Linear and network polymer electrolytes based on low melting prepolymers

Prepolymers E4C3E4 and E3C3E3, where E represents an oxyethylene unit and C -3 the spacer group -O(CH2)(3)O-, were prepared by anionic polymerization o f ethylene oxide using propane-1,3-diol as initiator. Oxymethylene-linking polymerization of the prepolymers gave high molar mass polymers with crysta lline melting points [T-m approximate to -8 degrees C for P(E4C3E4) and -16 degrees C for P(E3C3E3)] and degrees of crystallinity [ca. 25% for P(E4C3E 4) and 1% for P(E3C3E3)] which could be related to the average E-sequence l ength. Inclusion of 2-methylenepropane-1,3-diol in the recipe for oxymethyl ene-linking polymerization gave crosslinkable polymers. Networks were obtai ned by photochemical crosslinking with benzophenone as sensitizer and netwo rk characteristics were determined by mechanical and swelling measurements. Linear and network polymer electrolytes were prepared by inclusion of lith ium perchlorate at concentrations corresponding to O:Li=25 and O:Li=70, and conductivities were determined over the temperature range -20 to +80 degre es C.