Sulfonation of cross‐linked asymmetric membranes based on polystyrene and divinylbenzene

Abstract Asymmetric microporous membranes based on polystyrene cross‐linked with divinyl benzene were prepared. They were sulfonated with sulfonic acid and washed with solutions of gradually increasing pH to reduce environmental shock. The sulfonation was monitored by infrared spectroscopy, and changes in wettability and sulfur content were also recorded. Morphologies and reverse osmosis performance of sulfonated membranes were measured, with both water flux and salt rejection increasing after treatment. © 1994 John Wiley & Sons, Inc.