Ionic conductivity measurements of a high temperature quaternary copolymer

This film ion containing copolymer, made of lithium-doped 1, 2, 4, 5-benzenetetracarboxylic dianhydride (PMDA), 4-aminophenyl ether (ODA), aminopropyldimethyl terminated polydimethylsiloxane (PSX) and 2,5-diaminobenzene sulfonic acid (DABSA) has been synthesized, cast and characterized by ac impedence analysis. In this copolymer the immoblized anionic groups (SO3− in DABSA provides mobile cation concentration and the motion of flexible PSX chains enhances ionic conduction. A multiple order of magnitude improvement in conductivity has been achieved by this copolymer over pure polyimide (PMDA-ODA). Its dc conductivity was found to reach 10−6 S/cm at 250°C, and is confirmed to be ionic in nature.