Preparation, Characterization, and Ion Conductivities of the Polymer Electrolytes Based on Poly(ethylene oxide)-g-Poly(ethylene glycol)

The comb-shaped polyethers, poly(ethylene oxide)-g-poly(ethylene glycol)s, (PEO-g-PEGs) were prepared by condensation polymerization of poly(ethylene glycol) (M̅w=400) and 3-chloro-2-chloromethyl-1-propene (CCMP) followed by a graft reaction with poly(ethylene glycol) methylether, and their ionic conduction behavior was investigated. The ionic conductivities of the PEO-g-PEG complexed with LiCF3SO3 were investigated by varing the side chain length of the graft polymers and also the salt concentration. The maximum ion conductivity obtained from the graft polymer-based polymer electrolytes was 4.0×10-5 S cm-1 at 25°C. The shift of the optimum [EO]/[LiCF3SO3] for maximum ion conductivity to a higher value compared to pristine and conventional linear PEO was observed, and it seemed to be due to the enhanced salt solvation imparted by the graft structure of PEO-g-PEG. The crosslinking of PEO-g-PEG by a free radical reaction could provide the improved mechanical property of the polymer electrolytes.