Fluorescence studies of the volume phase transition and dynamic fluctuation in polyacrylamide gels with a dansyl group induced by the composition change in an acetone/water mixed solvent

Abstract

Fluorescence studies have been made on the ionic poly(acrylamide) gels and linear poly(acrylamide) having a side-chain dansyl fluorescent probe. The gels undergo a discontinuous first-order volume phase transition at 60% acetone volume content in the mixed solvent of acetone/water at 20°C. According to fluorescence data, the phase transition from the swollen to collapsed state is accompanied by the change in hydrophobic interaction of the main chains of the gel. The rotational diffusion coefficient becomes infinite and shows a sharp peak at the phase transition point due to the dynamic fluctuation of the network of the gel