Influence of the poly(ethylene oxide)/polybutadiene IPN morphology on the ionic conductivity of ionic liquid

Solid polymer electrolytes (SPEs) were prepared by incorporating either aqueous LiClO4 or 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI) ionic liquid into Poly(ethylene oxide) (PEO)/polybutadiene (PB) Interpenetrating Polymer Networks (IPNs). With a given PEO/PB ratio, either transparent or translucent films depending on the synthesis route of these IPNs, have been investigated. TEM observations confirm that the morphology of these IPN films depends also on the PEO weight proportion whereas mechanical properties measured by DMA are only slightly modified. Measurements of ionic conductivity of SPEs are also very dependent on the IPNs morphology. For instance, EMITFSI ionic conductivity increases over four orders of magnitude from 2.2 × 10−7 to 2.5 × 10−3 S cm−1 at 30 °C.