Preparation and characterization of novel negatively charged hybrid membranes

Charged hybrid membranes with anionic‐ or cationic‐exchange groups have attracted increasing interest due to their higher thermal stabilities and structural flexibilities which are considered suitable for use in some harsh conditions, such as higher temperature and strongly oxidizing circumstances, for industrial applications. To develop new routes to synthesize the negatively charged hybrid membranes, a series of hybrid membranes were prepared via free radical polymerization of glycidylmethacrylate (GMA) and γ‐methacryloxypropyl trimethoxy silane (MPTMS) monomers, and ring‐opening of epoxide to create negatively charged ? SO₃H groups in the polymer chains. The fundamental properties of these prepared membranes were characterized through TGA, ion‐change capacity (IEC), and MALDI–TOF mass spectra. TGA showed that the thermal degradation temperature of these membranes could reach up to 300°C and the temperature of the first endothermic peak decreased with an increase in the content of ? SO₃H groups. IEC measurements showed that their IECs were within the range of 0.22–0.35 mmol g^?1. MALDI–TOF spectrometry indicated that the incorporation of GMA into the hybrid matrix could improve the structural stability of the membranes. These findings demonstrated that the ion‐exchange properties and structural stability of negatively charged hybrid membranes can be conveniently controlled by adjusting the GMA moiety in the hybrid matrix. Copyright © 2009 John Wiley & Sons, Ltd.