Steady state fluorescence technique for studying phase transitions in PAAm-PNIPA mixture

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Date

2009

Authors

Evingür, Gülşen Akın
Aktaş, Demet Kaya
Pekcan, Önder

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Volume Title

Publisher

Taylor & Francis

Research Projects

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Abstract

The steady state fluorescence (SSF) technique was used to study the sol-gel phase transition during free radical crosslinking copolymerisation of various amounts of acrylamide (AAm) and N-isopropylacrylamide (NIPA) mixtures. NN'-methylenebis (acrylamide) (BIS) and ammonium persulfate (APS) were used as crosslinker and an initiator respectively. Pyranine (8-hydroxypyrene-1 3 6-trisulfonic acid trisodium salt HPTS) was added as a fluoroprobe for monitoring the polymerisation. It was observed that pyranine molecules bind to AAm and NIPA chains upon the initiation of the polymerisation 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 without disturbing the system mechanically and to test the universality of the sol-gel transition as a function of polymer concentration ratios. Observations around the gel point of PAAm-PNIPA mixtures show that the gel fraction exponent obeyed the percolation result.

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Keywords

Acrylamide-NIPA, Mixture, Hydrogel, Percolation, Critical phenomena, Fluorescence

Turkish CoHE Thesis Center URL

Citation

10

WoS Q

N/A

Scopus Q

N/A

Source

Volume

82

Issue

1

Start Page

53

End Page

65