in blends over the neat (unblended) diblock copolymer is achieved within minutes of thermal annealing as a result of the significantly higher power law exponent for ordering kinetics in the blends. Moreover, the blends are demonstrated to be capable of rapid and robust domain alignment within micrometer-scale trenches, in contrast to the corresponding neat diblock copolymer. These results can be attributed to the lowering of energy barriers associated with domain boundaries by bringing the system closer to an order-disorder transition through low molecular weight homopolymer blending.

Triclosan/copolymer containing toothpastes for oral health.

PubMed

Riley, Philip; Lamont, Thomas

2013-12-05

Periodontal disease and dental caries are highly prevalent oral diseases that can lead to pain and discomfort, oral hygiene and aesthetic problems, and eventually tooth loss, all of which can be costly to treat and are a burden to healthcare systems. Triclosan is an antibacterial agent with low toxicity, which, along with a copolymer for aiding retention, can be added to toothpastes to reduce plaque and gingivitis (inflammation of the gums). It is important that these additional ingredients do not interfere with the anticaries effect of the fluoride present in toothpastes, and that they are safe. To assess the effects of triclosan/copolymer containing fluoride toothpastes, compared with fluoride toothpastes, for the long-term control of caries, plaque and gingivitis in children and adults. We searched the Cochrane Oral Health Group's Trials Register (to 19 August 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 7), MEDLINE via OVID (1946 to 19 August 2013), EMBASE via OVID (1980 to 19 August 2013), and the US National Institutes of Health Trials Register (clinicaltrials.gov) (to 19 August 2013). We applied no restrictions regarding language or date of publication in the searches of the electronic databases. We included randomised controlled trials (RCTs) assessing the effects triclosan/copolymer containing toothpastes on oral health. Two review authors independently assessed the search results against the inclusion criteria for this review, extracted data and carried out risk of bias assessments. We attempted to contact study authors for missing information or clarification when feasible. We combined sufficiently similar studies in meta-analyses using random-effects models when there were at least four studies (fixed-effect models when fewer than four studies), reporting mean differences (MD) for continuous data and risk ratios (RR) for dichotomous data. We included 30 studies, analysing 14,835 participants, in

Synthesis of ethylene-propylene rubber graft copolymers by borane approach

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

Chung, T.C.; Janvikul, W.; Bernard, R.

1994-01-01

This paper describes a new method to prepare graft copolymers which have an EP rubber backbone and several free radical polymerized polymers grafted thereto. The process involves hydroboration of commercial EPDM rubbers, such as poly(ethylene-co-propylene-co-1,4-hexadiene) and poly(ethylene-co-propylene-co-5-ethylidene-2-norbornene), with 9-borabicyclononane (9-BBN). The resulting secondary alkyl-9-BBN moieties in the EPDM copolymer were then exposed to oxygen in the presence of free radical polymerizable monomers. Under certain conditions, the selective autoxidation reaction of secondary alkyl-9-BBN took place to create desirable polymeric radicals which can in situ initiate free radical polymerization. High graft efficiency was observed with controllable copolymer compositions. The graft copolymer ofmore » EP-g-PMMA is used to show the chemistry as well as some of the physical properties.« less

Engineering topochemical polymerizations using block copolymer templates.

PubMed

Zhu, Liangliang; Tran, Helen; Beyer, Frederick L; Walck, Scott D; Li, Xin; Agren, Hans; Killops, Kato L; Campos, Luis M

2014-09-24

With the aim to achieve rapid and efficient topochemical polymerizations in the solid state, via solution-based processing of thin films, we report the integration of a diphenyldiacetylene monomer and a poly(styrene-b-acrylic acid) block copolymer template for the generation of supramolecular architectural photopolymerizable materials. This strategy takes advantage of non-covalent interactions to template a topochemical photopolymerization that yields a polydiphenyldiacetylene (PDPDA) derivative. In thin films, it was found that hierarchical self-assembly of the diacetylene monomers by microphase segregation of the block copolymer template enhances the topochemical photopolymerization, which is complete within a 20 s exposure to UV light. Moreover, UV-active cross-linkable groups were incorporated within the block copolymer template to create micropatterns of PDPDA by photolithography, in the same step as the polymerization reaction. The materials design and processing may find potential uses in the microfabrication of sensors and other important areas that benefit from solution-based processing of flexible conjugated materials.

Phase behaviors of supramolecular graft copolymers with reversible bonding

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

Zhang, Xu; Wang, Liquan, E-mail: jlin@ecust.edu.cn, E-mail: lq-wang@ecust.edu.cn; Jiang, Tao

2013-11-14

Phase behaviors of supramolecular graft copolymers with reversible bonding interactions were examined by the random-phase approximation and real-space implemented self-consistent field theory. The studied supramolecular graft copolymers consist of two different types of mutually incompatible yet reactive homopolymers, where one homopolymer (backbone) possesses multifunctional groups that allow second homopolymers (grafts) to be placed on. The calculations carried out show that the bonding strength exerts a pronounced effect on the phase behaviors of supramolecular graft copolymers. The length ratio of backbone to graft and the positions of functional groups along the backbone are also of importance to determine the phase behaviors.more » Phase diagrams were constructed at high bonding strength to illustrate this architectural dependence. It was found that the excess unbounded homopolymers swell the phase domains and shift the phase boundaries. The results were finally compared with the available experimental observations, and a well agreement is shown. The present work could, in principle, provide a general understanding of the phase behaviors of supramolecular graft copolymers with reversible bonding.« less

Protein resistance of dextran and dextran-PEG copolymer films

PubMed Central

Kozak, Darby; Chen, Annie; Bax, Jacinda; Trau, Matt

2011-01-01

The protein resistance of dextran and dextran-poly(ethylene glycol) (PEG) copolymer films was examined on an organosilica particle-based assay support. Comb-branched dextran-PEG copolymer films were synthesized in a two step process using the organosilica particle as a solid synthetic support. Particles modified with increasing amounts (0.1-1.2 mg m−2) of three molecular weights (10 000, 66 900, 400 000 g mol−1) of dextran were found to form relatively poor protein-resistant films compared to dextran-PEG copolymers and previously studied PEG films. The efficacy of the antifouling polymer films was found to be dependent on the grafted amount and its composition, with PEG layers being the most efficient, followed by dextran-PEG copolymers, and dextran alone being the least efficient. Immunoglobulin gamma (IgG) adsorption decreased from ~ 5 to 0.5 mg m−2 with increasing amounts of grafted dextran, but bovine serum albumin (BSA) adsorption increased above monolayer coverage (to ~2 mg m−2) indicating ternary adsorption of the smaller protein within the dextran layer. PMID:21614699

Advances in proton-exchange membranes for fuel cells: an overview on proton conductive channels (PCCs).

PubMed

Wu, Liang; Zhang, Zhenghui; Ran, Jin; Zhou, Dan; Li, Chuanrun; Xu, Tongwen

2013-04-14

Proton-exchange membranes (PEM) display unique ion-selective transport that has enabled a breakthrough in high-performance proton-exchange membrane fuel cells (PEMFCs). Elemental understanding of the morphology and proton transport mechanisms of the commercially available Nafion® has promoted a majority of researchers to tune proton conductive channels (PCCs). Specifically, knowledge of the morphology-property relationship gained from statistical and segmented copolymer PEMs has highlighted the importance of the alignment of PCCs. Furthermore, increasing efforts in fabricating and aligning artificial PCCs in field-aligned copolymer PEMs, nanofiber composite PEMs and mesoporous PEMs have set new paradigms for improvement of membrane performances. This perspective profiles the recent development of the channels, from the self-assembled to the artificial, with a particular emphasis on their formation and alignment. It concludes with an outlook on benefits of highly aligned PCCs for fuel cell operation, and gives further direction to develop new PEMs from a practical point of view.

BODIPY-Based Donor-Acceptor Pi-Conjugated Alternating Copolymers

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

Popere, Bhooshan C.; Della Pelle, Andrea M.; Thayumanavan, S.

2011-06-28

Four novel π-conjugated copolymers incorporating 4,4-difluoro-4-borata-3a-azonia-4a-aza-s-indacene (BODIPY) core as the “donor” and quinoxaline (Qx), 2,1,3-benzothiadiazole (BzT), N,N'-di(2'-ethyl)hexyl-3,4,7,8-naphthalenetetracarboxylic diimide (NDI), and N,N'-di(2'-ethyl)hexyl-3,4,9,10-perylene tetracarboxylic diimide (PDI) as acceptors were designed and synthesized via Sonogashira polymerization. The polymers were characterized by ¹H NMR spectroscopy, gel permeation chromatography (GPC), UV–vis absorption spectroscopy, and cyclic voltammetry. Density functional theory (DFT) calculations were performed on polymer repeat units, and the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels were estimated from the optimized geometry using B3LYP functional and 6-311g(d,p) basis set. Copolymers with Qx and BzT possessed HOMO and LUMOmore » energy levels comparable to those of BODIPY homopolymer, while PDI stabilized both HOMO and LUMO levels. Semiconductor behavior of these polymers was estimated in organic thin-film transistors (OTFT). While the homopolymer, Qx, and BzT-based copolymers showed only p-type semiconductor behavior, copolymers with PDI and NDI showed only n-type behavior.« less

Generation of Synthetic Copolymer Libraries by Combinatorial Assembly on Nucleic Acid Templates.

PubMed

Kong, Dehui; Yeung, Wayland; Hili, Ryan

2016-07-11

Recent advances in nucleic acid-templated copolymerization have expanded the scope of sequence-controlled synthetic copolymers beyond the molecular architectures witnessed in nature. This has enabled the power of molecular evolution to be applied to synthetic copolymer libraries to evolve molecular function ranging from molecular recognition to catalysis. This Review seeks to summarize different approaches available to generate sequence-defined monodispersed synthetic copolymer libraries using nucleic acid-templated polymerization. Key concepts and principles governing nucleic acid-templated polymerization, as well as the fidelity of various copolymerization technologies, will be described. The Review will focus on methods that enable the combinatorial generation of copolymer libraries and their molecular evolution for desired function.

A mathematical model for regulating monomer composition of the microbially synthesized polyhydroxyalkanoate copolymers.

PubMed

Xu, Jun; Guo, Baohua; Zhang, Zengmin; Wu, Qiong; Zhou, Quan; Chen, Jinchun; Chen, Guoqiang; Li, Guodong

2005-06-30

A mathematical model is proposed for predicting the copolymer composition of the microbially synthesized polyhydroxyalkanoate (PHA) copolymers. Based on the biochemical reactions involved in the precursor formation and polymerization pathways, the model correlates the copolymer composition with the cultivation conditions, the enzyme levels and selectivity, and the metabolic pathways. It suggests the following points: (1) in the case of a sole carbon source, the copolymer composition depends mainly on the topology of the metabolic pathways and the selectivity of both the enzymes involved in the precursor formation and the polymerization route; (2) the copolymer composition can be varied in a wide range via alteration of the flux ratio of different types of monomers channeled from two or more independent and simultaneous pathways; (3) the enzymes which should be over-expressed or inhibited to obtain the desired copolymer composition can be predicted. For example, inhibition of the beta-oxidation pathway will increase the content of the monomer units with longer chain length. To test the model, various experiments were envisaged by varying cultivation time, concentration and chain length of the sole carbon source, and molar ratio of the cosubstrates. The predictions from the model agree well with the experimental results. Therefore, the proposed model will be useful in predicting the PHA copolymer composition under different biochemical reaction conditions. In other words, it can provide a guide for the synthesis of desired PHA copolymers.

A semiflexible alternating copolymer chain adsorption on a flat and a fluctuating surface.

PubMed

Mishra, Pramod Kumar

2010-04-21

A lattice model of a directed self-avoiding walk is used to investigate adsorption properties of a semiflexible alternating copolymer chain on an impenetrable flat and fluctuating surface in two (square, hexagonal and rectangular lattice) and three dimensions (cubic lattice). In the cubic lattice case the surface is two-dimensional impenetrable flat and in two dimensions the surface is a fluctuating impenetrable line (hexagonal lattice) and also flat impenetrable line (square and rectangular lattice). Walks of the copolymer chains are directed perpendicular to the plane of the surface and at a suitable value of monomer surface attraction, the copolymer chain gets adsorbed on the surface. To calculate the exact value of the monomer surface attraction, the directed walk model has been solved analytically using the generating function method to discuss results when one type of monomer of the copolymer chain has attractive, repulsive or no interaction with the surface. Results obtained in the flat surface case show that, for a stiffer copolymer chain, adsorption transition occurs at a smaller value of monomer surface attraction than a flexible copolymer chain while in the case of a fluctuating surface, the adsorption transition point is independent of bending energy of the copolymer chain. These features are similar to that of a semiflexible homopolymer chain adsorption.

Modeling random methyl branching in ethylene/ propylene copolymers using metathesis chemistry: synthesis and thermal behavior.

PubMed

Sworen, John C; Smith, Jason A; Wagener, Kenneth B; Baugh, Lisa S; Rucker, Steven P

2003-02-26

The structure of random ethylene/propylene (EP) copolymers has been modeled using step polymerization chemistry. Six ethylene/propylene model copolymers have been prepared via acyclic diene metathesis (ADMET) polymerization and characterized for primary and higher level structure using in-depth NMR, IR, DSC, WAXD, and GPC analysis. These copolymers possess 1.5, 7.1, 13.6, 25.0, 43.3, and 55.6 methyl branches per 1000 carbons. Examination of these macromolecules by IR and WAXD analysis has demonstrated the first hexagonal phase in EP copolymers containing high ethylene content (90%) without the influence of sample manipulation (temperature, pressure, or radiation). Thermal behavior studies have shown that the melting point and heat of fusion decrease as the branch content increases. Further, comparisons have been made between these random ADMET EP copolymers, random EP copolymers made by typical chain addition techniques, and precisely branched ADMET EP copolymers.

Fast assembly of ordered block copolymer nanostructures through microwave annealing.

PubMed

Zhang, Xiaojiang; Harris, Kenneth D; Wu, Nathanael L Y; Murphy, Jeffrey N; Buriak, Jillian M

2010-11-23

Block copolymer self-assembly is an innovative technology capable of patterning technologically relevant substrates with nanoscale precision for a range of applications from integrated circuit fabrication to tissue interfacing, for example. In this article, we demonstrate a microwave-based method of rapidly inducing order in block copolymer structures. The technique involves the usage of a commercial microwave reactor to anneal block copolymer films in the presence of appropriate solvents, and we explore the effect of various parameters over the polymer assembly speed and defect density. The approach is applied to the commonly used poly(styrene)-b-poly(methyl methacrylate) (PS-b-PMMA) and poly(styrene)-b-poly(2-vinylpyridine) (PS-b-P2VP) families of block copolymers, and it is found that the substrate resistivity, solvent environment, and anneal temperature all critically influence the self-assembly process. For selected systems, highly ordered patterns were achieved in less than 3 min. In addition, we establish the compatibility of the technique with directed assembly by graphoepitaxy.

Magnetic hydrogels from alkyne/cobalt carbonyl-functionalized ABA triblock copolymers

DOE PAGES

Jiang, Bingyin; Hom, Wendy L.; Chen, Xianyin; ...

2016-03-09

A series of alkyne-functionalized poly(4-(phenylethynyl)styrene)- block-poly(ethylene oxide)- block-poly(4-(phenylethynyl)styrene) (PPES-b-PEO-b-PPES) ABA triblock copolymers was synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. PES n[Co 2(CO) 6] x-EO 800-PES n[Co 2(CO) 6] x ABA triblock copolymer/cobalt adducts (10–67 wt % PEO) were subsequently prepared by reaction of the alkyne-functionalized PPES block with Co 2(CO) 8 and their phase behavior was studied by TEM. Heating triblock copolymer/cobalt carbonyl adducts at 120 °C led to cross-linking of the PPES/Co domains and the formation of magnetic cobalt nanoparticles within the PPES/Co domains. Magnetic hydrogels could be prepared by swelling the PEO domains of the cross-linkedmore » materials with water. Furthermore, swelling tests, rheological studies and actuation tests demonstrated that the water capacity and modulus of the hydrogels were dependent upon the composition of the block copolymer precursors.« less

Two-Dimensional Liquid Chromatography Analysis of Polystyrene/Polybutadiene Block Copolymers.

PubMed

Lee, Sanghoon; Choi, Heejae; Chang, Taihyun; Staal, Bastiaan

2018-05-15

A detailed characterization of a commercial polystyrene/polybutadiene block copolymer material (Styrolux) was carried out using two-dimensional liquid chromatography (2D-LC). The Styrolux is prepared by statistical linking reaction of two different polystyrene- block-polybutadienyl anion precursors with a multivalent linking agent. Therefore, it is a mixture of a number of branched block copolymers different in molecular weight, composition, and chain architecture. While individual LC analysis, including size exclusion chromatography, interaction chromatography, or liquid chromatography at critical condition, is not good enough to resolve all the polymer species, 2D-LC separations coupling two chromatography methods were able to resolve all polymer species present in the sample; at least 13 block copolymer species and a homopolystyrene blended. Four different 2D-LC analyses combining a different pair of two LC methods provide their characteristic separation results. The separation characteristics of the 2D-LC separations are compared to elucidate the elution characteristics of the block copolymer species.

Synthesis, characterization and antimicrobial activity of biodegradable conducting polypyrrole-graft-chitosan copolymer

NASA Astrophysics Data System (ADS)

Cabuk, Mehmet; Alan, Yusuf; Yavuz, Mustafa; Unal, Halil Ibrahim

2014-11-01

In this study, polypyrrole-graft-chitosan (PPy-g-CS) copolymer was chemically synthesized and its structural and morphological properties characterized by FTIR, UV-vis, SEM, XRD, TGA and zeta-potential techniques. The results revealed that there were strong interactions between PPy and CS chains. The electrical conductivity of CS increased to semiconducting range by grafting. The crystallinity and thermal stability of PPy-g-CS copolymer improved when compared to CS. The copolymer was tested against various bacterial and fungal strains at various concentrations and results obtained were compared with the reference antibiotics. The results indicated that the antibacterial activity of PPy-g-CS copolymer was stronger than CS and PPy alone. The antibacterial activity of the PPy-g-CS copolymer observed to increase with rising concentration, and showed stronger activity against bacteria than Penicillin (10 mg), Rifampicin (5 mg) and Trimethoprim (25 mg), whereas showed equipotent activity with Amikacin (30 mg) and Erythromycin (15 mg) antibiotics.

Ordering transition in salt-doped diblock copolymers

DOE PAGES

Qin, Jian; de Pablo, Juan J.

2016-04-26

Lithium salt-doped block copolymers offer promise for applications as solid electrolytes in lithium ion batteries. Control of the conductivity and mechanical properties of these materials, for membrane applications relies critically on the ability to predict and manipulate their microphase separation temperature. Past attempts to predict the so-called "order-disorder transition temperature" of copolymer electrolytes have relied on approximate treatments of electrostatic interactions. In this work, we introduce a coarse-grained simulation model that treats Coulomb interactions explicitly, and we use it to investigate the ordering transition of charged block copolymers. The order-disorder transition temperature is determined from the ordering free energy, whichmore » we calculate with a high level of precision using a density-of-states approach. Our calculations allow us to discern a delicate competition between two physical effects: ion association, which raises the transition temperature, and solvent dilution, which lowers the transition temperature. Lastly, in the intermediate salt concentration regime, our results predict that the order-disorder transition temperature increases with salt content, in agreement with available experimental data.« less

21 CFR 177.1020 - Acrylonitrile/butadiene/sty-rene co-polymer.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Acrylonitrile/butadiene/sty-rene co-polymer. 177... SERVICES (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1020 Acrylonitrile/butadiene/sty-rene co-polymer. Acrylonitrile...

Ion Conduction in Microphase-Separated Block Copolymer Electrolytes

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

Kambe, Yu; Arges, Christopher G.; Patel, Shrayesh

2017-01-01

Microphase separation of block copolymers provides a promising route towards engineering a mechanically robust ion conducting film for electrochemical devices. The separation into two different nano-domains enables the film to simultaneously exhibit both high ion conductivity and mechanical robustness, material properties inversely related in most homopolymer and random copolymer electrolytes. To exhibit the maximum conductivity and mechanical robustness, both domains would span across macroscopic length scales enabling uninterrupted ion conduction. One way to achieve this architecture is through external alignment fields that are applied during the microphase separation process. In this review, we present the progress and challenges for aligningmore » the ionic domains in block copolymer electrolytes. A survey of alignment and characterization is followed by a discussion of how the nanoscale architecture affects the bulk conductivity and how alignment may be improved to maximize the number of participating conduction domains.« less

Photo-responsive block copolymer micelles: design and behavior.

PubMed

Gohy, Jean-François; Zhao, Yue

2013-09-07

Stimuli-responsive block copolymer micelles are the topic of intense research since they are able to show sharp and eventually reversible responses to various environmental changes and find applications in various fields including controlled drug delivery. Among all the available stimuli, light has recently attracted much attention since it can be localized in time and space, and it can also be triggered from outside of the system. In this tutorial review, we highlight the progress realized in recent years. More precisely, we provide some guidelines towards the rational design of photo-responsive block copolymers and we present the different photo-responsive moieties that have been used so far. We also discuss the different types of irreversible and reversible responses encountered by photo-responsive block copolymer micelles. Finally, we suggest possible future developments including the design of biocompatible systems operating at excitation wavelengths compatible for biomedical applications.

Synthesis of biodegradable and electroactive multiblock polylactide and aniline pentamer copolymer for tissue engineering applications.

PubMed

Huang, Lihong; Zhuang, Xiuli; Hu, Jun; Lang, Le; Zhang, Peibiao; Wang, Yu; Chen, Xuesi; Wei, Yen; Jing, Xiabin

2008-03-01

To obtain one biodegradable and electroactive polymer as the scaffold for tissue engineering, the multiblock copolymer PLAAP was designed and synthesized with the condensation polymerization of hydroxyl-capped poly( l-lactide) (PLA) and carboxyl-capped aniline pentamer (AP). The PLAAP copolymer exhibited excellent electroactivity, solubility, and biodegradability. At the same time, as one scaffold material, PLAAP copolymer possesses certain mechanical properties with the tensile strength of 3 MPa, tensile Young 's modulus of 32 MPa, and breaking elongation rate of 95%. We systematically studied the compatibility of PLAAP copolymer in vitro and proved that the electroactive PLAAP copolymer was innocuous, biocompatible, and helpful for the adhesion and proliferation of rat C6 cells. Moreover, the PLAAP copolymer stimulated by electrical signals was demonstrated as accelerating the differentiation of rat neuronal pheochromocytoma PC-12 cells. This biodegradable and electroactive PLAAP copolymer thus possessed the properties in favor of the long-time application in vivo as nerve repair scaffold materials in tissue engineering.

Novel Pentablock Copolymers as Thermosensitive Self-Assembling Micelles for Ocular Drug Delivery

PubMed Central

Alami-Milani, Mitra; Zakeri-Milani, Parvin; Valizadeh, Hadi; Salehi, Roya; Salatin, Sara; Naderinia, Ali; Jelvehgari, Mitra

2017-01-01

Many studies have focused on how drugs are formulated in the sol state at room temperature leading to the formation of in situ gel at eye temperature to provide a controlled drug release. Stimuli-responsive block copolymer hydrogels possess several advantages including uncomplicated drug formulation and ease of application, no organic solvent, protective environment for drugs, site-specificity, prolonged and localized drug delivery, lower systemic toxicity, and capability to deliver both hydrophobic and hydrophilic drugs. Self-assembling block copolymers (such as diblock, triblock, and pentablock copolymers) with large solubility variation between hydrophilic and hydrophobic segments are capable of making temperature-dependent micellar assembles, and with further increase in the temperature, of jellifying due to micellar aggregation. In general, molecular weight, hydrophobicity, and block arrangement have a significant effect on polymer crystallinity, micelle size, and in vitro drug release profile. The limitations of creature triblock copolymers as initial burst release can be largely avoided using micelles made of pentablock copolymers. Moreover, formulations based on pentablock copolymers can sustain drug release for a longer time. The present study aims to provide a concise overview of the initial and recent progresses in the design of hydrogel-based ocular drug delivery systems. PMID:28507933

High-Tg Polynorbornene-Based Block and Random Copolymers for Butanol Pervaporation Membranes

NASA Astrophysics Data System (ADS)

Register, Richard A.; Kim, Dong-Gyun; Takigawa, Tamami; Kashino, Tomomasa; Burtovyy, Oleksandr; Bell, Andrew

Vinyl addition polymers of substituted norbornene (NB) monomers possess desirably high glass transition temperatures (Tg); however, until very recently, the lack of an applicable living polymerization chemistry has precluded the synthesis of such polymers with controlled architecture, or copolymers with controlled sequence distribution. We have recently synthesized block and random copolymers of NB monomers bearing hydroxyhexafluoroisopropyl and n-butyl substituents (HFANB and BuNB) via living vinyl addition polymerization with Pd-based catalysts. Both series of polymers were cast into the selective skin layers of thin film composite (TFC) membranes, and these organophilic membranes investigated for the isolation of n-butanol from dilute aqueous solution (model fermentation broth) via pervaporation. The block copolymers show well-defined microphase-separated morphologies, both in bulk and as the selective skin layers on TFC membranes, while the random copolymers are homogeneous. Both block and random vinyl addition copolymers are effective as n-butanol pervaporation membranes, with the block copolymers showing a better flux-selectivity balance. While polyHFANB has much higher permeability and n-butanol selectivity than polyBuNB, incorporating BuNB units into the polymer (in either a block or random sequence) limits the swelling of the polyHFANB and thereby improves the n-butanol pervaporation selectivity.

Preparation and infrared/raman classification of 630 spectroscopically encoded styrene copolymers.

PubMed

Fenniri, Hicham; Chun, Sangki; Terreau, Owen; Bravo-Vasquez, Juan-Pablo

2008-01-01

The barcoded resins (BCRs) were introduced recently as a platform for encoded combinatorial chemistry. One of the main challenges yet to be overcome is the demonstration that a large number of BCRs could be generated and classified with high confidence. Here, we describe the synthesis and classification of 630 polystyrene-based copolymers prepared from the combinatorial association of 15 spectroscopically active styrene monomers. Each of the 630 copolymers displayed a unique vibrational fingerprint (infrared and Raman), which was converted into a spectral vector. To each of the 630 copolymers, a vector of the known (reference) composition was assigned. Unknown (prediction) vectors were decoded using multivariate data analysis. From the inner product of the reference and prediction vectors, a correlation map comparing 396 900 copolymer pairs (630 x 630) was generated. In 100% of the cases, the highest correlation was obtained for polymer pairs in which the reference and prediction vectors correspond to copolymers prepared from identical styrene monomers, thus demonstrating the high reliability of this encoding strategy. We have also established that the spectroscopic barcodes generated from the Raman and infrared spectra are independent of the copolymers' morphology (beaded versus bulk polymers). Besides the demonstration of the generality of the polymer barcoding strategy, the analytical methods developed here could in principle be extended to the investigation of the composition and purity of any other synthetic polymer and biopolymer library, or even scaffold-based combinatorial libraries.

Hairy and Slippery Polyoxazoline-Based Copolymers on Model and Cartilage Surfaces.

PubMed

Morgese, Giulia; Ramakrishna, Shivaprakash N; Simic, Rok; Zenobi-Wong, Marcy; Benetti, Edmondo M

2018-02-12

Comb-like polymers presenting a hydroxybenzaldehyde (HBA)-functionalized poly(glutamic acid) (PGA) backbone and poly(2-methyl-2-oxazoline) (PMOXA) side chains chemisorb on aminolized substrates, including cartilage surfaces, forming layers that reduce protein contamination and provide lubrication. The structure, physicochemical, biopassive, and tribological properties of PGA-PMOXA-HBA films are finely determined by the copolymer architecture, its reactivity toward the surface, i.e. PMOXA side-chain crowding and HBA density, and by the copolymer solution concentration during assembly. Highly reactive species with low PMOXA content form inhomogeneous layers due to the limited possibility of surface rearrangements by strongly anchored copolymers, just partially protecting the functionalized surface from protein contamination and providing a relatively weak lubrication on cartilage. Biopassivity and lubrication can be improved by increasing copolymer concentration during assembly, leading to a progressive saturation of surface defects across the films. In a different way, less reactive copolymers presenting high PMOXA side-chain densities form uniform, biopassive, and lubricious films, both on model aminolized silicon oxide surfaces, as well as on cartilage substrates. When assembled at low concentrations these copolymers adopt a "lying down" conformation, i.e. adhering via their backbones onto the substrates, while at high concentrations they undergo a conformational transition, assuming a more densely packed, "standing up" structure, where they stretch perpendicularly from the substrate. This specific arrangement reduces protein contamination and improves lubrication both on model as well as on cartilage surfaces.

Block and Graft Copolymers of Polyhydroxyalkanoates

NASA Astrophysics Data System (ADS)

Marchessault, Robert H.; Ravenelle, François; Kawada, Jumpei

2004-03-01

Polyhydroxyalkanoates (PHAs) were modified for diblock copolymer and graft polymer by catalyzed transesterification in the melt and by chemical synthesis to extend the side chains of the PHAs, and the polymers were studied by transmission electron microscopy (TEM) X-ray diffraction, thermal analysis and nuclear magnetic resonance (NMR). Catalyzed transesterification in the melt is used to produce diblock copolymers of poly[3-hydroxybutyrate] (PHB) and monomethoxy poly[ethylene glycol] (mPEG) in a one-step process. The resulting diblock copolymers are amphiphilic and self-assemble into sterically stabilized colloidal suspensions of PHB crystalline lamellae. Graft polymer was synthesized in a two-step chemical synthesis from biosynthesized poly[3-hydroxyoctanoate-co-3-hydroxyundecenoate] (PHOU) containing ca. 25 mol chains. 11-mercaptoundecanoic acid reacts with the side chain alkenes of PHOU by the radical addition creating thioether linkage with terminal carboxyl functionalities. The latter groups were subsequently transformed into the amide or ester linkage by tridecylamine or octadecanol, respectively, producing new graft polymers. The polymers have different physical properties than poly[3-hydroxyoctanoate] (PHO) which is the main component of the PHOU, such as non-stickiness and higher thermal stability. The combination of biosynthesis and chemical synthesis produces a hybrid thermoplastic elastomer with partial biodegradability.

``Sequence space soup'' of proteins and copolymers

NASA Astrophysics Data System (ADS)

Chan, Hue Sun; Dill, Ken A.

1991-09-01

To study the protein folding problem, we use exhaustive computer enumeration to explore ``sequence space soup,'' an imaginary solution containing the ``native'' conformations (i.e., of lowest free energy) under folding conditions, of every possible copolymer sequence. The model is of short self-avoiding chains of hydrophobic (H) and polar (P) monomers configured on the two-dimensional square lattice. By exhaustive enumeration, we identify all native structures for every possible sequence. We find that random sequences of H/P copolymers will bear striking resemblance to known proteins: Most sequences under folding conditions will be approximately as compact as known proteins, will have considerable amounts of secondary structure, and it is most probable that an arbitrary sequence will fold to a number of lowest free energy conformations that is of order one. In these respects, this simple model shows that proteinlike behavior should arise simply in copolymers in which one monomer type is highly solvent averse. It suggests that the structures and uniquenesses of native proteins are not consequences of having 20 different monomer types, or of unique properties of amino acid monomers with regard to special packing or interactions, and thus that simple copolymers might be designable to collapse to proteinlike structures and properties. A good strategy for designing a sequence to have a minimum possible number of native states is to strategically insert many P monomers. Thus known proteins may be marginally stable due to a balance: More H residues stabilize the desired native state, but more P residues prevent simultaneous stabilization of undesired native states.

Rapid Ordering in “Wet Brush” Block Copolymer/Homopolymer Ternary Blends

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

Doerk, Gregory S.; Yager, Kevin G.

The ubiquitous presence of thermodynamically unfavored but kinetically trapped topological defects in nanopatterns formed via self-assembly of block copolymer thin films may prevent their use for many envisioned applications. Here, we demonstrate that lamellae patterns formed by symmetric polystyrene-block-poly(methyl methacrylate) diblock copolymers self-assemble and order extremely rapidly when the diblock copolymers are blended with low molecular weight homopolymers of the constituent blocks. Being in the “wet brush” regime, the homopolymers uniformly distribute within their respective self-assembled microdomains, preventing increases in domain widths. An order-of-magnitude increase in topological grain size in blends over the neat (unblended) diblock copolymer is achieved withinmore » minutes of thermal annealing as a result of the significantly higher power law exponent for ordering kinetics in the blends. Moreover, the blends are demonstrated to be capable of rapid and robust domain alignment within micrometer-scale trenches, in contrast to the corresponding neat diblock copolymer. Furthermore, these results can be attributed to the lowering of energy barriers associated with domain boundaries by bringing the system closer to an order–disorder transition through low molecular weight homopolymer blending.« less

Rapid Ordering in “Wet Brush” Block Copolymer/Homopolymer Ternary Blends

DOE PAGES

Doerk, Gregory S.; Yager, Kevin G.

2017-12-01

The ubiquitous presence of thermodynamically unfavored but kinetically trapped topological defects in nanopatterns formed via self-assembly of block copolymer thin films may prevent their use for many envisioned applications. Here, we demonstrate that lamellae patterns formed by symmetric polystyrene-block-poly(methyl methacrylate) diblock copolymers self-assemble and order extremely rapidly when the diblock copolymers are blended with low molecular weight homopolymers of the constituent blocks. Being in the “wet brush” regime, the homopolymers uniformly distribute within their respective self-assembled microdomains, preventing increases in domain widths. An order-of-magnitude increase in topological grain size in blends over the neat (unblended) diblock copolymer is achieved withinmore » minutes of thermal annealing as a result of the significantly higher power law exponent for ordering kinetics in the blends. Moreover, the blends are demonstrated to be capable of rapid and robust domain alignment within micrometer-scale trenches, in contrast to the corresponding neat diblock copolymer. Furthermore, these results can be attributed to the lowering of energy barriers associated with domain boundaries by bringing the system closer to an order–disorder transition through low molecular weight homopolymer blending.« less

Toxicological assessment of Anionic Methacrylate Copolymer: I. Characterization, bioavailability and genotoxicity.

PubMed

Eisele, Johanna; Haynes, Geoff; Kreuzer, Knut; Hall, Caroline

2016-12-01

Anionic Methacrylate Copolymer (AMC) is a fully polymerized copolymer used in the pharmaceutical industry as an enteric/delayed-release coating to permit the pH-dependent release of active ingredients in the gastrointestinal tract from oral dosage forms. This function is of potential use for food supplements. Oral administration of radiolabeled copolymer to rats resulted in the detection of chemically unchanged copolymer in the feces, with negligible absorption (<0.1%). AMC is therefore determined not to be bioavailable. Within a genotoxicity test battery AMC did not show any evidence of genotoxicity in bacteria and mammalian cells. Furthermore, no genotoxic effects occurred in vivo within a micronucleus test. There would therefore appear to be no safety concerns under intended conditions of oral use for the discussed toxicological endpoints. Copyright © 2016 Elsevier Inc. All rights reserved.

Block copolymer micelles for controlled delivery of glycolytic enzyme inhibitors.

PubMed

Akter, Shanjida; Clem, Brian F; Lee, Hyun Jin; Chesney, Jason; Bae, Younsoo

2012-03-01

To develop block copolymer micelles as an aqueous dosage form for a potent glycolytic enzyme inhibitor, 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO). The micelles were prepared from poly(ethylene glycol)-poly(aspartate hydrazide) [PEG-p(HYD)] block copolymers to which 3PO was conjugated through an acid-labile hydrazone bond. The optimal micelle formulation was determined following the screening of block copolymer library modified with various aromatic and aliphatic pendant groups. Both physical drug entrapment and chemical drug conjugation methods were tested to maximize 3PO loading in the micelles during the screening. Particulate characterization showed that the PEG-p(HYD) block copolymers conjugated with 3PO (2.08∼2.21 wt.%) appeared the optimal polymer micelles. Block copolymer compositions greatly affected the micelle size, which was 38 nm and 259 nm when 5 kDa and 12 kDa PEG chains were used, respectively. 3PO release from the micelles was accelerated at pH 5.0, potentiating effective drug release in acidic tumor environments. The micelles retained biological activity of 3PO, inhibiting various cancer cells (Jurkat, He-La and LLC) in concentration ranges similar to free 3PO. A novel micelle formulation for controlled delivery of 3PO was successfully prepared.

Formation of nanophases in epoxy thermosets containing amphiphilic block copolymers with linear and star-like topologies.

PubMed

Wang, Lei; Zhang, Chongyin; Cong, Houluo; Li, Lei; Zheng, Sixun; Li, Xiuhong; Wang, Jie

2013-07-11

In this work, we investigated the effect of topological structures of block copolymers on the formation of the nanophase in epoxy thermosets containing amphiphilic block copolymers. Two block copolymers composed of poly(ε-caprolactone) (PCL) and poly(2,2,2-trifluoroethyl acrylate) (PTFEA) blocks were synthesized to possess linear and star-shaped topologies. The star-shaped block copolymer composed a polyhedral oligomeric silsesquioxane (POSS) core and eight poly(ε-caprolactone)-block-poly(2,2,2-trifluoroethyl acrylate) (PCL-b-PTFEA) diblock copolymer arms. Both block copolymers were synthesized via the combination of ring-opening polymerization and reversible addition-fragmentation chain transfer/macromolecular design via the interchange of xanthate (RAFT/MADIX) process; they were controlled to have identical compositions of copolymerization and lengths of blocks. Upon incorporating both block copolymers into epoxy thermosets, the spherical PTFEA nanophases were formed in all the cases. However, the sizes of PTFEA nanophases from the star-like block copolymer were significantly lower than those from the linear diblock copolymer. The difference in the nanostructures gave rise to the different glass transition behavior of the nanostructured thermosets. The dependence of PTFEA nanophases on the topologies of block copolymers is interpreted in terms of the conformation of the miscible subchain (viz. PCL) at the surface of PTFEA microdomains and the restriction of POSS cages on the demixing of the thermoset-philic block (viz. PCL).

Drilling fluid containing a copolymer filtration control agent

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

Lucas, J. M.

1985-10-15

The invention relates to an aqueous drilling fluid composition, a filtration control agent for utilization in said aqueous drilling fluid, and a method of forming a filter cake on the wall of a well for the reduction of filtrate from said drilling fluid, by utilization of a copolymer of: a (meth) acrylamido alkyl sulfonic acid or alkali metal salt thereof; and N, N-dialkyl (meth) acrylamide. The copolymer may be cross-linked with N,N'-methylenebisacrylamide or other appropriate cross-linking agent.

Application of Bottlebrush Block Copolymers as Photonic Crystals.

PubMed

Liberman-Martin, Allegra L; Chu, Crystal K; Grubbs, Robert H

2017-07-01

Brush block copolymers are a class of comb polymers that feature polymeric side chains densely grafted to a linear backbone. These polymers display interesting properties due to their dense functionality, low entanglement, and ability to rapidly self-assemble to highly ordered nanostructures. The ability to prepare brush polymers with precise structures has been enabled by advancements in controlled polymerization techniques. This Feature Article highlights the development of brush block copolymers as photonic crystals that can reflect visible to near-infrared wavelengths of light. Fabrication of these materials relies on polymer self-assembly processes to achieve nanoscale ordering, which allows for the rapid preparation of photonic crystals from common organic chemical feedstocks. The characteristic physical properties of brush block copolymers are discussed, along with methods for their preparation. Strategies to induce self-assembly at ambient temperatures and the use of blending techniques to tune photonic properties are emphasized. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and characterization of POSS-(PAA)8 star copolymers and GICs for dental applications.

PubMed

Zelmer, Christina; Wang, David K; Keen, Imelda; Hill, David J T; Symons, Anne L; Walsh, Laurence J; Rasoul, Firas

2016-04-01

To investigate the application of a new type of multiarm polymer resins in the formulation of Glass Ionic Cements. A series of star copolymers of t-butyl acrylate has been prepared by ATRP using a multiarm POSS-Br8 initiator. The resulting POSS-co-t-butyl acrylate star copolymers with eight arms were subsequently hydrolysed by trifluoroacetic acid to produce the corresponding POSS-co-acrylic acid star copolymers. All of the copolymers have been characterized by (1)H and (13)C NMR and FTIR spectroscopies and TGA/DSC. The as-prepared star copolymers were mixed with the glass powder from Fuji IX GP to produce the GIC samples for compression testing. The new type of multiarm polymer resins have been shown to have narrow molecular weight distributions and thermal properties of the acrylic acid copolymers are similar to that of poly(acrylic acid), with a two stage degradation profile involving transitions at ≈140°C and 250°C, corresponding to anhydride formation and loss of carbon dioxide, respectively. In aqueous solution the POSS-co-acrylic acid copolymers form aggregates with ≈33nm dimensions. When aqueous solutions of POSS-(PAA)8 are mixed with a glass powder, a rigid glass ionomer cement, GIC, is formed with a maximum compressive stress significantly greater than that for a linear PAA GIC of a comparable polymer molecular weight. Therefore, these POSS-(PAA)8 copolymers demonstrate the potential for the application of well characterized star copolymers in the future development of new GICs as dental materials. Copyright © 2016 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Biological materials: Part A. tuning LCST of raft copolymers and gold/copolymer hybrid nanoparticles and Part B. Biobased nanomaterials

NASA Astrophysics Data System (ADS)

Chen, Ning

The research described in this dissertation is comprised of two major parts. The first part studied the effects of asymmetric amphiphilic end groups on the thermo-response of diblock copolymers of (oligo/di(ethylene glycol) methyl ether (meth)acrylates, OEGA/DEGMA) and the hybrid nanoparticles of these copolymers with a gold nanoparticle core. Placing the more hydrophilic end group on the more hydrophilic block significantly increased the cloud point compared to a similar copolymer composition with the end group placement reversed. For a given composition, the cloud point was shifted by as much as 28 °C depending on the placement of end groups. This is a much stronger effect than either changing the hydrophilic/hydrophobic block ratio or replacing the hydrophilic acrylate monomer with the equivalent methacrylate monomer. The temperature range of the coil-globule transition was also altered. Binding these diblock copolymers to a gold core decreased the cloud point by 5-15 °C and narrowed the temperature range of the coil-globule transition. The effects were more pronounced when the gold core was bound to the less hydrophilic block. Given the limited numbers of monomers that are approved safe for in vivo use, employing amphiphilic end group placement is a useful tool to tune a thermo-response without otherwise changing the copolymer composition. The second part of the dissertation investigated the production of value-added nanomaterials from two biorefinery "wastes": lignin and peptidoglycan. Different solvents and spinning methods (melt-, wet-, and electro-spinning) were tested to make lignin/cellulose blended and carbonized fibers. Only electro-spinning yielded fibers having a small enough diameter for efficient carbonization (≤ 5-10 μm), but it was concluded that cellulose was not a suitable binder. Cellulose lignin fibers before carbonization showed up to 90% decrease in moisture uptake compared to pure cellulose. Peptidoglycan (a bacterial cell wall

Adsorption of Poly(ethylene oxide)-Poly(lactide) Copolymers. Effects of Composition and Degradation.

PubMed

Muller, Dries; Carlsson, Fredrik; Malmsten, Martin

2001-04-01

The effect of chemical degradation of two diblock copolymers of poly(ethylene oxide) (E) and poly(lactide) (L), E(39)L(5) and E(39)L(20), on their adsorption at silica and methylated silica was investigated with in situ ellipsometry. Steric stablization of polystyrene dispersions was investigated in relation to degradation. Hydrolysis of the poly(lactide) block of the copolymers was followed at different temperatures and pH by using HPLC to measure the occurrence of lactic acid in solution. The block copolymers were quite stable in pH-unadjusted solution at low temperature, whereas degradation was facilitated by increasing temperature or lowering of the pH. Lower degradation rates of E(39)L(20) where observed at low temperature in comparison with those of E(39)L(5), whereas the degradation rates of the copolymers were quantitatively similar at high temperature. The adsorption of the copolymers at methylated silica substrates decreased with increasing degree of degradation due to the reduction in the ability of hydrophobic block to anchor the copolymer layer at the surface. At silica the adsorption initially increased with increasing degradation, particularly for E(39)L(20) due to deposition of aggregates onto the surface. After extensive degradation the adsorption of the copolymers at both silica and methylated silica resembled that of the corresponding poly(ethylene oxide) homopolymer. Overall, it was found that the eventual reduction in adsorption occurred at a lower degree of degradation for E(39)L(5) than for E(39)L(20). Mean-field calculations showed a reduced anchoring for the block copolymers with decreasing poly(lactide) block length at hydrophobic surfaces. In accordance with this finding, it was observed that polystyrene dispersions were stabilized by E(39)L(20) or E(39)L(5) in a way that depended on both the lactide block length and the degree of degradation. Upon degradation of the hydrophobic block, stabilization of the polystyrene dispersions was

Degradable ketal-based block copolymer nanoparticles for anticancer drug delivery: a systematic evaluation.

PubMed

Louage, Benoit; Zhang, Qilu; Vanparijs, Nane; Voorhaar, Lenny; Vande Casteele, Sofie; Shi, Yang; Hennink, Wim E; Van Bocxlaer, Jan; Hoogenboom, Richard; De Geest, Bruno G

2015-01-12

Low solubility of potent (anticancer) drugs is a major driving force for the development of noncytotoxic, stimuli-responsive nanocarriers, including systems based on amphiphilic block copolymers. In this regard, we investigated the potential of block copolymers based on 2-hydroxyethyl acrylate (HEA) and the acid-sensitive ketal-containing monomer (2,2-dimethyl-1,3-dioxolane-4-yl)methyl acrylate (DMDMA) to form responsive drug nanocarriers. Block copolymers were successfully synthesized by sequential reversible addition-fragmentation chain transfer (RAFT) polymerization, in which we combined a hydrophilic poly(HEA)x block with a (responsive) hydrophobic poly(HEAm-co-DMDMAn)y copolymer block. The DMDMA content of the hydrophobic block was systematically varied to investigate the influence of polymer design on physicochemical properties and in vitro biological performance. We found that a DMDMA content higher than 11 mol % is required for self-assembly behavior in aqueous medium. All particles showed colloidal stability in PBS at 37 °C for at least 4 days, with sizes ranging from 23 to 338 nm, proportional to the block copolymer DMDMA content. Under acidic conditions, the nanoparticles decomposed into soluble unimers, of which the decomposition rate was inversely proportional to the block copolymer DMDMA content. Flow cytometry and confocal microscopy showed dose-dependent, active in vitro cellular uptake of the particles loaded with hydrophobic octadecyl rhodamine B chloride (R18). The block copolymers showed no intrinsic in vitro cytotoxicity, while loaded with paclitaxel (PTX), a significant decrease in cell viability was observed comparable or better than the two commercial PTX nanoformulations Abraxane and Genexol-PM at equal PTX dose. This systematic approach evaluated and showed the potential of these block copolymers as nanocarriers for hydrophobic drugs.

Highly durable polymer electrolyte membranes at elevated temperature: Cross-linked copolymer structure consisting of poly(benzoxazine) and poly(benzimidazole)

NASA Astrophysics Data System (ADS)

Kim, Sung-Kon; Kim, Ki-Hyun; Park, Jung Ock; Kim, Kihyun; Ko, Taeyun; Choi, Seong-Woo; Pak, Chanho; Chang, Hyuk; Lee, Jong-Chan

2013-03-01

For polymer electrolyte membrane fuel cell (PEMFC) applications at elevated temperature (>100 °C), a series of cross-linked benzoxazine-benzimidazole copolymer, P(HFa-co-BI), membranes are prepared by casting a solution of poly[2,2‧-(m-phenylene)-5,5‧-bibenzimidazole] (PBI) and di-functional benzoxazine monomer, 6,6‧-(hexafluoroisopropylidene)bis(3-phenyl-3,4-dihydro-2H-benzoxazine) (HFa), in N,N-dimethylacetamide prior to stepwise heating to 250 °C. The films are also viable to manufacture to large quantities and area by roll-to-roll coating. The resulting cross-linked copolymer, P(HFa-co-BI), membranes are found to be thermally and mechanically stable. Although the proton conductivity values of P(HFa-co-BI) membranes are smaller than that of the PBI membrane, their cell performance (0.68 V at 0.2 A cm-2 at 150 °C) is close to that of PBI membrane and their long-term durability (ca. 3116 cycles on in situ accelerated lifetime mode of load cycling testing) is found to be far superior to the PBI membrane.

21 CFR 177.1315 - Ethylene-1, 4-cyclohexylene dimethylene terephthalate copolymers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethylene-1, 4-cyclohexylene dimethylene... Ethylene-1, 4-cyclohexylene dimethylene terephthalate copolymers. Ethylene-1, 4-cyclohexylene dimethylene... purposes of this section, ethylene-1,4-cyclohexylene dimethylene terephthalate copolymers (1,4-benzene...

Synthesis and photooxidation of styrene copolymer bearing camphorquinone pendant groups

PubMed Central

Moszner, Norbert; Lukáč, Ivan

2012-01-01

Summary (±)-10-Methacryloyloxycamphorquinone (MCQ) was synthesized from (±)-10-camphorsulfonic acid either by a known seven-step synthetic route or by a novel, shorter five-step synthetic route. MCQ was copolymerized with styrene (S) and the photochemical behavior of the copolymer MCQ/S was compared with that of a formerly studied copolymer of styrene with monomers containing the benzil (BZ) moiety (another 1,2-dicarbonyl). Irradiation (λ > 380 nm) of aerated films of styrene copolymers with monomers containing the BZ moiety leads to the insertion of two oxygen atoms between the carbonyl groups of BZ and to the formation of benzoyl peroxide (BP) as pendant groups on the polymer backbone. An equivalent irradiation of MCQ/S led mainly to the insertion of only one oxygen atom between the carbonyl groups of camphorquinone (CQ) and to the formation of camphoric anhydride (11) covalently bound to the polymer backbone. While the decomposition of pendant BP groups formed in irradiated films of styrene copolymers with pendant BZ groups leads to crosslinking, only small molecular-weight changes in irradiated MCQ/S were observed. PMID:22509202

Photooxidative degradation of clear ultraviolet absorbing acrylic copolymer surfaces

NASA Technical Reports Server (NTRS)

Gupta, A.; Liang, R. H.; Vogl, O.; Pradellok, W.; Huston, A. L.; Scott, G. W.

1983-01-01

Photodegradation of copolymer of methyl methacrylate and 2(2'-hydroxy 5'vinyl-phenyl) 2H-benzotriazole has been investigated in order to determine the changes in the chemical composition of the surface of the copolymer on photooxidation. An electronic energy transfer mechanism has been postulated in order to interpret the observed photochemical changes in the polymer. Preliminary examination of the photophysical properties of the chromophore provides support for such a mechanism.

Improved block copolymer domain dispersity on chemical patterns via homopolymer-blending and molecular transfer printing

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

Liu, Guoliang; Nealey, Paul F.

Herein we have investigated the domain width distributions of block copolymers and their ternary blends after directed assembly on chemically patterned surfaces with and without density multiplication. On chemical patterns with density multiplication, the width of the interpolated block copolymer domains was bimodal. Once blended with the corresponding homopolymers, the block copolymers exhibited unimodal distributions of domain width due to the redistribution of homopolymers in the block copolymer domains. When the block copolymers were blended with hydroxyl-terminated homopolymers, the homopolymers with functional end-groups healed the chemical patterns and facilitated the formation of nanostructures with further improved domain width distributions. Lastly,more » it is demonstrated that the block copolymers achieved the most improved domain width distributions when directed to assemble without density multiplication on one-to-one chemical patterns generated by molecular transfer printing.« less

Drilling fluid containing a copolymer filtration control agent

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

Enright, D.P.; Lucas, J.M.; Perricone, A.C.

1981-10-06

The invention relates to an aqueous drilling fluid composition, a filtration control agent for utilization in said aqueous drilling fluid, and a method of forming a filter cake on the wall of a well for the reduction of filtrate from said drilling fluid, by utilization of a copolymer of: (1) a (Meth) acrylamido alkyl sulfonic acid or alkali metal salt thereof; and (2) a (Meth) acrylamide or n-alkyl (Meth) acrylamide. The copolymer may be cross-linked with a quaternary ammonium salt cross-linking agent.

Poly(trimethylene carbonate)/Poly(malic acid) Amphiphilic Diblock Copolymers as Biocompatible Nanoparticles.

PubMed

Barouti, Ghislaine; Khalil, Ali; Orione, Clement; Jarnouen, Kathleen; Cammas-Marion, Sandrine; Loyer, Pascal; Guillaume, Sophie M

2016-02-18

Amphiphilic polycarbonate-poly(hydroxyalkanoate) diblock copolymers, namely, poly(trimethylene carbonate) (PTMC)-b-poly(β-malic acid) (PMLA), are reported for the first time. The synthetic strategy relies on commercially available catalysts and initiator. The controlled ring-opening polymerization (ROP) of trimethylene carbonate (TMC) catalyzed by the organic guanidine base 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), associated with iPrOH as an initiator, provided iPrO-PTMC-OH, which served as a macroinitiator in the controlled ROP of benzyl β-malolactonate (MLABe) catalyzed by the neodymium triflate salt (Nd(OTf)3). The resulting hydrophobic iPrO-PTMC-b-PMLABe-OH copolymers were then hydrogenolyzed into the parent iPrO-PTMC-b-PMLA-OH copolymers. A range of well-defined copolymers, featuring different sizes of segments (Mn,NMR up to 9300 g mol(-1) ; ÐM =1.28-1.40), were thus isolated in gram quantities, as evidenced by NMR spectroscopy, size exclusion chromatography, thermogravimetric analysis, differential scanning calorimetry, and contact angle analyses. Subsequently, PTMC-b-PMLA copolymers with different hydrophilic weight fractions (11-75 %) self-assembled in phosphate-buffered saline upon nanoprecipitation into well-defined nano-objects with Dh =61-176 nm, a polydispersity index <0.25, and a negative surface charge, as characterized by dynamic light scattering and zeta-potential analyses. In addition, these nanoparticles demonstrated no significant effect on cell viability at low concentrations, and a very low cytotoxicity at high concentrations only for PTMC-b-PMLA copolymers exhibiting hydrophilic fractions over 47 %, thus illustrating the potential of these copolymers as promising nanoparticles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

21 CFR 175.365 - Vinylidene chloride copolymer coatings for polycarbonate film.

Code of Federal Regulations, 2010 CFR

2010-04-01

... polycarbonate film. 175.365 Section 175.365 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH... chloride copolymer coatings for polycarbonate film. Vinylidene chloride copolymer coatings identified in this section and applied on polycarbonate film may be safely used as food-contact surfaces, in...

Radical-initiated controlled synthesis of homo- and copolymers based on acrylonitrile

NASA Astrophysics Data System (ADS)

Grishin, D. F.; Grishin, I. D.

2015-07-01

Data on the controlled synthesis of polyacrylonitrile and acrylonitrile copolymers with other (meth)acrylic and vinyl monomers upon radical initiation and metal complex catalysis are analyzed. Primary attention is given to the use of metal complexes for the synthesis of acrylonitrile-based (co)polymers with defined molecular weight and polydispersity in living mode by atom transfer radical polymerization. The prospects for using known methods of controlled synthesis of macromolecules for the preparation of acrylonitrile homo- and copolymers as carbon fibre precursors are estimated. The major array of published data analyzed in the review refers to the last decade. The bibliography includes 175 references.

Fabrication of supramolecular star-shaped amphiphilic copolymers for ROS-triggered drug release.

PubMed

Zuo, Cai; Peng, Jinlei; Cong, Yong; Dai, Xianyin; Zhang, Xiaolong; Zhao, Sijie; Zhang, Xianshuo; Ma, Liwei; Wang, Baoyan; Wei, Hua

2018-03-15

Star-shaped copolymers with branched structures can form unimolecular micelles with better stability than the micelles self-assembled from conventional linear copolymers. However, the synthesis of star-shaped copolymers with precisely controlled degree of branching (DB) suffers from complicated sequential polymerizations and multi-step purification procedures, as well as repeated optimizations of polymer compositions. The use of a supramolecular host-guest pair as the block junction would significantly simplify the preparation. Moreover, the star-shaped copolymer-based unimolecular micelle provides an elegant solution to the tradeoff between extracellular stability and intracellular high therapeutic efficacy if the association/dissociation of the supramolecular host-guest joint can be triggered by the biologically relevant stimuli. For this purpose, in this study, a panel of supramolecular star-shaped amphiphilic block copolymers with 9, 12, and 18 arms were designed and fabricated by host-guest complexations between the ring-opening polymerization (ROP)-synthesized star-shaped poly(ε-caprolactone) (PCL) with 3, 4, and 6 arms end-capped with ferrocene (Fc) (PCL-Fc) and the atom transfer radical polymerization (ATRP)-produced 3-arm poly(oligo ethylene glycol) methacrylates (POEGMA) with different degrees of polymerization (DPs) of 24, 30, 47 initiated by β-cyclodextrin (β-CD) (3Br-β-CD-POEGMA). The effect of DB and polymer composition on the self-assembled properties of the five star-shaped copolymers was investigated by dynamic light scattering (DLS), transmission electron microscopy (TEM), and fluorescence spectrometery. Interestingly, the micelles self-assembled from 12-arm star-shaped copolymers exhibited greater stability than the 9- and 18-arm formulations. The potential of the resulting supramolecular star-shaped amphiphilic copolymers as drug carriers was evaluated by an in vitro drug release study, which confirmed the ROS-triggered accelerated drug

Perpendicularly Aligned, Anion Conducting Nanochannels in Block Copolymer Electrolyte Films

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

Arges, Christopher G.; Kambe, Yu; Suh, Hyo Seon

Connecting structure and morphology to bulk transport properties, such as ionic conductivity, in nanostructured polymer electrolyte materials is a difficult proposition because of the challenge to precisely and accurately control order and the orientation of the ionic domains in such polymeric films. In this work, poly(styrene-block-2-vinylpyridine) (PSbP2VP) block copolymers were assembled perpendicularly to a substrate surface over large areas through chemical surface modification at the substrate and utilizing a versatile solvent vapor annealing (SVA) technique. After block copolymer assembly, a novel chemical vapor infiltration reaction (CVIR) technique selectively converted the 2-vinylpyridine block to 2-vinyl n-methylpyridinium (NMP+ X-) groups, which aremore » anion charge carriers. The prepared block copolymer electrolytes maintained their orientation and ordered nanostructure upon the selective introduction of ion moieties into the P2VP block and post ion-exchange to other counterion forms (X- = chloride, hydroxide, etc.). The prepared block copolymer electrolyte films demonstrated high chloride ion conductivities, 45 mS cm(-1) at 20 degrees C in deionized water, the highest chloride ion conductivity for anion conducting polymer electrolyte films. Additionally, straight-line lamellae of block copolymer electrolytes were realized using chemoepitaxy and density multiplication. The devised scheme allowed for precise and accurate control of orientation of ionic domains in nanostructured polymer electrolyte films and enables a platform for future studies that examines the relationship between polymer electrolyte structure and ion transport.« less

Photodegradable neutral-cationic brush block copolymers for nonviral gene delivery.

PubMed

Hu, Xianglong; Li, Yang; Liu, Tao; Zhang, Guoying; Liu, Shiyong

2014-08-01

We report on the fabrication of a photodegradable gene-delivery vector based on PEO-b-P(GMA-g-PDMAEMA) neutral-cationic brush block copolymers that possess cationic poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) brushes for DNA compaction, poly(ethylene oxide) (PEO) as a hydrophilic block, and poly(glycidyl methacrylate) (PGMA) as the backbone. The PEO-b-P(GMA-g-PDMAEMA) copolymers were synthesized through the combination of reversible addition-fragmentation transfer (RAFT) polymerization and postmodification. A photocleavable PEO-based macroRAFT agent was first synthesized; next, the PEO-b-PGMA block copolymer was prepared by RAFT polymerization of GMA; this was followed by a click reaction to introduce the RAFT initiators on the side chains of the PGMA block; then, RAFT polymerization of DMAEMA afforded the PEO-b-P(GMA-g-PDMAEMA) copolymer. The obtained neutral-cationic brush block copolymer could effectively complex plasmid DNA (pDNA) into nanoparticles at an N/P ratio (i.e., the number of nitrogen residues per DNA phosphate) of 4. Upon UV irradiation, pDNA could be released owing to cleavage of the pDNA-binding cationic PDMAEMA side chains as well as the nitrobenzyl ester linkages at the diblock junction point. In addition, in vitro gene transfection results demonstrated that the polyplexes could be effectively internalized by cells with good transfection efficiency, and the UV irradiation protocol could considerably enhance the efficiency of gene transfection. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

PAA-PAMPS copolymers as an efficient tool to control CaCO3 scale formation.

PubMed

Dietzsch, Michael; Barz, Matthias; Schüler, Timo; Klassen, Stefanie; Schreiber, Martin; Susewind, Moritz; Loges, Niklas; Lang, Michael; Hellmann, Nadja; Fritz, Monika; Fischer, Karl; Theato, Patrick; Kühnle, Angelika; Schmidt, Manfred; Zentel, Rudolf; Tremel, Wolfgang

2013-03-05

Scale formation, the deposition of certain minerals such as CaCO3, MgCO3, and CaSO4·2H2O in industrial facilities and household devices, leads to reduced efficiency or severe damage. Therefore, incrustation is a major problem in everyday life. In recent years, double hydrophilic block copolymers (DHBCs) have been the focus of interest in academia with regard to their antiscaling potential. In this work, we synthesized well-defined blocklike PAA-PAMPS copolymers consisting of acrylic acid (AA) and 2-acrylamido-2-methyl-propane sulfonate (AMPS) units in a one-step reaction by RAFT polymerization. The derived copolymers had dispersities of 1.3 and below. The copolymers have then been investigated in detail regarding their impact on the different stages of the crystallization process of CaCO3. Ca(2+) complexation, the first step of a precipitation process, and polyelectrolyte stability in aqueous solution have been investigated by potentiometric measurements, isothermal titration calorimetry (ITC), and dynamic light scattering (DLS). A weak Ca(2+) induced copolymer aggregation without concomitant precipitation was observed. Nucleation, early particle growth, and colloidal stability have been monitored in situ with DLS. The copolymers retard or even completely suppress nucleation, most probably by complexation of solution aggregates. In addition, they stabilize existing CaCO3 particles in the nanometer regime. In situ AFM was used as a tool to verify the coordination of the copolymer to the calcite (104) crystal surface and to estimate its potential as a growth inhibitor in a supersaturated CaCO3 environment. All investigated copolymers instantly stopped further crystal growth. The carboxylate richest copolymer as the most promising antiscaling candidate proved its enormous potential in scale inhibition as well in an industrial-filming test (Fresenius standard method).

Creating surfactant nanoparticles for block copolymer composites through surface chemistry.

PubMed

Kim, Bumjoon J; Bang, Joona; Hawker, Craig J; Chiu, Julia J; Pine, David J; Jang, Se Gyu; Yang, Seung-Man; Kramer, Edward J

2007-12-04

A simple strategy to tailor the surface of nanoparticles for their specific adsorption to and localization at block copolymer interfaces was explored. Gold nanoparticles coated by a mixture of low molecular weight thiol end-functional polystyrene (PS-SH) (Mn = 1.5 and 3.4 kg/mol) and poly(2-vinylpyridine) homopolymers (P2VP-SH) (Mn = 1.5 and 3.0 kg/mol) were incorporated into a lamellar poly(styrene-b-2-vinylpyridine) diblock copolymer (PS-b-P2VP) (Mn = 196 kg/mol). A library of nanoparticles with varying PS and P2VP surface compositions (FPS) and high polymer ligand areal chain densities was synthesized. The location of the nanoparticles in the PS-b-P2VP block copolymer was determined by transmission electron microscopy. Sharp transitions in particle location from the PS domain to the PS/P2VP interface, and subsequently to the P2VP domain, were observed at FPS = 0.9 and 0.1, respectively. This extremely wide window of FPS values where the polymer-coated gold nanoparticles adsorb to the interface suggests a redistribution of PS and P2VP polymers on the Au surface, inducing the formation of amphiphilic nanoparticles at the PS/P2VP interface. In a second and synthetically more challenging approach, gold nanoparticles were covered with a thiol terminated random copolymer of styrene and 2-vinylpyridine synthesized by RAFT polymerization. Two different random copolymers were considered, where the molecular weight was fixed at 3.5 kg/mol and the relative incorporation of styrene and 2-vinylpyridine repeat units varied (FPS = 0.52 and 0.40). The areal chain density of these random copolymers on Au is unfortunately not high enough to preclude any contact between the P2VP block of the block copolymer and the Au surface. Interestingly, gold nanoparticles coated by the random copolymer with FPS = 0.4 were dispersed in the P2VP domain, while those with FPS = 0.52 were located at the interface. A simple calculation for the adsorption energy to the interface of the nanoparticles

Highly Ordered Block Copolymer Templates for the Generation of Nanostructured Materials

NASA Astrophysics Data System (ADS)

Bhoje Gowd, E.; Nandan, Bhanu; Bigall, Nadja C.; Eychmuller, Alexander; Stamm, Manfred

2009-03-01

Among many different types of self-assembled materials, block copolymers have attracted immense interest for applications in nanotechnology. Block copolymer thin film can be used as a template for patterning of hard inorganic materials such as metal nanoparticles. In the present work, we demonstrate a new approach to fabricate highly ordered arrays of nanoscopic inorganic dots and wires using switchable block copolymer thin films. Various inorganic nanoparticles from a simple aqueous solution were directly deposited on the surface reconstructed block copolymer templates. The preferential interaction of the nanoparticles with one of the blocks is mainly responsible for the lateral distribution of the nanoparticles in addition to the capillary forces. Subsequent stabilization by UV-irradiation followed by pyrolysis in air at 450 ^oC removes the polymer to produce highly ordered metallic nanostructures. This method is highly versatile as the procedure used here is simple, eco-friendly and provides a facile approach to fabricate a broad range of nanoscaled architectures with tunable lateral spacing.

Biodegradable hyperbranched amphiphilic polyurethane multiblock copolymers consisting of poly(propylene glycol), poly(ethylene glycol), and polycaprolactone as in situ thermogels.

PubMed

Li, Zibiao; Zhang, Zhongxing; Liu, Kerh Li; Ni, Xiping; Li, Jun

2012-12-10

This paper reports the synthesis and characterization of new hyperbranched amphiphilic polyurethane multiblock copolymers consisting of poly(propylene glycol) (PPG), poly(ethylene glycol) (PEG), and polycaprolactone (PCL) segments as in situ thermogels. The hyperbranched poly(PPG/PEG/PCL urethane)s, termed as HBPEC copolymers, were synthesized from PPG-diol, PEG-diol, and PCL-triol by using 1,6-hexamethylene diisocyanate (HMDI) as a coupling agent. The compositions and structures of HBPEC copolymers were determined by GPC and 1H NMR spectroscopy. We carried out comparative studies of the new hyperbranched copolymers with their linear counterparts, the linear poly(PPG/PEG/PCL urethane) (LPEC) copolymer and Pluronic F127 PEG-PPG-PEG block copolymer, in terms of their self-assembly and aggregation behaviors and thermoresponsive properties. HBPEC copolymers were found to show thermoresponsive micelle formation and aggregation behaviors. Particularly, the lower critical solution temperature (LCST) of the copolymers was significantly affected by the copolymer architecture. HBPEC copolymers showed much lower LCST than LPEC, the linear counterpart. Our studies revealed that the effect of hyperbranch architecture was more prominent in the gelation of the copolymers. The aqueous solutions of HBPEC copolymers exhibited thermogelling behaviors at critical gelation concentrations (CGCs) ranging from 4.3 to 7.4 wt %. These values are much lower than those reported on other PCL-contained linear thermogelling copolymers and Pluronic F127 copolymer. In addition, the CGC of HBPEC copolymers is much lower than the control LPEC copolymer. More interestingly, at high temperatures, while LPEC and other linear thermogelling copolymers formed turbid sol, HBPEC formed a dehydrated gel. Our data suggest that these phenomena are caused by the hyperbranched structure of HBPEC copolymers, which could increase the interaction of copolymer branches and enhance the chain association through

Thin Films of Novel Linear-Dendritic Diblock Copolymers

NASA Astrophysics Data System (ADS)

Iyer, Jyotsna; Hammond, Paula

1998-03-01

A series of diblock copolymers with one linear block and one dendrimeric block have been synthesized with the objective of forming ultrathin film nanoporous membranes. Polyethyleneoxide serves as the linear hydrophilic portion of the diblock copolymer. The hyperbranched dendrimeric block consists of polyamidoamine with functional end groups. Thin films of these materials made by spin casting and the Langmuir-Blodgett techniques are being studied. The effect of the polyethylene oxide block size and the number and chemical nature of the dendrimer end group on the nature and stability of the films formed willbe discussed.

High aspect ratio sub-15 nm silicon trenches from block copolymer templates.

PubMed

Gu, Xiaodan; Liu, Zuwei; Gunkel, Ilja; Chourou, S T; Hong, Sung Woo; Olynick, Deirdre L; Russell, Thomas P

2012-11-08

High-aspect-ratio sub-15-nm silicon trenches are fabricated directly from plasma etching of a block copolymer mask. A novel method that combines a block copolymer reconstruction process and reactive ion etching is used to make the polymer mask. Silicon trenches are characterized by various methods and used as a master for subsequent imprinting of different materials. Silicon nanoholes are generated from a block copolymer with cylindrical microdomains oriented normal to the surface. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

76 FR 42613 - National Emission Standards for Hazardous Air Pollutants for Polyvinyl Chloride and Copolymers...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-19

... National Emission Standards for Hazardous Air Pollutants for Polyvinyl Chloride and Copolymers Production... Polyvinyl Chloride and Copolymers Production is being extended for 14 days. DATES: Comments. The public... for the May 20, 2011, Proposed Polyvinyl Chloride and Copolymers Production Rule, the EPA is extending...

Monte Carlo studies on the interfacial properties and interfacial structures of ternary symmetric blends with gradient copolymers.

PubMed

Sun, Dachuan; Guo, Hongxia

2012-08-09

Using Monte Carlo simulation methods, the effects of the comonomer sequence distribution on the interfacial properties (including interfacial tension, interfacial thickness, saturated interfacial area per copolymer, and bending modulus) and interfacial structures (including chain conformations and comonomer distributions of the simulated copolymers at the interfaces) of a ternary symmetric blend containing two immiscible homopolymers and one gradient copolymer are investigated. We find that copolymers with a larger composition gradient width have a broader comonomer distribution along the interface normal, and hence more pronouncedly enlarge the interfacial thickness and reduce the interfacial tension. Furthermore, the counteraction effect, which arises from the tendency of heterogeneous segments in gradient copolymers to phase separate and enter their miscible phases to reduce the local enthalpy, decreases the stretching of copolymers along the interface normal direction. As a result, copolymers with a larger width of gradient composition can occupy a larger interfacial area and form softer monolayers at saturation and are more efficient in facilitating the formation of bicontinuous microemulsions. Additionally, chain length ratio, segregation strength, and interactions between homopolymers and copolymers can alter the interfacial character of gradient copolymers. There exists a strong coupling between the comonomer sequence distribution, chain conformation, and interfacial properties. Especially, bending modulus is mainly determined by the complicated interplay of interfacial copolymer density and interfacial chain conformation.

Barite formation in the presence of a commercial copolymer

NASA Astrophysics Data System (ADS)

Ruiz-Agudo, Cristina; Putnis, Christine; Ruiz-Agudo, Encarnacion; Putnis, Andrew

2015-04-01

Fluid composition can significantly modify the mechanisms of mineral formation. Particularly, the presence of organic additives in the aqueous media has been shown to alter the precipitation of minerals substantially (e.g. calcium carbonate, barium carbonate and barium sulfate). Despite the numerous studies dealing with barite precipitation and the influence of organic additives (e.g. Benton et al. 1993, Qi et al., 2000, Wang and Cölfen, 2006, Mavredaki et al., 2011), the details of the mechanism of barite formation in the presence of organic additives, particularly at the early stages of this process, are yet to be fully resolved. Here, we present observations on the initial stages of barite formation from aqueous solutions, as well as the alterations induced by a commercial copolymer (maleic acid/allyl sulfonic acid copolymer with phosphonate groups), commonly used as a scale inhibitor in oil recovery. Most synthetic commercial additives contain the same functional groups (e.g. carboxylate, phosphonate and/or sulfonate groups). Thus our work may help to understand the mechanism by which copolymers modify crystallization processes and aid in the selection of the most appropriate inhibitors for hindering or controlling barite scale formation. Barite scaling is one of the main problems in many industrial processes (such as, paper-making, chemical manufacturing, cement operations, off-shore oil extraction, geothermal energy production). Using Atomic Force Microscopy (AFM), we show that barite growth is significantly influenced by the presence of the copolymer. In its absence, barium sulfate growth occurs by 2D island nucleation and spreading. The addition of small amounts (0.1 ppm and 0.5 ppm) of the copolymer enhances 2D nucleation but blocks growth. Just 1 ppm of inhibitor is enough to block barite nucleation and growth by adsorption of a copolymer layer onto the barite surface. Transmission electron microscopy (TEM) was also used to gain better insights into the

Characteristics of immobilized aminoacylase from Aspergillus oryzae on macroporous copolymers.

PubMed

He, B L; Jiang, P; Qiu, Y B

1990-01-01

Aminoacylase from Aspergillus oryzae was adsorbed on functionallized macroporous copolymers where the enzyme showed excellent catalyzing activity and operation stability. Various factors which effect the activity of the immobilized aminoacylase such as temperature, pH and ionic strength were investigated. The continuous operation of the enzyme immobilized on macroporous copolymers was compared with that of the enzyme immobilized on DEAE-Sephadex.

Ordered porous mesostructured materials from nanoparticle-block copolymer self-assembly

DOEpatents

Warren, Scott; Wiesner, Ulrich; DiSalvo, Jr., Francis J

2013-10-29

The invention provides mesostructured materials and methods of preparing mesostructured materials including metal-rich mesostructured nanoparticle-block copolymer hybrids, porous metal-nonmetal nanocomposite mesostructures, and ordered metal mesostructures with uniform pores. The nanoparticles can be metal, metal alloy, metal mixture, intermetallic, metal-carbon, metal-ceramic, semiconductor-carbon, semiconductor-ceramic, insulator-carbon or insulator-ceramic nanoparticles, or combinations thereof. A block copolymer/ligand-stabilized nanoparticle solution is cast, resulting in the formation of a metal-rich (or semiconductor-rich or insulator-rich) mesostructured nanoparticle-block copolymer hybrid. The hybrid is heated to an elevated temperature, resulting in the formation of an ordered porous nanocomposite mesostructure. A nonmetal component (e.g., carbon or ceramic) is then removed to produce an ordered mesostructure with ordered and large uniform pores.

Humidity-Induced Phase Transitions in Ion-Containing Block Copolymer Membranes

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

Park, Moon Jeong; Nedoma, Alisyn J.; Geissler, Phillip L.

2008-08-21

The phase behavior of ion-containing block copolymer membranes in equilibrium with humidified air is studied as a function of the relative humidity (RH) of the surrounding air, ion content of the copolymer, and temperature. Increasing RH at constant temperature results in both disorder-to-order and order-to-order transitions. In-situ small-angle neutron scattering experiments on the open block copolymer system, when combined with water uptake measurement, indicate that the disorder-to-order transition is driven by an increase in the partial molar entropy of the water molecules in the ordered phase relative to that in the disordered phase. This is in contrast to most systemsmore » wherein increasing entropy results in stabilization of the disordered phase.« less

Solid-state NMR characterization of copolymers of nylon 11 and nylon 12.

PubMed

Johnson, C G; Mathias, L J

1997-05-01

Solid-state 13C and 15N NMR spectroscopy, in conjunction with differential scanning calorimetry, wide-angle X-ray diffraction and infrared spectroscopy, were used to characterize a series of nylon 11 and 12 copolymers with mole percentages of nylon 12 monomer of 0, 15, 35, 50, 65, 85, and 100%. Monotonic melting point (Tm) and heat of fusion depressions were observed for the copolymer series with the 65 mol% nylon 12 copolymer having the lowest apparent crystallinity and Tm at 148 degrees C. Solid-state 15N NMR spectra showed a smooth shift of the main peak position for the as-prepared copolymers from 84 ppm for the alpha-form of pure nylon 11 to 89 ppm for the gamma-form of pure nylon 12. Similar behavior was seen for FTIR amide V and VI modes which are also sensitive to the alpha- and gamma-crystal forms. 13C NMR T1 measurements showed that the overall most mobile sample was the 65:35 copolymer. The amide group of the 1:1 copolymer was labelled using 15N-labelled amino acids available through the Gabriel synthesis; an annealed, solution-cast film of this sample showed a T1N value of 349 s, similar to values seen for annealed nylon 11 and nylon 12 homopolymers. The WAXS pattern for the 65 mol% nylon 12 sample showed a sharp peak at 2 theta = 21.3, overlapping a broad peak centered at 2 theta = 21.0. These are consistent with the values seen for gamma-form nylon 12. The 1:1 copolymer (15N labelled) was shown to be polymorphic, like the homopolymers after specific treatments, with a gamma-like phase formed upon solvent casting, and an alpha-like phase dominating for as-polymerized material and precipitated flakes.

Responsive linear-dendritic block copolymers.

PubMed

Blasco, Eva; Piñol, Milagros; Oriol, Luis

2014-06-01

The combination of dendritic and linear polymeric structures in the same macromolecule opens up new possibilities for the design of block copolymers and for applications of functional polymers that have self-assembly properties. There are three main strategies for the synthesis of linear-dendritic block copolymers (LDBCs) and, in particular, the emergence of click chemistry has made the coupling of preformed blocks one of the most efficient ways of obtaining libraries of LDBCs. In these materials, the periphery of the dendron can be precisely functionalised to obtain functional LDBCs with self-assembly properties of interest in different technological areas. The incorporation of stimuli-responsive moieties gives rise to smart materials that are generally processed as self-assemblies of amphiphilic LDBCs with a morphology that can be controlled by an external stimulus. Particular emphasis is placed on light-responsive LDBCs. Furthermore, a brief review of the biomedical or materials science applications of LDBCs is presented. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oligosaccharide/silicon-containing block copolymers with 5 nm features for lithographic applications.

PubMed

Cushen, Julia D; Otsuka, Issei; Bates, Christopher M; Halila, Sami; Fort, Sébastien; Rochas, Cyrille; Easley, Jeffrey A; Rausch, Erica L; Thio, Anthony; Borsali, Redouane; Willson, C Grant; Ellison, Christopher J

2012-04-24

Block copolymers demonstrate potential for use in next-generation lithography due to their ability to self-assemble into well-ordered periodic arrays on the 3-100 nm length scale. The successful lithographic application of block copolymers relies on three critical conditions being met: high Flory-Huggins interaction parameters (χ), which enable formation of <10 nm features, etch selectivity between blocks for facile pattern transfer, and thin film self-assembly control. The present paper describes the synthesis and self-assembly of block copolymers composed of naturally derived oligosaccharides coupled to a silicon-containing polystyrene derivative synthesized by activators regenerated by electron transfer atom transfer radical polymerization. The block copolymers have a large χ and a low degree of polymerization (N) enabling formation of 5 nm feature diameters, incorporate silicon in one block for oxygen reactive ion etch contrast, and exhibit bulk and thin film self-assembly of hexagonally packed cylinders facilitated by a combination of spin coating and solvent annealing techniques. As observed by small angle X-ray scattering and atomic force microscopy, these materials exhibit some of the smallest block copolymer features in the bulk and in thin films reported to date.

The Origin of Hierarchical Structure Formation in Highly Grafted Symmetric Supramolecular Double-Comb Diblock Copolymers.

PubMed

Hofman, Anton H; Reza, Mehedi; Ruokolainen, Janne; Ten Brinke, Gerrit; Loos, Katja

2017-09-01

Involving supramolecular chemistry in self-assembling block copolymer systems enables design of complex macromolecular architectures that, in turn, could lead to complex phase behavior. It is an elegant route, as complicated and sensitive synthesis techniques can be avoided. Highly grafted double-comb diblock copolymers based on symmetric double hydrogen bond accepting poly(4-vinylpyridine)-block-poly(N-acryloylpiperidine) diblock copolymers and donating 3-nonadecylphenol amphiphiles are realized and studied systematically by changing the molecular weight of the copolymer. Double perpendicular lamellae-in-lamellae are formed in all complexes, independent of the copolymer molecular weight. Temperature-resolved measurements demonstrate that the supramolecular nature and ability to crystallize are responsible for the formation of such multiblock-like structures. Because of these driving forces and severe plasticization of the complexes in the liquid crystalline state, this supramolecular approach can be useful for steering self-assembly of both low- and high-molecular-weight block copolymer systems. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and characterization of functional acrylic copolymers via RAFT mini-emulsion polymerization

NASA Astrophysics Data System (ADS)

Yılmaz, Onur; Özkan, ćiǧdem Kılıçarislan; Yılmaz, Catalina N.; Yorgancıoǧlu, Ali; Özgünay, Hasan; Karavana, Hüseyin Ata

2017-12-01

Copolymers bearing reactive functional groups with controlled molecular weights are of importance since they can be used in many fields such as composites, coatings, membranes, catalysis, biology, optoelectronics, pharmaceuticals, etc. In the present study low molecular weight copolymers based on butyl acrylate (BA) and methyl methacrylate (MMA) in combination with reactive functional monomers of vinyl trietoxysilane (VTES), 3-trimetoxysilylpropyl methacrylate (TMSPMA) and glycidyl methacrylate (GMA) were synthesized via RAFT mini-emulsion technique using 2-cyano 2-propyldodecyldithiocarbonate as CTA agent. The results showed that the average molecular weights of copolymers were close to the theoretical values. On the other hand, PDI values were found to be higher than conventional RAFT polymers. The particle sizes of the latexes were small with very homogenous distributions and good stability. FTIR, H-NMR and TGA results verified the success of copolymer syntheses.

Applying thermosettable zwitterionic copolymers as general fouling-resistant and thermal-tolerant biomaterial interfaces.

PubMed

Chou, Ying-Nien; Chang, Yung; Wen, Ten-Chin

2015-05-20

We introduced a thermosettable zwitterionic copolymer to design a high temperature tolerance biomaterial as a general antifouling polymer interface. The original synthetic fouling-resistant copolymer, poly(vinylpyrrolidone)-co-poly(sulfobetaine methacrylate) (poly(VP-co-SBMA)), is both thermal-tolerant and fouling-resistant, and the antifouling stability of copolymer coated interfaces can be effectively controlled by regulating the VP/SBMA composition ratio. We studied poly(VP-co-SBMA) copolymer gels and networks with a focus on their general resistance to protein, cell, and bacterial bioadhesion, as influenced by the thermosetting process. Interestingly, we found that the shape of the poly(VP-co-SBMA) copolymer material can be set at a high annealing temperature of 200 °C while maintaining good antifouling properties. However, while the zwitterionic PSBMA polymer gels were bioinert as expected, control of the fouling resistance of the PSBMA polymer networks was lost in the high temperature annealing process. A poly(VP-co-SBMA) copolymer network composed of PSBMA segments at 32 mol % showed reduced fibrinogen adsorption, tissue cell adhesion, and bacterial attachment, but a relatively higher PSBMA content of 61 mol % was required to optimize resistance to platelet adhesion and erythrocyte attachment to confer hemocompatibility to human blood. We suggest that poly(VP-co-SBMA) copolymers capable of retaining stable fouling resistance after high temperature shaping have a potential application as thermosettable materials in a bioinert interface for medical devices, such as the thermosettable coating on a stainless steel blood-compatible metal stent investigated in this study.

Biocompatible Polysiloxane-Containing Diblock Copolymer PEO-b-PγMPS for Coating Magnetic Nanoparticles

PubMed Central

Chen, Hongwei; Wu, Xinying; Duan, Hongwei; Wang, Y. Andrew; Wang, Liya; Zhang, Minming; Mao, Hui

2009-01-01

We report a biocompatible polysiloxane containing amphiphilic diblock copolymer, poly(ethylene oxide)-block-poly(γ-methacryloxypropyltrimethoxysilane) (PEO-b-PγMPS), for coating and stabilizing nanoparticles for biomedical applications. Such amphiphilic diblock copolymer which comprises both a hydrophobic segment with “surface anchoring moiety” (silane group) and a hydrophilic segment with PEO (Mn=5000 g/mol) was obtained by the reversible addition fragmentation chain transfer (RAFT) polymerization using the PEO macromolecular chain transfer agent. When used for coating paramagnetic iron oxide nanoparticles (IONPs), copolymers were mixed with hydrophobic oleic acid coated core size uniformed IONPs (D=13 nm) in co-solvent tetrahydrofuran. After being aged over a period of time, resulting monodispersed IONPs can be transferred into aqueous medium. With proper PγMPS block length (Mn=10,000 g/mol), polysiloxane containing diblock copolymers formed a thin layer of coating (~3 nm) around monocrystalline nanoparticles as measured by transmission electron microscopy (TEM). Magnetic resonance imaging (MRI) experiments showed excellent T2 weighted contrast effect from coated IONPs with a transverse relaxivity r2=98.6 mM−1s−1 (at 1.5 Tesla). Such thin coating layer has little effect on the relaxivity when compared to that of IONPs coated with conventional amphiphilic copolymer. Polysiloxane containing diblock copolymer coated IONPs are stable without aggregation or binding to proteins in serum when incubated for 24 h in culture medium containing 10% serum. Furthermore, much lower level of intracellular uptake by macrophage cells was observed with polysiloxane containing diblock copolymers coated IONPs, suggesting the reduction of non-specific cell uptakes and antibiofouling effect. PMID:20161520

Ultrahigh-Density Nanowire Arrays Grown in Self-Assembled Diblock Copolymer Templates

NASA Astrophysics Data System (ADS)

Thurn-Albrecht, T.; Schotter, J.; Kästle, G. A.; Emley, N.; Shibauchi, T.; Krusin-Elbaum, L.; Guarini, K.; Black, C. T.; Tuominen, M. T.; Russell, T. P.

2000-12-01

We show a simple, robust, chemical route to the fabrication of ultrahigh-density arrays of nanopores with high aspect ratios using the equilibrium self-assembled morphology of asymmetric diblock copolymers. The dimensions and lateral density of the array are determined by segmental interactions and the copolymer molecular weight. Through direct current electrodeposition, we fabricated vertical arrays of nanowires with densities in excess of 1.9 × 1011 wires per square centimeter. We found markedly enhanced coercivities with ferromagnetic cobalt nanowires that point toward a route to ultrahigh-density storage media. The copolymer approach described is practical, parallel, compatible with current lithographic processes, and amenable to multilayered device fabrication.

Ultrahigh-density nanowire arrays grown in self-assembled diblock copolymer templates.

PubMed

Thurn-Albrecht, T; Schotter, J; Kästle, G A; Emley, N; Shibauchi, T; Krusin-Elbaum, L; Guarini, K; Black, C T; Tuominen, M T; Russell, T P

2000-12-15

We show a simple, robust, chemical route to the fabrication of ultrahigh-density arrays of nanopores with high aspect ratios using the equilibrium self-assembled morphology of asymmetric diblock copolymers. The dimensions and lateral density of the array are determined by segmental interactions and the copolymer molecular weight. Through direct current electrodeposition, we fabricated vertical arrays of nanowires with densities in excess of 1.9 x 10(11) wires per square centimeter. We found markedly enhanced coercivities with ferromagnetic cobalt nanowires that point toward a route to ultrahigh-density storage media. The copolymer approach described is practical, parallel, compatible with current lithographic processes, and amenable to multilayered device fabrication.

Thin Film Assembly of Spider Silk-like Block Copolymers

DTIC Science & Technology

2011-01-01

Shipley, N. H.; Lewis, R. V. Int. J. Biol.Macromol. 1999, 24, 271. (c) Thiel, B. L.; Guess, K. B.; Viney, C. Biopolymers 1997, 41, 703. (13) Silk ...Film Assembly of Spider Silk -like Block Copolymers Sreevidhya T. Krishnaji,†,‡ Wenwen Huang,§ Olena Rabotyagova,†,‡ Eugenia Kharlampieva, ) Ikjun Choi...Received November 26, 2010 We report the self-assembly of monolayers of spider silk -like block copolymers. Langmuir isotherms were obtained for a series of

In-situ Polymerization of Polyaniline/Polypyrrole Copolymer using Different Techniques

NASA Astrophysics Data System (ADS)

Hammad, A. S.; Noby, H.; Elkady, M. F.; El-Shazly, A. H.

2018-01-01

The morphology and surface area of the poly(aniline-co-pyrrole) copolymer (PANPY) are important properties which improve the efficiency of the copolymer in various applications. In this investigation, different techniques were employed to produce PANPY in different morphologies. Aniline and pyrrole were used as monomers, and ammonium peroxydisulfate (APS) was used as an oxidizer with uniform molar ratio. Rapid mixing, drop-wise mixing, and supercritical carbon dioxide (ScCO2) polymerization techniques were appointed. The chemical structure, crystallinity, porosity, and morphology of the composite were distinguished by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET) analysis, and transmission electron microscopy (TEM) respectively. The characterization tests indicated that the polyaniline/polypyrrole copolymer was successfully prepared with different morphologies. Based on the obtained TEM, hollow nanospheres were formed using rapid mixing technique with acetic acid that have a diameter of 75 nm and thickness 26 nm approximately. Also, according to the XRD, the produced structures have a semi- crystalline structure. The synthesized copolymer with ScCO2-assisted polymerization technique showed improved surface area (38.1 m2/g) with HCl as dopant.

40 CFR 180.1162 - Acrylate polymers and copolymers; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Acrylate polymers and copolymers... RESIDUES IN FOOD Exemptions From Tolerances § 180.1162 Acrylate polymers and copolymers; exemption from the requirement of a tolerance. (a) Acrylate polymers and copolymers are exempt from the requirement of a...

40 CFR 180.1162 - Acrylate polymers and copolymers; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Acrylate polymers and copolymers... RESIDUES IN FOOD Exemptions From Tolerances § 180.1162 Acrylate polymers and copolymers; exemption from the requirement of a tolerance. (a) Acrylate polymers and copolymers are exempt from the requirement of a...

40 CFR 180.1162 - Acrylate polymers and copolymers; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Acrylate polymers and copolymers... RESIDUES IN FOOD Exemptions From Tolerances § 180.1162 Acrylate polymers and copolymers; exemption from the requirement of a tolerance. (a) Acrylate polymers and copolymers are exempt from the requirement of a...

40 CFR 180.1162 - Acrylate polymers and copolymers; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Acrylate polymers and copolymers... RESIDUES IN FOOD Exemptions From Tolerances § 180.1162 Acrylate polymers and copolymers; exemption from the requirement of a tolerance. (a) Acrylate polymers and copolymers are exempt from the requirement of a...

New inorganic/organic copolymers (ORMOCER{reg_sign}s) for dental applications

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

Wolter, H.; Storch, W.; Ott, H.

1994-12-31

Urethane and thioether (meth)acrylate alkoxysilanes have been used, as sol-gel precursors, for the preparation of a special family of inorganic/organic copolymers (ORMOCER{reg_sign}s). The basic silane type offers the following structural and synthetic possibilities for modifying the properties of the resulting copolymers: variation of the number of alkoxy groups, combination with other, different, sol-gel precursors, variation of the number of attached (meth)acrylate groups (1--5), and variation within the molecular segment (kind, structure and length) connecting the inorganic with the organic polymer structure. To achieve the additional organic polymer structure in the cured copolymer the use of different radically induced polymerization approachesmore » (UV-, visible light-, thermal- and redox induced) is possible. Taking the incorporation of fillers into account, the Young`s modulus of these copolymers is adjustable in a range of 1--17,000 MPa, and the thermal expansion coefficient in a range of 17--250{center_dot}10{sup {minus}6}{center_dot}K{sup {minus}1} (5--50 C). Other advantages are the low shrinkage (1--2,8 vol.-%), the high flexural strength (up to 160 MPa), and the high abrasion resistance. This new copolymer type seems to have significant potential for medical applications, especially as dental filling material to replace the currently used controversial amalgam fillings.« less

Aqueous self-assembly of poly(ethylene oxide)-block-poly(ε-caprolactone) (PEO-b-PCL) copolymers: disparate diblock copolymer compositions give rise to nano- and meso-scale bilayered vesicles

NASA Astrophysics Data System (ADS)

Qi, Wei; Ghoroghchian, P. Peter; Li, Guizhi; Hammer, Daniel A.; Therien, Michael J.

2013-10-01

Nanoparticles formed from diblock copolymers of FDA approved PEO and PCL have generated considerable interest as in vivo drug delivery vehicles. Herein, we report the synthesis of the most extensive family PEO-b-PCL copolymers that vary over the largest range of number-average molecular weights (Mn: 3.6-57k), PEO weight fractions (fPEO: 0.08-0.33), and PEO chain lengths (0.75-5.8k) reported to date. These polymers were synthesized in order to establish the full range of aqueous phase behaviours of these diblock copolymers and to specifically identify formulations that were able to generate bilayered vesicles (polymersomes). Cryogenic transmission electron microscopy (cryo-TEM) was utilized in order to visualize the morphology of these structures upon aqueous self-assembly of dry polymer films. Nanoscale polymersomes were formed from PEO-b-PCL copolymers over a wide range of PEO weight fractions (fPEO: 0.14-0.27) and PEO molecular weights (0.75-3.8k) after extrusion of aqueous suspensions. Comparative morphology diagrams, which describe the nature of self-assembled structures as a function of diblock copolymer molecular weight and PEO weight fraction, show that in contrast to micron-scale polymersomes, which form only from a limited range of PEO-b-PCL diblock copolymer compositions, a multiplicity of PEO-b-PCL diblock copolymer compositions are able to give rise to nanoscale vesicles. These data underscore that PEO-b-PCL compositions that spontaneously form micron-sized polymersomes, as well as those that have previously been reported to form polymersomes via a cosolvent fabrication system, provide only limited insights into the distribution of PEO-b-PCL diblocks that give rise to nanoscale vesicles. The broad range of polymersome-forming PEO-b-PCL compositions described herein suggest the ability to construct extensive families of nanoscale vesicles of varied bilayer thickness, providing the ability to tune the timescales of vesicle degradation and encapsulant

The effect of copolymers on the interfaces in incompatible homopolymers blend: Molecular dynamics study

NASA Astrophysics Data System (ADS)

Ryu, Jiho; Lee, Won Bo

2015-03-01

Using molecular dynamics simulations the effect of copolymers as compatibilizer for reducing interfacial tension and enhancement of interfacial adhesion at the interface of thermodynamic unfavorable homopolymers blend is studied with block- and graft-copolymers. We have calculated local pressure tensor of system along the axis perpendicular to interface, varying bending potential energy of one part, which consist of just one kind of beads, of copolymer chain to examine the effect of stiffness of surfactin molecules. Here we consider symmetric diblock copolymer (f =1/2) having 1/2 N make of beads of type A and the other part made of beads of type B, and graft copolymer having backbone linear chain consist of 1/2 N beads of type of A and branched with two side-chain consist of 1/4 N beads of type B. All simulations were performed under the constant NPT ensemble at T* =1, ρ* ~0.85. Also we studied changes of effect of copolymers with increasing pairwise repulsive interaction potential between two beads of types A and B while homopolymers chain length are fixed, N =30. Chemical and Biomolecular Engineering, Sogang University, Seoul, South Korea.

Proteins detection by polymer optical fibers sensitised with overlayers of block and random copolymers

NASA Astrophysics Data System (ADS)

El Sachat, Alexandros; Meristoudi, Anastasia; Markos, Christos; Pispas, Stergios; Riziotis, Christos

2014-03-01

A low cost and low complexity optical detection method of proteins is presented by employing a detection scheme based on electrostatic interactions, and implemented by sensitization of a polymer optical fibers' (POF) surface by thin overlayers of properly designed sensitive copolymer materials with predesigned charges. This method enables the fast detection of proteins having opposite charge to the overlayer, and also the effective discrimination of differently charged proteins like lysozyme (LYS) and bovine serum albumin (BSA). As sensitive materials the block and the random copolymers of the same monomers were employed, namely the block copolymer poly(styrene-b-2vinylpyridine) (PS-b- P2VP) and the corresponding random copolymer poly(styrene-r-2vinylpyridine) (PS-r-P2VP), of similar composition and molecular weights. Results show systematically different response between the block and the random copolymers, although of the same order of magnitude, drawing thus important conclusions on their applications' techno-economic aspects given that they have significantly different associated manufacturing method and costs. The use of the POF platform, in combination with those adaptable copolymer sensing materials could lead to efficient low cost bio-detection schemes.

Fluids Density Functional Theory of Salt-Doped Block Copolymers

NASA Astrophysics Data System (ADS)

Brown, Jonathan R.; Hall, Lisa M.

Block copolymers have attracted a great deal of recent interest as potential non-flammable, solid-state, electrolyte materials for batteries or other charge carrying applications. The microphase separation in block copolymers combines the properties of a conductive (though mechanically soft) polymer with a mechanically robust (though non-conductive) polymer. We use fluids density functional theory (fDFT) to study the phase behavior of salt-doped block copolymers. Because the salt prefers to preferentially solvate into the conductive phase, salt doping effectively enhances the segregation strength between the two polymer types. We consider the effects of this preferential solvation and of charge correlations by separately modeling the ion-rich phase, without bonding, using the Ornstein-Zernike equation and the hypernetted-chain closure. We use the correlations from this subsystem in the inhomogeneous fDFT calculations. Initial addition of salt increases the domain spacing and sharpens the interfacial region, but for high salt loadings the interface can broaden. Addition of salt can also drive a system with a low copolymer segregation strength to order by first passing through a two phase regime with a salt-rich ordered phase and a salt-poor disordered phase. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award Number DE-SC0014209.

Gyroid Nickel Nanostructures from Diblock Copolymer Supramolecules

PubMed Central

Vukovic, Ivana; Punzhin, Sergey; Voet, Vincent S. D.; Vukovic, Zorica; de Hosson, Jeff Th. M.; ten Brinke, Gerrit; Loos, Katja

2014-01-01

Nanoporous metal foams possess a unique combination of properties - they are catalytically active, thermally and electrically conductive, and furthermore, have high porosity, high surface-to-volume and strength-to-weight ratio. Unfortunately, common approaches for preparation of metallic nanostructures render materials with highly disordered architecture, which might have an adverse effect on their mechanical properties. Block copolymers have the ability to self-assemble into ordered nanostructures and can be applied as templates for the preparation of well-ordered metal nanofoams. Here we describe the application of a block copolymer-based supramolecular complex - polystyrene-block-poly(4-vinylpyridine)(pentadecylphenol) PS-b-P4VP(PDP) - as a precursor for well-ordered nickel nanofoam. The supramolecular complexes exhibit a phase behavior similar to conventional block copolymers and can self-assemble into the bicontinuous gyroid morphology with two PS networks placed in a P4VP(PDP) matrix. PDP can be dissolved in ethanol leading to the formation of a porous structure that can be backfilled with metal. Using electroless plating technique, nickel can be inserted into the template's channels. Finally, the remaining polymer can be removed via pyrolysis from the polymer/inorganic nanohybrid resulting in nanoporous nickel foam with inverse gyroid morphology. PMID:24797367

Gyroid nickel nanostructures from diblock copolymer supramolecules.

PubMed

Vukovic, Ivana; Punzhin, Sergey; Voet, Vincent S D; Vukovic, Zorica; de Hosson, Jeff Th M; ten Brinke, Gerrit; Loos, Katja

2014-04-28

Nanoporous metal foams possess a unique combination of properties - they are catalytically active, thermally and electrically conductive, and furthermore, have high porosity, high surface-to-volume and strength-to-weight ratio. Unfortunately, common approaches for preparation of metallic nanostructures render materials with highly disordered architecture, which might have an adverse effect on their mechanical properties. Block copolymers have the ability to self-assemble into ordered nanostructures and can be applied as templates for the preparation of well-ordered metal nanofoams. Here we describe the application of a block copolymer-based supramolecular complex - polystyrene-block-poly(4-vinylpyridine)(pentadecylphenol) PS-b-P4VP(PDP) - as a precursor for well-ordered nickel nanofoam. The supramolecular complexes exhibit a phase behavior similar to conventional block copolymers and can self-assemble into the bicontinuous gyroid morphology with two PS networks placed in a P4VP(PDP) matrix. PDP can be dissolved in ethanol leading to the formation of a porous structure that can be backfilled with metal. Using electroless plating technique, nickel can be inserted into the template's channels. Finally, the remaining polymer can be removed via pyrolysis from the polymer/inorganic nanohybrid resulting in nanoporous nickel foam with inverse gyroid morphology.

(Electro)Mechanical Properties of Olefinic Block Copolymers

NASA Astrophysics Data System (ADS)

Spontak, Richard

2014-03-01

Conventional styrenic triblock copolymers (SBCs) swollen with a midblock-selective oil have been previously shown to exhibit excellent electromechanical properties as dielectric elastomers. In this class of electroactive polymers, compliant electrodes applied as active areas to opposing surfaces of an elastomer attract each other, and thus compress the elastomer due to the onset of a Maxwell stress, upon application of an external electric field. This isochoric process is accompanied by an increase in lateral area, which yields the electroactuation strain (measuring beyond 300% in SBC systems). Performance parameters such as the Maxwell stress, transverse strain, dielectric breakdown, energy density and electromechanical efficiency are determined directly from the applied electric field and resulting electroactuation strain. In this study, the same principle used to evaluate SBC systems is extended to olefinic block copolymers (OBCs), which can be described as randomly-coupled multiblock copolymers that consist of crystallizable polyethylene hard segments and rubbery poly(ethylene-co-octene) soft segments. Considerations governing the development of a methodology to fabricate electroresponsive OBC systems are first discussed for several OBCs differing in composition and bulk properties. Evidence of electroactuation in selectively-solvated OBC systems is presented and performance metrics measured therefrom are quantitatively compared with dielectric elastomers derived from SBC and related materials.

High-frequency ultrasound-responsive block copolymer micelle.

PubMed

Wang, Jie; Pelletier, Maxime; Zhang, Hongji; Xia, Hesheng; Zhao, Yue

2009-11-17

Micelles of a diblock copolymer composed of poly(ethylene oxide) and poly(2-tetrahydropyranyl methacrylate) (PEO-b-PTHPMA) in aqueous solution could be disrupted by high-frequency ultrasound (1.1 MHz). It was found that, upon exposure to a high-intensity focused ultrasound (HIFU) beam at room temperature, the pH value of the micellar solution decreased over irradiation time. The infrared spectroscopic analysis of solid block copolymer samples collected from the ultrasound irradiated micellar solution revealed the formation of carboxylic acid dimers and hydroxyl groups. These characterization results suggest that the high-frequency HIFU beam could induce the hydrolysis reaction of THPMA at room temperature resulting in the cleavage of THP groups. The disruption of PEO-b-PTHPMA micelles by ultrasound was investigated by using dynamic light scattering, atomic force microscopy, and fluorescence spectroscopy. On the basis of the pH change, it was found that the disruption process was determined by a number of factors such as the ultrasound power, the micellar solution volume and the location of the focal spot of the ultrasound beam. This study shows the potential to develop ultrasound-sensitive block copolymer micelles by having labile chemical bonds in the polymer structure, and to use the high-frequency HIFU to trigger a chemical reaction for the disruption of micelles.

Nonlinear optical measurements of conducting copolymers of aniline under CW laser excitation

NASA Astrophysics Data System (ADS)

Pramodini, S.; Poornesh, P.

2015-08-01

Synthesis and measurements of third-order optical nonlinearity and optical limiting of conducting copolymers of aniline are presented. Single beam z-scan technique was employed for the nonlinear optical studies. Continuous wave He-Ne laser operating at 633 nm was used as the source of excitation. Copolymer samples exhibited reverse saturable absorption (RSA) process. The nonlinear refraction studies depict that the copolymers exhibit self-defocusing property. The estimated values of βeff, n2 and χ(3) were found to be of the order of 10-2 cm/W, 10-5 esu and 10-7 esu respectively. Self-diffraction rings were observed due to refractive index change when exposed to the laser beam. A good optical limiting and clamping of power of ∼0.9 mW and ∼0.05 mW was observed. Therefore, copolymers of aniline emerge as a potential candidate for photonic device applications.

Design, synthesis, and characterization of lightly sulfonated multigraft acrylate-based copolymer superelastomers

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

Misichronis, Konstantinos; Wang, Weiyu; Cheng, Shiwang

2018-01-29

Multigraft copolymer superelastomers consisting of a poly(n-butyl acrylate) backbone and polystyrene side chains were synthesized and the viscoelastic properties of the non-sulfonated and sulfonated final materials were investigated using extensional rheology (SER3). The non-linear viscoelastic experiments revealed significantly increased true stresses (up to 10 times higher) after sulfonating only 2–3% of the copolymer while the materials maintained high elongation (<700%). The linear viscoelastic experiments showed that the storage and loss modulus are increased by sulfonation and that the copolymers can be readily tuned and further improved by increasing the number of branching points and the molecular weight of the backbone.more » Here, in this way, we show that by tuning not only the molecular characteristics of the multigraft copolymers but also their architecture and chemical interaction, we can acquire thermoplastic superelastomer materials with desired viscoelastic properties.« less

Cathepsin S-cleavable, multi-block HPMA copolymers for improved SPECT/CT imaging of pancreatic cancer.

PubMed

Fan, Wei; Shi, Wen; Zhang, Wenting; Jia, Yinnong; Zhou, Zhengyuan; Brusnahan, Susan K; Garrison, Jered C

2016-10-01

This work continues our efforts to improve the diagnostic and radiotherapeutic effectiveness of nanomedicine platforms by developing approaches to reduce the non-target accumulation of these agents. Herein, we developed multi-block HPMA copolymers with backbones that are susceptible to cleavage by cathepsin S, a protease that is abundantly expressed in tissues of the mononuclear phagocyte system (MPS). Specifically, a bis-thiol terminated HPMA telechelic copolymer containing 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Three maleimide modified linkers with different sequences, including cathepsin S degradable oligopeptide, scramble oligopeptide and oligo ethylene glycol, were subsequently synthesized and used for the extension of the HPMA copolymers by thiol-maleimide click chemistry. All multi-block HPMA copolymers could be labeled by (177)Lu with high labeling efficiency and exhibited high serum stability. In vitro cleavage studies demonstrated highly selective and efficient cathepsin S mediated cleavage of the cathepsin S-susceptible multi-block HPMA copolymer. A modified multi-block HPMA copolymer series capable of Förster Resonance Energy Transfer (FRET) was utilized to investigate the rate of cleavage of the multi-block HPMA copolymers in monocyte-derived macrophages. Confocal imaging and flow cytometry studies revealed substantially higher rates of cleavage for the multi-block HPMA copolymers containing the cathepsin S-susceptible linker. The efficacy of the cathepsin S-cleavable multi-block HPMA copolymer was further examined using an in vivo model of pancreatic ductal adenocarcinoma. Based on the biodistribution and SPECT/CT studies, the copolymer extended with the cathepsin S susceptible linker exhibited significantly faster clearance and lower non-target retention without compromising tumor targeting. Overall, these results indicate that

Block copolymer adhesion promoters via ring-opening metathesis polymerization

DOEpatents

Kent, Michael S.; Saunders, Randall

1997-01-01

Coupling agents based on functionalized block copolymers for bonding thermoset polymers to solid materials. These are polymers which possess at least two types of functional groups, one which is able to attach to and react with solid surfaces, and another which can react with a thermoset resin, which are incorporated as pendant groups in monomers distributed in blocks (typically two) along the backbone of the chain. The block copolymers in this invention are synthesized by living ring-opening metathesis polymerization.

Novel Self-Assembling Amino Acid-Derived Block Copolymer with Changeable Polymer Backbone Structure.

PubMed

Koga, Tomoyuki; Aso, Eri; Higashi, Nobuyuki

2016-11-29

Block copolymers have attracted much attention as potentially interesting building blocks for the development of novel nanostructured materials in recent years. Herein, we report a new type of self-assembling block copolymer with changeable polymer backbone structure, poly(Fmoc-Ser) ester -b-PSt, which was synthesized by combining the polycondensation of 9-fluorenylmethoxycarbonyl-serine (Fmoc-Ser) with the reversible addition-fragmentation chain transfer (RAFT) polymerization of styrene (St). This block copolymer showed the direct conversion of the backbone structure from polyester to polypeptide through a multi O,N-acyl migration triggered by base-induced deprotection of Fmoc groups in organic solvent. Such polymer-to-polymer conversion was found to occur quantitatively without decrease in degree of polymerization and to cause a drastic change in self-assembling property of the block copolymer. On the basis of several morphological analyses using FTIR spectroscopy, atomic force, and transmission and scanning electron microscopies, the resulting peptide block copolymer was found to self-assemble into a vesicle-like hollow nanosphere with relatively uniform diameter of ca. 300 nm in toluene. In this case, the peptide block generated from polyester formed β-sheet structure, indicating the self-assembly via peptide-guided route. We believe the findings presented in this study offer a new concept for the development of self-assembling block copolymer system.

Beyond native block copolymer morphologies

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

Doerk, Gregory S.; Yager, Kevin G.

Block copolymers self-assemble into a range of canonical morphologies. Here, we review a broad range of techniques for inducing these materials to form structures beyond the ‘native’ morphologies seen in the bulk equilibrium phase diagram. Methods that exploit intrinsic encoding (molecular design) and external enforcement (directed assembly) are compared.

Beyond native block copolymer morphologies

DOE PAGES

Doerk, Gregory S.; Yager, Kevin G.

2017-09-20

Block copolymers self-assemble into a range of canonical morphologies. Here, we review a broad range of techniques for inducing these materials to form structures beyond the ‘native’ morphologies seen in the bulk equilibrium phase diagram. Methods that exploit intrinsic encoding (molecular design) and external enforcement (directed assembly) are compared.

PCL-PDMS-PCL copolymer-based microspheres mediate cardiovascular differentiation from embryonic stem cells

NASA Astrophysics Data System (ADS)

Song, Liqing

Poly-epsilon-caprolactone (PCL) based copolymers have received much attention as drug or growth factor delivery carriers and tissue engineering scaffolds due to their biocompatibility, biodegradability, and tunable biophysical properties. Copolymers of PCL and polydimethylsiloxane (PDMS) also have shape memory behaviors and can be made into thermoresponsive shape memory polymers for various biomedical applications such as smart sutures and vascular stents. However, the influence of biophysical properties of PCL-PDMS-PCL copolymers on stem cell lineage commitment is not well understood. In this study, PDMS was used as soft segments of varying length to tailor the biophysical properties of PCL-based co-polymers. While low elastic modulus (<10 kPa) of the tri-block copolymer PCL-PDMS-PCL affected cardiovascular differentiation of embryonic stem cells, the range of 60-100 MPa PCL-PDMS-PCL showed little influence on the differentiation. Then different size (30-140 mum) of microspheres were fabricated from PCL-PDMS-PCL copolymers and incorporated within embryoid bodies (EBs). Mesoderm differentiation was induced using bone morphogenetic protein (BMP)-4 for cardiovascular differentiation. Differential expressions of mesoderm progenitor marker KDR and vascular markers CD31 and VE-cadherin were observed for the cells differentiated from EBs incorporated with microspheres of different size, while little difference was observed for cardiac marker alpha-actinin expression. Small size of microspheres (30 mum) resulted in higher expression of KDR while medium size of microspheres (94 mum) resulted in higher CD31 and VE-cadherin expression. This study indicated that the biophysical properties of PCL-based copolymers impacted stem cell lineage commitment, which should be considered for drug delivery and tissue engineering applications.

Molecular origin of photovoltaic performance in donor- block-acceptor all-conjugated block copolymers

DOE PAGES

Smith, Kendall A.; Lin, Yen -Hao; Mok, Jorge W.; ...

2015-11-03

All-conjugated block copolymers may be an effective route to self-assembled photovoltaic devices, but we lack basic information on the relationship between molecular characteristics and photovoltaic performance. Here, we synthesize a library of poly(3-hexylthiophene) (P3HT) block poly((9,9-dialkylfluorene)-2,7-diyl-alt-[4,7-bis(alkylthiophen-5-yl)-2,1,3-benzothiadiazole]-2',2''-diyl) (PFTBT) donor- block-acceptor all-conjugated block copolymers and carry out a comprehensive study of processing conditions, crystallinity, domain sizes, and side-chain structure on photovoltaic device performance. We find that all block copolymers studied exhibit an out-of-plane crystal orientation after deposition, and on thermal annealing at high temperatures the crystal orientation flips to an in-plane orientation. By varying processing conditions on polymer photovoltaic devices, we showmore » that the crystal orientation has only a modest effect (15-20%) on photovoltaic performance. The addition of side-chains to the PFTBT block is found to decrease photovoltaic power conversion efficiencies by at least an order of magnitude. Through grazing-incidence X-ray measurements we find that the addition of side-chains to the PFTBT acceptor block results in weak segregation and small (< 10 nm) block copolymer self-assembled donor and acceptor domains. This work is the most comprehensive to date on all-conjugated block copolymer systems and suggests that photovoltaic performance of block copolymers depends strongly on the miscibility of donor and acceptor blocks, which impacts donor and acceptor domain sizes and purity. Lastly, strategies for improving the device performance of block copolymer photovoltaics should seek to increase segregation between donor and acceptor polymer domains.« less

Molecular Dynamics Study of Polystyrene-b-poly(ethylene oxide) Asymmetric Diblock Copolymer Systems.

PubMed

Dobies, M; Makrocka-Rydzyk, M; Jenczyk, J; Jarek, M; Spontak, R J; Jurga, S

2017-09-12

Two polystyrene-b-poly(ethylene oxide) (PS-b-PEO) diblock copolymers differing in molecular mass (49 and 78 kDa) but possessing the same PEO cylindrical morphology are examined to elucidate their molecular dynamics. Of particular interest here is the molecular motion of the PEO blocks involved in the rigid amorphous fraction (RAF). An analysis of complementary thermal calorimetry and X-ray scattering data confirms the presence of microphase-separated morphology as well as semicrystalline structure in each copolymer. Molecular motion within the copolymer systems is monitored by dielectric and nuclear magnetic resonance spectroscopies. The results reported herein reveal the existence of two local Arrhenius-type processes attributed to the noncooperative local motion of PEO segments involved in fully amorphous and rigid amorphous PEO microphases. In both systems, two structural relaxations governed by glass-transition phenomena are identified and assigned to cooperative segmental motion in the fully amorphous phase (the α process) and the RAF (the α c process). We measure the temperature dependence of the dynamics associated with all of the processes mentioned above and propose that these local processes are associated with corresponding cooperative segmental motion in both copolymer systems. In marked contrast to the thermal activation of the α process as discerned in both copolymers, the α c process appears to be a sensitive probe of the copolymer nanostructure. That is, the copolymer with shorter PEO blocks exhibits more highly restricted cooperative dynamics of PEO segments in the RAF, which can be explained in terms of the greater constraint imposed by the glassy PS matrix on the PEO blocks comprising smaller cylindrical microdomains.

Molecular origin of photovoltaic performance in donor- block-acceptor all-conjugated block copolymers

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

Smith, Kendall A.; Lin, Yen -Hao; Mok, Jorge W.

All-conjugated block copolymers may be an effective route to self-assembled photovoltaic devices, but we lack basic information on the relationship between molecular characteristics and photovoltaic performance. Here, we synthesize a library of poly(3-hexylthiophene) (P3HT) block poly((9,9-dialkylfluorene)-2,7-diyl-alt-[4,7-bis(alkylthiophen-5-yl)-2,1,3-benzothiadiazole]-2',2''-diyl) (PFTBT) donor- block-acceptor all-conjugated block copolymers and carry out a comprehensive study of processing conditions, crystallinity, domain sizes, and side-chain structure on photovoltaic device performance. We find that all block copolymers studied exhibit an out-of-plane crystal orientation after deposition, and on thermal annealing at high temperatures the crystal orientation flips to an in-plane orientation. By varying processing conditions on polymer photovoltaic devices, we showmore » that the crystal orientation has only a modest effect (15-20%) on photovoltaic performance. The addition of side-chains to the PFTBT block is found to decrease photovoltaic power conversion efficiencies by at least an order of magnitude. Through grazing-incidence X-ray measurements we find that the addition of side-chains to the PFTBT acceptor block results in weak segregation and small (< 10 nm) block copolymer self-assembled donor and acceptor domains. This work is the most comprehensive to date on all-conjugated block copolymer systems and suggests that photovoltaic performance of block copolymers depends strongly on the miscibility of donor and acceptor blocks, which impacts donor and acceptor domain sizes and purity. Lastly, strategies for improving the device performance of block copolymer photovoltaics should seek to increase segregation between donor and acceptor polymer domains.« less

Preparation and characterization of poly(acrylic acid)-hydroxyethyl cellulose graft copolymer.

PubMed

Abdel-Halim, E S

2012-10-01

Poly(acrylic acid) hydroxyethyl cellulose [poly(AA)-HEC] graft copolymer was prepared by polymerizing acrylic acid (AA) with hydroxyethyl cellulose (HEC) using potassium bromate/thiourea dioxide (KBrO(3)/TUD) as redox initiation system. The polymerization reaction was carried out under a variety of conditions including concentrations of AA, KBrO(3) and TUD, material to liquor ratio and polymerization temperature. The polymerization reaction was monitored by withdrawing samples from the reaction medium and measuring the total conversion. The rheological properties of the poly(AA)-HEC graft copolymer were investigated. The total conversion and rheological properties of the graft copolymer depended on the ratio of KBrO(3) to TUD and on acrylic acid concentration as well as temperature and material to liquor ratio. Optimum conditions of the graft copolymer preparation were 30 mmol KBrO(3) and 30 mmol TUD/100g HEC, 100% AA (based on weight of HEC), duration 2h at temperature 50 °C using a material to liquor ratio of 1:10. Copyright © 2012. Published by Elsevier Ltd.

Mesostructured Block Copolymer Nanoparticles: Versatile Templates for Hybrid Inorganic/Organic Nanostructures

PubMed Central

Connal, Luke A.; Lynd, Nathaniel A.; Robb, Maxwell J.; See, Kimberly A.; Jang, Se Gyu; Spruell, Jason M.

2012-01-01

We present a versatile strategy to prepare a range of nanostructured poly(styrene)-block-poly(2-vinyl pyridine) copolymer particles with tunable interior morphology and controlled size by a simple solvent exchange procedure. A key feature of this strategy is the use of functional block copolymers incorporating reactive pyridyl moieties which allow the absorption of metal salts and other inorganic precursors to be directed. Upon reduction of the metal salts, well-defined hybrid metal nanoparticle arrays could be prepared, while the use of oxide precursors followed by calcination permits the synthesis of silica and titania particles. In both cases, ordered morphologies templated by the original block copolymer domains were obtained. PMID:23335837

Assessment of new biocompatible poly(N-(morpholino)ethyl methacrylate)-based copolymers by transfection of immortalized keratinocytes.

PubMed

Van Overstraeten-Schlögel, Nancy; Shim, Yong-Ho; Tevel, Virginie; Piel, Géraldine; Piette, Jacques; Dubois, Philippe; Raes, Martine

2012-02-01

Skin carcinomas are among the most commonly diagnosed tumors in the world. In this study, we investigated the transfection of immortalized keratinocytes, used as an in vitro model for skin carcinoma, using the antisense technology and poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA)-based copolymers. In order to improve the transfection efficiency of the classic PDMAEMA polymers, copolymers were synthesized including a poly(N-morpholino)ethylmethacrylate) (PMEMA) moiety for an improved proton-sponge effect, intended to favour the release of the oligonucleotide from the acidic endosome. These copolymers were synthesized either statistically (with alternating PDMAEMA and PMEMA fragments) or in blocks (one PDMAEMA block followed by one PMEMA block). MTT assays were performed using the PDMAEMA-PMEMA copolymers and revealed no significant cytotoxicity of these polymers at an N/P ratio of 7.3. Using fluorescent oligonucleotides and analyzing transfection efficiency by flow cytometry, we noticed no significant differences between the two kinds of copolymers. However copolymers with a higher DMAEMA content and a higher Mn were also those displaying the highest vectorization efficiency. Confocal microscopy showed that these copolymers induced a fine granular distribution of the transfected antisense oligonucleotides inside the cells. We also assessed the functionality of the transfected antisense oligonucleotide by transfecting immortalized GFP expressing keratinocytes with a GFP antisense oligonucleotide using these copolymers. A significant silencing was achieved with a PDMAEMA-PMEMA in block copolymer (Mn=41,000, 89 % PDMAEMA). Together, these results suggest that PDMAEMA-PMEMA copolymers combining low toxicity, vectorization and proton sponge properties, can be efficiently used to transfect immortalized keratinocytes and so open new perspectives in the therapy of skin carcinomas as well as of other skin diseases of genetic or immunological origin. © 2012 Informa

Reordering transitions during annealing of block copolymer cylinder phases

DOE PAGES

Majewski, Pawel W.; Yager, Kevin G.

2015-10-06

While equilibrium block-copolymer morphologies are dictated by energy-minimization effects, the semi-ordered states observed experimentally often depend on the details of ordering pathways and kinetics. In this study, we explore reordering transitions in thin films of block-copolymer cylinder-forming polystyrene- block-poly(methyl methacrylate). We observe several transient states as films order towards horizontally-aligned cylinders. In particular, there is an early-stage reorganization from randomly-packed cylinders into hexagonally-packed vertically-aligned cylinders; followed by a reorientation transition from vertical to horizontal cylinder states. These transitions are thermally activated. The growth of horizontal grains within an otherwise vertical morphology proceeds anisotropically, resulting in anisotropic grains in the finalmore » horizontal state. The size, shape, and anisotropy of grains are influenced by ordering history; for instance, faster heating rates reduce grain anisotropy. These results help elucidate aspects of pathway-dependent ordering in block-copolymer thin films.« less

Inducing Order from Disordered Copolymers: On Demand Generation of Triblock Morphologies Including Networks

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

Tureau, Maëva S.; Kuan, Wei-Fan; Rong, Lixia

Disordered block copolymers are generally impractical in nanopatterning applications due to their inability to self-assemble into well-defined nanostructures. However, inducing order in low molecular weight disordered systems permits the design of periodic structures with smaller characteristic sizes. Here, we have induced nanoscale phase separation from disordered triblock copolymer melts to form well-ordered lamellae, hexagonally packed cylinders, and a triply periodic gyroid network structure, using a copolymer/homopolymer blending approach, which incorporates constituent homopolymers into selective block domains. This versatile blending approach allows one to precisely target multiple nanostructures from a single disordered material and can be applied to a wide varietymore » of triblock copolymer systems for nanotemplating and nanoscale separation applications requiring nanoscale feature sizes and/or high areal feature densities.« less

Block copolymer adhesion promoters via ring-opening metathesis polymerization

DOEpatents

Kent, M.S.; Saunders, R.

1997-02-18

Coupling agents are disclosed based on functionalized block copolymers for bonding thermoset polymers to solid materials. These are polymers which possess at least two types of functional groups, one which is able to attach to and react with solid surfaces, and another which can react with a thermoset resin, which are incorporated as pendant groups in monomers distributed in blocks (typically two) along the backbone of the chain. The block copolymers in this invention are synthesized by living ring-opening metathesis polymerization. 18 figs.

MinC/MinD copolymers are not required for Min function

PubMed Central

Park, Kyung-Tae; Du, Shishen; Lutkenhaus, Joe

2015-01-01

Summary In Escherichia coli, precise placement of the cytokinetic Z ring at midcell requires the concerted action of the three Min proteins. MinD activates MinC, an inhibitor of FtsZ, at least in part, by recruiting it to the membrane and targeting it to the Z ring, while MinE stimulates the MinD ATPase inducing an oscillation that directs MinC/MinD activity away from midcell. Recently, MinC and MinD were shown to form copolymers of alternating dimers of MinC and MinD and it was suggested that these copolymers are the active form of MinC/MinD. Here, we use MinD mutants defective in binding MinC to generate heterodimers with wild type MinD that are unable to form MinC/MinD copolymers. Similarly, MinC mutants defective in binding to MinD were used to generate heterodimers with wild type MinC that are unable to form copolymers. Such heterodimers are active and in the case of MinC were shown to mediate spatial regulation of the Z ring demonstrating that MinC/MinD copolymer formation is not required. Our results are consistent with a model in which a membrane anchored MinC/MinD complex is targeted to the Z ring through the conserved carboxy tail of FtsZ leading to breakage of FtsZ filaments. PMID:26268537

Nanostructured Block Copolymer Solutions and Composites: Mechanical and Structural Properties

NASA Astrophysics Data System (ADS)

Walker, Lynn

2015-03-01

Self-assembled block copolymer templates are used to control the nanoscale structure of materials that would not otherwise order in solution. In this work, we have developed a technique to use close-packed cubic and cylindrical mesophases of a thermoreversible block copolymer (PEO-PPO-PEO) to impart spatial order on dispersed nanoparticles. The thermoreversible nature of the template allows for the dispersion of particles synthesized outside the template. This feature extends the applicability of this templating method to many particle-polymer systems, including proteins, and also permits a systematic evaluation of the impact of design parameters on the structure and mechanical properties of the nanocomposites. The criteria for forming co-crystals have been characterized using small-angle scatting and the mechanical properties of these soft crystals determined. Numerous crystal structures have been reported for the block copolymer system and we have taken advantage of several to generate soft co-crystals. The result of this templating is spatially ordered nanoparticle arrays embedded within the block copolymer nanostructure. These soft materials can be shear aligned into crystals with long range order and this shear alignment is discussed. Finally, the dynamics of nanoparticles within the nanostructured material are characterized with fluorescence recovery after photobleaching (FRAP). The applications and general behavior of these nanostructured hydrogels are outlined.

Evaluation of molecular volume change of block copolymer depending on temperature: A SANS study

DOE PAGES

Kim, Tae-Hwan; Do, Changwoo; Han, Young-Soo

2017-12-24

Amphiphilic Pluronic triblock copolymers form various self-assembled structures such as sphere, cylinder, lamellae and so on, depending on temperature, leading to the increase of hydrophobicity of block copolymers. However, the effective molecular volume change of the block copolymer has not been fully exploited yet, when temperature increases. Here in this paper, we have investigated the effective molecular volume change of the block copolymer upon heating by using the contrast variation small angle neutron scattering. The scattering length densities (SLDs) of the block copolymer were experimentally obtained from the neutron scattering contrast variation method between the solvent and the block copolymermore » at varying temperature. Even though the SLD, which is the intrinsic property of the material, should not be changed by temperature elevation, it was dependent on temperature, indicating that the molecular volume is changed. Therefore, we obtained the increase rate of the molecular volume change of the block copolymer (the effective molecular volume change) from the comparison of the calculated SLD and the standard SLD, which is evaluated by plotting the SANS intensity at the first order Bragg peak as the function of temperature at each volume fraction of D 2O and H 2O that is about 25.5%–51.3% depending on temperature.« less

Evaluation of molecular volume change of block copolymer depending on temperature: A SANS study

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

Kim, Tae-Hwan; Do, Changwoo; Han, Young-Soo

Amphiphilic Pluronic triblock copolymers form various self-assembled structures such as sphere, cylinder, lamellae and so on, depending on temperature, leading to the increase of hydrophobicity of block copolymers. However, the effective molecular volume change of the block copolymer has not been fully exploited yet, when temperature increases. Here in this paper, we have investigated the effective molecular volume change of the block copolymer upon heating by using the contrast variation small angle neutron scattering. The scattering length densities (SLDs) of the block copolymer were experimentally obtained from the neutron scattering contrast variation method between the solvent and the block copolymermore » at varying temperature. Even though the SLD, which is the intrinsic property of the material, should not be changed by temperature elevation, it was dependent on temperature, indicating that the molecular volume is changed. Therefore, we obtained the increase rate of the molecular volume change of the block copolymer (the effective molecular volume change) from the comparison of the calculated SLD and the standard SLD, which is evaluated by plotting the SANS intensity at the first order Bragg peak as the function of temperature at each volume fraction of D 2O and H 2O that is about 25.5%–51.3% depending on temperature.« less

Controlled self-assembly of conjugated rod-coil block copolymers for applications in organic optoelectronics

NASA Astrophysics Data System (ADS)

Tao, Yuefei

Organic electronics are of great interest in manufacturing light weight, mechanical flexible, and inexpensive large area devices. While significant improvements have been made over the last several years and it is now clear that morphology on the lengthscale of exciton diffusion (10nm) is of crucial importance, a clear relationship between structure and device properties has not emerged. This lack of understanding largely emerges from an inability to control morphology on this lengthscale. This thesis will center around an approach, based on block copolymer self-assembly, to generate equilibrium nanostructures on the 10 nm lengthscale of exciton diffusion and study their effects on device performance. Self-assembly of semiconducting block copolymers is complicated by the non-classical chain shape of conjugated polymers. Unlike classical polymers, the chains do not assume a Gaussian coil shape which is stretched near block copolymer interfaces, instead the chains are elongated and liquid crystalline. Previous work has demonstrated how these new molecular interactions and shapes control the phase diagram of so-called rod-coil block copolymers. Here, we will focus on controlling domain size, orientation, and chemical structure. While domain size can be controlled directly through molecular weight, this requires significant additional synthesis of domain size is to be varied. Here, the domain size is controlled by blending homopolymers into a self-assembling rod-coil block copolymer. When coil-like blocks are incorporated, the domains swell, as expected. When rod-like blocks are incorporated, they interdigitate with the rods of the block copolymers. This results in an increase in interfacial area which forces the coils to rearrange and an overall decrease in domain size with increasing rod content. Control over lamellar orientation is crucial in order to design and control charge transport pathways and exciton recombination or separation interfaces. While numerous

Millisecond ordering of block-copolymer films via photo-thermal gradients

DOE PAGES

Majewski, Pawel W.; Yager, Kevin G.

2015-03-12

For the promise of self-assembly to be realized, processing techniques must be developed that simultaneously enable control of the nanoscale morphology, rapid assembly, and, ideally, the ability to pattern the nanostructure. Here, we demonstrate how photo-thermal gradients can be used to control the ordering of block-copolymer thin films. Highly localized laser heating leads to intense thermal gradients, which induce a thermophoretic force on morphological defects. This increases the ordering kinetics by at least 3 orders-of-magnitude, compared to conventional oven annealing. By simultaneously exploiting the thermal gradients to induce shear fields, we demonstrate uniaxial alignment of a block-copolymer film in lessmore » than a second. Finally, we provide examples of how control of the incident light-field can be used to generate prescribed configurations of block-copolymer nanoscale patterns.« less

Principle of two-dimensional characterization of copolymers.

PubMed

Weidner, Steffen; Falkenhagen, Jana; Krueger, Ralph-Peter; Just, Ulrich

2007-07-01

Two-dimensional polymer characterization is used for a simultaneous analysis of molar masses and chemical heterogeneities (e.g., end groups, copolymer composition, etc.). This principle is based on coupling of two different chromatographic modes. Liquid adsorption chromatography at critical conditions (LACCC) is applied for a separation according to the chemical heterogeneity, whereas in the second-dimension fractions are analyzed with regard to their molar mass distribution by means of size exclusion chromatography (SEC). Because appropriate standards for a calibration of the SEC are seldom available, matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) was used to substitute the SEC. The LACCC-MALDI MS coupling enables acquiring additional structural information on copolymer composition, which can considerably enhance the performance of this coupled method.

Rapid ordering of block copolymer thin films

NASA Astrophysics Data System (ADS)

Majewski, Pawel W.; Yager, Kevin G.

2016-10-01

Block-copolymers self-assemble into diverse morphologies, where nanoscale order can be finely tuned via block architecture and processing conditions. However, the ultimate usage of these materials in real-world applications may be hampered by the extremely long thermal annealing times—hours or days—required to achieve good order. Here, we provide an overview of the fundamentals of block-copolymer self-assembly kinetics, and review the techniques that have been demonstrated to influence, and enhance, these ordering kinetics. We discuss the inherent tradeoffs between oven annealing, solvent annealing, microwave annealing, zone annealing, and other directed self-assembly methods; including an assessment of spatial and temporal characteristics. We also review both real-space and reciprocal-space analysis techniques for quantifying order in these systems.

Surface functionalization of carbon nanotubes by direct encapsulation with varying dosages of amphiphilic block copolymers

NASA Astrophysics Data System (ADS)

Yao, Xueping; Li, Jie; Kong, Liang; Wang, Yong

2015-08-01

Encapsulation of carbon nanotubes (CNTs) by amphiphilic block copolymers is an efficient way to stabilize CNTs in solvents. However, the appropriate dosages of copolymers and the assembled structures are difficult to predict and control because of the insufficient understanding on the encapsulation process. We encapsulate multiwalled CNTs with polystyrene-block-poly (4-vinyl pyridine) (PS-b-P4VP) by directly mixing them in acetic acid under sonication. The copolymer forms a lamellar structure along the surface of CNTs with the PS blocks anchoring on the tube wall and the P4VP blocks exposed to the outside. The encapsulated CNTs achieve good dispersibility in polar solvents over long periods. To increase our understanding of the encapsulation process we investigate the assembled structures and stability of copolymer/CNTs mixtures with changing mass ratios. Stable dispersions are obtained at high mass ratios between the copolymer and CNTs, i.e. 2 or 3, with the presence of free spherical micelles. Transmission electron microscopy and thermal gravimetric analysis determine that the threshold for the complete coverage of CNTs by the copolymer occurs at the mass ratio of 1.5. The coated copolymer layer activates the surface of CNTs, enabling further functionalization of CNTs. For instance, atomic layer deposition of TiO2 produces conformal thin layers on the encapsulated CNTs while isolated TiO2 bumps are produced on the pristine, inert CNTs.

Structure-property relationships in semicrystalline copolymers and ionomers

NASA Astrophysics Data System (ADS)

Wakabayashi, Katsuyuki

Many outstanding physical properties of ethylene/(meth)acrylic acid (E/(M)AA) copolymers and ionomers are associated with their nanometer-scale morphology, which consists of ethylene crystallites, amorphous segments, and acid/ionic functional groups. The goal of this dissertation is a fundamental understanding of the interplay between these structural motifs and the consequent effects on the material properties. We identify small-strain modulus as a key mechanical property and investigate its dependence upon material structure through X-ray scattering, calorimetry, and mechanical property measurements. We first treat E/(M)AA copolymers as composites of polyethylene crystallites and amorphous regions, and establish a quantitative combining rule to describe the copolymer modulus. At temperatures above the Tg of the copolymers, a monotonic increase in modulus with crystallinity is quantitatively described by the Davies equation for two-phase composites, which serves as the basis for separating the effects of amorphous and crystalline phases throughout this dissertation. The room-temperature modulus of E/(M)AA copolymers is concurrently affected by ethylene crystallinity and proximity to the amorphous phase Tg, which rises through room temperature with increasing comonomer content. In E/(M)AA ionomers, phase separation and aggregation of ionic groups provide additional stiffness and toughness. Ionomers are modeled as composites of crystallites and ionically crosslinked rubber, whose amorphous phase modulus far above the ionomer Tg is satisfactorily described by simple rubber elasticity theory. Thermomechanical analyses probe the multi-step relaxation behavior of E/(M)AA ionomers and lead to the development of a new semicrystalline ionomer morphological model, wherein secondary crystallites and ionic aggregates together form rigid percolated pathways throughout the amorphous phase. Metal soaps are oligomeric analogs of E/(M)AA ionomers, which can be blended into

Non-Surface Activity of Cationic Amphiphilic Diblock Copolymers

NASA Astrophysics Data System (ADS)

Ranjan Nayak, Rati; Yamada, Tasuku; Matsuoka, Hideki

2011-09-01

Cationic amphiphilic diblock copolymers containing quaternized poly (2-vinylpyridine) chain as a hydrophilic segment (PIp-b-PNMe2VP) were synthesized by living anionic polymerization. By IR measurement, we confirmed the quaternization of the polymer (PIp-b-PNMe2VP), and determined the degree of quaternization by conductometric titration. The surface tension experiment showed that the polymers are non-surface active in nature. The foam formation of the polymer solutions was also investigated with or without added salt. Almost no foam formation behavior was observed without added salt, while a little foam was observed in the presence of 1M NaCl. The critical micelle concentration (cmc) of the diblock copolymers with 3 different chain lengths was measured by the static light scattering method. The cmc values obtained in this study were much lower than the values obtained for anionic non-surface active diblock polymers studied previously. The hydrodynamic radii of the polymer micelle increased slightly in the presence of 1 M NaCl. The transmission electron microscopic images revealed spherical micelles in pure water. In the presence of salt, the cmc values increased as was the case for anionic polymers, which is unlike conventional surfactant systems but consistent with non-surface active anionic block copolymers. The microviscosity of the micelle core was evaluated using Coumarin-153 as a fluorescent anisotropy probe using steady-sate fluorescence depolarization. Non-surface activity has been proved to be universal for ionic amphiphilic block copolymers both for anionic and cationic. Hence, the origin of non-surface activity is not the charged state of water surface itself, but should be an image charge repulsion at the air/water interface.

Characterisation of polyhydroxyalkanoate copolymers with controllable four-monomer composition.

PubMed

Dai, Yu; Lambert, Lynette; Yuan, Zhiguo; Keller, Jurg

2008-03-20

Polyhydroxyalkanoate (PHA) copolymers comprising the four monomers 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), 3-hydroxy-2-methylvalerate (3HMV) and 3-hydroxy-2-methylbutyrate (3HMB) were generated using the recently discovered Defluviicoccus vanus-related glycogen accumulating organisms (DvGAOs) under anaerobic conditions without applying any nutrient limitations. The composition could be manipulated in a defined range by modifying the ratio of propionate and acetate provided in the feed stream. The PHAs produced were characterised as random copolymers (from propionate alone) or a mixture of random copolymers (from mixture of propionate and acetate) through microstructure analysis using 13C NMR spectroscopy. The sequence distribution of all eight comonomer pairs in the carbonyl region of 3HB and 3HV was identified and assigned with confidence utilising two-dimensional heteronuclear multiple bond coherence (HMBC) spectroscopy. Weight average molecular weights were in the range 390-560 kg/mol. Differential scanning calorimetry (DSC) traces showed that the melting temperature (Tm) varied between 70 and 161 degrees C and glass transition temperature (Tg) ranged from -8 to 0 degrees C. The incorporation of considerable amounts of 3HMV and 3HMB monomer units introduced additional "defects" into the PHBV copolymer structure and hence greatly lowered the crystallinity. The data indicate the potential of these four-monomer PHAs to be employed for practical applications, considering their favourable properties and the cost-effective production process using a mixed culture and simple carbon sources.

21 CFR 172.808 - Copolymer condensates of ethylene oxide and propylene oxide.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Copolymer condensates of ethylene oxide and... ethylene oxide and propylene oxide. Copolymer condensates of ethylene oxide and propylene oxide may be... percent aqueous solution. (2) α-Hydro-omega-hydroxy-poly (oxy-ethylene)poly(oxypropylene)-(53-59 moles...

Field-theoretic simulations of block copolymer nanocomposites in a constant interfacial tension ensemble.

PubMed

Koski, Jason P; Riggleman, Robert A

2017-04-28

Block copolymers, due to their ability to self-assemble into periodic structures with long range order, are appealing candidates to control the ordering of functionalized nanoparticles where it is well-accepted that the spatial distribution of nanoparticles in a polymer matrix dictates the resulting material properties. The large parameter space associated with block copolymer nanocomposites makes theory and simulation tools appealing to guide experiments and effectively isolate parameters of interest. We demonstrate a method for performing field-theoretic simulations in a constant volume-constant interfacial tension ensemble (nVγT) that enables the determination of the equilibrium properties of block copolymer nanocomposites, including when the composites are placed under tensile or compressive loads. Our approach is compatible with the complex Langevin simulation framework, which allows us to go beyond the mean-field approximation. We validate our approach by comparing our nVγT approach with free energy calculations to determine the ideal domain spacing and modulus of a symmetric block copolymer melt. We analyze the effect of numerical and thermodynamic parameters on the efficiency of the nVγT ensemble and subsequently use our method to investigate the ideal domain spacing, modulus, and nanoparticle distribution of a lamellar forming block copolymer nanocomposite. We find that the nanoparticle distribution is directly linked to the resultant domain spacing and is dependent on polymer chain density, nanoparticle size, and nanoparticle chemistry. Furthermore, placing the system under tension or compression can qualitatively alter the nanoparticle distribution within the block copolymer.

Formation and Characterization of Anisotropic Block Copolymer Gels

NASA Astrophysics Data System (ADS)

Liaw, Chya Yan; Joester, Derk; Burghardt, Wesley; Shull, Kenneth

2012-02-01

Cylindrical micelles formed from block copolymer solutions closely mimic biological fibers that are presumed to guide mineral formation during biosynthesis of hard tissues like bone. The goal of our work is to use acrylic block copolymers as oriented templates for studying mineral formation reactions in model systems where the structure of the underlying template is well characterized and reproducible. Self-consistent mean field theory is first applied to investigate the thermodynamically stable micellar morphologies as a function of temperature and block copolymer composition. Small-angle x-ray scattering, optical birefringence and shear rheometry are used to study the morphology development during thermal processing. Initial experiments are based on a thermally-reversible alcohol-soluble system that can be converted to an aqueous gel by hydrolysis of a poly(t-butyl methacrylate) block to a poly(methacrylic acid) block. Aligned cylindrical domains are formed in the alcohol-based system when shear is applied in an appropriate temperature regime, which is below the critical micelle temperature but above the temperature at which the relaxation time of the gels becomes too large. Processing strategies for producing the desired cylindrical morphologies are being developed that account for both thermodynamic and kinetic effects.

Micellar Packing in Aqueous Solutions of As-Received and Pure Pluronic Block Copolymers

NASA Astrophysics Data System (ADS)

Ryu, Chang; Park, Han Jin

2013-03-01

Pluronic block copolymers (Pluronics) are produced on a commercial scale to enable wide range of novel applications from emulsification and colloidal stabilization as nonionic surfactants. While the Pluronic block copolymers offer the advantages of being readily available for such applications, it contains non-micellizable low molecular weight (MW) impurities that would interfere with the self-assembly and micellar packing of PEO-PPO-PEO triblock copolymers in aqueous solutions. The impacts of the low MW impurities will be discussed on the micellar packing of Pluronics F108 and F127 solutions, which form BCC and FCC. While as-received Pluronic samples typically contain about 20 wt.% low MW impurities, we were able to reduce the impurity level to less than 2 wt.% using our large scale purification technique. Comparative studies on small angle x-ray scattering (SAXS) experiments on as-received and purified Pluronics solutions revealed that the contents of triblock copolymers in solutions essentially governs the inter-micellar distance of Pluronic cubic structures. A universal relationship between triblock copolymer concentration and SAXS-based domain spacing has been finally discussed. Funding from Agency for Defense Development, Korea.

Facile synthesis of main-chain degradable block copolymers for performance enhanced dismantlable adhesion.

PubMed

Sato, Eriko; Hagihara, Takashi; Matsumoto, Akikazu

2012-04-01

Block copolymers consisting of readily degradable polyperoxides and non-degradable vinyl polymers as the block segments were successfully synthesized by reversible chain transfer catalyzed polymerization, which is one of living radical polymerization techniques. The block copolymers showed characteristic morphology and wettability being different from the polymer blends. When block copolymers containing polyperoxide and polymethacrylate blocks were heated below 150 °C, the polyperoxide blocks were completely degraded and the polymethacrylate blocks were recovered without degradation. Block copolymers containing a poly(2-ethylhexyl methacrylate) block were then investigated as a dismantlable adhesion material, which requires adequate bonding strength during use and easy debonding on demand. Among the several block copolymers, the one consisting of poly(2-ethylhexyl methacrylate) and polyperoxide from methyl sorbate (PPMS) (M(n) = 4900) exhibited good performance as a pressure-sensitive adhesive (PSA). After heating the test specimens in a temperature range from 60 to 100 °C, PSA performance, which was evaluated by 180° peel strength and shear holding power measurements, was significantly diminished. Especially, after heating at 100 °C for 1 h, spontaneous debonding of some test specimens was observed because of the evolution of volatile acetaldehyde from PPMS.

21 CFR 177.1480 - Nitrile rubber modified acrylonitrile-methyl acrylate copolymers.

Code of Federal Regulations, 2013 CFR

2013-04-01

...) Specifications. (i) Nitrogen content is in the range 16.5-19 percent as determined by Kjeldahl analysis. (ii... copolymers in the form of particles of a size that will pass through a U.S. standard sieve No. 6 and that will be held on a U.S. standard sieve No. 10: (i) Extracted copolymer not to exceed 2.0 parts per...

21 CFR 177.1480 - Nitrile rubber modified acrylonitrile-methyl acrylate copolymers.

Code of Federal Regulations, 2011 CFR

2011-04-01

...) Specifications. (i) Nitrogen content is in the range 16.5-19 percent as determined by Kjeldahl analysis. (ii... copolymers in the form of particles of a size that will pass through a U.S. standard sieve No. 6 and that will be held on a U.S. standard sieve No. 10: (i) Extracted copolymer not to exceed 2.0 parts per...

21 CFR 177.1480 - Nitrile rubber modified acrylonitrile-methyl acrylate copolymers.

Code of Federal Regulations, 2012 CFR

2012-04-01

...) Specifications. (i) Nitrogen content is in the range 16.5-19 percent as determined by Kjeldahl analysis. (ii... copolymers in the form of particles of a size that will pass through a U.S. standard sieve No. 6 and that will be held on a U.S. standard sieve No. 10: (i) Extracted copolymer not to exceed 2.0 parts per...

The Synthesis and Structural Characterization of Graft Copolymers Composed of γ-PGA Backbone and Oligoesters Pendant Chains

NASA Astrophysics Data System (ADS)

Kwiecień, Iwona; Radecka, Iza; Kowalczuk, Marek; Jelonek, Katarzyna; Orchel, Arkadiusz; Adamus, Grażyna

2017-10-01

The novel copolymers composed of poly-γ-glutamic acid (γ-PGA) and oligoesters have been developed. The structures of the obtained copolymers including variety of end groups were determined at the molecular level with the aid of electrospray ionization multistage mass spectrometry (ESI-MSn). The fragmentation experiment performed for the selected sodium adducts of the copolymers confirmed that the developed methods lead to the formation of graft copolymers composed of poly-γ-glutamic acid (γ-PGA) backbone and oligoesters pendant chains. Moreover, it was established that fragmentation of selected sodium adducts of graft copolymers proceeded via random breakage of amide bonds along the backbone and ester bonds of the oligoesters pendant chains. Considering potential applications of the synthesized copolymers in the area of biomaterials, the hydrolytic degradation under laboratory conditions and in vitro cytotoxicity tests were performed. The ESI-MSn technique applied in this study has been proven to be a useful tool in structural studies of novel graft copolymers as well as their degradation products. [Figure not available: see fulltext.

Addition of poly (propylene glycol) to multiblock copolymer to optimize siRNA delivery.

PubMed

Dai, Zhi; Arévalo, Maria T; Li, Junwei; Zeng, Mingtao

2014-01-01

Previous studies have examined different strategies for siRNA delivery with varying degrees of success. These include use of viral vectors, cationic liposomes, and polymers. Several copolymers were designed and synthesized based on blocks of poly(ethylene glycol) PEG, poly(propylene glycol) PPG, and poly(l-lysine). These were designated as P1, P2, and P3. We studied the copolymer self-assembly, siRNA binding, particle size, surface potential, architecture of the complexes, and siRNA delivery. Silencing of GFP using copolymer P3 to deliver GFP-specific siRNA to Neuro-2a cells expressing GFP was almost as effective as using Lipofectamine 2000, with minimal cytotoxicity. Thus, we have provided a new copolymer platform for siRNA delivery that we can continue to modify for improved delivery of siRNA in vitro and eventually in vivo.

Electrically conductive doped block copolymer of polyacetylene and polyisoprene. [Soluble in organic solvents

DOEpatents

Aldissi, M.

1984-06-27

An electrically conductive block copolymer of polyisoprene and polyacetylene and a method of making the same are disclosed. The polymer is prepared by first polymerizing isoprene with n-butyllithium in a toluene solution to form an active isoprenyllithium polymer. The active polymer is reacted with an equimolar amount of titanium butoxide and subsequently exposed to gaseous acetylene. A block copolymer of polyisoprene and polyacetylene is formed. The copolymer is soluble in common solvents and may be doped with I/sub 2/ to give it an electrical conductivity in the metallic regime.

Organisation and shape of micellar solutions of block copolymers

NASA Astrophysics Data System (ADS)

Gaspard, J. P.; Creutz, S.; Bouchat, Ph.; Jérôme, R.; Cohen Stuart, M.

1997-02-01

Diblock copolymers of polymethacrylic acid sodium salt, forming the hair, and styrene derivatives have been studied in aqueous solutions by SANS and SAXS. The influence of both the chemical nature and the length of the hydrophobic bloxk on the size and shape of micelles have been investigated. The micellar core size is in agreement with the theoretical evaluation for copolymers with a short hydrophobic sequence. In contrast, in case of larger hydrophobic blocks, the measured size is incompatible with a star-like model. Various hypotheses are presented for the latter.

Amino Acid Block Copolymers with Broad Antimicrobial Activity and Barrier Properties.

PubMed

Bevilacqua, Michael P; Huang, Daniel J; Wall, Brian D; Lane, Shalyn J; Edwards, Carl K; Hanson, Jarrod A; Benitez, Diego; Solomkin, Joseph S; Deming, Timothy J

2017-10-01

Antimicrobial properties of a long-chain, synthetic, cationic, and hydrophobic amino acid block copolymer are reported. In 5 and 60 min time-kill assays, solutions of K 100 L 40 block copolymers (poly(l-lysine·hydrochloride) 100 -b-poly(l-leucine) 40 ) at concentrations of 10-100 µg mL -1 show multi-log reductions in colony forming units of Gram-positive and Gram-negative bacteria, as well as yeast, including multidrug-resistant strains. Driven by association of hydrophobic segments, K 100 L 40 copolymers form viscous solutions and self-supporting hydrogels in water at concentrations of 1 and 2 wt%, respectively. These K 100 L 40 preparations provide an effective barrier to microbial contamination of wounds, as measured by multi-log decreases of tissue-associated bacteria with deliberate inoculation of porcine skin explants, porcine open wounds, and rodent closed wounds with foreign body. Based on these findings, amino acid copolymers with the features of K 100 L 40 can combine potent, direct antimicrobial activity and barrier properties in one biopolymer for a new approach to prevention of wound infections. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Separation of Poly(styrene-block-t-butyl methacrylate) Copolymers by Various Liquid Chromatography Techniques

PubMed Central

Šmigovec Ljubič, Tina; Pahovnik, David; Žigon, Majda; Žagar, Ema

2012-01-01

The separation of a mixture of three poly(styrene-block-t-butyl methacrylate) copolymers (PS-b-PtBMA), consisting of polystyrene (PS) blocks of similar length and t-butyl methacrylate (PtBMA) blocks of different lengths, was performed using various chromatographic techniques, that is, a gradient liquid chromatography on reversed-phase (C18 and C8) and normal-phase columns, a liquid chromatography under critical conditions for polystyrene as well as a fully automated two-dimensional liquid chromatography that separates block copolymers by chemical composition in the first dimension and by molar mass in the second dimension. The results show that a partial separation of the mixture of PS-b-PtBMA copolymers can be achieved only by gradient liquid chromatography on reversed-phase columns. The coelution of the two block copolymers is ascribed to a much shorter PtBMA block length, compared to the PS block, as well as a small difference in the length of the PtBMA block in two of these copolymers, which was confirmed by SEC-MALS and NMR spectroscopy. PMID:22489207

Customization of copolymers to optimize selectivity and yield in polymer-driven antibody purification processes.

PubMed

Capito, Florian; Skudas, Romas; Stanislawski, Bernd; Kolmar, Harald

2013-01-01

This manuscript describes customization of copolymers to be used for polymer-driven protein purification in bioprocessing. To understand how copolymer customization can be used for fine-tuning, precipitation behavior was analyzed for five target antibodies (mAbs) and BSA as model impurity protein, at ionic strength similar to undiluted cell culture fluid. In contrast to the use of standardized homopolymers, customized copolymers, composed of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and 4-(acryloylamino)benzoic acid (ABZ), exhibited antibody precipitation yields exceeding 90%. Additionally, copolymer average molecular weight (Mw ) was varied and its influence on precipitation yield and contaminant coprecipitation was investigated. Results revealed copolymer composition as the major driving force for precipitation selectivity, which was also dependent on protein hydrophobicity. By adjusting ABZ content and Mw of the precipitant for each of the mAbs, conditions were found that allowed for high precipitation yield and selectivity. These findings may open up new avenues for using polymers in antibody purification processes. © 2013 American Institute of Chemical Engineers.

Universal Ferroelectric Switching Dynamics of Vinylidene Fluoride-trifluoroethylene Copolymer Films

PubMed Central

Hu, Wei Jin; Juo, Deng-Ming; You, Lu; Wang, Junling; Chen, Yi-Chun; Chu, Ying-Hao; Wu, Tom

2014-01-01

In this work, switching dynamics of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer films are investigated over unprecedentedly wide ranges of temperature and electric field. Remarkably, domain switching of copolymer films obeys well the classical domain nucleation and growth model although the origin of ferroelectricity in organic ferroelectric materials inherently differs from the inorganic counterparts. A lower coercivity limit of 50 MV/m and 180° domain wall energy of 60 mJ/m2 are determined for P(VDF-TrFE) films. Furthermore, we discover in copolymer films an anomalous temperature-dependent crossover behavior between two power-law scaling regimes of frequency-dependent coercivity, which is attributed to the transition between flow and creep motions of domain walls. Our observations shed new light on the switching dynamics of semi-crystalline ferroelectric polymers, and such understandings are critical for realizing their reliable applications. PMID:24759786

21 CFR 177.1570 - Poly-1-butene resins and butene/ethylene copolymers.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Poly-1-butene resins and butene/ethylene... Substances for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1570 Poly-1-butene resins and butene/ethylene copolymers. The poly-1-butene resins and butene/ethylene copolymers...

Effect of nanoscale morphology on selective ethanol transport through block copolymer membranes

USDA-ARS?s Scientific Manuscript database

We report on the effect of block copolymer domain size on transport of liquid mixtures through the membranes by presenting pervaporation data of an 8 wt% ethanol/water mixture through A-B-A and B-A-B triblock copolymer membranes. The A-block was chosen to facilitate ethanol transport while the B-blo...

Synthesis and morphology of hydroxyapatite/polyethylene oxide nanocomposites with block copolymer compatibilized interfaces

NASA Astrophysics Data System (ADS)

Lee, Ji Hoon; Shofner, Meisha

2012-02-01

In order to exploit the promise of polymer nanocomposites, special consideration should be given to component interfaces during synthesis and processing. Previous results from this group have shown that nanoparticles clustered into larger structures consistent with their native shape when the polymer matrix crystallinity was high. Therefore in this research, the nanoparticles are disguised from a highly-crystalline polymer matrix by cloaking them with a matrix-compatible block copolymer. Specifically, spherical and needle-shaped hydroxyapatite nanoparticles were synthesized using a block copolymer templating method. The block copolymer used, polyethylene oxide-b-polymethacrylic acid, remained on the nanoparticle surface following synthesis with the polyethylene oxide block exposed. These nanoparticles were subsequently added to a polyethylene oxide matrix using solution processing. Characterization of the nanocomposites indicated that the copolymer coating prevented the nanoparticles from assembling into ordered clusters and that the matrix crystallinity was decreased at a nanoparticle spacing of approximately 100 nm.

Synthesis of Eugenol–Lauryl Methacrylate Copolymers via Cationic Polymerization

NASA Astrophysics Data System (ADS)

Fajrin, A.; Marliana, SD; Handayani, D. S.

2018-04-01

Eugenol is one of the most abundant natural resources in Indonesia. The recently bio-based polymer resin is created based on eugenol because eugenol is functionalized with the polymerizable group. In order to improve the functional properties of eugenol, in this research Eugenol–Lauryl Methacrylate copolymers (co-poly(Eg-LMA)) were synthesized by cationic polymerization using H2SO4 as an initiator under the nitrogen atmosphere. Structure identification of the copolymer showed the absorption of the vinyl group from the monomers disappear at the analysis through FTIR at the wave number 1637-1639 and 985-995 cm-1 and also 1H-NMR on the chemical shift 5,97 and 5,08 ppm. The resulting copolymers obtained brown powder in 32.03 % yieldsand melting point at 96 – 97 °C. Solubility test of the co-poly(Eg-LMA) showed that the polymer couldnot soluble in water but soluble in chloroform, diethyl ether, and benzene. Average molecular weight of co-poly(Eg-LMA) Led Ostwald viscometry was obtained 42020 with the degree of polymerization by 200.

Assessment of PLGA-PEG-PLGA Copolymer Hydrogel for Sustained Drug Delivery in the Ear

PubMed Central

Feng, Liang; Ward, Jonette A.; Li, S. Kevin; Tolia, Gaurav; Hao, Jinsong; Choo, Daniel I.

2014-01-01

Temperature sensitive copolymer systems were previously studied using modified diffusion cells in vitro for intratympanic injection, and the PLGA-PEG-PLGA copolymer systems were found to provide sustained drug delivery for several days. The objectives of the present study were to assess the safety of PLGA-PEG-PLGA copolymers in intratympanic injection in guinea pigs in vivo and to determine the effects of additives glycerol and poloxamer in PLGA-PEG-PLGA upon drug release in the diffusion cells in vitro for sustained inner ear drug delivery. In the experiments, the safety of PLGA-PEG-PLGA copolymers to inner ear was evaluated using auditory brainstem response (ABR). The effects of the additives upon drug release from PLGA-PEG-PLGA hydrogel were investigated in the modified Franz diffusion cells in vitro with cidofovir as the model drug. The phase transition temperatures of the PLGA-PEG-PLGA copolymers in the presence of the additives were also determined. In the ABR safety study, the PLGA-PEG-PLGA copolymer alone did not affect hearing when delivered at 0.05-mL dose but caused hearing loss after 0.1-mL injection. In the drug release study, the incorporation of the bioadhesive additive, poloxamer, in the PLGA-PEG-PLGA formulations was found to decrease the rate of drug release whereas the increase in the concentration of the humectant additive, glycerol, provided the opposite effect. In summary, the PLGA-PEG-PLGA copolymer did not show toxicity to the inner ear at the 0.05-mL dose and could provide sustained release that could be controlled by using the additives for inner ear applications. PMID:24438444

Rapid ordering of block copolymer thin films

DOE PAGES

Majewski, Pawel W.; Yager, Kevin G.

2016-08-18

Block-copolymers self-assemble into diverse morphologies, where nanoscale order can be finely tuned via block architecture and processing conditions. However, the ultimate usage of these materials in real-world applications may be hampered by the extremely long thermal annealing times—hours or days—required to achieve good order. Here, we provide an overview of the fundamentals of block-copolymer self-assembly kinetics, and review the techniques that have been demonstrated to influence, and enhance, these ordering kinetics. We discuss the inherent tradeoffs between oven annealing, solvent annealing, microwave annealing, zone annealing, and other directed self-assembly methods; including an assessment of spatial and temporal characteristics. Here, wemore » also review both real-space and reciprocal-space analysis techniques for quantifying order in these systems.« less

Salt-Induced Block Copolymer Micelles as Nanoreactors for the Formation of CdS Nanoparticles

DTIC Science & Technology

2001-11-01

or corona of micelles is presented. Poly(styrene-block-2-vinylpyridine) ( PS - b - P2VP ) and cadmium ions form aggregates of single micelles, called...ratio and block copolymer concentration in THF etc. EXPERIMENTAL DETAILS The synthesis of the PS - b - P2VP block copolymer was performed using sequential...nanoparticles: PS - b - P2VP block copolymer was dissolved in THF at different concentrations under vigorous stirring for 1 hour. Cd(Ac)2.2H 20 dissolved in a

Microphase separation in thin films of lamellar forming polydisperse di-block copolymers

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

Kumar, Rajeev; Lokitz, Bradley S.; Sides, Scott W.

Despite the ubiquity of polydispersity in chain lengths of di-block copolymers, its effects on microphase separation in thin films have eluded a clear understanding. In this paper, we have studied effects of polydispersity on the microphase separation in thin films of lamellar forming di-block copolymers using self-consistent field theory (SCFT) and neutron reflectivity experiments. Di-block copolymers containing a polydisperse block of poly(glycidylmethacrylate) (PGMA) connected to a near-monodisperse block poly(2-vinyl-4,4-dimethyl-d 6 azlactone) (PVDMA-d 6) are considered in this work. Effects of chain length polydispersity, film thickness, substrate–monomer and monomer–monomer interactions on the microphase segregation are studied using SCFT. The theoretical studymore » reveals that in comparison to a film created with monodisperse di-block copolymers, an increase in polydispersity tends to decrease the number of lamellar strata that can be packed in a film of given thickness. This is a direct consequence of an increase in lamellar domain spacing with an increase in polydispersity index. Furthermore, it is shown that polydispersity induces conformational asymmetry and an increase in the polydispersity index leads to an increase in the effective Kuhn segment length of the polydisperse blocks. It is shown that the conformational asymmetry effects, which are entropic in origin and of increasing importance as film thickness decreases, drive the polydisperse blocks to the middle of the films despite favorable substrate interactions. These predictions are verified by results from neutron reflectivity experiments on thin films made from moderately polydisperse PGMA-PVDMA-d 6 di-block copolymer deposited on silicon substrates. In conclusion, results from SCFT are used to predict neutron reflectivity profiles, providing a facile and robust route to obtain useful physical insights into the structure of polydisperse diblock copolymers at interfaces.« less

Microphase separation in thin films of lamellar forming polydisperse di-block copolymers

DOE PAGES

Kumar, Rajeev; Lokitz, Bradley S.; Sides, Scott W.; ...

2015-02-03

Despite the ubiquity of polydispersity in chain lengths of di-block copolymers, its effects on microphase separation in thin films have eluded a clear understanding. In this paper, we have studied effects of polydispersity on the microphase separation in thin films of lamellar forming di-block copolymers using self-consistent field theory (SCFT) and neutron reflectivity experiments. Di-block copolymers containing a polydisperse block of poly(glycidylmethacrylate) (PGMA) connected to a near-monodisperse block poly(2-vinyl-4,4-dimethyl-d 6 azlactone) (PVDMA-d 6) are considered in this work. Effects of chain length polydispersity, film thickness, substrate–monomer and monomer–monomer interactions on the microphase segregation are studied using SCFT. The theoretical studymore » reveals that in comparison to a film created with monodisperse di-block copolymers, an increase in polydispersity tends to decrease the number of lamellar strata that can be packed in a film of given thickness. This is a direct consequence of an increase in lamellar domain spacing with an increase in polydispersity index. Furthermore, it is shown that polydispersity induces conformational asymmetry and an increase in the polydispersity index leads to an increase in the effective Kuhn segment length of the polydisperse blocks. It is shown that the conformational asymmetry effects, which are entropic in origin and of increasing importance as film thickness decreases, drive the polydisperse blocks to the middle of the films despite favorable substrate interactions. These predictions are verified by results from neutron reflectivity experiments on thin films made from moderately polydisperse PGMA-PVDMA-d 6 di-block copolymer deposited on silicon substrates. In conclusion, results from SCFT are used to predict neutron reflectivity profiles, providing a facile and robust route to obtain useful physical insights into the structure of polydisperse diblock copolymers at interfaces.« less

Microphase separation in thin films of lamellar forming polydisperse di-block copolymers

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

Kumar, Rajeev; Lokitz, Bradley S.; Sides, Scott W.

Despite the ubiquity of polydispersity in chain lengths of di-block copolymers, its effects on microphase separation in thin films have eluded a clear understanding. In this work, we have studied effects of polydispersity on the microphase separation in thin films of lamellar forming di-block copolymers using self-consistent field theory (SCFT) and neutron reflectivity experiments. Di-block copolymers containing a polydisperse block of poly(glycidylmethacrylate) (PGMA) connected to a near-monodisperse block poly(2-vinyl-4,4-dimethyl-d6 azlactone) (PVDMA-d6) are considered in this work. Effects of chain length polydispersity, film thickness, substrate-monomer and monomer-monomer interactions on the microphase segregation are studied using SCFT. The theoretical study reveals thatmore » in comparison to a film created with monodisperse di-block copolymers, an increase in polydispersity tends to decrease the number of lamellar strata that can be packed in a film of given thickness. This is a direct consequence of an increase in lamellar domain spacing with an increase in polydispersity index. Furthermore, it is shown that polydispersity induces conformational asymmetry and an increase in the polydispersity index leads to an increase in the effective Kuhn segment length of the polydisperse blocks. It is shown that the conformational asymmetry effects, which are entropic in origin and of increasing importance as film thickness decreases, drive the polydisperse blocks to the middle of the films despite favorable substrate interactions. These predictions are verified by results from neutron reflectivity experiments on thin films made from moderately polydisperse PGMA-PVDMA-d6 di-block copolymer deposited on silicon substrates. Finally, results from SCFT are used to predict neutron reflectivity profiles, providing a facile and robust route to obtain useful physical insights into the structure of polydisperse diblock copolymers at interfaces.« less

Achieving Continuous Anion Transport Domains Using Block Copolymers Containing Phosphonium Cations

DOE PAGES

Zhang, Wenxu; Liu, Ye; Jackson, Aaron C.; ...

2016-06-22

Triblock and diblock copolymers based on isoprene (Ip) and chloromethylstyrene (CMS) were synthesized in this paper by sequential polymerization using reversible addition–fragmentation chain transfer radical polymerization (RAFT). The block copolymers were quaternized with tris(2,4,6-trimethoxyphenyl)phosphine (Ar 3P) to prepare soluble ionomers. The ionomers were cast from chloroform to form anion exchange membranes (AEMs) with highly ordered morphologies. At low volume fractions of ionic blocks, the ionomers formed lamellar morphologies, while at moderate volume fractions (≥30% for triblock and ≥22% for diblock copolymers) hexagonal phases with an ionic matrix were observed. Ion conductivities were higher through the hexagonal phase matrix than inmore » the lamellar phases. Finally, promising chloride conductivities (20 mS/cm) were achieved at elevated temperatures and humidified conditions.« less

Highχ block copolymers for directed self-assembly patterning without the need for topcoat or solvent annealing

NASA Astrophysics Data System (ADS)

Xu, Kui; Hockey, Mary Ann; Calderas, Eric; Guerrero, Douglas; Sweat, Daniel; Fiehler, Jeffrey

2017-03-01

High-χ block copolymers for directed self-assembly (DSA) patterning that do not need topcoat or solvent annealing have been developed. A variety of functionalities have been successfully added into the block copolymers, such as balanced surface energy between the polymer blocks, outstandingly high χ, tunable glass transition temperature (Tg), and selective crosslinking. Perpendicular orientation control, as desired for patterning, of the block copolymers can be simply achieved by thermal annealing due to the equal surface energy of the polymer blocks at the annealing temperatures, which allows avoiding solvent annealing or top-coat. The χ value can be tuned up to achieve L0 as low as 8-10 nm for lamellar-structured block copolymers and hole/pillar size as small as 5-6 nm for cylinder-structured block copolymers. The Tg of the block copolymers can be tuned to improve the kinetics of thermal annealing by enhancing the polymer chain mobility. Block-selective crosslinking facilitates the pattern transfer by mitigating pattern collapse during wet etching and improving oxygen plasma etching selectivity between the polymer blocks. This paper provides an introductory review of our high-χ block copolymer materials with various functionalities for achieving improved DSA performance.

21 CFR 177.2470 - Polyoxymethylene copolymer.

Code of Federal Regulations, 2014 CFR

2014-04-01

... paragraph (a) of this section may contain optional adjuvant substances required in its production. The quantity of any optional adjuvant substance employed in the production of the copolymer does not exceed the... (3,5-di-tert-butyl-4-hydroxyhydrocinnamate)] methane. (2) Lubricant: N,N′Distearoylethyl-enediamine...

Inverse design of bulk morphologies in block copolymers using particle swarm optimization

NASA Astrophysics Data System (ADS)

Khadilkar, Mihir; Delaney, Kris; Fredrickson, Glenn

Multiblock polymers are a versatile platform for creating a large range of nanostructured materials with novel morphologies and properties. However, achieving desired structures or property combinations is difficult due to a vast design space comprised of parameters including monomer species, block sequence, block molecular weights and dispersity, copolymer architecture, and binary interaction parameters. Navigating through such vast design spaces to achieve an optimal formulation for a target structure or property set requires an efficient global optimization tool wrapped around a forward simulation technique such as self-consistent field theory (SCFT). We report on such an inverse design strategy utilizing particle swarm optimization (PSO) as the global optimizer and SCFT as the forward prediction engine. To avoid metastable states in forward prediction, we utilize pseudo-spectral variable cell SCFT initiated from a library of defect free seeds of known block copolymer morphologies. We demonstrate that our approach allows for robust identification of block copolymers and copolymer alloys that self-assemble into a targeted structure, optimizing parameters such as block fractions, blend fractions, and Flory chi parameters.

Phase transition of LB films of mixed diblock copolymer at the air/water interface

NASA Astrophysics Data System (ADS)

Seo, Y. S.; Kim, K. S.; Samuilov, V.; Rafailovich, M. H.; Sokolov, J.; Lammertink, Rob G. H.; Vancso, G. J.

2000-03-01

We have studied the morphology of Langmuir blodgett films at the air/water interface of mixed diblock copolymer films. Solutions of poly(styrene-b-ferrocenyldimethylsilane) and PS-b-P2VP mixed in a ratio of 20/80 in chloroform were spread at the air/water interface. The morphology of the films was studied with AFM as a function of the surface pressure and the diblock copolymer molecular weight. The results show that the two diblock copolymers can be induced to mix at the air/water interface with increasing surface pressure. A reversible transition from spherical to cylindrical morphologies is induced in the mixture which can not be observed in films formed of the two components separately. The effective surface phase diagram as a function of block copolymer composition and pressure will be presented.

Anomalous Micellization of Pluronic Block Copolymers

NASA Astrophysics Data System (ADS)

Leonardi, Amanda; Ryu, Chang Y.

2014-03-01

Poly(ethylene oxide) - poly(propylene oxide) - poly(ethylene oxide) (PEO-PPO-PEO) block copolymers, commercially known as Pluronics, are a unique family of amphiphilic triblock polymers, which self-assemble into micelles in aqueous solution. These copolymers have shown promise in therapeutic, biomedical, cosmetic, and nanotech applications. As-received samples of Pluronics contain low molecular weight impurities (introduced during the manufacturing and processing), that are ignored in most applications. It has been observed, however, that in semi-dilute aqueous solutions, at concentrations above 1 wt%, the temperature dependent micellization behavior of the Pluronics is altered. Anomalous behavior includes a shift of the critical micellization temperature and formation of large aggregates at intermediate temperatures before stable sized micelles form. We attribute this behavior to the low molecular weight impurities that are inherent to the Pluronics which interfere with the micellization process. Through the use of Dynamic Light Scattering and HPLC, we compared the anomalous behavior of different Pluronics of different impurity levels to their purified counterparts.

Location-Specific Measurements of The Glass Transition Temperature in Fluorescently Labeled Diblock Copolymers

NASA Astrophysics Data System (ADS)

Christie, Dane; Register, Richard; Priestley, Rodney

Block copolymers can self-assemble into periodic structures containing a high internal surface area, nanoscale domain periods, and periodically varying composition profiles. Depending on their components, block copolymers may also exhibit variations in their dynamic properties e.g., glass transition temperature (Tg) across the domain period. Measuring the variation of Tg across the domain period of block copolymers has remained a significant challenge due to the nanometer length scale of the domain period. Here we use fluorescence spectroscopy and the selective incorporation of a pyrene-containing methacrylate monomer at various positions along the chain to characterize the distribution of glass transition temperatures across the domain period of an amorphous block copolymer. The pyrene-containing monomer location is determined from the monomer segment distribution calculated using self-consistent field theory. Our model system is a lamella-forming diblock copolymer of poly(butyl methacrylate - b- methyl methacrylate). We show that Tg is asymmetrically distributed across the interface; as the interface is approached, larger gradients in Tg exist in the hard PMMA-rich domain than in the soft PBMA-rich domain. By characterizing Tg of PBMA or PMMA interfacial segments, we show that polymer dynamics at the interface are heterogeneous; there is a 15 K difference in Tg measured between PBMA interfacial segments and PMMA interfacial segments.

Synthesis and characterization of donor-acceptor copolymers carrying triphenylamine units for photovoltaic applications

NASA Astrophysics Data System (ADS)

Neumann, Katharina; Thelakkat, Mukundan

2012-09-01

The synthesis and analysis of solution processable polymers for organic solar cells is crucial for innovative solar cell technologies such as printing processes. In the field of donor materials for photovoltaic applications, polymers based on tetraphenylamine (TPA) are well known hole conducting materials. Here, we synthesized two conjugated TPA containing copolymers via Suzuki polycondensation. We investigated the tuning of the energy levels of the TPA based polymers by two different concepts. Firstly, we introduced an acceptor unit in the side chain. The main-chain of this copolymer was built from TPA units. The resulting copolymer 2-(4-((4'-((4-(2-ethylhexyloxy)phenyl)(paratolyl) amino)biphenyl-4-yl)(para-tolyl)amino)benzylidene) malononitrile P1 showed a broader absorption up to 550 nm. Secondly, we used a donor-acceptor concept by synthesizing a copolymer with alternating electron donating TPA and electron withdrawing Thieno[3,4-b]thiophene ester units. Consequently, the absorption maximum in the copolymer octyl-6-(4-((4-(2-ethylhexyloxy)phenyl)(p-tolyl)amino)phenyl)-4-methylthieno[3,4-b]thiophene-2-carboxylate P2 was red shifted to 580 nm. All three polymers showed high thermal stability. By UV-vis and Cyclic voltammetry measurements the optical and electrochemical properties of the polymers were analyzed.

Ion Conduction in Perfectly Aligned Block Copolymer-Ionic Liquid Mixtures

NASA Astrophysics Data System (ADS)

Choi, Jae-Hong; Elabd, Yossef A.; Winey, Karen I.

2011-03-01

Our earlier work to correlate the transport measurements in diblock copolymer-ionic liquid mixtures was limited by our bulk samples that have only partial alignment. Here, thin films with perfect alignment of lamellar microdomains from mixtures of a poly(methyl methacrylate- b -styrene) diblock copolymer and an ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, have been studied. The morphologies will be characterized by cross-sectional transmission electron microscopy. Ion conduction will be presented within and through the thin film.

pH-sensitive methacrylic copolymer gels and the production thereof

DOEpatents

Mallapragada, Surya K [Ames, IA; Anderson, Brian C [Lake Bluff, IA

2007-05-15

The present invention provides novel gel forming methacrylic blocking copolymers that exhibit cationic pH-sensitive behavior as well as good water solubility. The copolymers are constructed by polymerization of a tertiary amine methacrylate with either a (poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) polymer, such as the commercially available Pluronic.RTM. polymers, or a poly(ethylene glycol)methyl ether polymer. The polymers may be used for drug and gene delivery, protein separation, as structural supplements, and more.

Interactions of poly(tert-butyl acrylate)-poly(styrene) diblock copolymers with lipids at the air-water interface.

PubMed

Mudgil, Poonam; Dennis, Gary R; Millar, Thomas J

2006-08-29

Diblock copolymers with hydrophilic poly(tert-butyl acrylate) (PtBA) and hydrophobic poly(styrene) (PS) blocks were synthesized with a view to use them as a surfactant in tear film for increasing the ocular comfort in dry eye syndrome. Interactions of six PtBA-PS copolymers with four important lipids found in the tear film, namely cholesterol, cholesteryl palmitate, dipalmitoyl phosphatidylcholine, and phosphatidylinositol, were studied at the air-water interface using a Langmuir trough. Thermodynamics of mixing of the copolymers and the lipids in the mixed monolayers was determined by calculating excess free energy of mixing. The diblock copolymers showed repulsive interactions with cholesteol and cholesteryl palmitate, near neutral interactions with dipalmitoyl phosphatidylcholine, and attractive interactions with phosphatidylinositol. The lipids interacted with the PS component of the copolymer. The results indicate that a copolymer with a small hydrophilic group and a big hydrophobic group can be a likely candidate for forming stable interactions with the lipids present in the tear film and hence increase the ocular comfort.

Electrochemical Deposition Of Conductive Copolymers

NASA Technical Reports Server (NTRS)

Nagasubramanian, Ganesan; Distefano, Salvador; Liang, Ranty H.

1991-01-01

Experiments show electrically conductive films are deposited on glassy carbon or indium tin oxide substrates by electrochemical polymerization of N-{(3-trimethoxy silyl) propyl} pyrrole or copolymerization with pyrrole. Copolymers of monomer I and pyrrole exhibit desired electrical conductivity as well as desired adhesion and other mechanical properties. When fully developed, new copolymerization process useful in making surface films of selectable conductivity.

[Antiviral and immunostimulating effect of maleic anhydride copolymers in experimental neuroviral infections].

PubMed

Davydova, A A; Stotskaia, L L; Berezina, L K; Osipova, L V; Barinskiĭ, I F

1986-01-01

The virus-inhibiting and immunostimulating activity of Soviet preparations, maleic anhydride copolymers, was demonstrated in alpha-, flavi-, and bunyavirus infections. Positive results were obtained in subcutaneous and intraperitoneal inoculations of the preparations used in prophylactic and therapeutic-prophylactic schedules. Stimulation of vaccination immunity was observed after combined use of copolymers and the vaccine against Eastern equine encephalomyelitis.

Anomalistic Self-Assembled Phase Behavior of Block Copolymer Blended with Organic Derivative Depending on Temperature

DOE PAGES

Kim, Tae-Hwan; Kim, Eunhye; Do, Changwoo; ...

2016-08-16

Amphiphilic Pluronic block copolymers have attracted great attention in a broad spectrum of potential applications due to the excellent phase behaviors in an aqueous solution, and many efforts have been made to investigate their phase behaviors under various external conditions. With a variety of external conditions, however, the closed looplike phase behaviors of a Pluronic block copolymer in an aqueous solution have not been reported yet. Herein, we report the closed looplike (CLL) phase behavior of a Pluronic P65 triblock copolymer blended with an organic derivative, 5-methylsalicylic acid (5mS), in aqueous solution, which is very unique for block copolymers. Asmore » the 5mS concentration increases, the isotropic to ordered phase or back to isotropic phase transition temperature is decreased while the number of closed loops is increased to two. To the best of our knowledge, this is the first demonstration of a CLL phase transition of a Pluronic block copolymer in an aqueous solution, which is readily applicable to optical devices such as optical sensors or optoelectronics, and nanotemplates for a highly ordered superlattice. Additionally, this provides new insight into the understanding on the phase behavior of a Pluronic block copolymer blended with additives.« less

Anomalistic Self-Assembled Phase Behavior of Block Copolymer Blended with Organic Derivative Depending on Temperature

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

Kim, Tae-Hwan; Kim, Eunhye; Do, Changwoo

Amphiphilic Pluronic block copolymers have attracted great attention in a broad spectrum of potential applications due to the excellent phase behaviors in an aqueous solution, and many efforts have been made to investigate their phase behaviors under various external conditions. With a variety of external conditions, however, the closed looplike phase behaviors of a Pluronic block copolymer in an aqueous solution have not been reported yet. Herein, we report the closed looplike (CLL) phase behavior of a Pluronic P65 triblock copolymer blended with an organic derivative, 5-methylsalicylic acid (5mS), in aqueous solution, which is very unique for block copolymers. Asmore » the 5mS concentration increases, the isotropic to ordered phase or back to isotropic phase transition temperature is decreased while the number of closed loops is increased to two. To the best of our knowledge, this is the first demonstration of a CLL phase transition of a Pluronic block copolymer in an aqueous solution, which is readily applicable to optical devices such as optical sensors or optoelectronics, and nanotemplates for a highly ordered superlattice. Additionally, this provides new insight into the understanding on the phase behavior of a Pluronic block copolymer blended with additives.« less

Lignin-derived thermoplastic co-polymers and methods of preparation

DOEpatents

Naskar, Amit K.; Saito, Tomonori; Pickel, Joseph M.; Baker, Frederick S.; Eberle, Claude Clifford; Norris, Robert E.; Mielenz, Jonathan Richard

2014-06-10

The present invention relates to a crosslinked lignin comprising a lignin structure having methylene or ethylene linking groups therein crosslinking between phenyl ring carbon atoms, wherein said crosslinked lignin is crosslinked to an extent that it has a number-average molecular weight of at least 10,000 g/mol, is melt-processible, and has either a glass transition temperature of at least 100.degree. C., or is substantially soluble in a polar organic solvent or aqueous alkaline solution. Thermoplastic copolymers containing the crosslinked lignin are also described. Methods for producing the crosslinked lignin and thermoplastic copolymers are also described.

Amphiphilic graft copolymers from end-functionalized starches: synthesis, characterization, thin film preparation, and small molecule loading.

PubMed

Ryno, Lisa M; Reese, Cassandra; Tolan, McKenzie; O'Brien, Jeffrey; Short, Gabriel; Sorriano, Gerardo; Nettleton, Jason; Fulton, Kayleen; Iovine, Peter M

2014-08-11

End-functionalized macromolecular starch reagents, prepared by reductive amination, were grafted onto a urethane-linked polyester-based backbone using copper-catalyzed azide-alkyne cycloaddition (CuAAC) chemistry to produce novel amphiphilic hybrid graft copolymers. These copolymers represent the first examples of materials where the pendant chains derived from starch biopolymers have been incorporated into a host polymer by a grafting-to approach. The graft copolymers were prepared in good yields (63-90%) with high grafting efficiencies (66-98%). Rigorous quantitative spectroscopic analyses of both the macromolecular building blocks and the final graft copolymers provide a comprehensive analytical toolbox for deciphering the reaction chemistry. Due to the modular nature of both the urethane-linked polyester synthesis and the postpolymerization modification, the starch content of these novel hybrid graft copolymers was easily tuned from 28-53% (w/w). The uptake of two low molecular weight guest molecules into the hybrid polymer thin films was also studied. It was found that binding of 1-naphthol and pterostilbene correlated linearly with amount of starch present in the hybrid polymer. The newly synthesized graft copolymers were highly processable and thermally stable, therefore, opening up significant opportunities in film and coating applications. These results represent a proof-of-concept system for not only the construction of starch-containing copolymers, but also the loading of these novel polymeric materials with active agents.

Structure and Dynamics Ionic Block co-Polymer Melts: Computational Study

NASA Astrophysics Data System (ADS)

Aryal, Dipak; Perahia, Dvora; Grest, Gary S.

Tethering ionomer blocks into co-polymers enables engineering of polymeric systems designed to encompass transport while controlling structure. Here the structure and dynamics of symmetric pentablock copolymers melts are probed by fully atomistic molecular dynamics simulations. The center block consists of randomly sulfonated polystyrene with sulfonation fractions f = 0 to 0.55 tethered to a hydrogenated polyisoprene (PI), end caped with poly(t-butyl styrene). We find that melts with f = 0.15 and 0.30 consist of isolated ionic clusters whereas melts with f = 0.55 exhibit a long-range percolating ionic network. Similar to polystyrene sulfonate, a small number of ionic clusters slow the mobility of the center of mass of the co-polymer, however, formation of the ionic clusters is slower and they are often intertwined with PI segments. Surprisingly, the segmental dynamics of the other blocks are also affected. NSF DMR-1611136; NERSC; Palmetto Cluster Clemson University; Kraton Polymers US, LLC.

Kinetic control of block copolymer self-assembly into multicompartment and novel geometry nanoparticles

NASA Astrophysics Data System (ADS)

Chen, Yingchao; Wang, Xiaojun; Zhang, Ke; Wooley, Karen; Mays, Jimmy; Percec, Virgil; Pochan, Darrin

2012-02-01

Micelles with the segregation of hydrophobic blocks trapped in the same nanoparticle core have been produced through co-self-assembly of two block copolymers in THF/water dilute solution. The dissolution of two block copolymer sharing the same polyacrylic acid PAA blocks in THF undergoes consequent aggregation and phase separation through either slow water titration or quick water addition that triggers the micellar formation. The combination and comparison of the two water addition kinetic pathways are the keys of forming multicompartment structures at high water content. Importantly, the addition of organic diamine provides for acid-base complexation with the PAA side chains which, in turn, plays the key role of trapping unlike hydrophobic blocks from different block copolymers into one nanoparticle core. The kinetic control of solution assembly can be applied to other molecular systems such as dendrimers as well as other block copolymer molecules. Transmission electron microscopy, cryogenic transmission electron microscopy, light scattering have been applied to characterize the micelle structures.

21 CFR 180.22 - Acrylonitrile copolymers.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Acrylonitrile copolymers. 180.22 Section 180.22 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Drug Administration, 5100 Paint Branch Pkwy., College Park, MD 20740, or available for inspection at...

21 CFR 180.22 - Acrylonitrile copolymers.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Acrylonitrile copolymers. 180.22 Section 180.22 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Drug Administration, 5100 Paint Branch Pkwy., College Park, MD 20740, or available for inspection at...

21 CFR 180.22 - Acrylonitrile copolymers.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Acrylonitrile copolymers. 180.22 Section 180.22 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Drug Administration, 5100 Paint Branch Pkwy., College Park, MD 20740, or available for inspection at...

21 CFR 180.22 - Acrylonitrile copolymers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Acrylonitrile copolymers. 180.22 Section 180.22 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Drug Administration, 5100 Paint Branch Pkwy., College Park, MD 20740, or available for inspection at...

RAFT polymerization of temperature- and salt-responsive block copolymers as reversible hydrogels.

PubMed

Hemp, Sean T; Smith, Adam E; Bunyard, W Clayton; Rubinstein, Michael H; Long, Timothy E

2014-05-13

Reversible-addition fragmentation chain transfer (RAFT) polymerization enabled the synthesis of novel, stimuli-responsive, AB and ABA block copolymers. The B block contained oligo(ethylene glycol) methyl ether methacrylate (OEG) and was permanently hydrophilic in the conditions examined. The A block consisted of diethylene glycol methyl ether methacrylate (DEG) and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (TMA). The A block displayed both salt- and temperature-response with lower critical solution temperatures (LCSTs) dependent on the molar content of TMA and the presence of salt. Higher TMA content in the AB diblock copolymers increased the critical micelle temperatures (CMT) in HPLC-grade water due to an increased hydrophilicity of the A block. Upon addition of 0.9 wt% NaCl, the CMTs of poly(OEG- b -DEG 95 TMA 5 ) decreased from 50 °C to 36 °C due to screening of electrostatic repulsion between the TMA units. ABA triblock copolymers displayed excellent hydrogel properties with salt- and temperature-dependent gel points. TMA incorporation in the A block increased the gel points for all triblock copolymers, and salt-response increased with higher TMA composition in the A block. For example, poly(DEG 98 TMA 2 - b -OEG- b -DEG 98 TMA 2 ) formed a hydrogel at 40 °C in HPLC-grade water and 26 °C in 0.9 wt% NaCl aqueous solution. These salt- and temperature-responsive AB diblock and ABA triblock copolymers find applications as drug delivery vehicles, adhesives, and hydrogels.

A Research Project on the Emulsifying and Homogenizing Properties of Block Copolymers in Polymer Blends.

DTIC Science & Technology

1987-06-15

Chain C.V. Berney Scattering in Heterogeneous P. Kofinas Block Copolymers R.E. Cohen 18. SANS Studies of the Configu- C.V. Berney rations of Single...Studies of the Configuratins C.V. Berney Single Chains in Heterogeneous Block P. Cheng Copolymers, J. Materials Research, P. Dofinas in press (1987) R.E...Cohen 2. A Reexamination of the Configurations C.V. Berney of Single-Chain Scattering in Hetero- P. Kofinas geneous Block Copolymers, R.E. Cohen

Dynamic NMR studies of polymer electrolyte materials for application to lithium-ion batteries and fuel cells

NASA Astrophysics Data System (ADS)

Khalfan, Amish N.

This dissertation investigates the structural and dynamical properties of polymer electrolyte materials for applications to lithium-ion batteries and fuel cells. The nuclear magnetic resonance (NMR) technique was used to characterize these materials. NMR aids in understanding the local environments of nuclei and the mobility of a molecular/ionic species. Five research projects were carried out, and they have been outlined in this work. NASA has developed rod-coil block copolymers for use as electrolytes in lithium-ion batteries. The copolymers exhibit a microphase separation within their structure leading to the formation of ionically conducting channels. We studied ion transport properties of the copolymers, and determined the predominant mechanism for transport to occur in the amorphous phase. Seven gel polymer electrolytes, each containing a mixture of LiBETI salt and organic solvents, were studied. Two of them incorporated BMI (1-n-butyl-3-methylimidazolium) ionic liquid. Ionic liquids are room temperature molten salts. BMI had been thought to enhance ion mobility. However, the BMI component was observed to restrict ion mobility. Gel polymer electrolytes containing LiTFSI salt and P13TFSI ionic liquid with or without the inclusion of ethylene carbonate (EC) were studied for application to lithium metal/air batteries, which have high theoretical energy densities. The addition of EC was found to improve lithium ion transport. The gels with EC therefore prove to be favorable for use as electrolytes in lithium metal/air batteries. Highly sulfonated poly(arylenethioethersulfone) (SPTES) membranes were examined for use in direct methanol fuel cells (DMFCs) as an alternative to the Nafion membrane. DMFCs use methanol as a fuel instead of reformed hydrogen as in conventional proton exchange membrane fuel cells. Compared to Nafion, the SPTES membranes were shown to retain water better at high temperatures and yield lower methanol diffusion. SPTES membranes with the

Tunable Encapsulation Structure of Block Copolymer Coated Single-Walled Carbon Nanotubes in Aqueous Solution

DOE PAGES

Han, Youngkyu; Ahn, Suk-Kyun; Zhang, Zhe; ...

2015-05-15

The nano-sized and shape-tunable molecular building blocks can provide great opportunities for the fabrication of precisely controlled nanostructures. In this work, we have fabricated a molecular building block of single-walled carbon nanotubes (SWNTs) coated by PPO-PEO-PPO block copolymers whose encapsulation structure can be controlled via temperature or addition of small molecules. The structure and optical properties of SWNT-block copolymers have been investigated by small angle neutron scattering (SANS), ultraviolet-visible (UV-vis) spectroscopy, atomic force microscopy (AFM), and molecular dynamics (MD) simulation. The structure of the hydrated block copolymer layer surrounding SWNT can be controlled reversibly by varying temperature as well asmore » by irreversibly adding 5-methylsalicylic acid (5MS). Increasing hydrophobicity of the polymers with temperature and strong tendency of 5MS to interact with both block copolymers and orbitals of the SWNTs are likely to be responsible for the significant structural change of the block copolymer encapsulation layer, from loose corona shell to tightly encapsulating compact shell. These result shows an efficient and simple way to fabricate and manipulate carbon-based nano building blocks in aqueous systems with tunable structure.« less

Single- and Multilayered Nanostructures via Laser-Induced Block Copolymer Self-Assembly

NASA Astrophysics Data System (ADS)

Majewski, Pawel; Yager, Kevin; Rahman, Atikur; Black, Charles

We present a novel method of accelerated self-assembly of block copolymer thin films utilizing laser light, called Laser Zone Annealing (LZA). In our approach, steep temperature transients are induced in block copolymer films by rastering narrowly focused laser line over the light-absorbing substrate. Extremely steep temperature gradients accelerate the process of self-assembly by several orders-of-magnitude compared to conventional oven annealing, and, when coupled to photo-thermal shearing, lead to global alignment of block copolymer domains assessed by GISXAS diffraction studies and real-space SEM imaging. We demonstrate monolithic alignment of various block-copolymer thin films including PS-b-PMMA, PS-b-PEO, PS-b-P2VP, PS-b-PI and observe different responsiveness to the shearing rate depending on the characteristic relaxation timescale of the particular material. Subsequently, we use the aligned polymeric films as templates for synthesis of single- and multi-layered arrays of inorganic, metallic or semiconducting nanowires and nanomeshes and investigate their anisotropic electro-optical properties. Research carried out in part at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886.

Effects of PEO-PPO-PEO Triblock Copolymers on Phospholipid Membrane Integrity under Osmotic Stress

PubMed Central

Wang, Jia-Yu; Chin, Jaemin; Marks, Jeremy D.; Lee, Ka Yee C.

2010-01-01

The effects of PEO-PPO-PEO triblock copolymers, mainly Poloxamer 188, on phospholipid membrane integrity under osmotic gradients were explored using giant unilamellar vesicles (GUVs). Fluorescence leakage assays showed two opposing effects of P188 on the structural integrity of GUVs depending on the duration of their incubation time. A two-state transition mechanism of interaction between the triblock copolymers and the phospholipid membrane is proposed: an adsorption (I) and an insertion (II) state. While the triblock copolymer in state I acts to moderately retard the leakage, their insertion in state II perturbs the lipid packing, thus increasing the membrane permeability. Our results suggest that the biomedical application of PEO-PPO-PEO triblock copolymers, either as cell membrane resealing agents or as accelerators for drug delivery, is directed by the delicate balance between these two states. PMID:20666423

Optical studies of native defects in π-conjugated donor-acceptor copolymers

NASA Astrophysics Data System (ADS)

Baniya, Sangita; Khanal, Dipak; Lafalce, Evan; You, Wei; Valy Vardeny, Z.

2018-04-01

We used multiple spectroscopies such as photoinduced absorption (PIA), magneto photoinduced absorption, and doping induced absorption for studying native defects in π-conjugated donor-acceptor copolymer chains of benzodithio-phene fluorinated benzotriazole. The PIA spectrum contains characteristic photoinduced absorption bands that are due to polarons and triplet exciton species, whose strengths have different dependencies on the modulation frequency, temperature, and laser excitation, as well as magnetic field response. We found that the native defects in the copolymer chains serve as efficient traps that ionize the photoexcited excitons, thereby generating charge carriers whose characteristic optical properties are similar, but not equal to those of intrachain polarons formed by doping. The native defects density is of the order of 1017 cm-3 indicating that most of the copolymer chains contain native defects upon synthesis; however, this does not preclude their used-for photovoltaic applications.

Supramolecular block copolymers by kinetically controlled co-self-assembly of planar and core-twisted perylene bisimides

PubMed Central

Görl, Daniel; Zhang, Xin; Stepanenko, Vladimir; Würthner, Frank

2015-01-01

New synthetic methodologies for the formation of block copolymers have revolutionized polymer science within the last two decades. However, the formation of supramolecular block copolymers composed of alternating sequences of larger block segments has not been realized yet. Here we show by transmission electron microscopy (TEM), 2D NMR and optical spectroscopy that two different perylene bisimide dyes bearing either a flat (A) or a twisted (B) core self-assemble in water into supramolecular block copolymers with an alternating sequence of (AmBB)n. The highly defined ultralong nanowire structure of these supramolecular copolymers is entirely different from those formed upon self-assembly of the individual counterparts, that is, stiff nanorods (A) and irregular nanoworms (B), respectively. Our studies further reveal that the as-formed supramolecular block copolymer constitutes a kinetic self-assembly product that transforms into thermodynamically more stable self-sorted homopolymers upon heating. PMID:25959777

Synthesis and Characterization of Fluorescently Labeled Diblock Copolymers for Location-Specific Measurements of The Glass Transition Temperature

NASA Astrophysics Data System (ADS)

Christie, Dane; Register, Richard; Priestley, Rodney

Interfaces play a determinant role in the size dependence of the glass transition temperature (Tg) of polymers confined to nanometric length scales. Interfaces are intrinsic in diblock copolymers, which, depending on their molecular weight and composition, are periodically nanostructured in the bulk. As a result diblock copolymers are model systems for characterizing the effect of interfaces on Tg in bulk nanostructured materials. Investigating the effect of intrinsic interfaces on Tg in diblock copolymers has remained unexplored due to their small periodic length scale. By selectively incorporating trace amounts of a fluorescent probe into a diblock copolymer, Tg can be characterized relative to the diblock copolymer's intrinsic interface using fluorescence spectroscopy. Here, pyrene is selectively incorporated into the poly(methyl methacrylate) (PMMA) block of lamellar forming diblock copolymers of poly(butyl- b-methyl methacrylate) (PBMA-PMMA). Preliminary results show a correlation of Tg as measured by fluorescence with the onset of Tg as measured by calorimetry in labeled homopolymers of PMMA. This result is consistent with previous characterizations of Tg using fluorescence spectroscopy. In selectively labeled diblock copolymers Tg is found to vary systematically depending on the distance of the probe from the PBMA-PMMA interface. We acknowledge funding from the Princeton Center for Complex Materials, a MRSEC supported by NSF Grant DMR 1420541.

MesoDyn simulation study on the phase morphologies of Miktoarm PEO-b-PMMA copolymer doped by nanoparticles

NASA Astrophysics Data System (ADS)

Mu, Dan; Li, Jian-Quan; Feng, Sheng-Yu

2013-03-01

The compatibility of six groups of 12 miktoarm poly(ethylene oxide)-block-poly(methyl methacrylate) (PEO-b-PMMA) copolymers is studied at 270, 298 and 400 K via mesoscopic modeling. The values of the order parameters depend on both the architectures of the block copolymers and the simulation temperature, while the tendency to change of the order parameters at low temperature, such as 270 and 298 K, is nearly the same. However, the values of order parameters of the copolymer in the same group are the same at high temperature, i.e. 400 K. Obviously, temperature has a more obvious effect on long and PEO-rich chains. A study of plain copolymers doped with nanoparticles shows that the microscopic phase is influenced by not only the properties of the nanoparticles, such as the size, number and density, but also the composition and architecture of copolymers. Increasing the size and the number of the nanoparticles used as a dopant plays the most significant role on determining the phase morphologies of the copolymers at lower and higher temperature, respectively. In paricular, the 23141 and 23241-type copolymers, which are both of PEO-rich composition, presents microscopic phase separation as perforated lamallae phase morphologies at 400 K, alternated with PEO and PMMA components.

Block Copolymer Electrolytes: Thermodynamics, Ion Transport, and Use in Solid- State Lithium/Sulfur Cells

NASA Astrophysics Data System (ADS)

Teran, Alexander Andrew

Nanostructured block copolymer electrolytes containing an ion-conducting block and a modulus-strengthening block are of interest for applications in solid-state lithium metal batteries. These materials can self-assemble into well-defined microstructures, creating conducting channels that facilitate ion transport. The overall objective of this dissertation is to gain a better understanding of the behavior of salt-containing block copolymers, and evaluate their potential for use in solid-state lithium/sulfur batteries. Anionically synthesized polystyrene-b-poly(ethylene oxide) (SEO) copolymers doped with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt were used as a model system. This thesis investigates the model system on several levels: from fundamental thermodynamic studies to bulk characterization and finally device assembly and testing. First, the thermodynamics of neat and salt-containing block copolymers was studied. The addition of salt to these materials is necessary to make them conductive, however even small amounts of salt can have significant effects on their phase behavior, and consequently their iontransport and mechanical properties. As a result, the effect of salt addition on block copolymer thermodynamics has been the subject of significant interest over the last decade. A comprehensive study of the thermodynamics of block copolymer/salt mixtures over a wide range of molecular weights, compositions, salt concentrations and temperatures was conducted. Next, the effect of molecular weight on ion transport in both homopolymer and copolymer electrolytes were studied over a wide range of chain lengths. Homopolymer electrolytes show an inverse relationship between conductivity and chain length, with a plateau in the infinite molecular weight limit. This is due to the presence of two mechanisms of ion conduction in homopolymers; the first mechanism is a result of the segmental motion of the chains surrounding the salt ions, 2 creating a liquid

Thermodynamics of Surfactants, Block Copolymers and Their Mixtures in Water: The Role of the Isothermal Calorimetry

PubMed Central

De Lisi, Rosario; Milioto, Stefania; Muratore, Nicola

2009-01-01

The thermodynamics of conventional surfactants, block copolymers and their mixtures in water was described to the light of the enthalpy function. The two methodologies, i.e. the van’t Hoff approach and the isothermal calorimetry, used to determine the enthalpy of micellization of pure surfactants and block copolymers were described. The van’t Hoff method was critically discussed. The aqueous copolymer+surfactant mixtures were analyzed by means of the isothermal titration calorimetry and the enthalpy of transfer of the copolymer from the water to the aqueous surfactant solutions. Thermodynamic models were presented to show the procedure to extract straightforward molecular insights from the bulk properties. PMID:19742173

Synthesis and Adsorption Properties of 4-Vinylpyridine and Styrene Copolymer In Situ Immobilized on Silica Surface

NASA Astrophysics Data System (ADS)

Yanovska, E. S.; Vretik, L. O.; Nikolaeva, O. A.; Polonska, Y.; Sternik, D.; Kichkiruk, O. Yu.

2017-03-01

Copolymer of 4-vinylpyridine with styrene was in situ immobilized on silica gel surface via the heterogeneous radical polymerization. Anchorage of the copolymer on the surface layer was confirmed by IR spectroscopy. The quantity of copolymer on the silica gel surface was evaluated as 25.73 wt.% by TG and DSC-MS analysis. "Islet" location of polymer layer on the silica surface was confirmed by the scanning electron microscopy. A high adsorption activity of silica gel with immobilized copolymer towards microquantitatives of Cu(II), Cd(II), Pb(II), Fe(III), and Ni(II) ions in steady state conditions as well as of Ni(II) ions in dynamic regime was found.

Synthesis and Adsorption Properties of 4-Vinylpyridine and Styrene Copolymer In Situ Immobilized on Silica Surface.

PubMed

Yanovska, E S; Vretik, L O; Nikolaeva, O A; Polonska, Y; Sternik, D; Kichkiruk, O Yu

2017-12-01

Copolymer of 4-vinylpyridine with styrene was in situ immobilized on silica gel surface via the heterogeneous radical polymerization. Anchorage of the copolymer on the surface layer was confirmed by IR spectroscopy. The quantity of copolymer on the silica gel surface was evaluated as 25.73 wt.% by TG and DSC-MS analysis. "Islet" location of polymer layer on the silica surface was confirmed by the scanning electron microscopy. A high adsorption activity of silica gel with immobilized copolymer towards microquantitatives of Cu(II), Cd(II), Pb(II), Fe(III), and Ni(II) ions in steady state conditions as well as of Ni(II) ions in dynamic regime was found.

21 CFR 180.22 - Acrylonitrile copolymers.

Code of Federal Regulations, 2014 CFR

2014-04-01

... extraction for finished food-contact articles, determined by a method of analysis titled “Gas-Solid... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Acrylonitrile copolymers. 180.22 Section 180.22 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...

Different copolymer films on ZnFeCo particles: Synthesis and anticorrosion properties

NASA Astrophysics Data System (ADS)

Ozyilmaz, A. Tuncay; Avsar, Busra; Ozyilmaz, Gul; Karahan, İ. Hakkı; Camurcu, Taskin; Colak, Fatma

2014-11-01

Zinc-iron-cobalt (ZnFeCo) particles were electrochemically deposited on carbon steel (CS) electrode applying current of 3 mA with chronopotentiometry technique. ZnFeCo particles had homogenous, smooth with prismatic structure. It was shown that the ZnFeCo particles exhibited important barrier effect on CS substrate. Poly(aniline-co-o-anisidine), poly(aniline-co-pyrrole), poly(aniline-co-N-methylpyrrole) and poly(o-anisidine-co-pyrrole) copolymer films were obtained on CS/ZnFeCo electrode. Evaluation of anticorrosion performance of copolymer coatings in 3.5% NaCl solution was investigated by using AC impedance spectroscopy (EIS) technique, anodic polarization and the Eocp-time curves. Copolymer films exhibited significant physical barrier behavior on ZnFeCo plated carbon steel, in longer exposure time.

A Theoretically Informed Model for the Rheology of Entangled Block Copolymer Nanocomposites

NASA Astrophysics Data System (ADS)

Su, Yongrui; Ramirez-Hernandez, Abelardo; Peters, Brandon; de Pablo, Juan J.

2014-03-01

The addition of nanoparticles to block copolymer systems has been shown to have important effects on their equilibrium structure and properties. Less is known about the non-equilibrium behavior of block polymer nanocomposites. A new particle-based, theoretically informed coarse-grained model for multicomponent nanocomposites is proposed to examine the effects of nanoparticles on the rheology of entangled block copolymer melts. Entanglements are treated at the two-molecule level, through slip-springs that couple the dynamics of neighboring pairs of chains. The inclusion of slip-springs changes the polymer dynamics from unentangled to entangled. The nanoparticles are functionalized with short polymer chains that can entangle with the copolymers. We study the nonlinear rheology of the resulting nanocomposites under shear flow with a dissipative particle dynamics (DPD) thermostat.

Design and Synthesis of Network-Forming Triblock Copolymers Using Tapered Block Interfaces

PubMed Central

Kuan, Wei-Fan; Roy, Raghunath; Rong, Lixia; Hsiao, Benjamin S.; Epps, Thomas H.

2012-01-01

We report a strategy for generating novel dual-tapered poly(isoprene-b-isoprene/styrene-b-styrene-b-styrene/methyl methacrylate-b-methyl methacrylate) [P(I-IS-S-SM-M)] triblock copolymers that combines anionic polymerization, atom transfer radical polymerization (ATRP), and Huisgen 1,3-dipolar cycloaddition click chemistry. The tapered interfaces between blocks were synthesized via a semi-batch feed using programmable syringe pumps. This strategy allows us to manipulate the transition region between copolymer blocks in triblock copolymers providing control over the interfacial interactions in our nanoscale phase-separated materials independent of molecular weight and block constituents. Additionally, we show the ability to retain a desirous and complex multiply-continuous network structure (alternating gyroid) in our dual-tapered triblock material. PMID:23066522

All-Atom Molecular Dynamics-Based Analysis of Membrane-Stabilizing Copolymer Interactions with Lipid Bilayers Probed under Constant Surface Tensions.

PubMed

Houang, Evelyne M; Bates, Frank S; Sham, Yuk Y; Metzger, Joseph M

2017-11-30

An all-atom phospholipid bilayer and triblock copolymer model was developed for molecular dynamics (MD) studies. These were performed to investigate the mechanism of interaction between membrane-stabilizing triblock copolymer P188 and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) lipid bilayers under applied lateral surface tension (γ) to model membrane mechanical stress. Results showed that P188 insertion is driven by the hydrophobic poly(propylene oxide) (PPO) core and dependent on bilayer area per lipid. Moreover, insertion of P188 increased the bilayer's resistance to mechanical rupture, as observed by a significant increase in the absolute lateral pressure required to disrupt the bilayer. To further investigate the specific chemical features of P188 underlying membrane stabilizer function, a series of MD simulations with triblock copolymers of the same class as P188 but of varying chemical composition and sizes were performed. Results showed that triblock copolymer insertion into the lipid bilayer is dependent on overall copolymer hydrophobicity, with higher copolymer hydrophobicity requiring a reduced bilayer area per lipid ratio for insertion. Further analysis revealed that the effect of copolymer insertion on membrane mechanical integrity was also dependent on hydrophobicity. Here, P188 insertion significantly increased the absolute apparent lateral pressure required to rupture the POPC bilayer, thereby protecting the membrane against mechanical stress. In marked contrast, highly hydrophobic copolymers decreased the lateral pressure necessary for membrane rupture and thus rendering the membrane significantly more susceptible to mechanical stress. These new in silico findings align with recent experimental findings using synthetic lipid bilayers and in muscle cells in vitro and mouse models in vivo. Collectively, these data underscore the importance of PEO-PPO-PEO copolymer chemical composition in copolymer-based muscle membrane stabilization

Synthesis of Medium-Chain-Length Polyhydroxyalkanoate Homopolymers, Random Copolymers, and Block Copolymers by an Engineered Strain of Pseudomonas entomophila.

PubMed

Wang, Ying; Chung, Ahleum; Chen, Guo-Qiang

2017-04-01

Medium-chain-length polyhydroxyalkanoates (mcl-PHAs), widely used in medical area, are commonly synthesized by Pseudomonas spp. This study tries to use β-oxidation pathways engineered P. entomophila to achieve single source of a series of mcl-monomers for microbial production of PHA homopolymers. The effort is proven successful for the first time to obtain a wide range of mcl-PHA homopolymers from engineered P. entomophila LAC23 grown on various fatty acids, respectively, ranging from poly(3-hydroxyheptanoate) to poly(3-hydroxytetradecanoate). Effects of a PHA monomer chain length on thermal and crystallization properties including the changes of T m , T g , and T d5% are investigated. Additionally, strain LAC23 is used to synthesize random copolymers of 3-hydroxyoctanoate (3HO) and 3-hydroxydodecanoate (3HDD) or 3-hydroxytetradecanoates, their compositions could be controlled by adjusting the ratios of two related fatty acids. Meanwhile, block copolymer P(3HO)-b-P(3HDD) is synthesized by the same strain. It is found for the first time that even- and odd number mcl-PHA homopolymers have different physical properties. When the gene of the PHA synthase in the engineered P. entomophila is replaced by phaC from Aeromonas hydrophila 4AK4, poly(3-hydroxybutyrate-co-30 mol%-3-hydroxyhexanoate) is synthesized. Therefore, P. entomophila can be used to synthesize the whole range of PHA (C7-C14) homopolymers, random- and block copolymers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Three-Tone Chemical Patterns for Block Copolymer Directed Self-Assembly

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

Williamson, Lance D.; Seidel, Robert N.; Chen, Xuanxuan

Chemical patterns for directed self-assembly (DSA) of lamellaeforming block copolymers (BCP) with density multiplication can be fabricated by patterning resist on a cross-linked polystyrene layer, etching to create guide stripes, and depositing end-grafted brushes in between the stripes as background. To date, two-tone chemical patterns have been targeted with the guide stripes preferentially wet by one block of the copolymer and the background chemistry weakly preferentially wet by the other block. In the course of fabricating chemical patterns in an all-track process using 300 mm wafers, it was discovered that the etching process followed by brush grafting could produce amore » three-tone pattern. We characterized the three regions of the chemical patterns with a combination of SEM, grazing-incidence small-angle X-ray scattering (GISAXS), and assessment of BCP-wetting behavior, and evaluated the DSA behavior on patterns over a range of guide stripe widths. In its best form, the three-tone pattern consists of guide stripes preferentially wet by one block of the copolymer, each flanked by two additional stripes that wet the other block of the copolymer, with a third chemistry as the background. Three-tone patterns guide three times as many BCP domains as two-tone patterns and thus have the potential to provide a larger driving force for the system to assemble into the desired architecture with fewer defects in shorter time and over a larger process window.« less

Morphological and physical characterization of poly(styrene-isobutylene-styrene) block copolymers and ionomers thereof

NASA Astrophysics Data System (ADS)

Baugh, Daniel Webster, III

Poly(styrene-isobutylene-styrene) block copolymers made by living cationic polymerization using a difunctional initiator and the sequential monomer addition technique were analyzed using curve-resolution software in conjunction with high-resolution GPC. Fractional precipitation and selective solvent extraction were applied to a representative sample in order to confirm the identity of contaminating species. The latter were found to be low molecular weight polystyrene homopolymer, diblock copolymer, and higher molecular weight segmented block copolymers formed by intermolecular electrophilic aromatic substitution linking reactions occurring late in the polymerization of the styrene outer blocks. Solvent-cast films of poly(styrene-isobutylene-styrene) (PS-PIB-PS) block copolymers and block ionomers were analyzed using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Four block copolymer samples with center block molecular weights of 52,000 g/mol and PS volume fractions (o sbPS) ranging from 0.17 to 0.31 were studied. All samples exhibited hexagonally packed cylinders of PS within the PIB matrix. Cylinder spacing was in the range 32 to 36 nm for most samples, while cylinder diameters varied from 14 to 21 nm. Porod analysis of the scattering data indicated the presence of isolated phase mixing and sharp phase boundaries. PS-PIB-PS block copolymers and ionomers therefrom were analyzed using dynamic mechanical analysis (DMA) and tensile testing. The study encompassed five block copolymer samples with similar PIB center blocks with molecular weights of approx52,000 g/mol and PS weight fractions ranging from 0.127 to 0.337. Ionomers were prepared from two of these materials by lightly sulfonating the PS outer blocks. Sulfonation levels varied from 1.7 to 4.7 mol % and the sodium and potassium neutralized forms were compared to the parent block copolymers. Dynamic mechanical analysis (DMA) of the block copolymer films indicated the existence

Hemicellulose block copolymers made from woods for wide-range directed self-assembly lithography enabling wider range of applicable patterning size

NASA Astrophysics Data System (ADS)

Morita, Kazuyo; Yamamoto, Kimiko

2017-03-01

Xylan, one of hemicellulose family, block copolymer was newly developed for wide-range directed self-assembly lithography (DSA). Xylan is higher hydrophilic material because of having many hydroxy groups in one molecule. It means that xylan block copolymer has a possibility of high-chi block copolymer. Generally, DSA is focused on microphase separation for smaller size with high-chi block copolymer and not well known for larger size. In this study, xylan block copolymer was confirmed enabling wider range of patterning size, from smaller size to larger size. The key of xylan block copolymer is a new molecular structure of block copolymer and sugar chain control technology. Sugar content is the important parameter for not only micro-phase separation property but also line edge roughness (LER) and defects. Based on the sugar control technology, wide-range (hp 8.3nm to 26nm L/S and CD 10nm to 51nm hole) DSA patterning was demonstrated. Additionally it was confirmed that xylan block copolymer is suitable for sequential infiltration synthesis (SIS) process.

Highly Efficient One-Pot Synthesis of COS-Based Block Copolymers by Using Organic Lewis Pairs.

PubMed

Yang, Jia-Liang; Cao, Xiao-Han; Zhang, Cheng-Jian; Wu, Hai-Lin; Zhang, Xing-Hong

2018-01-31

A one-pot synthesis of block copolymer with regioregular poly(monothiocarbonate) block is described via metal-free catalysis. Lewis bases such as guanidine, quaternary onium salts, and Lewis acid triethyl borane (TEB) were equivalently combined and used as the catalysts. By using polyethylene glycol (PEG) as the macromolecular chain transfer agent (CTA), narrow polydispersity block copolymers were obtained from the copolymerization of carbonyl sulfide (COS) and propylene oxide (PO). The block copolymers had a poly(monothiocarbonate) block with perfect alternating degree and regioregularity. Unexpectedly, the addition of CTA to COS/PO copolymerization system could dramatically improve the turnover frequency (TOF) of PO (up to 240 h -1 ), higher than that of the copolymerization without CTA. In addition, the conversion of CTA could be up to 100% in most cases, as revealed by ¹H NMR spectra. Of consequence, the number-average molecular weights ( M n s) of the resultant block copolymers could be regulated by varying the feed ratio of CTA to PO. Oxygen-sulfur exchange reaction (O/S ER), which can generate randomly distributed thiocarbonate and carbonate units, was effectively suppressed in all of the cases in the presence of CTA, even at 80 °C. This work presents a versatile method for synthesizing sulfur-containing block copolymers through a metal-free route, providing an array of new block copolymers.

Measurement of Diffusion in Entangled Rod-Coil Triblock Copolymers

NASA Astrophysics Data System (ADS)

Olsen, B. D.; Wang, M.

2012-02-01

Although rod-coil block copolymers have attracted increasing attention for functional nanomaterials, their dynamics relevant to self-assembly and processing have not been widely investigated. Because the rod and coil blocks have different reptation behavior and persistence lengths, the mechanism by which block copolymers will diffuse is unclear. In order to understand the effect of the rigid block on reptation, tracer diffusion of a coil-rod-coil block copolymer through an entangled coil polymer matrix was experimentally measured. A monodisperse, high molecular weight coil-rod-coil triblock was synthesized using artificial protein engineering to prepare the helical rod and bioconjugaiton of poly(ethylene glycol) coils to produce the final triblock. Diffusion measurements were performed using Forced Rayleigh scattering (FRS), at varying ratios of the rod length to entanglement length, where genetic engineering is used to control the protein rod length and the polymer matrix concentration controls the entanglement length. As compared to PEO homopolymer tracers, the coil-rod-coil triblocks show markedly slower diffusion, suggesting that the mismatch between rod and coil reptation mechanisms results in hindered diffusion of these molecules in the entangled state.

Synthesis and characterization of poly(L-alanine)-block-poly(ethylene glycol) monomethyl ether as amphiphilic biodegradable co-polymers.

PubMed

Zhang, Guolin; Ma, Jianbiao; Li, Yanhong; Wang, Yinong

2003-01-01

Di-block co-polymers of poly(L-alanine) with poly(ethylene glycol) monomethyl ether (MPEG) were synthesized as amphiphilic biodegradable co-polymers. The ring-opening polymerization of N-carboxy-L-alanine anhydride (NCA) in dichloromethane was initiated by amino-terminated poly(ethylene glycol) monomethyl ether (MPEG-NH2, M(n) = 2000) to afford poly(L-alanine)-block-MPEG. The weight ratio of two blocks in the co-polymers could be altered by adjusting the feeding ratio of NCA to MPEG-NH2. Their chemical structures were characterized on the basis of infrared spectrometry and nuclear magnetic resonance. According to circular dichroism measurement, the poly(L-alanine) chain on the co-polymers in an aqueous medium had a alpha-helix conformation. Two melting points from MPEG block and poly(L-alanine), respectively, could be observed in differential scanning calorimetry curves of the co-polymers, suggesting that a micro-domain phase separation appeared in their bulky states. The co-polymers could take up some water and the capacity was dependent on the ratio of poly(L-alanine) block to MPEG. Such co-polymers might be useful in drug-delivery systems and other biomedical applications.

Rheological properties of reactive extrusion modified waxy starch and waxy starch-polyacrylamide copolymer gels

USDA-ARS?s Scientific Manuscript database

The rheological properties of modified waxy starch and waxy starch-polyacrylamide graft copolymers prepared by reactive extrusion were investigated. Both materials can absorb huge amount of water and form gels. The modified waxy starch and waxy starch-polyacrylamide graft copolymer gels all exhibite...

Constructing a molecular theory of self-assembly: Interplay of ideas from surfactants and block copolymers.

PubMed

Nagarajan, Ramanathan

2017-06-01

Low molecular weight surfactants and high molecular weight block copolymers display analogous self-assembly behavior in solutions and at interfaces, generating nanoscale structures of different shapes. Understanding the link between the molecular structure of these amphiphiles and their self-assembly behavior has been the goal of theoretical studies. Despite the analogies between surfactants and block copolymers, models predicting their self-assembly behavior have evolved independent of one another, each overlooking the molecular feature considered critical to the other. In this review, we focus on the interplay of ideas pertaining to surfactants and block copolymers in three areas of self-assembly. First, we show how improved free energy models have evolved by applying ideas from surfactants to block copolymers and vice versa, giving rise to a unitary theoretical framework and better predictive capabilities for both classes of amphiphiles. Second we show that even though molecular packing arguments are often used to explain aggregate shape transitions resulting from self-assembly, the molecular packing considerations are more relevant in the case of surfactants whereas free energy criteria are relevant for block copolymers. Third, we show that even though the surfactant and block copolymer aggregates are small nanostructures, the size differences between them is significant enough to make the interfacial effects control the solubilization of molecules in surfactant micelles while the bulk interactions control the solubilization in block copolymer micelles. Finally, we conclude by identifying recent theoretical progress in adapting the micelle model to a wide variety of self-assembly phenomena and the challenges to modeling posed by emerging novel classes of amphiphiles with complex biological, inorganic or nanoparticle moieties. Published by Elsevier B.V.

Modeling and self-assembly behavior of PEG-PLA-PEG triblock copolymers in aqueous solution

NASA Astrophysics Data System (ADS)

Wu, Xiaohan; Li, Suming; Coumes, Fanny; Darcos, Vincent; Lai Kee Him, Joséphine; Bron, Patrick

2013-09-01

A series of poly(ethylene glycol)-polylactide-poly(ethylene glycol) (PEG-PLA-PEG) triblock copolymers with symmetric or asymmetric chain structures were synthesized by combination of ring-opening polymerization and copper-catalyzed click chemistry. The resulting copolymers were used to prepare self-assembled aggregates by dialysis. Various architectures such as nanotubes, polymersomes and spherical micelles were observed from transmission electron microscopy (TEM), cryo-TEM and atomic force microscopy (AFM) measurements. The formation of diverse aggregates is explained by modeling from the angle of both geometry and thermodynamics. From the angle of geometry, a ``blob'' model based on the Daoud-Cotton model for star polymers is proposed to describe the aggregate structures and structural changes with copolymer composition and molar mass. In fact, the copolymer chains extend in aqueous medium to form single layer polymersomes to minimize the system's free energy if one of the two PEG blocks is short enough. The curvature of polymersomes is dependent on the chain structure of copolymers, especially on the length of PLA blocks. A constant branch number of aggregates (f) is thus required to preserve the morphology of polymersomes. Meanwhile, the aggregation number (Nagg) determined from the thermodynamics of self-assembly is roughly proportional to the total length of polymer chains. Comparing f to Nagg, the aggregates take the form of polymersomes if Nagg ~ f, and change to nanotubes if Nagg > f to conform to the limits from both curvature and aggregation number. The length of nanotubes is mainly determined by the difference between Nagg and f. However, the hollow structure becomes unstable when both PEG segments are too long, and the aggregates eventually collapse to yield spherical micelles. Therefore, this work gives new insights into the self-assembly behavior of PEG-PLA-PEG triblock copolymers in aqueous solution which present great interest for biomedical and

Microwave based synthesis and spectral characterization of thermo-sensitive poly(N,N-diethylacrylamide) grafted pectin copolymer.

PubMed

Işıklan, Nuran; Tokmak, Şeyma

2018-07-01

The functionalization of polysaccharides with synthetic polymers has attracted great attention owing to its application in many industrial fields. The aim of this work was to study the impact of pectin functionalization with N,N-diethylacrylamide (DEAAm). Pectin was modified via microwave-induced graft copolymerization of DEAAm using ceric ammonium nitrate (CAN) and N,N,N',N'-tetramethylethylenediamine (TEMED). FTIR, 13 C NMR, DSC/TGA, XRD, and SEM techniques were used to verify the structure of graft copolymers. Various reaction conditions such as microwave irradiation time, temperature, microwave power, monomer, initiator, and TEMED concentrations were investigated to get a maximum grafting yield of 192%. Lower critical solution temperatures (LCST) of graft copolymers were determined by UV spectroscopy. Graft copolymers were found to be thermo-sensitive, with LCST of 31°C and high thermal resistance. Biocompatibility test of copolymers showed that copolymers were not cytotoxic to L929 fibroblasts cells and can be used as a biomaterial. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis and Characterization of Comb and Centipede Multigraft Copolymers P nBA- g-PS with High Molecular Weight Using Miniemulsion Polymerization

DOE PAGES

Wang, Wenwen; Wang, Weiyu; Lu, Xinyi; ...

2014-10-23

For this study, comb and centipede multigraft copolymers, poly(n-butyl acrylate)-g-polystyrene (PnBA-g-PS) with PnBA backbones and PS side chains, were synthesized via high-vacuum anionic polymerization and miniemulsion polymerization. Single-tailed and double-tailed PS macromonomers were synthesized by anionic polymerization and Steglich esterification. Subsequently, the copolymerization of each macromonomer and nBA was carried out in miniemulsion, and multigraft copolymers were obtained. The latex particles of multigraft copolymers were characterized using dynamic light scattering. The molecular weights of macromonomers and multigraft copolymers were analyzed by size exclusion chromatography. Moreover, the molecular weights and structures of macromonomers were investigated by matrix-assisted laser desorption/ionization time-of-flight massmore » spectrometry and 1H nuclear magnetic resonance spectroscopy. The weight contents of PS in comb and centipede multigraft copolymers were calculated by 1H nuclear magnetic resonance spectroscopy. The thermal properties of multigraft copolymers were characterized by thermogravimetric analysis and differential scanning calorimetry. The microphase separation of multigraft copolymers was observed by atomic force microscopy and transmission electronic microscopy. Rheological measurements showed that comb and centipede multigraft copolymers have elastic properties when the weight content of PS side chains is 26–32 wt %. Centipede multigraft copolymers possess better elastic properties than comb multigraft copolymers with the similar weight content of PS. In conclusion, these findings are similar to previous results on poly(isoprene-g-polystyrene) comb and centipede copolymers made by anionic polymerization.« less

21 CFR 177.1050 - Acrylonitrile/styrene copoly-mer modified with butadiene/styrene elastomer.

Code of Federal Regulations, 2013 CFR

2013-04-01

... chapter as Type VI-B under conditions for use E, F, or G described in table 2 of § 176.170(c) of this... copol-ymer is extracted with 250 milliliters spectral grade n-heptane at reflux temperature for 2 hours. (e) Accelerated extraction end test. The modified copolymer shall yield acrylonitrile monomer not in...

21 CFR 177.1050 - Acrylonitrile/styrene copoly-mer modified with butadiene/styrene elastomer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... chapter as Type VI-B under conditions for use E, F, or G described in table 2 of § 176.170(c) of this... copol-ymer is extracted with 250 milliliters spectral grade n-heptane at reflux temperature for 2 hours. (e) Accelerated extraction end test. The modified copolymer shall yield acrylonitrile monomer not in...

21 CFR 177.1050 - Acrylonitrile/styrene copoly-mer modified with butadiene/styrene elastomer.

Code of Federal Regulations, 2012 CFR

2012-04-01

... chapter as Type VI-B under conditions for use E, F, or G described in table 2 of § 176.170(c) of this... copol-ymer is extracted with 250 milliliters spectral grade n-heptane at reflux temperature for 2 hours. (e) Accelerated extraction end test. The modified copolymer shall yield acrylonitrile monomer not in...

Real-time monitoring of anticancer drug release with highly fluorescent star-conjugated copolymer as a drug carrier.

PubMed

Qiu, Feng; Wang, Dali; Zhu, Qi; Zhu, Lijuan; Tong, Gangsheng; Lu, Yunfeng; Yan, Deyue; Zhu, Xinyuan

2014-04-14

Chemotherapy is one of the major systemic treatments for cancer, in which the drug release kinetics is a key factor for drug delivery. In the present work, a versatile fluorescence-based real-time monitoring system for intracellular drug release has been developed. First, two kinds of star-conjugated copolymers with different connections (e.g., pH-responsive acylhydrazone and stable ether) between a hyperbranched conjugated polymer (HCP) core and many linear poly(ethylene glycol) (PEG) arms were synthesized. Owing to the amphiphilic three-dimensional architecture, the star-conjugated copolymers could self-assemble into multimicelle aggregates from unimolecular micelles with excellent emission performance in the aqueous medium. When doxorubicin (DOX) as a model drug was encapsulated into copolymer micelles, the emission of star-conjugated copolymer and DOX was quenched. In vitro biological studies revealed that fluorescent intensities of both star-conjugated copolymer and DOX were activated when the drug was released from copolymeric micelles, resulting in the enhanced cellular proliferation inhibition against cancer cells. Importantly, pH-responsive feature of the star-conjugated copolymer with acylhydrazone linkage exhibited accelerated DOX release at a mildly acidic environment, because of the fast breakage of acylhydrazone in endosome or lysosome of tumor cells. Such fluorescent star-conjugated copolymers may open up new perspectives to real-time study of drug release kinetics of polymeric drug delivery systems for cancer therapy.

A facile synthesis of poly(aniline-co-o-bromoaniline) copolymer: Characterization and application as semiconducting material

NASA Astrophysics Data System (ADS)

Mahudeswaran, A.; Vivekanandan, J.; Vijayanand, P. S.; Kojima, T.; Kato, S.

2016-01-01

Poly(aniline-co-o-bromoaniline) (p(an-co-o-BrAn)) copolymer has been synthesized using chemical oxidation method in the hydrochloric acid medium. Copolymerization of aniline with o-bromoaniline of different compositions, such as 1:1, 1:2, 2:1, 1:3 and 3:1 molar ratios were prepared. The synthesized copolymer is soluble in polar solvents like dimethyl sulphoxide (DMSO), dimethyl formamide (DMF), Tetrahydrofuran (THF) and 1-methyl 2-pyrrolidone (NMP). The copolymer is analyzed by various characterization techniques, such as FTIR, UV-Visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), conductivity, Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). FTIR spectrum confirms the characteristic peaks of the copolymer containing benzenoid and quinoid ring stretching. UV spectrum reveals the formation of π-π∗ transition and n-π∗ transition between the energy levels. XRD peaks reveal that the copolymer possesses amorphous nature. Morphological study reveals that the agglomerated particles form globular structure and size of the each particle is about 100 nm. The electrical conductivity of the copolymers is found in the range of 10-5Scm-1. These organic semiconductor materials can be used to fabricate thinner and cheaper environmental friendly optoelectronic devices that will replace the conventional inorganic semiconductors.

Influence of chain microstructure on thermodegradative behavior of furfuryl methacrylate-N-vinylpyrrolidone random copolymers by thermogravimetry

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

Peniche, C.; Zaldivar, D.; Bulay, A.

1993-12-20

The thermal behavior of random copolymers of furfuryl methacrylate (F) and N-vinyl-pyrrolidone (P) was studied by means of dynamic thermogravimetric analysis (TGA) in the range 100--600 C. The dynamic experiments show that these copolymers exhibit two degradation steps in the intervals 260--320 C and 350--520 C, respectively. The normalized weight loss in the low temperature interval increases as the mole fraction of F in the copolymer m[sub F] increases, whereas an inverted trend in the high temperature interval is observed. The apparent activation energy E[sub a] of the first degradation step for copolymers prepared with different composition, was obtained accordingmore » to the treatment suggested by Broido. A plot of the values of E[sub a] versus the F dead molar fraction in the copolymer chains m[sub FF] gave a straight line that indicates that there is a direct relationship between the thermogravimetric behavior of these systems and their corresponding microstructure, that is, the distribution of comonomeric units along the copolymers chains. The first decomposition step was also studied by isothermal TGA and a good linearity for the variation of the weight loss percentage [Delta]W versus m[sub F] at least during the first 30 min of treatment was obtained.« less

Chirality plays critical roles in enhancing the aqueous solubility of nocathiacin I by block copolymer micelles.

PubMed

Feng, Kun; Wang, Shuzhen; Ma, Hairong; Chen, Yijun

2013-01-01

Although drug solubilization by block copolymer micelles has been extensively studied, the rationale behind the choice of appropriate block copolymer micelles for various poorly water-soluble drugs has been of relatively less concern. The objective of this study was to use methoxy-poly(ethylene glycol)-polylactate micelles (MPEG-PLA) to solubilize glycosylated antibiotic nocathiacin I and to compare the effects of chirality on the enhancement of aqueous solubility. Nocathiacin I-loaded MPEG-PLA micelles with opposite optical property in PLA were synthesized and characterized. The drug release profile, micelle stability and preliminary safety properties of MPEG-PLA micelles were evaluated. Meanwhile, three other poorly water-soluble chiral compound-loaded micelles were also prepared and compared.  The aqueous solubility of nocathiacin I was greatly enhanced by both L- and D-copolymers, with the degree of enhancement appearing to depend on the chirality of the copolymers. Comparison of different chiral compounds confirmed the trend that aqueous solubility of chiral compounds can be more effectively enhanced by block copolymer micelles with specific stereochemical configuration. The present study introduced chiral concept on the selection and preparation of block copolymer micelles for the enhancement of aqueous solubility of poorly water-soluble drugs. © 2012 The Authors. JPP © 2012 Royal Pharmaceutical Society.

In vitro evaluation of anticancer nanomedicines based on doxorubicin and amphiphilic Y-shaped copolymers

PubMed Central

Li, Di; Ding, Jian Xun; Tang, Zhao Hui; Sun, Hai; Zhuang, Xiu Li; Xu, Jing Zhe; Chen, Xue Si

2012-01-01

Four monomethoxy poly(ethylene glycol)-poly(L-lactide-co-glycolide)2 (mPEG-P( LA-co-GA)2) copolymers were synthesized by ring-opening polymerization of L-lactide and glycolide with double hydroxyl functionalized mPEG (mPEG-(OH)2) as macroinitiator and stannous octoate as catalyst. The copolymers self-assembled into nanoscale micellar/vesicular aggregations in phosphate buffer at pH 7.4. Doxorubicin (DOX), an anthracycline anticancer drug, was loaded into the micellar/vesicular nanoparticles, yielding micellar/vesicular nanomedicines. The in vitro release behaviors could be adjusted by content of hydrophobic polyester and pH of the release medium. In vitro cell experiments showed that the intracellular DOX release could be adjusted by content of P(LA-co-GA), and the nanomedicines displayed effective proliferation inhibition against Henrietta Lacks’s cells with different culture times. Hemolysis tests indicated that the copolymers were hemocompatible, and the presence of copolymers could reduce the hemolysis ratio of DOX significantly. These results suggested that the novel anticancer nanomedicines based on DOX and amphiphilic Y-shaped copolymers were attractive candidates as tumor tissular and intracellular targeting drug delivery systems in vivo, with enhanced stability during circulation and accelerated drug release at the target sites. PMID:22701317

Double-bond-containing polyallene-based triblock copolymers via phenoxyallene and (meth)acrylate

NASA Astrophysics Data System (ADS)

Ding, Aishun; Lu, Guolin; Guo, Hao; Huang, Xiaoyu

2017-03-01

A series of ABA triblock copolymers, consisting of double-bond-containing poly(phenoxyallene) (PPOA), poly(methyl methacrylate) (PMMA), or poly(butyl acrylate) (PBA) segments, were synthesized by sequential free radical polymerization and atom transfer radical polymerization (ATRP). A new bifunctional initiator bearing azo and halogen-containing ATRP initiating groups was first prepared followed by initiating conventional free radical homopolymerization of phenoxyallene with cumulated double bond to give a PPOA-based macroinitiator with ATRP initiating groups at both ends. Next, PMMA-b-PPOA-b-PMMA and PBA-b-PPOA-b-PBA triblock copolymers were synthesized by ATRP of methyl methacrylate and n-butyl acrylate initiated by the PPOA-based macroinitiator through the site transformation strategy. These double-bond-containing triblock copolymers are stable under UV irradiation and free radical circumstances.

Structural Color for Additive Manufacturing: 3D-Printed Photonic Crystals from Block Copolymers.

PubMed

Boyle, Bret M; French, Tracy A; Pearson, Ryan M; McCarthy, Blaine G; Miyake, Garret M

2017-03-28

The incorporation of structural color into 3D printed parts is reported, presenting an alternative to the need for pigments or dyes for colored parts produced through additive manufacturing. Thermoplastic build materials composed of dendritic block copolymers were designed, synthesized, and used to additively manufacture plastic parts exhibiting structural color. The reflection properties of the photonic crystals arise from the periodic nanostructure formed through block copolymer self-assembly during polymer processing. The wavelength of reflected light could be tuned across the visible spectrum by synthetically controlling the block copolymer molecular weight and manufacture parts that reflected violet, green, or orange light with the capacity to serve as selective optical filters and light guides.

Nitroxide-mediated radical ring-opening copolymerization: chain-end investigation and block copolymer synthesis.

PubMed

Delplace, Vianney; Harrisson, Simon; Tardy, Antoine; Gigmes, Didier; Guillaneuf, Yohann; Nicolas, Julien

2014-02-01

Well-defined, degradable copolymers are successfully prepared by nitroxide-mediated radical ring opening polymerization (NMrROP) of oligo(ethylene glycol) methyl ether methacrylate (OEGMA) or methyl methacrylate (MMA), a small amount of acrylonitrile (AN) and cyclic ketene acetals (CKAs) of different structures. Phosphorous nuclear magnetic resonance allows in-depth chain-end characterization and gives crucial insights into the nature of the copoly-mer terminal sequences and the living chain fractions. By using a small library of P(OEGMA-co-AN-co-CKA) and P(MMA-co-AN-co-CKA) as macroinitiators, chain extensions with styrene are performed to furnish (amphiphilic) block copolymers comprising a degradable segment. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dispersion and alignment of nanorods in cylindrical block copolymer thin films.

PubMed

Rasin, Boris; Chao, Huikuan; Jiang, Guoqian; Wang, Dongliang; Riggleman, Robert A; Composto, Russell J

2016-02-21

Although significant progress has been made in controlling the dispersion of spherical nanoparticles in block copolymer thin films, our ability to disperse and control the assembly of anisotropic nanoparticles into well-defined structures is lacking in comparison. Here we use a combination of experiments and field theoretic simulations to examine the assembly of gold nanorods (AuNRs) in a block copolymer. Experimentally, poly(2-vinylpyridine)-grafted AuNRs (P2VP-AuNRs) are incorporated into poly(styrene)-b-poly(2-vinylpyridine) (PS-b-P2VP) thin films with a vertical cylinder morphology. At sufficiently low concentrations, the AuNRs disperse in the block copolymer thin film. For these dispersed AuNR systems, atomic force microscopy combined with sequential ultraviolet ozone etching indicates that the P2VP-AuNRs segregate to the base of the P2VP cylinders. Furthermore, top-down transmission electron microscopy imaging shows that the P2VP-AuNRs mainly lie parallel to the substrate. Our field theoretic simulations indicate that the NRs are strongly attracted to the cylinder base where they can relieve the local stretching of the minority block of the copolymer. These simulations also indicate conditions that will drive AuNRs to adopt a vertical orientation, namely by increasing nanorod length and/or reducing the wetting of the short block towards the substrate.

Characterisation and toxicological assessment of Neutral Methacrylate Copolymer for GRAS evaluation.

PubMed

Eisele, Johanna; Haynes, Geoff; Kreuzer, Knut; Rosamilia, Tiana

2013-12-01

Neutral Methacrylate Copolymer is a fully polymerised copolymer used in the pharmaceutical industry to permit pH-independent delayed release of active ingredients from oral dosage forms. This function has potential use with food supplements and this article describes available information on the safety of the substance. Oral administration of radiolabelled copolymer to rats resulted in the detection of chemically unchanged copolymer in the faeces, with negligible absorption. Safety studies revealed no adverse toxicity following repeated administration at doses of up to 2000 mg/kg bw/d in a sub-chronic study in rats or 250 mg/kg bw/d in a sub-chronic study in dogs. No reproductive toxicity occurred at up to 2000 mg/kg bw/d in rats or rabbits. The substance shows no evidence of genotoxicity, has low acute toxicity and no irritation or sensitisation potential. An ADI value of 20 mg/kg bw was concluded from two alternative approaches. Daily exposure from use in dietary supplements is estimated as up to 10.0 mg/kg bw in adults and 13.3 mg/kg bw in children. There would therefore appear to be no safety concerns under the intended conditions of use. The information provided is intended to support an evaluation that the substance may be "generally recognized as safe" (GRAS). Copyright © 2013 Elsevier Inc. All rights reserved.

Insensitive explosive composition of halogenated copolymer and triaminotrinitrobenzene

DOEpatents

Benziger, Theodore M.

1976-01-01

A highly insensitive and heat resistant plastic-bonded explosive containing 90 wt % triaminotrinitrobenzene and 10 wt % of a fully saturated copolymer of chlorotrifluoroethylene and vinylidene fluoride is readily manufactured by the slurry process.

High-temperature two-dimensional liquid chromatography of ethylene-vinylacetate copolymers.

PubMed

Ginzburg, Anton; Macko, Tibor; Dolle, Volker; Brüll, Robert

2010-10-29

Temperature rising elution fractionation hyphenated to size exclusion chromatography (TREF×SEC) is a routine technique to determine the chemical heterogeneity of semicrystalline olefin copolymers. Its applicability is limited to well crystallizing samples. High-temperature two-dimensional liquid chromatography, HT 2D-LC, where the chromatographic separation by HPLC is hyphenated to SEC (HPLC×SEC) holds the promise to separate such materials irrespective of their crystallizability. A model blend consisting of ethylene-vinyl acetate (EVA) copolymers covering a broad range of chemical composition distribution including amorphous and semicrystalline copolymers and a polyethylene standard was separated by HT 2D-LC at 140°C. Both axes of the contour plot, i.e. the compositional axis from the HPLC and the molar mass axis from the SEC separation were calibrated for the first time. Therefore, a new approach to determine the void and dwell volume of the developed HT 2D-LC instrument was applied. The results from the HT 2D-LC separation are compared to those from a cross-fractionation (TREF×SEC) experiment. Copyright © 2010. Published by Elsevier B.V.

Directing self-assembly of gold nanoparticles in diblock copolymer scaffold

NASA Astrophysics Data System (ADS)

Li, Qifang; He, Jinbo; Glogowski, Elizabeth; Emrick, Todd; Russell, Thomas

2007-03-01

A versatile hierarchical approach for directing self -assembly of gold nanostructures with size 2-3nm in diblock copolymer scaffolds is found. Diblock copolymer polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) is used to form a regular scaffold of highly anisotropic, stripe-like domains, and controlled differential wetting by dichloromethane and thermal annealing guides gold nanoparticles with half hydrophilic ligand to aggregate selectively along the scaffold, producing highly organized metal nanostructures. In as-cast block-copolymer and gold nanoparticles thin films, micelle structure and gold nanoparticles random distribution on scaffold are typically observed. However, samples annealed in dichloromethane exhibit well-defined short-range ordered nanostructure with gold nanoparticles located at the interface of PS and P2VP nanoscale domain. After annealing at 170 C, the gold nanoparticles at interface migrated into the middle of P2VP phase and exhibited long-range ordered hierarchical structures. Synergistic interactions between the gold nanoparticles and the PS-b-P2VP caused an orientation of the microdomains normal to the film surface.

Using tethered triblock copolymers to mediate the interaction between substrates

NASA Astrophysics Data System (ADS)

Chern, Shyh-Shi; Zhulina, Ekaterina B.; Pickett, Galen T.; Balazs, Anna C.

1998-04-01

Using scaling analysis and a self-consistent field (SCF) theory, we compress two copolymer-coated surfaces and isolate conditions that yield multiple, distinct minima in the interaction profile. We focus on planar surfaces that are coated with ABC triblock copolymers. Tethered to the surface by the last monomer in the C block, the copolymers are grafted at relatively low densities. The surrounding solution is a poor solvent for both the A and C blocks, and is a good solvent for the B blocks. Through scaling theory, we pinpoint the parameters that yield two minima in the interaction profile. The SCF calculations reveal the changes in the morphology of the polymers as the layers are compressed. Through both studies, we determine how the morphological changes give rise to the observed surface interactions. The results provide guidelines for creating polymer-coated colloidal systems that can form two stable crystal structures. Such systems could be used for bistable, optical switches. The findings also yield a prescription for creating systems that exhibit additional minima in the free energy of interaction.

Incorporating fluorinated moieties in fully conjugated donor-acceptor block copolymers

NASA Astrophysics Data System (ADS)

Lee, Youngmin; Wang, Qing; Gomez, Enrique D.

Fully conjugated donor-acceptor block copolymers are promising candidates for photovoltaics due to their ability to microphase separate at length scales commensurate with exciton diffusion lengths. These materials can also serve as model systems to study the relationship between molecular structure, microstructure, and optoelectronic properties of conjugated polymers. The development of new donor-acceptor block copolymers relies on the manipulation of the chemical structure to fine tune properties and improve overall performance when employed in photovoltaic devices. To this end, we have demonstrated the incorporation of fluorinated moieties in conjugated block copolymers. The introduction of fluorine, a strong electron withdrawing element, is known to influence phase separation and the bandgap, and as a result, optoelectronic properties. Fluorine was introduced to the acceptor block of poly(3-hexylthiophene-2,5-diyl)-block-poly((9,9-bis(2-octyl)fluorene-2,7-diyl)-alt-(4,7-di(thiophene-2-yl)-2,1,3-benzothiadiazole)-5 ',5?-diyl) (P3HT- b-PFTBT). PFTBTs were prepared with di-fluorinated and mono-fluorinated TBT. We find that fluorination impacts the bandgap, morphology and performance in devices.

Flash NanoPrecipitation of organic actives via confined micromixing and block copolymer stabilization

NASA Astrophysics Data System (ADS)

Johnson, Brian K.

This dissertation provides a method and the understanding required to produce nanoparticles of organic actives using Flash NanoPrecipitation . The process comprises mixing a solvent phase containing molecularly dissolved amphiphilic block copolymer and an organic active with an anti-solvent. One block of the copolymer precipitates to alter the nucleation and growth of the organic active while the other remains in solution for particle stabilization. A custom built confined impinging jets (CIJ) mixer provides optimum micromixing at the laboratory or full scale within milliseconds. Comparison to other reactor designs is provided. The resulting nanoparticles have functional surfaces tailored to meet the needs of pharmaceutical or specialty chemical formulations. Example beta-carotene nanoparticles with a polyethylene oxide surface are produced at high concentration, high yield, low stabilizer content, and a size suitable for sterile filtration or larger. The technical challenges in nanoparticle production are explained via the characteristic times for mixing, copolymer aggregation, and organic active particle formation. The time for Flash NanoPrecipitation is shown to depend strongly on the time for copolymer aggregation, and control of the organic nucleation versus growth is critical to achieve nanoparticles. Mixing operating lines explain the impact of solubility differences between the colloidal stabilizer and the organic active as function of mixing rate. Techniques to measure the solubility of the copolymer and DeltaG° , DeltaH°, and DeltaS° of micellization are demonstrated. An analytical CIJ mixer is developed by quantifying the characteristic time and physical mechanism of mixing. The methodology described to find an absolute mixing lifetime is also applied to a vortex mixer at a spectrum of flow ratios away from one. Dimensional analysis using the process Damkohler number, defined as the ratio of the mixing to the process time, is applied to precipitation

Preparation of dual-stimuli-responsive liposomes using methacrylate-based copolymers with pH and temperature sensitivities for precisely controlled release.

PubMed

Sugimoto, Takumi; Yamazaki, Naoko; Hayashi, Takaaki; Yuba, Eiji; Harada, Atsushi; Kotaka, Aki; Shinde, Chiharu; Kumei, Takayuki; Sumida, Yasushi; Fukushima, Mitsuhiro; Munekata, Yuki; Maruyama, Keiichi; Kono, Kenji

2017-07-01

Dual-signal-sensitive copolymers were synthesized by copolymerization of methoxy diethylene glycol methacrylate, methacrylic acid, and lauroxy tetraethylene glycol methacrylate, which respectively provide temperature sensitivity, pH sensitivity, and anchoring to liposome surfaces. These novel copolymers, with water solubility that differs depending on temperature and pH, are soluble in water under neutral pH and low-temperature conditions, but they become water-insoluble and form aggregates under acidic pH and high-temperature conditions. Liposomes modified with these copolymers exhibited enhanced content release at weakly acidic pH with increasing temperature, although no temperature-dependent content release was observed in neutral conditions. Interaction between the copolymers and the lipid monolayer at the air-water interface revealed that the copolymer chains penetrate more deeply into the monolayer with increasing temperature at acidic pH than at neutral pH, where the penetration of copolymer chains was moderate and temperature-independent at neutral pH. Interaction of the copolymer-modified liposomes with HeLa cells demonstrated that the copolymer-modified liposomes were adsorbed quickly and efficiently onto the cell surface and that they were internalized more gradually than the unmodified liposomes through endocytosis. Furthermore, the copolymer-modified liposomes enhanced the content release in endosomes with increasing temperature, but no such temperature-dependent enhancement of content release was observed for unmodified liposomes. Copyright © 2017 Elsevier B.V. All rights reserved.

Polydiacetylene/triblock copolymer nanoblend applied as a sensor for micellar casein: A thermodynamic approach.

PubMed

de Souza, Luana Cypriano; de Paula Rezende, Jaqueline; Pires, Ana Clarissa dos Santos; da Silva, Luis Henrique Mendes; da Silva, Maria do Carmo Hespanhol; Castrillon, Elkin Dario Castellon; de Andrade, Nélio José

2016-04-15

Polydiacetylene (PDA) and triblock copolymer nanoblends were synthesized to detect micellar casein (MC), the main milk protein and an indicator of milk quality. UV-Vis spectrum showed that MC induced blue-to-red transition in nanoblends. When nanoblends and MC were separated by dialysis membrane colorimetric response (CR) was similar, whereas a remarkable CR reduction was noticed after addition of dialyzed-MC, suggesting that small molecules present in MC (salts) caused PDA color change. Interaction enthalpy variation between nanoblends and MC showed an abrupt increase that coincided with MC concentration when colorimetric transition occurred. Copolymer hydrophobic/hydrophilic balance and presence of other molecules in the system affected nanoblends CR. MC salts were found to interact with nanoblends leading to color changes. MC concentration, MC salt release, copolymer hydrophobic/hydrophilic balance, and presence of other molecules in the system affected responses of the sensors. These results contribute to future applications of PDA/copolymer nanosensors to dairy models. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synthesis and Characterization of Solution and Melt Processible Poly(Acrylonitrile-Co-Methyl Acrylate) Statistical Copolymers

NASA Astrophysics Data System (ADS)

Pisipati, Padmapriya

Polyacrylonitrile (PAN) and its copolymers are used in a wide variety of applications ranging from textiles to purification membranes, packaging material and carbon fiber precursors. High performance polyacrylonitrile copolymer fiber is the most dominant precursor for carbon fibers. Synthesis of very high molecular weight poly(acrylonitrile-co-methyl acrylate) copolymers with weight average molecular weights of at least 1.7 million g/mole were synthesized on a laboratory scale using low temperature, emulsion copolymerization in a closed pressure reactor. Single filaments were spun via hybrid dry-jet gel solution spinning. These very high molecular weight copolymers produced precursor fibers with tensile strengths averaging 954 MPa with an elastic modulus of 15.9 GPa (N = 296). The small filament diameters were approximately 5 im. Results indicated that the low filament diameter that was achieved with a high draw ratio, combined with the hybrid dry-jet gel spinning process lead to an exponential enhancement of the tensile properties of these fibers. Carbon fibers for polymer matrix composites are currently derived from polyacrylonitrile copolymer fiber precursors where solution spinning accounts for ˜40 % of the total fiber production cost. To expand carbon fiber applications into the automotive industry, the cost of the carbon fiber needs to be reduced from 8 to ˜3-5. In order to develop an alternative melt processing route several benign plasticizers have been investigated. A low temperature, persulfate-metabisulfite initiated emulsion copolymerization was developed to synthesize poly(acrylonitrile-co-methyl acrylate) copolymers with acrylonitrile contents between 91-96 wt% with a molecular weight range of 100-200 kg/mol. This method was designed for a potential industrial scale up. Furthermore, water was investigated as a potential melting point depressant for these copolymers. Twenty-five wt% water lead to a decrease in the Tm of a 93/7 wt/wt % poly

21 CFR 177.1430 - Isobutylene-butene copolymers.

Code of Federal Regulations, 2013 CFR

2013-04-01

...) of this section. (b) Specifications: Isobutylene-butene copolymers Molecular weight (range) Viscosity...: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. (2) Viscosity. Viscosity shall be determined by ASTM method D445-74, “Test for Kinematic Viscosity of Transparent and...

21 CFR 177.1430 - Isobutylene-butene copolymers.

Code of Federal Regulations, 2012 CFR

2012-04-01

...) of this section. (b) Specifications: Isobutylene-butene copolymers Molecular weight (range) Viscosity...: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. (2) Viscosity. Viscosity shall be determined by ASTM method D445-74, “Test for Kinematic Viscosity of Transparent and...

21 CFR 177.1430 - Isobutylene-butene copolymers.

Code of Federal Regulations, 2011 CFR

2011-04-01

...) of this section. (b) Specifications: Isobutylene-butene copolymers Molecular weight (range) Viscosity...: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. (2) Viscosity. Viscosity shall be determined by ASTM method D445-74, “Test for Kinematic Viscosity of Transparent and...

Multi-armed poly(L-glutamic acid)-graft-oligoethylenimine copolymers as efficient nonviral gene delivery vectors.

PubMed

Chen, Lei; Tian, Huayu; Chen, Jie; Chen, Xuesi; Huang, Yubin; Jing, Xiabin

2010-01-01

The application of polyethylenimine (PEI) in gene delivery has been severely limited by significant cytotoxicity that results from a nondegradable methylene backbone and high cationic charge density. It is therefore necessary to develop novel biodegradable PEI derivates for low-toxic, highly efficient gene delivery. A series of novel cationic copolymers with various charge density were designed and synthesized by grafting different kinds of oligoethylenimine (OEI) onto a determinate multi-armed poly(L-glutamic acid) backbone. The molecular structures of multi-armed poly(L-glutamic acid)-graft-OEI (MP-g-OEI) copolymers were characterized using nuclear magnetic resonance, viscosimetry and gel permeation chromatography. Moreover, the MP-g-OEI/DNA complexes were measured by a gel retardation assay, dynamic light scattering and atomic force microscopy to determine DNA binding ability, particle size, zeta potential, complex formation and shape, respectively. MP-g-OEI copolymers were also evaluated in Chinese hamster ovary and human embryonic kidney-293 cells for their cytotoxicity and transfection efficiency. The particle sizes of MP-g-OEI/DNA complexes were in a range of 109.6-182.6 nm and the zeta potentials were in a range of 29.2-44.5 mV above the N/P ratio of 5. All the MP-g-OEI copolymers exhibited lower cytotoxicity and higher gene transfection efficiency than PEI25k in the absence and presence of serum with different cell lines. Importantly, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay revealed that the cytotoxicity of MP-g-OEI copolymers varied with their molecular weight and charge density, and two of MP-g-OEI copolymers (OEI600-MP and OEI1800-MP) could achieve optimal transfection efficiency at a similar low N/P ratio as that for PEI25k. MP-g-OEI copolymers demonstrated considerable potential as nonviral vectors for gene therapy. Copyright 2009 John Wiley & Sons, Ltd.

Synthesis of carboxylic block copolymers via reversible addition fragmentation transfer polymerization for tooth erosion prevention.

PubMed

Lei, Y; Wang, T; Mitchell, J W; Qiu, J; Kilpatrick-Liverman, L

2014-12-01

Dental professionals are seeing a growing population of patients with visible signs of dental erosion. The approach currently being used to address the problem typically leverages the enamel protection benefits of fluoride. In this report, an alternative new block copolymer with a hydrophilic polyacrylic acid (PAA) block and a hydrophobic poly(methyl methacrylate) (PMMA) block was developed to similarly reduce the mineral loss from enamel under acidic conditions. This series of PMMA-b-PAA block copolymers was synthesized by reversible addition fragmentation transfer (RAFT) polymerization. Their structures were characterized by gel permeation chromatography (GPC) and (1)H nuclear magnetic resonance (NMR) spectra. The molar fractions of acrylic acid (AA) in the final block copolymer were finely controlled from 0.25 to 0.94, and the molecular weight (Mn) of PMMA-b-PAA was controlled from 10 kDa to 90 kDa. The binding capability of the block copolymer with hydroxyapatite (HAP) was investigated by ultraviolet-visible spectroscopy (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy. FTIR spectra confirmed that the PMMA-b-PAA block copolymer could bind to HAP via bridging bidentate bonds. Both UV-Vis and FTIR spectra additionally indicated that a high polymer concentration and low solution pH favored the polymer binding to HAP. The erosion-preventing efficacy of the PMMA-b-PAA block copolymer in inhibiting HAP mineral loss was quantitatively evaluated by atomic absorption spectroscopy (AAS). Based on the results, polymer treatment reduced the amount of calcium released by 27% to 30% in comparison with the unprotected samples. Scanning electron microscope (SEM) observations indicated that PMMA-b-PAA polymer treatment protected enamel from acid erosion. This new amphiphilic block copolymer has significant potential to be integrated into dentifrices or mouthrinses as an alternative non-fluoride ingredient to reduce tooth erosion. © International & American

Synthesis of Carboxylic Block Copolymers via Reversible Addition Fragmentation Transfer Polymerization for Tooth Erosion Prevention

PubMed Central

Lei, Y.; Wang, T.; Mitchell, J.W.; Qiu, J.; Kilpatrick-Liverman, L.

2014-01-01

Dental professionals are seeing a growing population of patients with visible signs of dental erosion. The approach currently being used to address the problem typically leverages the enamel protection benefits of fluoride. In this report, an alternative new block copolymer with a hydrophilic polyacrylic acid (PAA) block and a hydrophobic poly(methyl methacrylate) (PMMA) block was developed to similarly reduce the mineral loss from enamel under acidic conditions. This series of PMMA-b-PAA block copolymers was synthesized by reversible addition fragmentation transfer (RAFT) polymerization. Their structures were characterized by gel permeation chromatography (GPC) and 1H nuclear magnetic resonance (NMR) spectra. The molar fractions of acrylic acid (AA) in the final block copolymer were finely controlled from 0.25 to 0.94, and the molecular weight (Mn) of PMMA-b-PAA was controlled from 10 kDa to 90 kDa. The binding capability of the block copolymer with hydroxyapatite (HAP) was investigated by ultraviolet–visible spectroscopy (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy. FTIR spectra confirmed that the PMMA-b-PAA block copolymer could bind to HAP via bridging bidentate bonds. Both UV-Vis and FTIR spectra additionally indicated that a high polymer concentration and low solution pH favored the polymer binding to HAP. The erosion-preventing efficacy of the PMMA-b-PAA block copolymer in inhibiting HAP mineral loss was quantitatively evaluated by atomic absorption spectroscopy (AAS). Based on the results, polymer treatment reduced the amount of calcium released by 27% to 30% in comparison with the unprotected samples. Scanning electron microscope (SEM) observations indicated that PMMA-b-PAA polymer treatment protected enamel from acid erosion. This new amphiphilic block copolymer has significant potential to be integrated into dentifrices or mouthrinses as an alternative non-fluoride ingredient to reduce tooth erosion. PMID:25248611

Aggregate morphologies of amphiphilic ABC triblock copolymer in dilute solution using self-consistent field theory.

PubMed

Wang, Rong; Tang, Ping; Qiu, Feng; Yang, Yuliang

2005-09-15

The complex microstructures of amphiphilic ABC linear triblock copolymers in which one of the end blocks is relatively short and hydrophilic, and the other two blocks B and C are hydrophobic in a dilute solution, have been investigated by the real-space implementation of self-consistent field theory (SCFT) in two dimensions (2D). In contrast to diblock copolymers in solution, the aggregation of triblock copolymers are more complicated due to the presence of the second hydrophobic blocks and, hence, big ranges of parameter space controlling the morphology. By tailoring the hydrophobic degree and its difference between the blocks B and C, the various shapes of vesicles, circlelike and linelike micelles possibly corresponding to spherelike, and rodlike micelles in 3D, and especially, peanutlike micelles not found in diblock copolymers are observed. The transition from vesicles to circlelike micelles occurs with increasing the hydrophobicity of the blocks B and C, while the transition from circlelike micelles to linelike micelles or from the mixture of micelles and vesicles to the long linelike micelles takes place when the repulsive interaction of the end hydrophobic block C is stronger than that of the middle hydrophobic block B. Furthermore, it is favorable for dispersion of the block copolymer in the solvent into aggregates when the repulsion of the solvent to the end hydrophobic block is larger than that of the solvent to the middle hydrophobic block. Especially when the bulk block copolymers are in a weak segregation regime, the competition between the microphase separation and macrophase separation exists and the large compound micelle-like aggregates are found due to the macrophase separation with increasing the hydrophobic degree of blocks B and C, which is absent in diblock copolymer solution. The simulation results successfully reproduce the existing experimental ones.

Structure-directing star-shaped block copolymers: supramolecular vesicles for the delivery of anticancer drugs.

PubMed

Yang, Chuan; Liu, Shao Qiong; Venkataraman, Shrinivas; Gao, Shu Jun; Ke, Xiyu; Chia, Xin Tian; Hedrick, James L; Yang, Yi Yan

2015-06-28

Amphiphilic polycarbonate/PEG copolymer with a star-like architecture was designed to facilitate a unique supramolecular transformation of micelles to vesicles in aqueous solution for the efficient delivery of anticancer drugs. The star-shaped amphipilic block copolymer was synthesized by initiating the ring-opening polymerization of trimethylene carbonate (TMC) from methyl cholate through a combination of metal-free organo-catalytic living ring-opening polymerization and post-polymerization chain-end derivatization strategies. Subsequently, the self-assembly of the star-like polymer in aqueous solution into nanosized vesicles for anti-cancer drug delivery was studied. DOX was physically encapsulated into vesicles by dialysis and drug loading level was significant (22.5% in weight) for DOX. Importantly, DOX-loaded nanoparticles self-assembled from the star-like copolymer exhibited greater kinetic stability and higher DOX loading capacity than micelles prepared from cholesterol-initiated diblock analogue. The advantageous disparity is believed to be due to the transformation of micelles (diblock copolymer) to vesicles (star-like block copolymer) that possess greater core space for drug loading as well as the ability of such supramolecular structures to encapsulate DOX. DOX-loaded vesicles effectively inhibited the proliferation of 4T1, MDA-MB-231 and BT-474 cells, with IC50 values of 10, 1.5 and 1.0mg/L, respectively. DOX-loaded vesicles injected into 4T1 tumor-bearing mice exhibited enhanced accumulation in tumor tissue due to the enhanced permeation and retention (EPR) effect. Importantly, DOX-loaded vesicles demonstrated greater tumor growth inhibition than free DOX without causing significant body weight loss or cardiotoxicity. The unique ability of the star-like copolymer emanating from the methyl cholate core provided the requisite modification in the block copolymer interfacial curvature to generate vesicles of high loading capacity for DOX with significant

RAFT-synthesized Graft Copolymers that Enhance pH-dependent Membrane Destabilization and Protein Circulation Times

PubMed Central

Crownover, Emily; Duvall, Craig L.; Convertine, Anthony; Hoffman, Allan S.; Stayton, Patrick S.

2012-01-01

Here we describe a new graft copolymer architecture of poly(propylacrylic acid) (polyPAA) that displays potent pH-dependent, membrane-destabilizing activity and in addition is shown to enhance protein blood circulation kinetics. PolyPAA containing a single telechelic alkyne functionality was prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization with an alkyne-functional chain transfer agent (CTA) and coupled to RAFT polymerized poly(azidopropyl methacrylate) (polyAPMA) through azide-alkyne [3+2] Huisgen cycloaddition. The graft copolymers become membrane destabilizing at endosomal pH values and are active at significantly lower concentrations than the linear polyPAA. A biotin terminated polyPAA graft copolymer was prepared by grafting PAA onto polyAPMA polymerized with a biotin functional RAFT CTA. The blood circulation time and biodistribution of tritium labeled avidin conjugated to the polyPAA graft copolymer was characterized along with a clinically utilized 40 kDa branched polyethylene glycol (PEG) also possessing biotin functionalization. The linear and graft polyPAA increase the area under the curve (AUC) over avidin alone by 9 and 12 times, respectively. Furthermore, polyPAA graft copolymer conjugates accumulated in tumor tissue significantly more than the linear polyPAA and the branched PEG conjugates. The collective data presented in this report indicate that the polyPAA graft copolymers exhibit robust pH-dependent, membrane-destabilizing activity, low cytotoxicity and significantly enhance blood circulation time and tumor accumulation. PMID:21699931

Antibacterial activity, thermal stability and ab initio study of copolymer containing sulfobetaine and carboxybetaine groups

NASA Astrophysics Data System (ADS)

Tarannum, Nazia; Singh, Meenakshi; Yadav, Anil K.

2017-10-01

Here, we have explored the antibacterial activity, thermal stability and theoretical study of two copolymers that contain sulfobetaine and carboetaine moiety. Copolymers were synthesized based on Schiff base chemistry with generation of zwitterionic centres by nucleophilic addition of sultone/lactone. To predict and confirm the molecular structure of zwitterionic polyelectrolyte molecule, the theoretical study of structural features and other thermodynamic characteristics of copolymer constituents was obtained by ab initio calculations. Various parameters such as geometry optimization, energy calculations, frequency calculations and intrinsic reaction coefficient (IRC) are simulated using Hartree Fock (HF) method. The geometry optimizations are analyzed at HF/3-21 G default level of theory. The vibrational frequency is calculated via density functional theory (DFT)/B3LYP 6-31G*(d) level whose values are in accord with the experimental observed frequency. Both copolymers have been successfully assessed for antibacterial activity against Staphylococcus aureus and Pseudomonas aeuroginosa bacterial strains by disc diffusion method. The antibacterial study helped in evaluating zone of inhibition, minimum inhibitory concentration and minimum bactericidal concentration. Sulfobetaine copolymer is found to be more effective in curtailing the infection caused by bacteria as compared to carbobetaine.

Dynamics of interacting edge defects in copolymer lamellae

NASA Astrophysics Data System (ADS)

Dalnoki-Veress, Kari; McGraw, Joshua D.; Rowe, Ian D. W.

2011-03-01

It is known that terraces at the interface of lamella forming diblock copolymers do not make discontinuous jumps in height. Rather, their profiles are smoothly varying. The width of the transition region between two lamellar heights is typically several hundreds of nanometres, resulting from a balance between surface tension, chain stretching penalties, and the enthalpy of mixing. What is less well known in these systems is what happens when two transition regions approach one another. In this study, we show that time dependent experimental data of interacting copolymer lamellar edges is consistent with a model that assumes a repulsion between adjacent edges. The range of the interaction between edge defects is consistent with the profile width of noninteracting diblock terraces. Financial support from NSERC of Canada is gratefully acknowledged.

Effect of molecular structure of aniline-formaldehyde copolymers on corrosion inhibition of mild steel in hydrochloric acid solution.

PubMed

Zhang, Yan; Nie, Mengyan; Wang, Xiutong; Zhu, Yukun; Shi, Fuhua; Yu, Jianqiang; Hou, Baorong

2015-05-30

Aniline-formaldehyde copolymers with different molecular structures have been prepared and investigated for the purpose of corrosion control of mild steel in hydrochloric acid. The copolymers were synthesized by a condensation polymerization process with different ratios of aniline to formaldehyde in acidic precursor solutions. The corrosion inhibition efficiency of as-synthesized copolymers for Q235 mild steel was investigated in 1.0 mol L(-1) hydrochloric acid solution by weight loss measurement, potentiodynamic polarization, and electrochemical impedance spectroscopy, respectively. All the results demonstrate that as-prepared aniline-formaldehyde copolymers are efficient mixed-type corrosion inhibitors for mild steels in hydrochloric acid. The corrosion inhibition mechanism is discussed in terms of the role of molecular structure on adsorption of the copolymers onto the steel surface in acid solution. Copyright © 2015. Published by Elsevier B.V.

Selective directed self-assembly of coexisting morphologies using block copolymer blends

NASA Astrophysics Data System (ADS)

Stein, A.; Wright, G.; Yager, K. G.; Doerk, G. S.; Black, C. T.

2016-08-01

Directed self-assembly (DSA) of block copolymers is an emergent technique for nano-lithography, but is limited in the range of structures possible in a single fabrication step. Here we expand on traditional DSA chemical patterning. A blend of lamellar- and cylinder-forming block copolymers assembles on specially designed surface chemical line gratings, leading to the simultaneous formation of coexisting ordered morphologies in separate areas of the substrate. The competing energetics of polymer chain distortions and chemical mismatch with the substrate grating bias the system towards either line/space or dot array patterns, depending on the pitch and linewidth of the prepattern. This is in contrast to the typical DSA, wherein assembly of a single-component block copolymer on chemical templates generates patterns of either lines/spaces (lamellar) or hexagonal dot arrays (cylinders). In our approach, the chemical template encodes desired local spatial arrangements of coexisting design motifs, self-assembled from a single, sophisticated resist.

Selective directed self-assembly of coexisting morphologies using block copolymer blends

PubMed Central

Stein, A.; Wright, G.; Yager, K. G.; Doerk, G. S.; Black, C. T.

2016-01-01

Directed self-assembly (DSA) of block copolymers is an emergent technique for nano-lithography, but is limited in the range of structures possible in a single fabrication step. Here we expand on traditional DSA chemical patterning. A blend of lamellar- and cylinder-forming block copolymers assembles on specially designed surface chemical line gratings, leading to the simultaneous formation of coexisting ordered morphologies in separate areas of the substrate. The competing energetics of polymer chain distortions and chemical mismatch with the substrate grating bias the system towards either line/space or dot array patterns, depending on the pitch and linewidth of the prepattern. This is in contrast to the typical DSA, wherein assembly of a single-component block copolymer on chemical templates generates patterns of either lines/spaces (lamellar) or hexagonal dot arrays (cylinders). In our approach, the chemical template encodes desired local spatial arrangements of coexisting design motifs, self-assembled from a single, sophisticated resist. PMID:27480327

Selective directed self-assembly of coexisting morphologies using block copolymer blends

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

Stein, A.; Wright, G.; Yager, K. G.

Directed self-assembly (DSA) of block copolymers is an emergent technique for nano-lithography, but is limited in the range of structures possible in a single fabrication step. We expand on traditional DSA chemical patterning. Moreover, a blend of lamellar- and cylinder-forming block copolymers assembles on specially designed surface chemical line gratings, leading to the simultaneous formation of coexisting ordered morphologies in separate areas of the substrate. The competing energetics of polymer chain distortions and chemical mismatch with the substrate grating bias the system towards either line/space or dot array patterns, depending on the pitch and linewidth of the prepattern. This contrastsmore » with typical DSA, wherein assembly of a single-component block copolymer on chemical templates generates patterns of either lines/spaces (lamellar) or hexagonal dot arrays (cylinders). In our approach, the chemical template encodes desired local spatial arrangements of coexisting design motifs, self-assembled from a single, sophisticated resist.« less

Selective directed self-assembly of coexisting morphologies using block copolymer blends

DOE PAGES

Stein, A.; Wright, G.; Yager, K. G.; ...

2016-08-02

Directed self-assembly (DSA) of block copolymers is an emergent technique for nano-lithography, but is limited in the range of structures possible in a single fabrication step. We expand on traditional DSA chemical patterning. Moreover, a blend of lamellar- and cylinder-forming block copolymers assembles on specially designed surface chemical line gratings, leading to the simultaneous formation of coexisting ordered morphologies in separate areas of the substrate. The competing energetics of polymer chain distortions and chemical mismatch with the substrate grating bias the system towards either line/space or dot array patterns, depending on the pitch and linewidth of the prepattern. This contrastsmore » with typical DSA, wherein assembly of a single-component block copolymer on chemical templates generates patterns of either lines/spaces (lamellar) or hexagonal dot arrays (cylinders). In our approach, the chemical template encodes desired local spatial arrangements of coexisting design motifs, self-assembled from a single, sophisticated resist.« less

21 CFR 177.1980 - Vinyl chloride-propylene copolymers.

Code of Federal Regulations, 2014 CFR

2014-04-01

... grams of granular sodium peroxide, 0.1 gram of powdered starch, and 0.02 gram potassium nitrate; and the... provisions of this section are not applicable to vinyl chloride-propylene copolymers used in food-packaging...

Block-copolymer-controlled growth of CaCO3 microrings.

PubMed

Gao, Yun-Xiang; Yu, Shu-Hong; Cong, Huaiping; Jiang, Jun; Xu, An-Wu; Dong, W F; Cölfen, Helmut

2006-04-06

A novel way for directed solution growth of hollow superstructures of CaCO3 has been successfully developed on the basis of controlled self-assembly and polymer concentration gradients using a double-hydrophilic block copolymer with a hydrophobic modification as a directing agent. A formation mechanism of such rings is proposed on the basis of the formation of CaCO3 nanoparticles in unstructured block copolymer assemblies with subsequent aggregation of these primary nanoparticles. This leads to the formation of a polymer concentration gradient from the inside to the outside of the particle. As the polymer contains multiple chelating units, this leads to a selective dissolution of the center of the particle.

Biodegradation of polystyrene-graft-starch copolymers in three different types of soil.

PubMed

Nikolic, Vladimir; Velickovic, Sava; Popovic, Aleksandar

2014-01-01

Materials based on polystyrene and starch copolymers are used in food packaging, water pollution treatment, and textile industry, and their biodegradability is a desired characteristic. In order to examine the degradation patterns of modified, biodegradable derivates of polystyrene, which may keep its excellent technical features but be more environmentally friendly at the same time, polystyrene-graft-starch biomaterials obtained by emulsion polymerization in the presence of new type of initiator/activator pair (potassium persulfate/different amines) were subjected to 6-month biodegradation by burial method in three different types of commercially available soils: soil rich in humus and soil for cactus and orchid growing. Biodegradation was monitored by mass decrease, and the highest degradation rate was achieved in soil for cactus growing (81.30%). Statistical analysis proved that microorganisms in different soil samples have different ability of biodegradation, and there is a significant negative correlation between the share of polystyrene in copolymer and degree of biodegradation. Grafting of polystyrene on starch on one hand prevents complete degradation of starch that is present (with maximal percentage of degraded starch ranging from 55 to 93%), while on the other hand there is an upper limit of share of polystyrene in the copolymer (ranging from 37 to 77%) that is preventing biodegradation of degradable part of copolymers.

Acid-Labile Amphiphilic PEO-b-PPO-b-PEO Copolymers: Degradable Poloxamer Analogs.

PubMed

Worm, Matthias; Kang, Biao; Dingels, Carsten; Wurm, Frederik R; Frey, Holger

2016-05-01

Poly ((ethylene oxide)-b-(propylene oxide)-b-(ethylene oxide)) triblock copolymers commonly known as poloxamers or Pluronics constitute an important class of nonionic, biocompatible surfactants. Here, a method is reported to incorporate two acid-labile acetal moieties in the backbone of poloxamers to generate acid-cleavable nonionic surfactants. Poly(propylene oxide) is functionalized by means of an acetate-protected vinyl ether to introduce acetal units. Three cleavable PEO-PPO-PEO triblock copolymers (Mn,total = 6600, 8000, 9150 g·mol(-1) ; Mn,PEO = 2200, 3600, 4750 g·mol(-1) ) have been synthesized using anionic ring-opening polymerization. The amphiphilic copolymers exhibit narrow molecular weight distributions (Ð = 1.06-1.08). Surface tension measurements reveal surface-active behavior in aqueous solution comparable to established noncleavable poloxamers. Complete hydrolysis of the labile junctions after acidic treatment is verified by size exclusion chromatography. The block copolymers have been employed as surfactants in a miniemulsion polymerization to generate polystyrene (PS) nanoparticles with mean diameters of ≈200 nm and narrow size distribution, as determined by dynamic light scattering and scanning electron microscopy. Acid-triggered precipitation facilitates removal of surfactant fragments from the nanoparticles, which simplifies purification and enables nanoparticle precipitation "on demand." © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gradient structure-induced temperature responsiveness in styrene/methyl methacrylate gradient copolymers micelles.

PubMed

Zheng, Chao; Huang, Haiying; He, Tianbai

2014-02-01

In this work, micelles are formed by gradient copolymer of styrene and methyl methacrylate in acetone-water mixture and their temperature responsiveness is investigated in a narrow range near room temperature. Three different kinds of structural transitions could be induced by temperature: unimers to micelle transition, shrinkage/stretching of micelles, and morphological transition from spherical micelles to vesicles. In addition, a model analysis on the interface of gradient copolymer micelle is made to better understand these phenomena. It is found that both position and composition of the interface could alter in response to the change in temperature. According to the experiments and model analysis, it is proposed that temperature responsiveness might be an intrinsic and universal property of gradient copolymer micelles, which only originates from the gradient structure. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation and properties of immobilized pectinase onto the amphiphilic PS-b-PAA diblock copolymers.

PubMed

Lei, Zhongli; Bi, Shuxian

2007-01-30

Well-defined amphiphilic block copolymers poly(styrene-b-acrylic acid) (PS-b-PAA) with controlled block length were synthesized using atom transfer radical polymerization (ATRP). Pectinase enzyme was immobilized on the well-defined amphiphilic block copolymers PS-b-PAA. The carboxyl groups on the amphiphilic PS-b-PAA diblock copolymers present a very simple, mild, and time-saving process for enzyme immobilization. Various characteristics of immobilized pectinase such as the pH and temperature stability, thermal stability, and storage stability were valuated. Among them the pH optimum and temperature optimum of free and immobilized pectinase were found to be pH 6.0 and 65 degrees C.

Conjugated block copolymers: A building block for high-performance organic photovoltaics

NASA Astrophysics Data System (ADS)

Guo, Changhe

State-of-the-art organic photovoltaics rely on kinetically trapped, partially phase-separated structures of donor/acceptor mixtures to create a high interfacial area for exciton dissociation and networks of bicontinuous phases for charge transport. Nevertheless, intrinsic structural disorder and weak intermolecular interactions in polymer blends limit the performance and stability of organic electronic devices. We demonstrate a potential strategy to control morphology and donor/acceptor heterojunctions through conjugated block copolymer poly(3-hexylthiophene)- block-poly((9,9-dioctylfluorene)-2,7-diyl-alt-[4,7-bis(thiophen-5-yl)-2,1,3-benzothiadiazole]-2',2''-diyl) (P3HT-b-PFTBT). Block copolymers can self-assemble into well-ordered nanostructures ideal for photovoltaic applications. When utilized as the photovoltaic active layer, P3HT-b-PFTBT block copolymer devices demonstrate thermal stability and photoconversion efficiency of 3% well beyond devices composed of the constituent polymer blends. Resonant soft X-ray scattering (RSOXS) is used to elucidate the structural origin for efficient block copolymer photovoltaics. Energy tuning in soft X-ray ranges gives RSOXS chemical sensitivity to characterize organic thin films with compositionally similar phases or complicated multiphase systems. RSOXS reveals that the remarkable performance of P3HT-b-PFTBT devices is due to self-assembly into nanoscale in-plane lamellar morphology, which not only establishes an equilibrium microstructure amenable for exciton dissociation but also provides pathways for efficient charge transport. Furthermore, we find evidence that covalent control of donor/acceptor interfaces in block copolymers has the potential to promote charge separation and optimize the photoconversion process by limiting charge recombination. To visualize the nanostructure in organic thin films, we introduce low energy-loss energy-filtered transmission electron microscopy (EFTEM) as an important alternative

Molecular Mobility in Phase Segregated Bottlebrush Block Copolymer Melts

NASA Astrophysics Data System (ADS)

Yavitt, Benjamin; Gai, Yue; Song, Dongpo; Winter, H. Henning; Watkins, James

We investigate the linear viscoelastic behavior of poly(styrene)-block-poly(ethylene oxide) (PS-b-PEO) brush block copolymer (BBCP) materials over a range of vol. fractions and with side chain lengths below the entanglement molecular weights. The high chain mobility of the brush architecture results in rapid micro-phase segregation of the brush copolymer segments, which occurs during thermal annealing at mild temperatures. Master curves of the dynamic moduli were obtained by time-temperature superposition. The reduced degree of chain entanglements leads to a unique liquid-like rheology similar to that of bottlebrush homopolymers, even in the phase segregated state. We also explore the alignment of phase segregated domains at exceptionally low strain amplitudes (γ = 0.01) and mild processing temperatures using small angle X-ray scattering (SAXS). Domain orientation occurred readily at strains within the linear viscoelastic regime without noticeable effect on the moduli. This interplay of high molecular mobility and rapid phase segregation that are exhibited simultaneously in BBCPs is in contrast to the behavior of conventional linear block copolymer (LBCP) analogs and opens up new possibilities for processing BBCP materials for a wide range of nanotechnology applications. NSF Center for Hierarchical Manufacturing at the University of Massachusetts, Amherst (CMMI-1025020).

Non-Classical Order in Sphere Forming ABAC Tetrablock Copolymers

NASA Astrophysics Data System (ADS)

Zhang, Jingwen; Sides, Scott; Bates, Frank

2013-03-01

AB diblock and ABC triblock copolymers have been studied thoroughly. ABAC tetrablock copolymers, representing the simplest variation from ABC triblock by breaking the molecular symmetry via inserting some of the A block in between B and C blocks, have been studied systematically in this research. The model system is poly(styrene-b-isoprene-b-styrene-b-ethylene oxide) (SISO) tetrablock terpolymers and the resulting morphologies were characterized by nuclear magnetic resonance, gel permeation chromatography, small-angle X-ray scattering, transmission electron microscopy, differential scanning calorimetry and dynamic mechanical spectroscopy. Two novel phases are first discovered in a single component block copolymers: hexagonally ordered spherical phase and tentatively identified dodecagonal quasicrystalline (QC) phase. In particular, the discovery of QC phase bridges the world of soft matters to that of metals. These unusual sets of morphologies will be discussed in the context of segregation under the constraints associated with the tetrablock molecular architecture. Theoretical calculations based on the assumption of Gaussian chain statistics provide valuable insights into the molecular configurations associated with these morphologies. the U.S. Department of Energy, Basic Energy Sciences, Division of Materials Science and Engineering, under contract number DEAC05-00OR22725 with UT-Battelle LLC at Oak Ridge National Lab.

Ductile electroactive biodegradable hyperbranched polylactide copolymers enhancing myoblast differentiation

PubMed Central

Xie, Meihua; Wang, Ling; Guo, Baolin; Wang, Zhong; Chen, Y. Eugene; Ma, Peter X.

2015-01-01

Myotube formation is crucial to restoring muscular functions, and biomaterials that enhance the myoblast differentiation into myotubes are highly desirable for muscular repair. Here, we report the synthesis of electroactive, ductile, and degradable copolymers and their application in enhancing the differentiation of myoblasts to myotubes. A hyperbranched ductile polylactide (HPLA) was synthesized and then copolymerized with aniline tetramer (AT) to produce a series of electroactive, ductile and degradable copolymers (HPLAAT). The HPLA and HPLAAT showed excellent ductility with strain to failure from 158.9% to 42.7% and modulus from 265.2 to 758.2 MPa. The high electroactivity of the HPLAAT was confirmed by UV spectrometer and cyclic voltammogram measurements. These HPLAAT polymers also showed improved thermal stability and controlled biodegradation rate compared to HPLA. Importantly, when applying these polymers for myotube formation, the HPLAAT significantly improved the proliferation of C2C12 myoblasts in vitro compared to HPLA. Furthermore, these polymers greatly promoted myogenic differentiation of C2C12 cells as measured by quantitative analysis of myotube number, length, diameter, maturation index, and gene expression of MyoD and TNNT. Together, our study shows that these electroactive, ductile and degradable HPLAAT copolymers represent significantly improved biomaterials for muscle tissue engineering compared to HPLA. PMID:26335860

Thickness-dependence of block copolymer coarsening kinetics

DOE PAGES

Black, Charles T.; Forrey, Christopher; Yager, Kevin G.

2017-03-31

In spite of active research, many fundamental aspects of block copolymer ordering remain unresolved. We studied the thickness-dependence of block copolymer grain coarsening kinetics, and find that thinner films order more rapidly than thicker films. Bilayer films, or monolayers with partial layers of islands, order more slowly than monolayers because of the greater amount of material that must rearrange in a coordinated fashion. Sub-monolayer films order much more rapidly than monolayers, exhibiting considerably smaller activation energies, as well as larger exponents for the time-growth power-law. Furthermore, by using molecular dynamics simulations, we directly study the motion of defects in thesemore » film regimes. Here, we attribute the enhanced grain growth in sub-monolayers to the film boundaries, where defects can be spontaneously eliminated. The boundaries thus act as efficient sinks for morphological defects, pointing towards methods for engineering rapid ordering of self-assembling thin films.« less

Thickness-dependence of block copolymer coarsening kinetics

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

Black, Charles T.; Forrey, Christopher; Yager, Kevin G.

In spite of active research, many fundamental aspects of block copolymer ordering remain unresolved. We studied the thickness-dependence of block copolymer grain coarsening kinetics, and find that thinner films order more rapidly than thicker films. Bilayer films, or monolayers with partial layers of islands, order more slowly than monolayers because of the greater amount of material that must rearrange in a coordinated fashion. Sub-monolayer films order much more rapidly than monolayers, exhibiting considerably smaller activation energies, as well as larger exponents for the time-growth power-law. Furthermore, by using molecular dynamics simulations, we directly study the motion of defects in thesemore » film regimes. Here, we attribute the enhanced grain growth in sub-monolayers to the film boundaries, where defects can be spontaneously eliminated. The boundaries thus act as efficient sinks for morphological defects, pointing towards methods for engineering rapid ordering of self-assembling thin films.« less

Silacyclobutane-based diblock copolymers with vinylferrocene, ferrocenylmethyl methacrylate, and [1]dimethylsilaferrocenophane.

PubMed

Gallei, Markus; Tockner, Stefan; Klein, Roland; Rehahn, Matthias

2010-05-12

Well-defined diblock copolymers have been prepared in which three different ferrocene-based monomers are combined with 1,1-dimethylsilacyclobutane (DMSB) and 1-methylsilacyclobutane, respectively, as their carbosilane counterparts. Optimized procedures are reported for the living anionic chain growth following sequential monomer addition protocols, ensuring narrow polydispersities and high blocking efficiencies. The DMSB-containing copolymers show phase segregation in the bulk state, leading to micromorphologies composed of crystalline DMSB phases and amorphous polymetallocene phases. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Poly(aryl ethers) and related polysiloxane copolymer molecular coatings: Preparation and radiation degradation

NASA Technical Reports Server (NTRS)

Mcgrath, J. E.

1982-01-01

The radiation degradation of poly(arylene ether sulfones) and related materials is studied. These basic studies are important both as a means to developing stronger, more stable matrix resins for composite materials, as well as to improve the data base in regard to chemical structure-physical property relationships. Thirty homo and copolymers were synthesized, at least partially characterized and, in several cases suitable film casting techniques were developed. Four samples were chosen for initial radiation degradation. Poly(dimethyl siloxane) soft bocks/segments can preferentially migrate to the surface of copolymer films. Since siloxanes are utilized as thermal control coatings, this form of 'molecular' coating is of interest. The chemistry for preparing such copolymers with any of the polymers described was demonstrated.

Pattern interpolation in thin films of lamellar, symmetric copolymers on nano-patterned substrates

NASA Astrophysics Data System (ADS)

Detcheverry, Francois; Nagpal, Umang; Liu, Guoliang; Nealey, Paul; de Pablo, Juan

2009-03-01

A molecular model of block copolymer systems is used to conduct a systematic study of the morphologies that arise when thin films of symmetric, lamellar forming block copolymer materials are deposited on nanopatterned surfaces. Over 500 distinct cases are considered. It is found that, in general, three distinct morphologies can arise depending on the strength of the substrate-polymer interactions, the film thickness, and the period of the substrate pattern. The relative stability of those morphologies is determined by direct calculation of the free energy differences. The dynamic propensity of those morphologies to emerge is examined by careful analysis of simulated trajectories. The results of this systematic study are used to interpret recent experimental data for films of polystyrene-PMMA copolymers on chemically nanopatterned surfaces.

Anionic polymerization of p-(2,2'-diphenylethyl)styrene and applications to graft copolymers.

PubMed

Huang, Minglu; Han, Bingyong; Lu, Jianmin; Yang, Wantai; Fu, Zhifeng

2017-01-01

Well-controlled anionic polymerization of an initiator-functionalized monomer, p -(2,2'-diphenylethyl)styrene (DPES), was achieved for the first time. The polymerization was performed in a mixed solvent of cyclohexane and tetrahydrofuran (THF) at 40 °C with n -BuLi as initiator. When the volume ratio of cyclohexane to THF was 20, the anionic polymerization of DPES showed living polymerization characteristics, and well-defined block copolymer PDPES- b -PS was successfully synthesized. Furthermore, radical polymerization of methyl methacrylate in the presence of PDPES effectively afforded a graft copolymer composed of a polystyrene backbone and poly(methyl methacrylate) branches. The designation of analogous monomers and polymers was of great significance to synthesize a variety of sophisticated copolymer and functionalize polymer materials.

Synthesis and solution self-assembly of side-chain cobaltocenium-containing block copolymers.

PubMed

Ren, Lixia; Hardy, Christopher G; Tang, Chuanbing

2010-07-07

The synthesis of side-chain cobaltocenium-containing block copolymers and their self-assembly in solution was studied. Highly pure monocarboxycobaltocenium was prepared and subsequently attached to side chains of poly(tert-butyl acrylate)-block-poly(2-hydroxyethyl acrylate), yielding poly(tert-butyl acrylate)-block-poly(2-acryloyloxyethyl cobaltoceniumcarboxylate). The cobaltocenium block copolymers exhibited vesicle morphology in the mixture of acetone and water, while micelles of nanotubes were formed in the mixture of acetone and chloroform.

Brushed block copolymer micelles with pH-sensitive pendant groups for controlled drug delivery.

PubMed

Lee, Hyun Jin; Bae, Younsoo

2013-08-01

To investigate the effects of small aliphatic pendent groups conjugated through an acid-sensitive linker to the core of brushed block copolymer micelles on particle properties. The brushed block copolymers were synthesized by conjugating five types of 2-alkanone (2-butanone, 2-hexanone, 2-octanone, 2-decanone, and 2-dodecanone) through an acid-labile hydrazone linker to poly(ethylene glycol)-poly(aspartate hydrazide) block copolymers. Only block copolymers with 2-hexanone and 2-octanone (PEG-HEX and PEG-OCT) formed micelles with a clinically relevant size (< 50 nm in diameter), low critical micelle concentration (CMC, < 20 μM), and drug entrapment yields (approximately 5 wt.%). Both micelles degraded in aqueous solutions in a pH-dependent manner, while the degradation was accelerated in an acidic condition (pH 5.0) in comparison to pH 7.4. Despite these similar properties, PEG-OCT micelles controlled the entrapment and pH-dependent release of a hydrophobic drug most efficiently, without altering particle size, shape, and stability. The molecular weight of PEG (12 kDa vs 5 kDa) induced no change in pH-controlled drug release rates of PEG-OCT micelles. Acid-labile small aliphatic pendant groups are useful to control the entrapment and release of a hydrophobic drug physically entrapped in the core of brushed block copolymer micelles.

On the role of methacrylic acid copolymers in the intracellular delivery of antisense oligonucleotides.

PubMed

Yessine, Marie-Andrée; Meier, Christian; Petereit, Hans-Ulrich; Leroux, Jean-Christophe

2006-05-01

The delivery of active biomacromolecules to the cytoplasm is a major challenge as it is generally hindered by the endosomal/lysosomal barrier. Synthetic titratable polyanions can overcome this barrier by destabilizing membrane bilayers at pH values typically found in endosomes. This study investigates how anionic polyelectrolytes can enhance the cytoplasmic delivery of an antisense oligonucleotide (ODN). Novel methacrylic acid (MAA) copolymers were examined for their pH-sensitive properties and ability to destabilize cell membranes in a pH-dependent manner. Ternary complex formulations prepared with the ODN, a cationic lipid and a MAA copolymer were systematically characterized with respect to their size, zeta potential, antisense activity, cytotoxicity and cellular uptake using the A549 human lung carcinoma cell line. The MAA copolymer substantially increased the activity of the antisense ODN in inhibiting the expression of protein kinase C-alpha. Uptake, cytotoxicity and antisense activity were strongly dependent on copolymer concentration. Metabolic inhibitors demonstrated that endocytosis was the major internalization pathway of the complexes, and that endosomal acidification was essential for ODN activity. Confocal microscopy analysis of cells incubated with fluorescently-labeled complexes revealed selective delivery of the ODN, but not of the copolymer, to the cytoplasm/nucleus. This study provides new insight into the mechanisms of intracellular delivery of macromolecular drugs, using synthetic anionic polyelectrolytes.

76 FR 30604 - National Emission Standards for Hazardous Air Pollutants for Polyvinyl Chloride and Copolymers...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-26

... National Emission Standards for Hazardous Air Pollutants for Polyvinyl Chloride and Copolymers Production... Standards for Hazardous Air Pollutants for Polyvinyl Chloride and Copolymers Production. The EPA is... present oral testimony at the public hearing, please contact Ms. Teresa Clemons, U.S. Environmental...

Master curve captures the effect of domain morphology on ethanol pervaporation through block copolymer membranes

USDA-ARS?s Scientific Manuscript database

We report on the effect of changing nanoscale morphology on pervaporation of ethanol/water mixtures through block copolymer membranes. Experiments were conducted using polystyrene-b-polybutadiene-b-polystyrene (SBS) copolymers with polybutadiene (PB) as the ethanol transporting block, using an 8 wt%...

Polystyrene/wood composites and hydrophobic wood coatings from water-based hydrophilic-hydrophobic block copolymers

Treesearch

Marja-Leena Kosonen; Bo Wang; Gerard T. Caneba; Douglas J. Gardner; Tim G. Rials

2000-01-01

The combination of synthetic thermoplastic polymers and wood is normally problematic because wood surfaces are hydrophilic while typical thermoplastic polymers are hydrophobic. A possible solution is to use block copolymer coupling agents. In this work we show the use of a potentially useful synthetic method of producing hydrophilic-hydrophobic block copolymers as...

PEO-PPO-PEO Tri-Block Copolymers for Gene Delivery Applications in Human Regenerative Medicine—An Overview

PubMed Central

Cucchiarini, Magali

2018-01-01

Lineal (poloxamers or Pluronic®) or X-shaped (poloxamines or Tetronic®) amphiphilic tri-block copolymers of poly(ethylene oxide) and poly(propylene oxide) (PEO-PPO-PEO) have been broadly explored for controlled drug delivery in different regenerative medicine approaches. The ability of these copolymers to self-assemble as micelles and to undergo sol-to-gel transitions upon heating has endowed the denomination of “smart” or “intelligent” systems. The use of PEO-PPO-PEO copolymers as gene delivery systems is a powerful emerging strategy to improve the performance of classical gene transfer vectors. This review summarizes the state of art of the application of PEO-PPO-PEO copolymers in both nonviral and viral gene transfer approaches and their potential as gene delivery systems in different regenerative medicine approaches. PMID:29518011

Synthesis of cellulose diacetate based copolymer electrospun nanofibers for tissues scaffold

NASA Astrophysics Data System (ADS)

Liang, Wencheng; Hou, Jia; Fang, Xiangchen; Bai, Fudong; Zhu, Tonghe; Gao, Feifei; Wei, Chao; Mo, Xiumei; Lang, Meidong

2018-06-01

In this study, a novel cellulose diacetate based copolymer used as tissues scaffold, cellulose diacetate-graft-poly(ethylene terephthalate) (CDA-g-PET) was developed by "graft onto" strategy using 3-Isocyanatomethyl-3,5,5-trimethylcyc-lohexyl isocyanate (IPDI) as a coupling reagent of cellulose diacetate and poly(ethylene terephthalate), and using dibutyltin dilaurate (DBTDL) and 1-butyl-3-methylimidazolium chloride salt ([Bmim]Cl) as catalysts. CDA-g-PET copolymers with five different grafting ratios were obtained by the regulation of the reaction time. It was proved by the FT-IR spectra of the purified copolymers that PET had been successfully grafted onto CDA backbone. Afterwards, CDA-g-PET nanofibers were fabricated via electrospinning and further were cross-linked by means of treating in glutaraldehyde (25%wt) aqueous solution for 48 h. The uniform and smooth fiber morphology was proved by SEM and the diameter decreased with the increase of grafting ratio. Moreover, the value of TGA revealed that the grafting PET onto CDA backbone would improve heat-resistant quality of CDA and help to improve the ability of thermo processing. The graft of PET onto CDA significantly enhanced mechanical property of copolymer compared with CDA. The results of hemolysis ratio indicated that hemolysis ratio has decreased compared with CDA, highlighting the potential application in the field of contacting with blood. In vitro cell viability indicated that CDA-g-PET would enhance biocompatibility compared with CDA.

21 CFR 177.1430 - Isobutylene-butene copolymers.

Code of Federal Regulations, 2014 CFR

2014-04-01

...: Isobutylene-butene copolymers Molecular weight (range) Viscosity (range) Maximum bromine value 1. Used as.../federal_register/code_of_federal_regulations/ibr_locations.html. (2) Viscosity. Viscosity shall be determined by ASTM method D445-74, “Test for Kinematic Viscosity of Transparent and Opaque Liquids,” which is...

PDMS-co-PVMS Copolymer Synthesis for Microfluidic Devices

NASA Astrophysics Data System (ADS)

Baiamonte, Arissa; Nguyen, Devin; Lwoya, Baraka; Kelly, Giovanni; Albert, Julie N. L.

Poly (dimethylsiloxane) (PDMS) is the predominant material used for the fabrication of microfluidic devices because it is an easily synthesized, biocompatible, and flexible material that forms a good seal with other surfaces. However, PDMS is chemically inert and therefore difficult to functionalize for targeted applications, it can swell in the presence of organic solvents, and it can contaminate microfluidic solutions with unreacted oligomers. Therefore, my research goal is to synthesize random copolymers of PDMS and poly (vinylmethylsiloxane) (PVMS) that retain the benefits of PDMS and can be functionalized easily via thiol-ene click reactions. In the first stage of this work, dichlorodimethylsilane and vinylmethyldichlorosilane were each reacted with water to produce n-membered dimethylsiloxane rings and n-membered vinylmethylsiloxane rings, respectively. In the next step, polymers are synthesized by reacting these rings with potassium hydroxide and heat to form PDMS, PVMS, and PDMS-co-PVMS copolymers. Several reaction conditions have been tested to determine the kinetics and to relate molecular weight of the polymer or copolymer to reaction time. The polymer is then cross-liked through hydroxyl end groups with vinylmethoxysiloxane homopolymer (PVMES) cross-linker, tin catalyst, and heat. Once the polymer is cross-linked, the surface can be modified via thiol-ene click reaction to provide a diversity of surface functionality for microfluidic device applications. In the present work, we functionalize with a fluorinated thiol to impart solvent resistance. Newcomb Tulane College Georges Lurcy Grant, National Academies Gulf Research Program Early Career Research Fellowship, Tulane CIF.

21 CFR 177.1980 - Vinyl chloride-propylene copolymers.

Code of Federal Regulations, 2013 CFR

2013-04-01

... contents of the cup are added 3.5 grams of granular sodium peroxide, 0.1 gram of powdered starch, and 0.02... applicable to vinyl chloride-propylene copolymers used in food-packaging adhesives complying with § 175.105...

21 CFR 177.1980 - Vinyl chloride-propylene copolymers.

Code of Federal Regulations, 2012 CFR

2012-04-01

... contents of the cup are added 3.5 grams of granular sodium peroxide, 0.1 gram of powdered starch, and 0.02... applicable to vinyl chloride-propylene copolymers used in food-packaging adhesives complying with § 175.105...

Poly(3-Hydroxypropionate): a Promising Alternative to Fossil Fuel-Based Materials

PubMed Central

Andreeßen, Björn; Taylor, Nicolas

2014-01-01

Polyhydroxyalkanoates (PHAs) are storage compounds synthesized by numerous microorganisms and have attracted the interest of industry since they are biobased and biodegradable alternatives to fossil fuel-derived plastics. Among PHAs, poly(3-hydroxypropionate) [poly(3HP)] has outstanding material characteristics and exhibits a large variety of applications. As it is not brittle like, e.g., the best-studied PHA, poly(3-hydroxybutyrate) [poly(3HB)], it can be used as a plasticizer in blends to improve their properties. Furthermore, 3-hydroxypropionic acid (3HP) is considered likely to become one of the new industrial building blocks, and it can be obtained from poly(3HP) by simple hydrolysis. Unfortunately, no natural organism is known to accumulate poly(3HP) so far. Thus, several efforts have been made to engineer genetically modified organisms capable of synthesizing the homopolymer or copolymers containing 3HP. In this review, the achievements made so far in efforts to obtain biomass which has accumulated poly(3HP) or 3HP-containing copolymers, as well as the properties of these polyesters and their applications, are compiled and evaluated. PMID:25149521

Nanoparticle string formation on self-assembled copolymer films

NASA Astrophysics Data System (ADS)

Jenczyk, J.; Woźniak-Budych, M.; Jarek, M.; Grzeszkowiak, M.; Nowaczyk, G.; Jurga, S.

2017-06-01

Nanoparticles (NP) string formations on self-assembled copolymeric substrates has been observed. These "thread of beads" like structures develop via simple colloidal droplet evaporation during meniscus rim withdrawal on polystyrene-block-poly(ethylene oxide) (PS-PEO) copolymer surfaces. It is shown that the process is triggered by the presence of the substrate impurities, which lead to NP aggregate formations serving as string initiation sites. The growth mechanism of these linear structures seems to be capillarity-driven. Moreover, there is an exceptional alignment coupling between NP strips and the block copolymer (BC) domains observed. BC directed NP assembly stems from a gold nanocrystal surface functionalization, which introduces selective affinity for one particular type of BC domain. The presented results reveal a potential fabrication method of NP wires characterized by remarkably low width and thickness comparable with the size of the individual constituent NP.

Hollow carbon nanospheres using an asymmetric triblock copolymer structure directing agent.

PubMed

Li, Yunqi; Tan, Haibo; Salunkhe, Rahul R; Tang, Jing; Shrestha, Lok Kumar; Bastakoti, Bishnu Prasad; Rong, Hongpan; Takei, Toshiaki; Henzie, Joel; Yamauchi, Yusuke; Ariga, Katsuhiko

2016-12-20

We introduce a simple method to prepare hollow carbon nanospheres (HCNs) by using triblock copolymer poly(styrene-b-2-vinylpyridine-b-ethylene oxide) (PS-b-P2VP-b-PEO) micelles as a new class of soft-templates. Simply by changing the solvent we can prepare ultra-small sized micelles of the triblock copolymer PS-b-P2VP-b-PEO soft template to obtain HCNs with ultra-small diameters (43 nm) and hollow cores (19 nm). Furthermore, we use these HCNs to make electric double-layer capacitors (EDLCs) that exhibit superior performance.

Merging Bottom-Up with Top-Down: Continuous Lamellar Networks and Block Copolymer Lithography

NASA Astrophysics Data System (ADS)

Campbell, Ian Patrick

Block copolymer lithography is an emerging nanopatterning technology with capabilities that may complement and eventually replace those provided by existing optical lithography techniques. This bottom-up process relies on the parallel self-assembly of macromolecules composed of covalently linked, chemically distinct blocks to generate periodic nanostructures. Among the myriad potential morphologies, lamellar structures formed by diblock copolymers with symmetric volume fractions have attracted the most interest as a patterning tool. When confined to thin films and directed to assemble with interfaces perpendicular to the substrate, two-dimensional domains are formed between the free surface and the substrate, and selective removal of a single block creates a nanostructured polymeric template. The substrate exposed between the polymeric features can subsequently be modified through standard top-down microfabrication processes to generate novel nanostructured materials. Despite tremendous progress in our understanding of block copolymer self-assembly, continuous two-dimensional materials have not yet been fabricated via this robust technique, which may enable nanostructured material combinations that cannot be fabricated through bottom-up methods. This thesis aims to study the effects of block copolymer composition and processing on the lamellar network morphology of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) and utilize this knowledge to fabricate continuous two-dimensional materials through top-down methods. First, block copolymer composition was varied through homopolymer blending to explore the physical phenomena surrounding lamellar network continuity. After establishing a framework for tuning the continuity, the effects of various processing parameters were explored to engineer the network connectivity via defect annihilation processes. Precisely controlling the connectivity and continuity of lamellar networks through defect engineering and

Polymer brushes on nanoparticles: their positioning in and influence on block copolymer morphology.

NASA Astrophysics Data System (ADS)

Kim, Bumjoon

2007-03-01

Polymers brushes grafted to the nanoparticle surface enable the precise positioning of particles within a block copolymer matrix by determining the compatibility of nanoparticles within a polymeric matrix and modifying the interfacial properties between polymers and inorganic nanoparticle. Short thiol terminated polystyrene (PS-SH), poly(2-vinylpyridine) (P2VP-SH) and PS-r-P2VP with the molecular weight (Mn) of 3 kg/mol were used to control the location of Au nanoparticles over PS-b-P2VP diblock copolymer template. We will discuss further the approach of varying the areal chain density (σ) of PS-SH brushes on the PS coated particles, which utilizes the preferential wetting of one block of a copolymer (P2VP) on the Au substrate. Such favorable interaction provides the strong binding of Au particles to the PS/P2VP interface as σ of PS chains on the Au particle decreases. We find that at σ above a certain value, the nanoparticles are segregated to the center of the PS domains while below this value they are segregated to the interface. The transition σ for PS-SH chains (Mn = 3.4 kg/mol) is 1.3 chains/nm^2 but unexpectedly scales as Mn-0.55 as Mn is varied from 1.5 to 13 kg/mol. In addition, we will discuss changes in block copolymer morphology that occur as the nanoparticle volume fraction (φ) is increased for nanoparticles that segregate to the domain center as well as those that segregate to the interface, the latter behaving as nanoparticle surfactants. Small φ of such surfactants added to lamellar diblock copolymers lead initially to a decrease in lamellar thickness, a consequence of decreasing interfacial tension, up to a critical value of φ beyond which the block copolymer adopts a bicontinuous morphology. I thank my collaborators G. H. Fredrickson, J. Bang, C. J. Hawker, and E. J. Kramer as well as funding by the MRL as UCSB from the NSF-MRSEC-Program Award DMR05-20418.

Optoelectronic Properties of Conjugated Block Copolymer with Flexible Linking Group

NASA Astrophysics Data System (ADS)

Hu, Zhiqi; Verduzco, Rafael

State-of-the-art organic photovoltaics (OPVs) are prepared by depositing a disordered, co-continuous donor and acceptor blend. While optimization of material processing has produced significant improvements in performance, a fundamental understanding of charge separation and recombination at the donor/acceptor interface is lacking. Block copolymers with donor and acceptor polymer blocks provide an opportunity for controlling the donor-accepter interfacial structure and understanding its relationship to charge separation and photovoltaic performance. Here, we report the synthesis and characterization of donor-linker-acceptor block copolymers for use in OPVs. A series of poly(3-hexylthiophene)-block- poly((9,9-dioctylfluorene)-2,7-diyl-alt-[4,7-bis(thiophen-5-yl)-2,1,3-benzothiadiazole]-2',2''-diyl) (P3HT-linkerPFTBT) are synthesized with flexible oligo-ethylene glycol (PEG) linkers. Photoluminescence measurements demonstrate that the insertion of a non-conjugated linker has a significant impact on energy transfer between the two blocks, and the block copolymers are used as additives for bulk heterojunction OPVs. This work provides insight into the charge separation process and demonstrates a technique for tailoring the donor-accepter interface in OPVs.

Two-dimensional phase separated structures of block copolymers on solids

NASA Astrophysics Data System (ADS)

Sen, Mani; Jiang, Naisheng; Endoh, Maya; Koga, Tadanori; Ribbe, Alexander

The fundamental, yet unsolved question in block copolymer (BCP) thin films is the self-organization process of BCPs at the solid-polymer melt interface. We here focus on the self-organization processes of cylinder-forming polystyrene-block-poly (4-vinylpyridine) diblock copolymer and lamellar-forming poly (styrene-block-butadiene-block-styrene) triblock copolymer on Si substrates as model systems. In order to reveal the buried interfacial structures, the following experimental protocols were utilized: the BCP monolayer films were annealed under vacuum at T>Tg of the blocks (to equilibrate the melts); vitrification of the annealed BCP films via rapid quench to room temperature; subsequent intensive solvent leaching (to remove unadsorbed chains) with chloroform, a non-selective good solvent for the blocks. The strongly bound BCP layers were then characterized by using atomic force microscopy, scanning electron microscopy, grazing incidence small angle X-ray scattering, and X-ray reflectivity. The results showed that both blocks lie flat on the substrate, forming the two-dimensional, randomly phase-separated structure irrespective of their microdomain structures and interfacial energetics. Acknowledgement of financial support from NSF Grant (CMMI -1332499).

Entropic effects, shape, and size of mixed micelles formed by copolymers with complex architectures

NASA Astrophysics Data System (ADS)

Kalogirou, Andreas; Gergidis, Leonidas N.; Moultos, Othonas; Vlahos, Costas

2015-11-01

The entropic effects in the comicellization behavior of amphiphilic A B copolymers differing in the chain size of solvophilic A parts were studied by means of molecular dynamics simulations. In particular, mixtures of miktoarm star copolymers differing in the molecular weight of solvophilic arms were investigated. We found that the critical micelle concentration values show a positive deviation from the analytical predictions of the molecular theory of comicellization for chemically identical copolymers. This can be attributed to the effective interactions between copolymers originated from the arm size asymmetry. The effective interactions induce a very small decrease in the aggregation number of preferential micelles triggering the nonrandom mixing between the solvophilic moieties in the corona. Additionally, in order to specify how the chain architecture affects the size distribution and the shape of mixed micelles we studied star-shaped, H-shaped, and homo-linked-rings-linear mixtures. In the first case the individual constituents form micelles with preferential and wide aggregation numbers and in the latter case the individual constituents form wormlike and spherical micelles.

Entropic effects, shape, and size of mixed micelles formed by copolymers with complex architectures.

PubMed

Kalogirou, Andreas; Gergidis, Leonidas N; Moultos, Othonas; Vlahos, Costas

2015-11-01

The entropic effects in the comicellization behavior of amphiphilic AB copolymers differing in the chain size of solvophilic A parts were studied by means of molecular dynamics simulations. In particular, mixtures of miktoarm star copolymers differing in the molecular weight of solvophilic arms were investigated. We found that the critical micelle concentration values show a positive deviation from the analytical predictions of the molecular theory of comicellization for chemically identical copolymers. This can be attributed to the effective interactions between copolymers originated from the arm size asymmetry. The effective interactions induce a very small decrease in the aggregation number of preferential micelles triggering the nonrandom mixing between the solvophilic moieties in the corona. Additionally, in order to specify how the chain architecture affects the size distribution and the shape of mixed micelles we studied star-shaped, H-shaped, and homo-linked-rings-linear mixtures. In the first case the individual constituents form micelles with preferential and wide aggregation numbers and in the latter case the individual constituents form wormlike and spherical micelles.

Amphiphilic Ferrocene-Containing PEG Block Copolymers as Micellar Nanocarriers and Smart Surfactants.

PubMed

Alkan, Arda; Wald, Sarah; Louage, Benoit; De Geest, Bruno G; Landfester, Katharina; Wurm, Frederik R

2017-01-10

An important and usually the only function of most surfactants in heterophase systems is stabilizing one phase in another, for example, droplets or particles in water. Surfactants with additional chemical or physical handles are promising in controlling the colloidal properties by external stimuli. The redox stimulus is an attractive feature; however, to date only a few ionic redox-responsive surfactants have been reported. Herein, the first nonionic and noncytotoxic ferrocene-containing block copolymers are prepared, carrying a hydrophilic poly(ethylene glycol) (PEG) chain and multiple ferrocenes in the hydrophobic segment. These amphiphiles were studied as redox-sensitive surfactants that destabilize particles as obtained in miniemulsion polymerization. Because of the nonionic nature of such PEG-based copolymers, they can stabilize nanoparticles even after the addition of ions, whereas particles stabilized with ionic surfactants would be destabilized by the addition of salt. The redox-active surfactants were prepared by the anionic ring-opening polymerization of ferrocenyl glycidyl ether, with PEG monomethyl ether as the macroinitiator. The resultant block copolymers with molecular weights (M n ) between 3600 and 8600 g mol -1 and narrow molecular weight distributions (M w /M n = 1.04-1.10) were investigated via 1 H nuclear magnetic resonance and diffusion ordered spectroscopy, size exclusion chromatography, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Furthermore, the block copolymers were used as building blocks for redox-responsive micelles and as redox-responsive surfactants in radical polymerization in miniemulsion to stabilize model polystyrene nanoparticles. Oxidation of iron to the ferrocenium species converted the amphiphilic block copolymers into double hydrophilic macromolecules, which led to the destabilization of the nanoparticles. This destabilization of nanoparticle dispersions may be useful for the formation of

Copolymer sealant compositions and method for making

NASA Technical Reports Server (NTRS)

Singh, Navjot (Inventor); Leman, John Thomas (Inventor); Whitney, John M. (Inventor); Krabbenhoft, Herman Otto (Inventor)

2002-01-01

Condensation curable poly(fluoroorgano)siloxane-poly(silarylene)siloxane block copolymer compositions having a glass transition temperature not exceeding about -54.degree. C. and excellent solvent resistance have been found useful as sealants. Polyalkoxysilylorgano compounds, such as 1,4-bis[trimethoxysilyl(ethyl)]benzene have been found to be effective as cross-linkers.

Copolymer sealant compositions and method for making

NASA Technical Reports Server (NTRS)

Singh, Navjot (Inventor); Leman, John Thomas (Inventor); Whitney, John M. (Inventor); Krabbenhoft, Herman Otto (Inventor)

2004-01-01

Condensation curable poly(fluoroorgano)siloxane-poly(silarylene)siloxane block copolymer compositions having a glass transition temperature not exceeding about -54.degree. C. and excellent solvent resistance have been found useful as sealants. Polyalkoxysilylorgano compounds, such as 1,4-bis[trimethoxysilyl(ethyl)]benzene have been found to be effective as cross-linkers.

Copolymer sealant compositions and method for making

NASA Technical Reports Server (NTRS)

Singh, Navjot (Inventor); Leman, John Thomas (Inventor); Whitney, John M. (Inventor); Krabbenhoft, Herman Otto (Inventor)

2003-01-01

Condensation curable poly(fluoroorgano)siloxane-poly(silarylene)siloxane block copolymer compositions having a glass transition temperature not exceeding about -54.degree. C. and excellent solvent resistance have been found useful as sealants. Polyalkoxysilylorgano compounds, such as 1,4-bis[trimethoxysilyl(ethyl)]benzene have been found to be effective as cross-linkers.

Copolymer semiconductors comprising thiazolothiazole or benzobisthiazole, or benzobisoxazole electron acceptor subunits, and electron donor subunits, and their uses in transistors and solar cells

DOEpatents

Jenekhe, Samson A; Subramaniyan, Selvam; Ahmed, Eilaf; Xin, Hao; Kim, Felix Sunjoo

2014-10-28

The inventions disclosed, described, and/or claimed herein relate to copolymers comprising copolymers comprising electron accepting A subunits that comprise thiazolothiazole, benzobisthiazole, or benzobisoxazoles rings, and electron donating subunits that comprise certain heterocyclic groups. The copolymers are useful for manufacturing organic electronic devices, including transistors and solar cells. The invention also relates to certain synthetic precursors of the copolymers. Methods for making the copolymers and the derivative electronic devices are also described.

Discovery of a Frank-Kasper [sigma] Phase in Sphere-Forming Block Copolymer Melts

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

Lee, Sangwoo; Bluemle, Michael J.; Bates, Frank S.

Sphere-forming block copolymers are known to self-assemble into body-centered cubic crystals near the order-disorder transition temperature. Small-angle x-ray scattering and transmission electron microscopy experiments on diblock and tetrablock copolymer melts have revealed an equilibrium phase characterized by a large tetragonal unit cell containing 30 microphase-separated spheres. This structure, referred to as the sigma ({sigma}) phase by Frank and Kasper more than 50 years ago, nucleates and grows from the body-centered cubic phase similar to its occurrence in metal alloys and is a crystal approximant to dodecagonal quasicrystals. Formation of the {sigma} phase in undiluted linear block copolymers (and certain branchedmore » dendrimers) appears to be mediated by macromolecular packing frustration, an entropic contribution to the interparticle interactions that control the sphere-packing geometry.« less

Long Range In-Plane Order of Oriented Diblock Copolymer Thin Films by Graphoepitaxy

NASA Astrophysics Data System (ADS)

Fontana, Scott; Dadmun, Mark; Lowndes, Douglas

2003-03-01

Previous work by Russell and coworkers has demonstrated that controlling the interfacial energies and wetting behavior of an asymmetric diblock copolymer enables the control of the orientation of its microphases. In particular the cylindrical phase can be readily aligned perpendicular to a substrate when it is placed on a surface that is neutral to both components of the copolymer. The minor phase, PMMA may then be removed using UV radiation leaving a nanoporous template. In this work, we will report long range, in-plane ordering of the hexagonally packed nanopores that is achieved using graphoepitaxy. The long range ordered and vertically aligned diblock copolymer film can be used to produce arrays of catalytic nickel dots, which grow vertically aligned carbon nano-fibers (VACNF), resulting in a well ordered array of VACNFs.

Chain exchange in triblock copolymer micelles

NASA Astrophysics Data System (ADS)

Lu, Jie; Lodge, Timothy; Bates, Frank

2015-03-01

Block polymer micelles offer a host of technological applications including drug delivery, viscosity modification, toughening of plastics, and colloidal stabilization. Molecular exchange between micelles directly influences the stability, structure and access to an equilibrium state in such systems and this property recently has been shown to be extraordinarily sensitive to the core block molecular weight in diblock copolymers. The dependence of micelle chain exchange dynamics on molecular architecture has not been reported. The present work conclusively addresses this issue using time-resolved small-angle neutron scattering (TR-SANS) applied to complimentary S-EP-S and EP-S-EP triblock copolymers dissolved in squalane, a selective solvent for the EP blocks, where S and EP refer to poly(styrene) and poly(ethylenepropylene), respectively. Following the overall SANS intensity as a function of time from judiciously deuterium labelled polymer and solvent mixtures directly probes the rate of molecular exchange. Remarkably, the two triblocks display exchange rates that differ by approximately ten orders of magnitude, even though the solvophobic S blocks are of comparable size. This discovery is considered in the context of a model that successfully explains S-EP diblock exchange dynamics.

Study of the therapeutic benefit of cationic copolymer administration to vascular endothelium under mechanical stress

PubMed Central

Giantsos-Adams, Kristina; Lopez-Quintero, Veronica; Kopeckova, Pavla; Kopecek, Jindrich; Tarbell, John M.; Dull, Randal

2015-01-01

Pulmonary edema and the associated increases in vascular permeability continue to represent a significant clinical problem in the intensive care setting, with no current treatment modality other than supportive care and mechanical ventilation. Therapeutic compound(s) capable of attenuating changes in vascular barrier function would represent a significant advance in critical care medicine. We have previously reported the development of HPMA-based copolymers, targeted to endothelial glycocalyx that are able to enhance barrier function. In this work, we report the refinement of copolymer design and extend our physiological studies todemonstrate that the polymers: 1) reduce both shear stress and pressure-mediated increase in hydraulic conductivity, 2) reduce nitric oxide production in response to elevated hydrostatic pressure and, 3) reduce the capillary filtration coefficient (Kfc) in an isolated perfused mouse lung model. These copolymers represent an important tool for use in mechanotransduction research and a novel strategy for developing clinically useful copolymers for the treatment of vascular permeability. PMID:20932573

Probing the Effect of Molecular Nonuniformity in Directed Self-Assembly of Diblock Copolymers in Nanoconfined Space.

PubMed

Pitet, Louis M; Alexander-Moonen, Els; Peeters, Emiel; Druzhinina, Tamara S; Wuister, Sander F; Lynd, Nathaniel A; Meijer, E W

2015-10-27

Various complex self-assembled morphologies of lamellar- and cylinder-forming block copolymers comprising poly(dimethylsiloxane)-b-polylactide (PDMS-b-PLA) confined in cylindrical channels were generated. Combining top-down lithography with bottom-up block copolymer self-assembly grants access to morphologies that are otherwise inaccessible with the bulk materials. Channel diameter (D) was systematically varied with four diblock copolymers having different compositions and bulk domain spacing (L0), corresponding to a range of frustration ratios (D/L0 from 2 to 4). Excessive packing frustration imposed by the channels leads to contorted domains. The resulting morphologies depend strongly on both D/L0 and copolymer composition. Under several circumstances, mixtures of complex morphologies were observed, which hypothetically arise from the severe sensitivity to D/L0 combined with the inherent compositional/molar mass dispersities associated with the nonuniform synthetic materials and silicon templates. Stochastic calculations offer compelling support for the hypothesis, and tractable pathways toward solving this apparent conundrum are proposed. The materials hold great promise for next-generation nanofabrication to address several emerging technologies, offering significantly enhanced versatility to basic diblock copolymers as templates for fabricating complex nanoscale objects.

Synthesis of poly glycidylmethacrylate grafted azobenzene copolymer: Photosensitivity and nonlinear optical properties

NASA Astrophysics Data System (ADS)

Sousani, Abbas; Moghadam, Peyman Najafi; Hasanzadeh, Reza; Motiei, Hamideh; Bagheri, Massoumeh

2016-01-01

In this work poly glycidylmethacrylate grafted 4-hydroxy-4‧-methoxy-azobenzene (Azo-PGMA) was synthesized. For this propose firstly 4-hydroxy-4‧-methoxy-azobenzene (AZO) was prepared, then poly glycidylmethacrylate was prepared by free radical polymerization of glycidylmethacrylate in the presence of benzoyl peroxide as initiator under inert atmosphere in dry THF. Finally the homopolymer was functionalized by AZO moieties. The characterization of the synthesized copolymer was carried out by 1H NMR, FT-IR, thermal gravimetric analyze (TGA), differential scanning calorimetry (DSC) and optical polarizing microscope (POM) analysis. The UV-vis studies were carried out on Azo-PGMA copolymer and the results showed that the synthesized Azo-PGMA copolymer has ultra-fast response to UV light and has slow relaxation time. Also the third-order nonlinear optical properties of the Azo-PGMA copolymer and AZO were studied by using Z-scan technique. Nonlinear refraction and absorption coefficients of the above mentioned materials were measured by the closed and open aperture Z-scan method using a continuous wave Nd-YAG laser at 532 nm. The positive nonlinear absorption in Azo-PGMA and AZO was investigated at the wavelength of λ = 532 nm, respectively and the measured values of nonlinear refraction in both of the samples were from the order of 10-8 cm2/W.

Local Structure and Ion Transport in Glassy Poly(ethylene oxide styrene) Copolymers

NASA Astrophysics Data System (ADS)

Yang, Han-Chang; Mays, Jimmy; Sokolov, Alexei P.; Winey, Karen I.

2014-03-01

Polymer electrolytes have attracted attention for a wide variety of applications in energy production such as lithium-ion batteries and fuel cells. The concept of free volume provides important information about ion mobility and chain dynamics in the polymer matrix. Researchers have recently demonstrated that ion transport in glassy polymer can be improved by designing a system with high free volume. We have studied the effect of temperature and humidity on the intermolecular correlations of poly(ethylene oxide styrene-block-styrene) (PEOSt- b-St) block copolymer and poly(ethylene oxide styrene) (PEOSt) homopolymer using in situ multi-angle x-ray scattering across a wide range of scattering angles (q = 0.007-1.5 Å-1) . An increase in backbone-to-backbone distance is observed, indicating an increase in free volume between different polymer main chains. Structural characterization of the polymer segments will be discussed together with conductivity and dielectric results to better understand the ion transport mechanism in the local environment of the polymer system. Department of Chemistry, University of Tennessee.

Characterization of 1:1 Random Copolymers Obtained from 6-, 7-, 11-, and 12-Carbon Amino Acids.

DTIC Science & Technology

1993-10-22

Random Copolymers Obtained From 6-, 7-, 11-, and 12-Carbon Amino Acids by C. G. Johnson and L. J. Mathias 0 T .... Prepared for Publication r. t in the...NOOOG4-f-j- From 6-, 7-, 11-, and 12-Carbon Amino Acids 1225 ~~~ :: V Co~de 413m(iUK C. G Johnson, and Lo J. Mathias ś RFORMING ORGANIZA7,iCN ;fAMjjS...distribution is unlimited. Copolymers were prepared from the title amino acids by rr ilt condensation under dry nitrogen. The resulting copolymers were

Block copolymer modified surfaces for conjugation of biomacromolecules with control of quantity and activity.

PubMed

Li, Xin; Wang, Mengmeng; Wang, Lei; Shi, Xiujuan; Xu, Yajun; Song, Bo; Chen, Hong

2013-01-29

Polymer brush layers based on block copolymers of poly(oligo(ethylene glycol) methacrylate) (POEGMA) and poly(glycidyl methacrylate) (PGMA) were formed on silicon wafers by activators generated by electron transfer atom transfer radical polymerization (AGET ATRP). Different types of biomolecule can be conjugated to these brush layers by reaction of PGMA epoxide groups with amino groups in the biomolecule, while POEGMA, which resists nonspecific protein adsorption, provides an antifouling environment. Surfaces were characterized by water contact angle, ellipsometry, and Fourier transform infrared spectroscopy (FTIR) to confirm the modification reactions. Phase segregation of the copolymer blocks in the layers was observed by AFM. The effect of surface properties on protein conjugation was investigated using radiolabeling methods. It was shown that surfaces with POEGMA layers were protein resistant, while the quantity of protein conjugated to the diblock copolymer modified surfaces increased with increasing PGMA layer thickness. The activity of lysozyme conjugated on the surface could also be controlled by varying the thickness of the copolymer layer. When biotin was conjugated to the block copolymer grafts, the surface remained resistant to nonspecific protein adsorption but showed specific binding of avidin. These properties, that is, well-controlled quantity and activity of conjugated biomolecules and specificity of interaction with target biomolecules may be exploited for the improvement of signal-to-noise ratio in sensor applications. More generally, such surfaces may be useful as biological recognition elements of high specificity for functional biomaterials.

Structure of block copolymer micelles in the presence of co-solvents

NASA Astrophysics Data System (ADS)

Robertson, Megan; Wang, Shu; Le, Kim Mai; Piemonte, Rachele; Madsen, Louis

2015-03-01

Amphiphilic block copolymer micelles in water are under broad exploration for drug delivery applications due to their high loading capacity and targeted drug delivery. We aim to understand the kinetic and thermodynamic processes that underlie the self-assembly of diblock copolymer micelle systems. The present work focuses on diblock copolymers containing poly(ethylene oxide) (a hydrophilic polymer) and polycaprolactone (a hydrophobic polymer), which spontaneously self-assemble into spherical micelles in water. Addition of a common good solvent (a co-solvent) for both of the constituting blocks, such as tetrahydrofuran (THF), reduces the interfacial tension at the core-corona interface. We are currently investigating the effect of this phenomenon on the micelle structural properties, using scattering experiments and nuclear magnetic resonance. We have characterized the hydrodynamic radius, core radius, corona thickness, aggregation number, degree of swelling of the micelle core with the co-solvent, and unimer (free chain) concentration, as a function of the co-solvent concentration. Fundamental knowledge from these studies will inform design of drug delivery systems by allowing us to tailor micelle properties for optimal cargo loading.

Block copolymer stabilized nonaqueous biocompatible sub-micron emulsions for topical applications.

PubMed

Atanase, Leonard Ionut; Riess, Gérard

2013-05-20

Polyethylene glycol (PEG) 400/Miglyol 812 non-aqueous sub-micron emulsions were developed due to the fact that they are of interest for the design of drug-loaded biocompatible topical formulations. These types of emulsions were favourably stabilized by poly (2-vinylpyridine)-b-poly (butadiene) (P2VP-b-PBut) copolymer with DPBut>DP2VP, each of these sequences being well-adapted to the solubility parameters of PEG 400 and Miglyol 812, respectively. This type of block copolymers, which might limit the Ostwald ripening, appeared to be more efficient stabilizers than low molecular weight non-ionic surfactants. The emulsion characteristics, such as particle size, stability and viscosity at different shear rates were determined as a function of the phase ratio, the copolymer concentration and storage time. It was further shown that Acyclovir, as a model drug of low water solubility, could be incorporated into the PEG 400 dispersed phase, with no significant modification of the initial emulsion characteristics. Copyright © 2013 Elsevier B.V. All rights reserved.

Influencing the structure of block copolymer micelles with small molecule additives

NASA Astrophysics Data System (ADS)

Robertson, Megan; Singh, Avantika; Cooksey, Tyler; Kidd, Bryce; Piemonte, Rachele; Wang, Shu; Mai Le, Kim; Madsen, Louis

Amphiphilic block copolymer micelles in water are under broad exploration for drug delivery applications due to their high loading capacity and targeted drug delivery. We aim to understand the kinetic and thermodynamic processes that underlie the self-assembly of diblock copolymer micelle systems. The present work focuses on diblock copolymers containing poly(ethylene oxide) (a hydrophilic polymer) and polycaprolactone (a hydrophobic polymer), which spontaneously self-assemble into spherical micelles in water. Addition of a common good solvent (a co-solvent) for both of the constituting blocks, such as tetrahydrofuran (THF), reduces the interfacial tension at the core-corona interface. We are currently investigating the effect of this phenomenon on the micelle structural properties, using small-angle scattering and nuclear magnetic resonance. We have characterized the hydrodynamic radius, core radius, corona thickness, aggregation number, degree of swelling of the micelle core with the co-solvent, and unimer (free chain) concentration, as a function of the co-solvent concentration. Fundamental knowledge from these studies will inform design of drug delivery systems by allowing us to tailor micelle properties for optimal cargo loading.

21 CFR 173.60 - Dimethylamine-epichlorohydrin copolymer.

Code of Federal Regulations, 2010 CFR

2010-04-01

... used as a decolorizing agent and/or flocculant in the clarification of refinery sugar liquors and juices. It is added only at the defecation/clarification stage of sugar liquor refining at a concentration not to exceed 150 parts per million of copolymer by weight of sugar solids. (d) To assure safe use...

21 CFR 173.60 - Dimethylamine-epichlorohydrin copolymer.

Code of Federal Regulations, 2011 CFR

2011-04-01

... used as a decolorizing agent and/or flocculant in the clarification of refinery sugar liquors and juices. It is added only at the defecation/clarification stage of sugar liquor refining at a concentration not to exceed 150 parts per million of copolymer by weight of sugar solids. (d) To assure safe use...

21 CFR 173.60 - Dimethylamine-epichlorohydrin copolymer.

Code of Federal Regulations, 2013 CFR

2013-04-01

... used as a decolorizing agent and/or flocculant in the clarification of refinery sugar liquors and juices. It is added only at the defecation/clarification stage of sugar liquor refining at a concentration not to exceed 150 parts per million of copolymer by weight of sugar solids. (d) To assure safe use...

21 CFR 173.60 - Dimethylamine-epichlorohydrin copolymer.

Code of Federal Regulations, 2014 CFR

2014-04-01

... agent and/or flocculant in the clarification of refinery sugar liquors and juices. It is added only at the defecation/clarification stage of sugar liquor refining at a concentration not to exceed 150 parts per million of copolymer by weight of sugar solids. (d) To assure safe use of the additive, the label...

21 CFR 173.60 - Dimethylamine-epichlorohydrin copolymer.

Code of Federal Regulations, 2012 CFR

2012-04-01

... used as a decolorizing agent and/or flocculant in the clarification of refinery sugar liquors and juices. It is added only at the defecation/clarification stage of sugar liquor refining at a concentration not to exceed 150 parts per million of copolymer by weight of sugar solids. (d) To assure safe use...

Materials Design for Block Copolymer Lithography

NASA Astrophysics Data System (ADS)

Sweat, Daniel Patrick

Block copolymers (BCPs) have attracted a great deal of scientific and technological interest due to their ability to spontaneously self-assemble into dense periodic nanostructures with a typical length scale of 5 to 50 nm. The use of self-assembled BCP thin-films as templates to form nanopatterns over large-area is referred to as BCP lithography. Directed self-assembly of BCPs is now viewed as a viable candidate for sub-20 nm lithography by the semiconductor industry. However, there are multiple aspects of assembly and materials design that need to be addressed in order for BCP lithography to be successful. These include substrate modification with polymer brushes or mats, tailoring of the block copolymer chemistry, understanding thin-film assembly and developing epitaxial like methods to control long range alignment. The rational design, synthesis and self-assembly of block copolymers with large interaction parameters (chi) is described in the first part of this dissertation. Two main blocks were chosen for introducing polarity into the BCP system, namely poly(4-hydroxystyrene) and poly(2-vinylpyridine). Each of these blocks are capable of ligating Lewis acids which can increase the etch contrast between the blocks allowing for facile pattern transfer to the underlying substrate. These BCPs were synthesized by living anionic polymerization and showed excellent control over molecular weight and dispersity, providing access to sub 5-nm domain sizes. Polymer brushes consist of a polymer chain with one end tethered to the surface and have wide applicability in tuning surface energy, forming responsive surfaces and increasing biocompatibility. In the second part of the dissertation, we present a universal method to grow dense polymer brushes on a wide range of substrates and combine this chemistry with BCP assembly to fabricate nanopatterned polymer brushes. This is the first demonstration of introducing additional functionality into a BCP directing layer and opens up

Ductile electroactive biodegradable hyperbranched polylactide copolymers enhancing myoblast differentiation.

PubMed

Xie, Meihua; Wang, Ling; Guo, Baolin; Wang, Zhong; Chen, Y Eugene; Ma, Peter X

2015-12-01

Myotube formation is crucial to restoring muscular functions, and biomaterials that enhance the myoblast differentiation into myotubes are highly desirable for muscular repair. Here, we report the synthesis of electroactive, ductile, and degradable copolymers and their application in enhancing the differentiation of myoblasts to myotubes. A hyperbranched ductile polylactide (HPLA) was synthesized and then copolymerized with aniline tetramer (AT) to produce a series of electroactive, ductile and degradable copolymers (HPLAAT). The HPLA and HPLAAT showed excellent ductility with strain to failure from 158.9% to 42.7% and modulus from 265.2 to 758.2 MPa. The high electroactivity of the HPLAAT was confirmed by UV spectrometer and cyclic voltammogram measurements. These HPLAAT polymers also showed improved thermal stability and controlled biodegradation rate compared to HPLA. Importantly, when applying these polymers for myotube formation, the HPLAAT significantly improved the proliferation of C2C12 myoblasts in vitro compared to HPLA. Furthermore, these polymers greatly promoted myogenic differentiation of C2C12 cells as measured by quantitative analysis of myotube number, length, diameter, maturation index, and gene expression of MyoD and TNNT. Together, our study shows that these electroactive, ductile and degradable HPLAAT copolymers represent significantly improved biomaterials for muscle tissue engineering compared to HPLA. Copyright © 2015 Elsevier Ltd. All rights reserved.

Acrylic Triblock Copolymers Incorporating Isosorbide for Pressure Sensitive Adhesives

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

Gallagher, James J.; Hillmyer, Marc A.; Reineke, Theresa M.

A new monomer acetylated acrylic isosorbide (AAI) was prepared in two steps using common reagents without the need for column chromatography. Free radical polymerization of AAI afforded poly(acetylated acrylic isosorbide) (PAAI), which exhibited a glass transition temperature (Tg) = 95 °C and good thermal stability (Td, 5% weight loss; N2 = 331 °C, air = 291 °C). A series of ABA triblock copolymers with either poly(n-butyl acrylate) (PnBA) or poly(2-ethylhexyl acrylate) (PEHA) as the low Tg midblocks and PAAI as the high Tg end blocks were prepared using Reversible Addition–Fragmentation chain Transfer (RAFT) polymerization. The triblock copolymers ranging from 8–24more » wt % PAAI were evaluated as pressure sensitive adhesives by 180° peel, loop tack, and static shear testing. While the PAAI-PEHA-PAAI series exhibited poor adhesive qualities, the PAAI-PnBA-PAAI series of triblock copolymers demonstrated peel forces up to 2.9 N cm–1, tack forces up to 3.2 N cm–1, and no shear failure up to 10000 min. Dynamic mechanical analysis indicated that PAAI-PEHA-PAAI lacked the dissipative qualities needed to form an adhesive bond with the substrate, while the PAAI-PnBA-PAAI series exhibited a dynamic mechanical response consistent with related high performing PSAs.« less

Pathway-engineering for highly-aligned block copolymer arrays

DOE PAGES

Choo, Youngwoo; Majewski, Paweł W.; Fukuto, Masafumi; ...

2017-12-06

While kinetic aspects of self-assembly can hinder ordering, non-equilibirum effects can also be exploited to enforce a particular kind of order. We develop a pathway-engineering approach, using it to select a particular arrangement of a block copolymer cylinder phase.

Pathway-engineering for highly-aligned block copolymer arrays

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

Choo, Youngwoo; Majewski, Paweł W.; Fukuto, Masafumi

While kinetic aspects of self-assembly can hinder ordering, non-equilibirum effects can also be exploited to enforce a particular kind of order. We develop a pathway-engineering approach, using it to select a particular arrangement of a block copolymer cylinder phase.

Widely Tunable Morphologies in Block Copolymer Thin Films Through Solvent Vapor Annealing Using Mixtures of Selective Solvents

PubMed Central

Chavis, Michelle A.; Smilgies, Detlef-M.; Wiesner, Ulrich B.; Ober, Christopher K.

2015-01-01

Thin films of block copolymers are extremely attractive for nanofabrication because of their ability to form uniform and periodic nanoscale structures by microphase separation. One shortcoming of this approach is that to date the design of a desired equilibrium structure requires synthesis of a block copolymer de novo within the corresponding volume ratio of the blocks. In this work, we investigated solvent vapor annealing in supported thin films of poly(2-hydroxyethyl methacrylate)-block-poly(methyl methacrylate) [PHEMA-b-PMMA] by means of grazing incidence small angle X–ray scattering (GISAXS). A spin-coated thin film of lamellar block copolymer was solvent vapor annealed to induce microphase separation and improve the long-range order of the self-assembled pattern. Annealing in a mixture of solvent vapors using a controlled volume ratio of solvents (methanol, MeOH, and tetrahydrofuran, THF), which are chosen to be preferential for each block, enabled selective formation of ordered lamellae, gyroid, hexagonal or spherical morphologies from a single block copolymer with a fixed volume fraction. The selected microstructure was then kinetically trapped in the dry film by rapid drying. To our knowledge, this paper describes the first reported case where in-situ methods are used to study the transition of block copolymer films from one initial disordered morphology to four different ordered morphologies, covering much of the theoretical diblock copolymer phase diagram. PMID:26819574

Mechanistic insights for block copolymer morphologies: how do worms form vesicles?

PubMed

Blanazs, Adam; Madsen, Jeppe; Battaglia, Giuseppe; Ryan, Anthony J; Armes, Steven P

2011-10-19

Amphiphilic diblock copolymers composed of two covalently linked, chemically distinct chains can be considered to be biological mimics of cell membrane-forming lipid molecules, but with typically more than an order of magnitude increase in molecular weight. These macromolecular amphiphiles are known to form a wide range of nanostructures (spheres, worms, vesicles, etc.) in solvents that are selective for one of the blocks. However, such self-assembly is usually limited to dilute copolymer solutions (<1%), which is a significant disadvantage for potential commercial applications such as drug delivery and coatings. In principle, this problem can be circumvented by polymerization-induced block copolymer self-assembly. Here we detail the synthesis and subsequent in situ self-assembly of amphiphilic AB diblock copolymers in a one pot concentrated aqueous dispersion polymerization formulation. We show that spherical micelles, wormlike micelles, and vesicles can be predictably and efficiently obtained (within 2 h of polymerization, >99% monomer conversion) at relatively high solids in purely aqueous solution. Furthermore, careful monitoring of the in situ polymerization by transmission electron microscopy reveals various novel intermediate structures (including branched worms, partially coalesced worms, nascent bilayers, "octopi", "jellyfish", and finally pure vesicles) that provide important mechanistic insights regarding the evolution of the particle morphology during the sphere-to-worm and worm-to-vesicle transitions. This environmentally benign approach (which involves no toxic solvents, is conducted at relatively high solids, and requires no additional processing) is readily amenable to industrial scale-up, since it is based on commercially available starting materials.

Phase diagrams of block copolymer melts by dissipative particle dynamics simulations

NASA Astrophysics Data System (ADS)

Gavrilov, Alexey A.; Kudryavtsev, Yaroslav V.; Chertovich, Alexander V.

2013-12-01

Phase diagrams for monodisperse and polydisperse diblock copolymer melts and a random multiblock copolymer melt are constructed using dissipative particle dynamics simulations. A thorough visual analysis and calculation of the static structure factor in several hundreds of points at each of the diagrams prove the ability of mesoscopic molecular dynamics to predict the phase behavior of polymer systems as effectively as the self-consistent field-theory and Monte Carlo simulations do. It is demonstrated that the order-disorder transition (ODT) curve for monodisperse diblocks can be precisely located by a spike in the dependence of the mean square pressure fluctuation on χN, where χ is the Flory-Huggins parameter and N is the chain length. For two other copolymer types, the continuous ODTs are observed. Large polydispersity of both blocks obeying the Flory distribution in length does not shift the ODT curve but considerably narrows the domains of the cylindrical and lamellar phases partially replacing them with the wormlike micelle and perforated lamellar phases, respectively. Instead of the pure 3d-bicontinuous phase in monodisperse diblocks, which could be identified as the gyroid, a coexistence of the 3d phase and cylindrical micelles is detected in polydisperse diblocks. The lamellar domain spacing D in monodisperse diblocks follows the strong-segregation theory prediction, D/N1/2 ˜ (χN)1/6, whereas in polydisperse diblocks it is almost independent of χN at χN < 100. Completely random multiblock copolymers cannot form ordered microstructures other than lamellas at any composition.

Free energy landscape and localization of nanoparticles at block copolymer model defects.

PubMed

Kim, Yongjoo; Chen, Hsieh; Alexander-Katz, Alfredo

2014-05-14

Nanoparticle localization in block copolymer model defects is studied using self-consistent field theory simulations. In particular we study the nanoparticle free energy landscape for three different model defects: X, T, Y shape defects. Our results indicate that nanoparticles can be strongly bound to certain locations in these defects. The symmetry of the defects affects in a non-trivial fashion the "stiffness of the trap", with the X shape defect displaying the deepest energy well. The T and Y defects exhibit orientations along which the potential energy well is rather shallow. Furthermore, we find that the free energy well is tunable by the size of the nanoparticles. Our results help to explain recent experimental observations in block copolymer templated assembly of nanoparticles. Furthermore, they may open new avenues to assemble arbitrary heterogeneous patterns with precise nanoparticle positions by carefully controlling the morphology of a block copolymer system by using directed self-assembly techniques.

Thermo-Responsive Amphiphilic Block Copolymers Stablilized Gold Nanoparticles: Synthesis and High Catalytic Properties.

PubMed

Lü, Jianhua; Yang, Yu; Gao, Junfang; Duan, Haichao; Lü, Changli

2018-06-19

A series of novel well-defined 8-hydroxyquinoline (HQ)-containing thermo-responsive amphiphilic diblock copolymers poly(styrene-co-5-(2-methacryloylethyloxy- methyl)-8-quinolinol)-b-poly(N-isopropylacrylamide) P(St-co-MQ)-b-PNIPAm (P1,2), P(NIPAm- co-MQ)-b-PSt (P3,4) and triblock copolymer poly(N-isopropylacrylamide)-b-poly(methyl- methacrylate-co-5-(2-methacryloylethyloxymethyl)-8-quinolinol)-b-polystyrene PNIPAm-b- P(MMA-co-MQ)-b-PSt (P5) were prepared by reversible addition fragmentation chain transfer (RAFT) polymerization, and their self-assembly behaviors were studied. The block copolymers P1-P5 stabilized gold nanoparticles (Au@P1-Au@P5) with small size and narrow distribution were obtained through in situ reduction of gold precursors in aqueous solution of polymer micelles with HQ as the coordination groups. The resulting Au@P nanohybrids possessed excellent catalytic activities for the reduction of nitrophenols using NaBH4. The size, morphology and surface chemistry of Au NPs could be controlled by adjusting the structure of block polymers with HQ in different block positions, which plays an important role in the catalytic properties. It was found that longer chain length of hydrophilic or hydrophobic segments of block copolymers were beneficial to elevate the catalytic activity of Au NPs for the reduction of nitrophenols, and the spherical nanoparticles (Au@P5) stabilized with triblock copolymer exhibit higher catalytic performance. Surprisingly, the gold nanowires (Au@P4) produced with P4 have a highest catalytic activity due to large abundance of grain boundaries. Excellent thermo-responsive behaviors for catalytic reaction make the as-prepared Au@P hybrids become an environmentally responsive nano-catalytic materials.

Adjustable bridge blocks make huge difference to the self-assembly of multiblock copolymers

NASA Astrophysics Data System (ADS)

Li, Weihua

We present theoretical studies on two types of multiblock copolymers, whose self-assemblies lead to a lot of novel ordered nanostructures. The first example is BABCB multiblock terpolymer, where A- and C-blocks separately aggregate into isolated domains and the three B-blocks with adjustable lengths form the matrix. As a result, the middle B-block forms a natural bridge connecting A- and C-domains. In contrast to ABC, the BABCB can form many binary spherical and cylindrical phases with tunable coordination numbers. In addition, the ABCB solution can form a lot of planet-satellite micellar superstructures with tunable number of satellites that varies from 3 to 20. The another system is AB-type multiblock copolymers. In contrast to the above system, there is no natural bridge. Accordingly, we introduce multiple arms into the architecture which tend to partition themselves into different domains to maximize their configurational entropy, thus forming effective bridges. Furthermore, each arm is devised as BAB triblock to enable adjustable length of bridges. With this copolymer, we predict a few non-classical ordered phases, including a square array cylinder. Our study opens the possibilities of fabricating desired nanostructures using designed block copolymers. National Natural Science Foundation of China (No. 21322407, 21574026).

Effect of chain structure on hydrogen bonding in vinyl acetate - vinyl alcohol copolymers

NASA Astrophysics Data System (ADS)

Merekalova, Nadezhda D.; Bondarenko, Galina N.; Denisova, Yuliya I.; Krentsel, Liya B.; Litmanovich, Arkadiy D.; Kudryavtsev, Yaroslav V.

2017-04-01

FTIR spectroscopy and semi-empirical AM1 method are used to study hydrogen bonding in multiblock and random equimolar copolymers of vinyl acetate and vinyl alcohol. An energetically beneficial zip-holder complex, built on multiple inter- and intrachain hydroxyl-hydroxyl bonds and an intrachain hydroxyl-acetyloxy bond, can be formed between two vinyl alcohol sequences. As a result, multiblock copolymers reveal stronger degree of association that affects crystallinity, as well as various rheological and relaxation properties discussed in the literature. Macromolecular complexes in random copolymers are weak and tend to be destroyed in the presence of residual DMF solvent and adsorbed water. Nevertheless, a rather stable interchain quaternary complex can be formed that includes vinyl alcohol and vinyl acetate units and DMF and water molecules. For a single chain it is shown that an H-bond between neighboring vinyl alcohol and vinyl acetate monomer units mostly engages a carbonyl oxygen atom of the vinyl acetate, if the vinyl alcohol belongs to a short (<5 units) sequence, and an ether oxygen atom in the other case. On the whole, the quantum chemistry calculations shed much light on the origin of distinctions in the copolymer FTIR spectra, which may seem subtle when considered standalone.

Dynamical self-arrest in symmetric and asymmetric diblock copolymer melts using a replica approach within a local theory.

PubMed

Wu, Sangwook

2009-03-01

We investigate dynamical self-arrest in a diblock copolymer melt using a replica approach within a self-consistent local method based on dynamical mean-field theory (DMFT). The local replica approach effectively predicts (chiN)_{A} for dynamical self-arrest in a block copolymer melt for symmetric and asymmetric cases. We discuss the competition of the cubic and quartic interactions in the Landau free energy for a block copolymer melt in stabilizing a glassy state depending on the chain length. Our local replica theory provides a universal value for the dynamical self-arrest in block copolymer melts with (chiN)_{A} approximately 10.5+64N;{-3/10} for the symmetric case.

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.

Interpreting Neutron Reflectivity Profiles of Diblock Copolymer Nanocomposite Thin Films Using Hybrid Particle-Field Simulations

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

Mahalik, Jyoti P.; Dugger, Jason W.; Sides, Scott W.

Mixtures of block copolymers and nanoparticles (block copolymer nanocomposites) are known to microphase separate into a plethora of microstructures, depending on the composition, length scale and nature of interactions among its different constituents. Theoretical and experimental works on this class of nanocomposites have already high-lighted intricate relations among chemical details of the polymers, nanoparticles, and various microstructures. Confining these nanocomposites in thin films yields an even larger array of structures, which are not normally observed in the bulk. In contrast to the bulk, exploring various microstructures in thin films by the experimental route remains a challenging task. Here in thismore » work, we construct a model for the thin films of lamellar forming diblock copolymers containing spherical nanoparticles based on a hybrid particle-field approach. The model is benchmarked by comparison with the depth profiles obtained from the neutron reflectivity experiments for symmetric poly(deuterated styrene-b-n butyl methacrylate) copolymers blended with spherical magnetite nanoparticles covered with hydrogenated poly(styrene) corona. We show that the model based on a hybrid particle-field approach provides details of the underlying microphase separation in the presence of the nanoparticles through a direct comparison to the neutron reflectivity data. This work benchmarks the application of the hybrid particle-field model to extract the interaction parameters for exploring different microstructures in thin films containing block copolymers and nanocomposites.« less

Nanostructured DPA-MPC-DPA triblock copolymer gel for controlled drug release of ketoprofen and spironolactone.

PubMed

Azmy, Bahaa; Standen, Guy; Kristova, Petra; Flint, Andrew; Lewis, Andrew L; Salvage, Jonathan P

2017-08-01

Uncontrolled rapid release of drugs can reduce their therapeutic efficacy and cause undesirable toxicity; however, controlled release from reservoir materials helps overcome this issue. The aims of this study were to determine the release profiles of ketoprofen and spironolactone from a pH-responsive self-assembling DPA-MPC-DPA triblock copolymer gel and elucidate underlying physiochemical properties. Drug release profiles from DPA 50 -MPC 250 -DPA 50 gel (pH 7.5), over 32 h (37 °C), were determined using UV-Vis spectroscopy. Nanoparticle size was measured by dynamic light scattering (DLS) and critical micelle concentration (CMC) by pyrene fluorescence. Polymer gel viscosity was examined via rheology, nanoparticle morphology investigated using scanning transmission electron microscopy (STEM) and the gel matrix observed using cryo-scanning electron microscopy (Cryo-SEM). DPA 50 -MPC 250 -DPA 50 copolymer (15% w/v) formed a free-standing gel (pH 7.5) that controlled drug release relative to free drugs. The copolymer possessed a low CMC, nanoparticle size increased with copolymer concentration, and DLS data were consistent with STEM. The gel displayed thermostable viscosity at physiological temperatures, and the gel matrix was a nanostructured aggregation of smaller nanoparticles. The DPA 50 -MPC 250 -DPA 50 copolymer gel could be used as a drug delivery system to provide the controlled drug release of ketoprofen and spironolactone. © 2017 Royal Pharmaceutical Society.

Interpreting Neutron Reflectivity Profiles of Diblock Copolymer Nanocomposite Thin Films Using Hybrid Particle-Field Simulations

DOE PAGES

Mahalik, Jyoti P.; Dugger, Jason W.; Sides, Scott W.; ...

2018-04-10

Mixtures of block copolymers and nanoparticles (block copolymer nanocomposites) are known to microphase separate into a plethora of microstructures, depending on the composition, length scale and nature of interactions among its different constituents. Theoretical and experimental works on this class of nanocomposites have already high-lighted intricate relations among chemical details of the polymers, nanoparticles, and various microstructures. Confining these nanocomposites in thin films yields an even larger array of structures, which are not normally observed in the bulk. In contrast to the bulk, exploring various microstructures in thin films by the experimental route remains a challenging task. Here in thismore » work, we construct a model for the thin films of lamellar forming diblock copolymers containing spherical nanoparticles based on a hybrid particle-field approach. The model is benchmarked by comparison with the depth profiles obtained from the neutron reflectivity experiments for symmetric poly(deuterated styrene-b-n butyl methacrylate) copolymers blended with spherical magnetite nanoparticles covered with hydrogenated poly(styrene) corona. We show that the model based on a hybrid particle-field approach provides details of the underlying microphase separation in the presence of the nanoparticles through a direct comparison to the neutron reflectivity data. This work benchmarks the application of the hybrid particle-field model to extract the interaction parameters for exploring different microstructures in thin films containing block copolymers and nanocomposites.« less

Azidated Ether-Butadiene-Ether Block Copolymers as Binders for Solid Propellants

NASA Astrophysics Data System (ADS)

Cappello, Miriam; Lamia, Pietro; Mura, Claudio; Polacco, Giovanni; Filippi, Sara

2016-07-01

Polymeric binders for solid propellants are usually based on hydroxyl-terminated polybutadiene (HTPB), which does not contribute to the overall energy output. Azidic polyethers represent an interesting alternative but may have poorer mechanical properties. Polybutadiene-polyether copolymers may combine the advantages of both. Four different ether-butadiene-ether triblock copolymers were prepared and azidated starting from halogenated and/or tosylated monomers using HTPB as initiator. The presence of the butadiene block complicates the azidation step and reduces the storage stability of the azidic polymer. Nevertheless, the procedure allows modifying the binder properties by varying the type and lengths of the energetic blocks.

Cycloolefin/cyanoacrylate (COCA) copolymers for 193-nm and 157-nm lithography

NASA Astrophysics Data System (ADS)

Dammel, Ralph R.; Sakamuri, Raj; Lee, Sang-Ho; Rahman, Dalil; Kudo, Takanori; Romano, Andrew R.; Rhodes, Larry F.; Lipian, John-Henry; Hacker, Cheryl; Barnes, Dennis A.

2002-07-01

The copolymerization reaction between methyl cyanoacrylate (MCA) and a variety of cycloolefins (CO) was investigated. Cycololefin/cyanoacrylate (COCA) copolymers were obtained in good yields and with lithographically interesting molecular weights for all cycoolefins studied. Anionic MCA homopolymerization could be largely suppressed using acetic acid. Based on NMR data, the copolymerization may tend to a 1:1 CO:MCA incorporation ratio but further work with better suppression of the anionic component is needed to confirm this. Lithographic tests on copolymers of appropriately substituted norbornenes and MCA showed semi-dense and isolated line performance down to 90 nm.

Drug-conjugated PLA-PEG-PLA copolymers: a novel approach for controlled delivery of hydrophilic drugs by micelle formation.

PubMed

Danafar, H; Rostamizadeh, K; Davaran, S; Hamidi, M

2017-12-01

A conjugate of the antihypertensive drug, lisinopril, with triblock poly(lactic acid)-poly(ethylene glycol)-poly(lactic acid) (PLA-PEG-PLA) copolymer was synthesized by the reaction of PLA-PEG-PLA copolymer with lisinopril in the presence of dicyclohexylcarbodiimide and dimethylaminopyridine. The conjugated copolymer was characterized in vitro by hydrogen nuclear magnetic resonance (HNMR), Fourier transform infrared (FTIR), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC) techniques. Then, the lisinopril conjugated PLA-PEG-PLA were self-assembled into micelles in aqueous solution. The resulting micelles were characterized further by various techniques such as dynamic light scattering (DLS) and atomic force microscopy (AFM). The results revealed that the micelles formed by the lisinopril-conjugated PLA-PEG-PLA have spherical structure with the average size of 162 nm. The release behavior of conjugated copolymer, micelles and micelles physically loaded by lisinopril were compared in different media. In vitro release study showed that in contrast to physically loaded micelles, the release rate of micelles consisted of the conjugated copolymer was dependent on pH of media where it was higher at lower pH compared to the neutral medium. Another feature of the conjugated micelles was their more sustained release profile compared to the lisinopril-conjugated copolymer and physically loaded micelles.

21 CFR 175.210 - Acrylate ester copolymer coating.

Code of Federal Regulations, 2014 CFR