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

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-pLCST, gels were not formed regardless of [NIPA]. The structure and mechanism of formation of self-crosslinked PNIPA gels are discussed.