A novel route was proposed for preparation of zwitterionic membranes, and it comprises (1) free radical polymerization between glycidylmethacrylate (GMA) and acrylic acid (AA) monomers and (2) subsequent ring-opening of epoxide and quaternary amination with trimethylamine hydrochloride. The reaction products were confirmed by FTIR spectra. The cation-exchange capacities (CIECs) and anion-exchange capacities (AIECs) of these zwitterionic membranes are within the range of (5.4-9.3) x 10(-2) and (30.6-11.1) x 10(-2) mmol g(-1), respectively. In addition, the CIEC increases as AA content increases, but the AIEC generally decreases. TGA and DITGA measurements reveal that their thermal stabilities can arrive at as high as 380 C. The water uptake is independent of pH. As for membrane potential and streaming potential, they both suggest that these membranes possess the characteristics of anion-exchange membranes and no IEP is observed. Permeation experiments of mixed KCI and glucose solution indicate that the transport behavior of ions is dependent on the membrane's charge density. (c) 2008 Elsevier B.V. All rights reserved.