Journal
EUROPEAN POLYMER JOURNAL
Volume 45, Issue 4, Pages 1260-1269Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.eurpolymj.2008.11.010
Keywords
Poly(N-isopropylacrylamide)-co-poly-(N-(3-aminopropyl) methacrylamide hydrochloride); One-shot and multi-step feeding copolymerization; Reactivity ratio; Thermo-induced phase separation
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Funding
- Thailand National Metal and Materials Technology Center
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Free radical copolymerizations of N-isopropyl acrylamide (NIPAM) and cationic N-(3-aminopropyl) methacrylamide hydrochloride (APMH) were investigated to prepare amine-functional temperature responsive copolymers. The reactivity ratios for NIPAM and APMH were evaluated in media of different ionic strength (r(NIPAM) = 0.7 and r(APMH) = 0.7-1.2). Phase separation behavior of the random copolymers with only 5 mol% of the APMH was found to be suppressed in pure water at temperatures up to 45 degrees C due to electrostatic repulsion among the cationic amine groups randomly distributed along the copolymer chain. Alternate sequential addition of PNIPAM/APMH mixtures and pure NIPAM was used to provide increased control of the location of APMH units along the chain. Consequently (close to) homo-PNIPAM block(s) were formed as evidenced by its characteristic phase transition at 33 degrees C. The influences of the monomer feeding time and feeding interval time to the APMH distribution were investigated to prepare copolymers with thermo-induced phase separation under physiologically relevant temperature and to determine the extent of conjugation to poly(ethylene oxide). (c) 2009 Elsevier Ltd. All rights reserved.
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