New phase diagram for N-arylacrylamide/acrylamide/sodium acrylate copolymer gel

Abstract

Examination was made of changes in the volume of N-arylacrylamide(NAA)/acrylamide/sodium acrylate copolymer gel immersed in acetone–water and dioxane–water mixtures. The gel underwent reversible volume change from a swollen to collapsed state via discontinuous volume change with increase in solvent composition. Volume change at the transition point decreased with increase in NAA content, and the transition point shifted first toward lower solvent content with increase in NAA content and then toward higher solvent content. This is a volume phase transition characterized by two conventional patterns. Plots of transition solvent composition as a function of gel polymer composition indicated a nobel phase diagram for the polymer gel, which is essentially equivalent to miscibility diagram usually observed for polymer solutions.