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

摘要

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 °C. Insolubilization of the PVAPSS film in hotwaterwas also achieved by self-crosslinking that occurred in the PVA-PSS systemin a temperature range of 130-180°C, even in the absence of SA. This self-crosslinking in the PVA-PSS systemis thought to proceed via PSS-catalyzed dehydration of PVA to formolefinicCH=CH-units and etherealO-units. Coloring of the PVA-PSS film to black by thermal treatment supported the formation of π-conjugated(CH=CH)_n-units. Both the PVA-PSS-SA and PVA-PSS films showed proton conductivity of approximately σ=0.1Scm~(-1) at 80°C and 95% relative humidity. The self-crosslinking observed with the PVA-PSS system was followed by gravimetry.