Gel Formation and Molecular Characteristics of Poly(N-isopropylacrylamide) Prepared by Free-Radical Redox Polymerization in Aqueous Solution

✍ Scribed by Yingjia Xu; Guang Li; Kazutoshi Haraguchi

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 531 KB
• Volume: 211
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.200900565

✦ Synopsis

Abstract

The molecular characteristics of poly(N‐isopropylacrylamide) (PNIPA), prepared by free‐radical polymerization using an aqueous redox initiator and reaction conditions comparable to those used in the synthesis of nanocomposite gels, were investigated by altering the monomer concentration ([NIPA]) and the polymerization temperature (T~p~) across the transition temperature (LCST). When T~p~n*) above which PNIPA partially forms gels in the absence of a chemical crosslinker, and the gel fraction increases with increasing [NIPA] and decreasing T~p~. In the range of n<n*, the molecular weight of soluble PNIPA correlated well with [NIPA]. When T~p~>LCST, gels were not formed regardless of [NIPA]. The structure and mechanism of formation of self‐crosslinked PNIPA gels are discussed.

magnified image