Swelling equilibria of poly(N-isopropylacrylamide) gel in glucose and starch aqueous solution

Swelling equilibria of poly(N-isopropylacrylamide) (NIPA) gel in starch-water and glucose-water aqueous solutions were measured at 20, 25, 30 and 33°C. Furthermore, solvent concentrations inside and outside the gel were measured at 20°C. The gel exhibited continuous deswelling behavior in starch-water aqueous solution. A large amount of starch could hardly penetrate into the gel network. On the other hand, a volume phase transition of the gel was observed in glucose-water aqueous solution. A significant amount of glucose could penetrate into the gel network. A solution model, based on the Flory-Huggins formula coupled with osmotic pressure by rubber elasticity proposed by Flory, was adopted to correlate the phase behavior of the gel in starch-water and glucose-water aqueous solutions. The volume change behavior and the equilibrium concentrations inside and outside the gel were successfully correlated by using the model.