Synthesis and Properties of Chemically Cross-Linked Poly(vinyl alcohol) Modified Quaterized Hydroxyethylcellulose Ethoxylate as Novel Alkaline Anion-Exchange Membrane

Much attention has been paid to alkaline ion-exchange membranes with high alkaline stability. In this work, chemically cross-linked poly(vinyl alcohol) modified quaterized hydroxyethylcellulose ethoxylate (PVA/QHECE) membranes were prepared and evaluated as OH--conducting polymer electrolytes. The membranes were characterized using Fourier transform infrared (FTIR) spectra, thermogravimetric (TG) analysis, and the alternating current (AC) impedance technique as for their inner structure, thermal stability, alkaline resistance stability, and OH- conductivity (sigma). The OH- conductivity of the membranes was investigated as a function of cross-linking time, the content of cross-linking agent, polymer composition, and water uptake. It was found that membrane swelling decreased with cross-linking time accompanied by an improvement in mechanical properties but no obvious decrease in OH- conductivity resulted from the reduced water uptake. The OH- conductivities in the range of 3.26 x 10(-4)-4.44 x 10(-4) S center dot cm(-1) were obtained at room temperature ((19 +/- 2) degrees C), depending on the different PVA/QHECE compositions. TG analysis showed that the PVA/QHECE membrane exhibited high thermal stability at up to 260 degrees C when the QHECE content was 42.9%. In addition, the membranes had a high alkaline stability without a loss of integrity and OH- conductivity after immersion in 6 mol center dot L-1 KOH at 80 degrees C for 168 h.