Monitoring the gelation of polyacrylamide-sodium alginate composite by fluorescence technique

Gülşen Akin Evingür, Filiz Tezcan, F. Bedia Erim, Önder Pekcan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


Polyacrylamide (PAAm)-sodium alginate (SA) composite was prepared with different amounts of SA varying in the range between 0.06% and 2% (w/v). The PAAm-SA composite was characterized by the steady-state fluorescence technique. Pyranine was added as a fluoroprobe for monitoring the polymerization. It was observed that pyranine molecules bind to AAm and SA chains upon the initiation of the polymerization. Thus, the fluorescence spectra of the bonded pyranines shift to the shorter wavelengths. Fluorescence spectra from the bonded pyranines allowed us to monitor the sol-gel phase transition, and to test the universality of the sol-gel transition as a function of SA contents. Observations around the critical point show that the gel fraction exponent, γ, and the weight average degree of polymerization exponent, , agreed with the percolation result for (<0.25% (w/v)) SA contents. However, classical results were produced at (<2% (w/v)) SA contents.

Original languageEnglish
Pages (from-to)530-541
Number of pages12
JournalPhase Transitions
Issue number6
Publication statusPublished - 1 Jun 2012


  • acrylamide
  • critical phenomena
  • fluorescence
  • sodium alginate
  • universality


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