Novel synthetic ion-exchange membranes composed of 4-vinylbenzyl chloride, styrene, and ethylmethacrylate were synthesized by radical polymerization using various monomer ratios. Copolymers with the desired molecular weights were successfully synthesized (Mn > 39.5 x 10(3) g/mol, Mw > 52.8 x 10(3) g/mol). After the radical polymerization, the ion-exchange membranes were prepared through amination and heat curing. The chemical structures of the membranes were characterized using Fourier-transform infrared spectroscopy and H-1 and C-13 nuclear magnetic resonance spectroscopy. The thermal, electrical, and other basic properties of the membranes, including water uptake and ion-exchange capacities, were measured. The glass temperature values of the polymers ranged from 67.5 to 81.2 degrees C. The nitrate permeation properties were also investigated by applying the membranes in a capacitive deionization system. Compared to conventional membranes, the nitrate concentrations in the cyclical charge and discharge currents indicated that the synthesized membranes were more efficient. (c) 2012 Elsevier B.V. All rights reserved.