Acrylonitrile copolymers: Synthesis, characterization, and formation of ultrafiltration membranes

A variety of poly(acrylonitrile-co-acrylamide) polymers of different compositions were synthesized by free radical copolymerization. Thin films were cast from polymer solutions, and coagulated into ultrafiltration membranes. The effect of preparative parameters on membrane gel structure was investigated. For nonsupported membranes, concentrated polymer solutions produce fine pore membranes with a lower flux; extending the drying time causes a diminution in membrane thickness, swelling index, and fluxes; the membrane thickness, swelling index, and permeate flux all increased with increasing coagulation bath temperature. For supported membranes, dilute polymer casting solutions, small casting gate opening, and added polyvinylpyrrolidone to the casting solution all increased the permeate flux. The membranes containing acrylamide were more hydrophilic, and had a smaller dispersion force component of the surface free energy than those prepared from the polyacrylonitrile homopolymer. (C) 1999 John Wiley & Sons, Inc.