Cross-Linked High Temperature Polymer Electrolytes

Aiming at the development of robust and durable aromatic polyethers that can be doped with phosphoric acid and still maintain their mechanical integrity at temperatures higher than 200 degrees C, we focused on the optimization of the chemical process for oxadiazole (OXD) cross-linked membranes through cyclodehydration of dihydrazide groups. Aromatic polyethers containing polar pyridine units in the main chain and bearing side carboxylic group have reacted with terephthalic dihydrazide (TDH) resulting initially in a dihydrazide (DHD) containing intermediate cross-linked membrane which resulted in the final OXD- cross-linked material after thermal treatment. The conversion of the dihydrazide to the 1,3,4-oxadiazole bridging groups was monitored with FT IR spectroscopy, in order to optimize the cross-linking conditions, while the obtained DHD and OXD- membranes were studied for their chemical, mechanical and thermal properties pointing out the advantages of the OXD-polymers.