Proton conducting membranes consisting of poly(vinyl alcohol) and poly(styrene sulfonic acid): Crosslinking of poly(vinyl alcohol) with and without succinic acid

Preparation of proton conducting PVA-PSS polymer films composed of cross-linked poly(vinyl alcohol) (PVA) and poly(styrene sulfonic acid) (PSS) is described. The PVA-PSS film was insolubilized in hot water by the crosslinking reaction with succinic acid (SA) in a temperature range of 180-200 degrees C. Insolubilization of the PVA-PSS film in hot water was also achieved by self-crosslinking that occurred in the PVA-PSS system in a temperature range of 130-180 degrees C, even in the absence of SA. This self-crosslinking in the PVA-PSS system is thought to proceed via PSS-catalyzed dehydration of PVA to form olefinic - CH=CH - units and ethereal -O- units. Coloring of the PVA-PSS film to black by thermal treatment supported the formation of n-conjugated - (CH=CH)(n)- units. Both the PVA-PSS-SA and PVA-PSS films showed proton conductivity of approximately sigma=0.1 Scm(-1) at 80 degrees C and 95% relative humidity. The self-crosslinking observed with the PVA-PSS system was followed by gravimetry. (C) 2013 Elsevier B.V. All rights reserved.