Structure and molecular mobility studies in novel polyurethane ionomers based on poly(ethylene oxide)

Novel polyurethane ionomers based on poly(ethylene oxide) with nonionic har d segments of varying length and flexible segments containing alkali ions ( or protons) have been prepared and their structure-property relationships h ave been investigated. Differential scanning calorimetry (DSC) and small-an gle X-ray scattering (SAXS) were employed for structural investigation, whe reas molecular mobility and ionic conductivity were studied by means of the rmally stimulated depolarization currents (TSDC) techniques and of broadban d (10(-2)-10(9) Hz) dielectric relaxation spectroscopy (DRS). The ionomers are characterized by the coexistence of the segment microphase separation a nd the ionic group segregation morphologies. Crystallization is observed at low hard segment contents (melting at about 305 K), the tendency for cryst allization decreasing upon hard segment extension and decreasing upon neutr alization. Values of ionic conductivity are in the range of 10(-4) S/m at 3 23 K, the conductivity in the amorphous polyurethanes bring governed by the motion of the polymeric chains. (C) 2000 Elsevier Science B.V. All rights reserved.