EFFECT OF ADDITIVES ON PHASE-TRANSITION OF N-ISOPROPYLACRYLAMIDE GELS

Effects of salts on volume phase transition of N-isopropylacrylamide gels and cloud points of poly-(N-isopropylacrylamide) solution were measured. The experiments were performed with inorganic salts and tetraalkylammonium salts. The transition temperature for inorganic salts was dependent on anions rather than cations, and the change in transition temperature was linearly correlated with the viscosity B coefficient of anions. On the other hand, the transition temperature for tetraalkylammonium bromides strongly depended on alkyl chain length, which was suspected to result from an adsorption of the salts to the polymer segments.