Perfluoro-p-xylene as a New Unique Monomer for Highly Stable Arylene Main-Chain Ionomers Applicable to Low-T and High-T Fuel Cell Membranes

Abstract

Abstract:In this study, we present the synthesis and the characterization of novel functionalized arylene main-chain ionomers based on perfluoro-p-xylene (PFX). The polymers were prepared by polycondensation of PFX and 4,4'-dihydroxybiphenyl or bisphenol 2,2-bis(4-hydroxyphenyl)-hexafluoropropane (bisphenol AF). After polymerization, the PFX unit was still able to undergo nucleophilic aromatic substitution reaction, which was used to introduce phosphonic acid groups into the polymer via a reaction with tris(trimethylsilyl)phosphite. Furthermore, electrophilic sulfonation of these polymers was possible in the bisphenol unit when using H2SO4/SO3 as the sulfonation agent. The so-obtained water-soluble PFX-based polyelectrolytes showed excellent chemical stability and were blended with polybenzimidazoles. The blend membranes formed flexible and mechanically robust films with excellent chemical and thermal stabilities.

Synthesis of Highly Sulfonated Poly(arylene ether) Containing Multiphenyl for Proton Exchange Membrane Materials

“…SP1-2.22, SP1-2.80, and P1-2.90 exhibited the proton conductivities of 143, 222, and 228 mS/cm at 80 ∘ C under fully hydrated states, respectively, higher than that of Nafion 117. Compared to other hydrocarbon-based membranes, the proton conductivity of SP1-demonstrated beneficial results; for example, a poly(aryl ether) comprising of fluorine and bisphenol A units showed a conductivity of 100 mS/cm at 80 ∘ C [24]. As mentioned above, proton conductivities of SP1-satisfy the requirement of proton exchange membrane for fuel cell.…”