Preparation of the crosslinked polymer electrolyte membranes based on a hyperbranched poly(amidoamine) and their proton conductivity

A series of novel crosslinked polymer electrolyte membranes were successfully prepared based on the modification of a hyperbranched poly(amidoamine) with terminal vinyl groups. The membranes possessed the different contents of proton-generating sites (i.e., protonated tertiary amine groups) and triflate (Tf2N-) in the crosslinked network. They showed good mechanical and thermal stability. The water uptakes of them were ca. 8.4-24.5%. Their proton conductivity was of the order of ca. 10 -5-10-2 S/cm in the range of 30-80 °C, and the proton conductivity increased with improving the protonation ratio. AFM results disclosed the micro-phase separation of the hydrophilic proton-generating sites and the hydrophobic domains of Tf2N- ions. The resulting locally continuous hydrophilic clusters could provide proton transport channels to produce the high proton conductivity. This kind of polymer electrolyte membranes may have potential applications in PEFCs and other electrochemical fields.