Effect of chemical structures of sulfonate-containing crosslinked polyurethane elastomers on ionic conductive property.

This work is a continuation of the preceding study on the conductivity of crosslinked polyurethane (PU) elastomers containing quaternary ammonium salt structure in main chain, and is concerned with the effect of chemical structures of crosslinked PU elastomers containing anionic sulfonate group in side chain on ionic conductive property. Anionic crosslinked PU elastomers were prepared from poly (oxypropylene) glycol, poly (oxytetramethylene) glycol, mixtures of each of these with poly (oxyethylene) glycol, poly (caprolactone) glycol, and poly (ethylene adipate) glycol with 2, 4-tolylene diisocyanate by prepolymer technique. NCO-terminated prepolymer was chainextended and cured by using N, N-bis (2-hydroxyethyl) -2-aminoethane sulfonic acid sodium salt as a part of chain extender. Ion content was varied by changing reactant ratio. Anionic crosslinked PU elastomers having ionic conductivity were successfully prepared. Thermal and tensile properties and ionic conductivity (complex impedance) were measured. It became apparent that the conductivity of anionic crosslinked PU elastomers were strongly affected by the compatibility of ionic group and polyols. The highest conductivity was attained by the system based on mixed polyol containing poly (oxyethylene) glycol. Temperature dependence of ionic conductivity obeyed Arrhenius equation for the PUs with phase-separation structure, and Vogel-Tamman-Fulcher equation for those with homogeneous phase strucuture.