Small-angle X-ray scattering from sulphonated polyurethane ionomers based on toluene diisocyanate

A series of sulphonated polyurethane ionomers based on poly(tetramethylene oxide), poly(propylene oxide), and polybutadiene (PTMO, PPO, and PBD) polyols was examined by small-angle X-ray scattering (SAXS). As the polyol molecular weight is increased, the ionic aggregate number density decreases and the aggregate size increases. PPO-based ionomers form smaller and more regularly spaced aggregates than do PTMO- or PBD-based ionomers. The limited data suggest that the aggregate size decreases with increasing valency. For PTMO-based materials neutralized with zinc and cadmium, increasing the temperature increased the fraction of ionic groups dissolved in the polymer matrix, especially for the zinc-neutralized sample. The degree of phase separation for these two samples paralleled the modulus-temperature trend.