Comparison of pH-sensitivity between two copolymer modified polyethersulfone hollow fiber membranes Original Research Article

The pH-sensitivity of two kinds of polyethersulfone (PES) hollow fiber membranes modified by two random copolymers, poly (acrylonitrile-co-acrylic acid) (P(AN-AA)) and poly(acrylonitrile-co-methyl acrylic acid) (P(AN-MAA)), was studied. The P(AN-AA) and P(AN-MAA) copolymers which had the same hydrophobic chains, comparable amounts of carboxyl groups but different hydrophilic chains, were synthesized via free radical polymerization and characterized by FT-IR, element analysis and 1H NMR. The copolymers could be directly blended with polyethersulfone to prepare hollow fiber membranes by dry–wet spinning technique. Both of the two copolymer modified PES hollow fiber membranes showed evident pH sensitivity. The flux variation for the P(AN-AA) modified PES hollow fiber was larger than that for the P(AN-MAA) between the pH values 2.0 and 11.0, since the single bondCH3 affected the dissociation of the carboxyl, and further affected the pH sensitivity of the modified hollow fiber membranes.