Vibrational spectra of polymers. III. Raman evidence for ion clustering in styrene/sodium p-styrene carboxylate copolymers

Abstract

The infrared and Raman spectra of a series of styrene/sodium p-styrene carboxylate ionomers with sodium p-styrene car-boxylate contents varying from zero to 13.6 mole % have been recorded, and some vibrational assignments are proposed. The bands appearing in the Raman spectra at 248 and 158 cm-¹ are attributed to ion multiplets and clusters, respectively. The relative intensities of these two bands have been used to determine the relative concentrations of ion pairs in these two different kinds of sites. The temperature invariance of the relative intensities of the two Raman bands between —258 and 250°C, together with our previous work on other ionomers, suggests that the distribution of ion pairs between clusters and multiplets depends on the proximity to the glass transition temperature.