Crosslinked oligosilylstyrene-poly(dimethylsiloxane) composite membranes were used to separate 1,2-dimethoxyethane (1,2-DME) from dilute aqueous solutions through a pervaporation process. The composite membranes were prepared through the casting of solutions of H-terminated oligosilylstyrene and vinyl-terminated poly(dimethylsiloxane) onto the surfaces of polysulfone ultrafiltration membranes. A crosslinked poly(dimethylsiloxane) gel was generated through the reaction of H-terminated oligosilylstyrene and vinyl-terminated poly(dimethylsiloxane), with a platinum complex used as a catalyst. The pervaporation characteristics of the composite membranes were investigated with respect to the feed composition of 1,2-DME, the feed temperature, the downstream pressure, and the top-layer thickness of the composite membranes. The composite membranes exhibited preferential selectivity to 1,2-DME. Depending on the operation conditions, the separation factor and permeation rate of 1,2-DME were 55-184 and 0.31-3.3 g/m(2) h, respectively. (C) 2004 Wiley Periodicals, Inc.