The effect of preparation temperature on the swelling behavior of poly(N-isopropylacrylamide) gels


SAYIL C., Okay O.

POLYMER BULLETIN, vol.45, no.2, pp.175-182, 2000 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 45 Issue: 2
  • Publication Date: 2000
  • Doi Number: 10.1007/s002890070046
  • Title of Journal : POLYMER BULLETIN
  • Page Numbers: pp.175-182

Abstract

The role of the preparation temperature of poly(N-isopropylacrylamide) (PNIPA) gels on their swelling behavior in water and in aqueous solutions of sodium dodecylbenzenesulfonate was investigated. PNIPA gels were prepared by free-radical crosslinking copolymerization of N-isopropylacrylamide and N,N'-methylene(bis) acrylamide in water at fixed monomer and crosslinker concentrations. The equilibrium swelling ratio of the gels increases first slightly up to about 20 degrees C then rapidly with increasing gel preparation temperature. Magnitude of the collapse transition in water at 34 degrees C becomes larger as the gel preparation temperature increases. Calculations indicate a decrease in the effective crosslink density of PNIPA gels with increasing preparation temperature. The gels prepared at temperatures higher then 20 degrees C were heterogeneous consisting of highly crosslinked regions interconnected by the PNIPA chains.