Polystyrene-PEG crosslinked block copolymers were prepared from styrene copolymerization by either poly(ethylene glycol dimethymethacrylate) (PEG-DM) or macronomer initiators (MIM). M(w) values of PEG of PEG-DM were 400, 600, 1000, 1500, 3000, 10,000, and 35,000, and of MIM, 400 and 1500. Swelling in H2O or CHCl3 of the sulfonated and unsulfonated block copolymers were determined under comparable conditions and found to be vary significantly. The ion-exchange capacity and selectivity coefficients of these ion-exchange resins were investigated. The capacities of the obtained ion exchangers were varied between 0.4 and 2.9 meq/g. (C) 1996 John Wiley & Sons, Inc.