PHASE INVERSION PROCESS OF AMPHIPHILIC CHARGED POLYACRYLONITRILES FORMOLECULAR-SIZE EXCLUSION MEMBRANE

Four types of polyacrylonitrile (PAN) copolymer having quaternary ammo nium groups with trimethyl, triethyl, dimethyloctyl and dimethylsteary l groups were used as materials of the ultrafiltration membrane. The u ltrafiltration membranes were prepared by the phase inversion method i n dimethylsulfoxide (DMSO)-polymer cast solution and a water coagulate system. The cast solution concentration and the coagulation temperatu re were changed in the range 8-11 wt% and 10-50 degrees C, respectivel y. The resulting copolymer membranes were tested by ultrafiltration fo r the permeation of dextran with various molecular weights. The role o f the amphiphilic quaternary charged group on the filtration propertie s 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 influ ence the copolymer phase inversion in the water coagulation medium. Th e 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.