Polyimide-polysiloxane-segmented copolymers as high-temperature polymer electrolytes

Based on the fact that the flexibility of the polymer backbone will affect the ion transport and sometimes enhance the ionic conductivity, copolymer electrolytes of 1,2,4,5-benzene-tetracarboxylic dianhydride (PMDA), 4-aminophenyl ether (ODA), and aminopropyldimethyl-terminated polydimethylsiloxane (PSX), with or without doping of lithium triflate, have been prepared and investigated by infrared spectroscopy and electrical conductivity measurements. The PSX was found to be incorporated into PMDA-ODA polyimide to form block copolymers, and the best conductivity (10^-7 s/cm at 300°C) is observed in the lithium triflate-doped PMDA-ODA-PSX copolymer with a composition of 4PMDA: 3DA: 0.6PSX: 2LiCF₃SO₃. This conductivity is about 100 times better than the result of the lithium-doped PMDA, ODA, and 2,5-diaminobenzene sulfonic acid (DABSA) copolymer (4PMDA: 3DA:1DABSA:1LiCF₃SO₃) recently reported by this group. © 1994 John Wiley & Sons, Inc.