PARTIAL CRYSTALLIZATION IN LIQUID POLYMER ELECTROLYTES BASED ON COPOLYMERS OF ETHYLENE-OXIDE PROPYLENE-OXIDE

Solutions of lithium perchlorate in a low molecular weight ethylene ox ide/propylene oxide (EO/PO) co-polymer were studied by differential sc anning calorimetry. The pure co-polymer was found to crystallise parti ally, while addition of the salt impaired crystallisation first by slo wing crystal growth then by slowing nucleation. At high salt concentra tions (approximately 1.0 molal) no crystallisation occurred. The solva tion of Li+-ions and the introduction of 'transient cross-linking' bet ween cations and anions effectively suppresses the separation of the p olymer into microregions of EO and PO. The crystallisation phenomena a re relevant to the use of these copolymers as 'model' polymer electrol yte systems.