Effect of κ-carrageenan on volume phase transition for polyacrylamide (PAAm) hydrogel using the fluorescence technique

Abstract

Steady-state fluorescence (SSF) technique was employed for studying swelling of polyacrylamide (PAAm) gels with various content of κ-carrageenan (κC). Disc shaped composite hydrogels were prepared by free-radical crosslinking copolymerization of acrylamide (AAm) with various amounts κC. N,N′-methylenebis (acrylamide) (BIS) and ammonium persulfate (APS) were used as crosslinker and initiator, respectively. Pyranine was introduced as a fluorescence probe. Fluorescence intensity of pyranine was monitored during in situ swelling processes of composite gels. It was observed that fluorescence intensity values decreased as swelling is proceeded. Li–Tanaka equation was used to determine the swelling time constants, τ and cooperative diffusion coefficients, D from intensity variations during the swelling processes. It was shown that swelling time constants, τ decreased and diffusion coefficients, D increased as the κC content in the composites are increased.