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Polymer Network Formation (polymer + network_formation)

Distribution by Scientific Domains
Polymers and Materials Science100%

Selected Abstracts

Synthesis of phenanthroline-terminated polymers and their Fe(II)-complexes

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2010
Miklós Nagy
Abstract Well-defined mono- and bifunctional, phenanthroline-terminated poly(ethylene glycol) and polyisobutylene capable of polymer network formation were synthesized. The starting materials mono- and bi-phenanthroline- (phen) terminated poly(ethylene glycols) (mPEG-phen, phen-PEG-phen) and polyisobutylenes (PIB-phen, phen-PIB-phen) were prepared by the Williamson synthesis and characterized by means of 1H NMR and MALDI-TOF mass spectrometry. According to UV,Vis spectrophotometry and ESI-TOF mass spectrometry, the phenanthroline-terminated polymers underwent quantitative complex formation with ferrous ions in solution. The aqueous solution of mPEG-phen shows self-assembly behavior. Important parameters, such as critical micelle concentration and hydrodynamic radius of the aggregates were also determined. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2709,2715, 2010 [source]

Crosslinking polymerization leading to interpenetrating polymer network formation.

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2003

Abstract As part of our continuing studies concerned with the elucidation of the crosslinking polymerization mechanism leading to interpenetrating polymer network (IPN) formation, in which IPNs consist of both polymethacrylates and polyurethane (PU) networks, this article explores the polyaddition crosslinking reactions of multifunctional poly(methyl methacrylate- co -2-methacryloyloxyethyl isocyanate) [poly(MMA- co -MOI)] [MMA/MOI = 90/10] with various diols leading to PU network formation. Thus, the equimolar polyaddition crosslinking reactions of poly(MMA- co -MOI) with ethylene glycol (EG), 1,6-hexane diol, and 1,10-decane diol (DD) were carried out in N -methyl pyrrolidone at a 0.25 mol/L isocyanate group concentration at 80 °C. The second-order rate constants decreased from EG to DD. The deviation of the actual gel point from the theoretical one was smaller from EG to DD. The intrinsic viscosity of resulting prepolymer demonstrated almost no variation with progressing polymerization for the EG system, whereas it gradually increased with conversion for the DD system. Close to the gel point conversion it increased rather drastically for both systems. The swelling ratio of resulting gel was higher from EG to DD. These are discussed mechanistically in terms of the significant occurrence of intramolecular cyclization and intramolecular crosslinking reactions leading to shrinkage of the molecular size. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3243,3248, 2003 [source]

Crosslinking polymerization leading to interpenetrating polymer network formation.

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2003

Abstract At the start of our research program concerned with the elucidation of the crosslinking polymerization mechanism leading to interpenetrating polymer network (IPN) formation, in which IPNs consist of both polymethacrylates and polyurethane (PU) networks, this article deals with the polyaddition crosslinking reaction leading to PU network formation. Therefore, 2-methacryloyloxyethyl isocyanate (MOI) was radically copolymerized with methyl methacrylate (MMA) in the presence of CBr4 as a chain-transfer agent. The resulting poly(MMA- co -MOI)s, having pendant isocyanate (NCO) groups as novel multifunctional polyisocyanates, were used for polyaddition crosslinking reactions with ethylene glycol as a typical diol. The second-order rate constants depended on both the functionality of poly(MMA- co -MOI) and the NCO group concentration. The actual gel points were compared with the theoretical ones calculated according to Macosko's equation; the deviation of the actual gel point from the theoretical value became more remarkable for a greater functionality of poly(MMA- co -MOI) and at a lower NCO group concentration or at a lower poly(MMA- co -MOI) concentration. These are discussed mechanistically, with consideration given to the significance of intramolecular cyclization and intramolecular crosslinking reactions leading to the shrinkage of the molecular size of the prepolymer, along with the data of the intrinsic viscosities of resulting prepolymers and the swelling ratios of resulting gels. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 606,615, 2003 [source]

Tailoring Polymeric Hydrogels through Cyclodextrin Host,Guest Complexation

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 3 2010
Xuhong Guo
Abstract A close correllation between molecular-level interactions and macroscopic characteristics of polymer networks exists. The characteristics of the polymeric hydrogels assembled from ,-cyclodextrin (,-CD) and adamantyl (AD) substituted poly(acrylate)s can be tailored through selective host,guest complexation between ,-CD and AD substituents and their tethers. Dominantly, steric effects and competitive intra- and intermolecular host,guest complexation are found to control poly(acrylate) isomeric inter-strand linkage in polymer network formation. This understanding of the factors involved in polymeric hydrogel formation points the way towards the construction of increasingly sophisticated biocompatible materials. [source]