Study on critical behaviour in N-isopropyl acrylamide gels by using fluorescence technique


Aktas D. , PEKCAN O.

PHASE TRANSITIONS, vol.79, no.11, pp.921-933, 2006 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 79 Issue: 11
  • Publication Date: 2006
  • Doi Number: 10.1080/01411590600970728
  • Title of Journal : PHASE TRANSITIONS
  • Page Numbers: pp.921-933

Abstract

The steady state fluorescence (SSF) technique was used to study the sol-gel transition for the solution free radical crosslinking copolymerization of N-isopropyl acrylamide (NIPA), with N,N'-methylenebis (acrylamide) (BIS) as crosslinker in the presence of ammonium persulfate (APS) as an initiator. Pyranine (8-hydroxypyrene-1,3,6-trisulfonic acid, trisodium salt, HPTS) was used as a floroprobe for monitoring the polymerization. Pyranine molecules start to bind to NIPA polymer chains upon the initiation of the polymerization, thus the spectra of the bonded pyranines shift to the shorter wavelengths. The get fraction exponent beta and the weight average degree of polymerization exponent gamma' agree best with the mean-field (Flory-Stockmayer) results near the gel point for various crosslinker contents.