Structure and electrical conductivity in novel polyurethane ionomers

Novel polyurethane (PU) ionomers based on poly(teramethylene oxide) (PTMO) or poly(ethylene oxide) (PEG), with nonionic hard segments of varying lengt h and flexible segments containing sodium ions (Nat), have been prepared an d their structure-property relationships have been investigated. The struct ure and the morphology were studied by means of differential scanning calor imetry (DSC), infrared (IR) spectroscopy and small-angle X-ray scattering ( SAXS). Ionic conductivity was studied by means of broadband dielectric rela xation spectroscopy (DRS, 10(-2)-10(9)Hz). PTMO-based ionomers are characte rized by the coexistence of segment microphase separation and ionic group s egregation morphologies. In the PEG-based ionomers, crystallization is obse rved at low hard segment content, with a tendency for crystallization to de crease upon hard segment extension. Values of ionic conductivity are in the range 10(-7) Sm-1 to 10(-4)Sm(-1) at 323 K for PU ionomers based on PTMO a nd PEG, respectively. (C) 2000 Society of Chemical Industry.