Sulfonated Fluorocarbon Polymers as Proton Exchange Membranes for Fuel Cells

Abstract

Novel diblock copolymers, based on sulfonated hydrophilic-hydrophobic blocks, were synthesized and investigated for their application as proton exchange membranes. A series of sulfonated poly (1 H, 1 H-Penta uoro n-propyl acrylate)-bpoly(benzenesulfonic acid) copolymers (P(PFPA)-b-P(BSFA)) with various uorinated block lengths were synthesized via the reversible addition-fragmentation chain-transfer (RAFT) process, and the ethyl group on the sulfonic structure underwent hydrolysis in hot water. The copolymers came to tough membranes through solvent casting, the performance and structural property relationships of these materials were studied, the sequence of diblock copolymers was supported by NMR tests, and GPC demonstrated the low PDI values. Proton conductivity measurements revealed that the proton conductivity improved with the increasing ratio of hydrophilic and hydrophobic block lengths, and the proton exchange membranes (PEMs) are bene cial in trans-plane conductivities. The copolymers exhibited higher strain-stress values along with the ability of greater water uptakes than Na on. They also depicted better proton conductivities in liquid water as well as under partially hydrated conditions at 80°C. The new materials are good candidates for use in PEM systems.