Some model solute affinity for a tactic P-HEMA membranes by the $K_D$ measurement

Abstract

Two series of membranes have been prepared by postcrosslinking highly syndiotactic and isotactic poly 2-hydroxyethyl methacrylate, P(HEMA). The crosslinker used was hexamethylene diisocynate (HMDIC). The distribution coefficients of the model solutes such as urea(and thiourea), its derivatives, homologous alcohol series, amide series in water-swollen isotactic and syndiotactic P(HEMA) membranes at $25\,^\circ\!C$ were measured. In addition the concentration effects of acetamide and butyramide were also measured. On the basis of hydrophobic interaction and the structural factors of tactic P(HEMA) membranes, the hydrophobic adsorption of the solutes in the polymer matrix were discussed. The results showed that ISO membrane has higher distribution coefficient than SYN membrane. As for concentration effects, the distribution coefficient was revealed minimum point. From the experimental observations it is concluded that the hydrophobicity is generally a controlling factor on the preferential sorption of solutes on the polymer matrix in the water-containing system. And the polymer conformation also affects the distribution of solvents.