Phase inversion process of amphiphilic charged polyacrylonitriles for molecular size exclusion membrane

Four types of polyacrylonitrile (PAN) copolymer having quaternary ammonium groups with trimethyl, triethyl, dimethyloctyl and dimethylstearyl groups were used as materials of the ultrafiltration membrane. The ultrafiltration membranes were prepared by the phase inversion method in dimethylsulfoxide (DMSO)-polymer cast solution and a water coagulate system. The cast solution concentration and the coagulation temperature were changed in the range 8-11 wt% and 10-50 degrees C, respectively. The resulting copolymer membranes were tested by ultrafiltration for the permeation of dextran with various molecular weights. The role of the amphiphilic quaternary charged group on the filtration properties of the membrane was examined by changing the aliphatic chain length of the quaternary ammonium group covalently bound to the PAN segments. We found that the aliphatic long chains in the charged membrane influence the copolymer phase inversion in the water coagulation medium. The effect of amphiphilic charged group on the membrane formation by the phase inversion and the resultant membrane properties were discussed. (C) 1997 Elsevier Science Ltd.