(The) swelling and mechanical properties of tactic poly(2-hydroxyethyl methacrylate) hydrogels

Abstract

The swelling and stress-elongation experiments have been performed for two kinds of tactic poly (2-hydroxyethyl methacrylate) (P-HEMA) with varying crosslinker concentrations. Isotactic and syndiotactic P-HEMA gels are swollen in aqueous salt solutions varying molal concentrations. The solute which we used are NaCl, $MgCl_2$, $Na_2SO_4$, $MgSO_4$ and urea. The water content and salt partition coefficient were determined. And stress-elongation curves of the gels are obtained. From these results, the effective number of chain ($υ\mid_e$) and the Flory-Huggins interaction parameter ($χ\mid_1$) are also obtained. The swelling experiment performed also varying solvents, and the degree of swelling is determined. The solubility parameter of P-HEMA is obtained as 13.6 using the correlation between the degree of swelling and the solubility parameter ($δ\mid_1$) of solvents. The mechanical properties of syndiotactic P-HEMA is stronger than that of isotactic P-HEMA, and the water contents of both gels become smaller when the crosslinking increases. This water content of isotactic P-HEMA is more than that of syndiotactic P-HEMA.