The dynamics of sulfonated polystyrene ionomers were investigated by using broadband dielectric relaxation spectroscopy. Dynamic mechanical analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry, and small-angle X-ray scattering were employed in a complementary role. Sulfonated polystyrene ionomers were prepared from the precursor sulfonic acid polystyrene, having 1 and 7 mol % sulfonic acid, by exchanging the protons of the acid functionality with Na, Cs, and Zn cations. Three dielectric relaxations were observed above the glass transition temperature: the segmental α process and relaxations associated with Maxwell-Wagner-Sillars interfacial polarization and electrode polarization. The low-frequency broadening of the a transition is related to constraints imposed by the ionic aggregates. A relaxation in the glassy state was observed for the precursor sulfonic acid polystyrene and ionomers and attributed to the local motion of sulfonated phenyl groups. The relaxation strengths of the β processes of the ionomers were suppressed by interaction with the cations that create physical cross-links, and the relaxation times decreased with increasing strength of the electrostatic interaction of the ion pairs.
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry