EFFECT OF SULFONATE GROUPS ON PERMEABILITY OF SOLUTES THROUGH MEMBRANES OF STYRENESULFONIC ACID-METHYL METHACRYLATE COPOLYMERS

Copolymer membranes composed of styrenesulfonic acid (SSA) methyl methacrylate (MMA) were prepared, in which 7. 8, 9. 8, 10. 6 or 14. 4 mol% of SSA was contained. The content of freezing water was determined by the DSC measurement, as was the content of non freezing water in the membrane. The water content of the membrane having 7. 8 mol% SSA was about 30 wt%, and was found to be non-freezing water. The content of freezing water increased remarkably with increasing the SSA content. Partition coefficients, diffusion coefficients and permeability coefficients for creatinine and the electrolytes such as KCl, NaCl, LiCl, KBr and KI were determined at 25 degree C. The partition coefficient of creatinine for the membrane having 7. 8 mol% SSA was highest, and the value decreased with increasing water content, whereas the diffusion coefficient increased.