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Copolymer Networks (copolymer + network)

Distribution by Scientific Domains

Polymers and Materials Science	83%

Selected Abstracts

Hyperbranched Fluoropolymers and their Hybridization into Complex Amphiphilic Crosslinked Copolymer Networks

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2007
Jeremy W. Bartels
Abstract This feature article highlights three types of hyperbranched fluoropolymers (HBFPs) with different structural features, which were synthesized by either polycondensation of fluorinated ABx monomers or self-condensing vinyl (co)polymerization of fluorinated inimers and/or fluorinated comonomers. Amphiphilic crosslinked networks with hybridization of these hydrophobic HBFPs and linear hydrophilic poly(ethylene glycol)s are also discussed. As microphase-segregated materials with nanoscale surface heterogeneities, these networks possessed unusual anti-biofouling abilities, atypical sequestration and release behaviors for guest molecules, and special mechanical properties. [source]

Thermosensitive Copolymer Networks Modify Gold Nanoparticles for Nanocomposite Entrapment

CHEMISTRY - A EUROPEAN JOURNAL, Issue 8 2007
Dongxiang Li Dr.
Abstract The core-shell gold nanoparticles and copolymer of N -isopropylacrylamide (NIPAM) and N,N,-methylenebisacrylamide (MBAA) hybrids (Au@copolymer) were fabricated through surface-initiated atom-transfer radical polymerization (ATRP) on the surface of gold nanoparticles in 2-propanol/water mixed solvents. The surface of citrate-stabilized gold nanoparticles was first modified by a disulfide initiator for ATRP. The slight cross-linking polymerization between NIPAM and MBAA occurred on the gold surface and resulted in the formation of core-shell Au@copolymer nanostructures that were characterized by TEM, and FTIR and UV-visible spectroscopy. Such synthesized Au@copolymer hybrids possess clearly thermosensitive properties and exhibit "inspire" and "expire" water behavior in response to temperature changes in aqueous solution. Because of this property, we enable to trap and encapsulate smaller nanoparticles by using the free space of the copolymer-network scaffold anchored at the gold surface. [source]

Original Fuel-Cell Membranes from Crosslinked Terpolymers via a "Sol,gel" Strategy

ADVANCED FUNCTIONAL MATERIALS, Issue 7 2010
Ozlem Sel
Abstract Hybrid organic/inorganic membranes that include a functionalized (-SO3H), interconnected silica network, a non-porogenic organic matrix, and a -SO3H-functionalized terpolymer are synthesized through a sol,gel-based strategy. The use of a novel crosslinkable poly(vinylidene fluoride- ter -perfluoro(4-methyl-3,6-dioxaoct-7-ene sulfonyl fluoride)- ter -vinyltriethoxysilane) (poly(VDF- ter -PFSVE- ter -VTEOS)) terpolymer allows a multiple tuning of the different interfaces to produce original hybrid membranes with improved properties. The synthesized terpolymer and the composite membranes are characterized, and the proton conductivity of a hybrid membrane in the absence of the terpolymer is promising, since 8,mS cm,1 is reached at room temperature, immersed in water, with an experimental ion-exchange-capacity (IECexp) value of 0.4,meq g,1. Furthermore, when the composite membranes contain the interfaced terpolymer, they exhibit both a higher proton conductivity (43,mS cm,1 at 65 °C under 100% relative humidity) and better stability than the standard hybrid membrane, arising from the occurrence of a better interface between the inorganic silica and the poly[(vinylidene fluoride)- co -hexafluoropropylene] (poly(VDF- co -HFP)) copolymer network. Accordingly, the hybrid SiO2 -SO3H/terpolymer/poly(VDF- co -HFP) copolymer membrane has potential use as an electrolyte in a polymer-electrolyte-membrane fuel cell operating at intermediate temperatures. [source]

Synthesis and characterization of a cured epoxy resin with a benzoxazine monomer containing allyl groups

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010
Shiao-Wei Kuo
Abstract Vinyl-terminated benzoxazine (VB-a), which can be polymerized through ring-opening polymerization, was synthesized through the Mannich condensation of bisphenol A, formaldehyde, and allylamine. This VB-a monomer was then blended with epoxy resin and then concurrently thermally cured to form an epoxy/VB-a copolymer network. To understand the curing kinetics of this epoxy/VB-a copolymer, dynamic differential scanning calorimetry measurements were performed by the Kissinger and Flynn,Wall,Ozawa methods. Fourier transform infrared (FTIR) analyses revealed the presence of thermal curing reactions and hydrogen-bonding interactions of the epoxy/VB-a copolymers. Meanwhile, a significant enhancement of the ring-opening and allyl polymerizations of the epoxy was observed. For these interpenetrating polymer networks, dynamic mechanical analysis and thermogravimetric analysis results indicate that the thermal properties increased with increasing VB-a content in the epoxy/VB-a copolymers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Structure and Properties of Poly(, -caprolactone) Networks with Modulated Water Uptake

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 23 2006
Jorge L. Escobar Ivirico
Abstract Summary: A PCL macromonomer was obtained by the reaction of PCL diol with methacrylic anhydride. The effective incorporation of the polymerizable end groups was assessed by FT-IR and 1H NMR spectroscopy. PCL networks were then prepared by photopolymerization of the PCL macromonomer. Furthermore, the macromonomer was copolymerized with HEA, with the aim of tailoring the hydrophilicity of the system. A set of hydrophilic semicrystalline copolymer networks were obtained. The phase microstructure of the new system and the network architecture was investigated by DSC, IR, DMS, TG, dielectric spectroscopy and water sorption studies. The presence of the hydrophilic units in the system prevented PCL crystallization on cooling; yet there was no effect on the glass transition process. The copolymer networks showed microphase separation and the , relaxation of the HEA units moved to lower temperatures as the amount of PCL in the system increased. Ideal structure, compatible with the experimental results, for the hydrophilized poly(, -caprolactone) networks with modulated water uptake. [source]

Poly(, -caprolactone)-Based Organogels and Hydrogels with Poly(ethylene glycol) Cross-Linkings

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 21 2004
Jean Coudane
Abstract Summary: The reaction of triphosgene with poly(ethylene glycol) yielded poly(ethylene glycol) dichloroformate. This difunctional cross-linker was allowed to react with poly(, -caprolactone) bearing carbanionic sites obtained by activation with lithium diisopropylamide. The reaction resulted in the cross-linking of poly(, -caprolactone) chains by poly(ethylene glycol) segments, giving copolymer networks that gel in both organic and aqueous media. Schematic of the PCL- g -PEG copolymers synthesized here. [source]