Preparation and properties of branched sulfonated poly(arylene ether ketone)/polytetrafluoroethylene composite materials for proton exchange membranes

Abstract

Branched sulfonated poly(arylene ether ketone)s (BSPAEKs) exhibit excellent oxidative stability and solubility, making them suitable for proton exchange membranes (PEMs). However, the mechanical properties of branched membranes cannot fully satisfy the requirements of PEMs. In this work, BSPAEK/polytetrafluoroethylene (PTFE) composite membranes are prepared by casting a BSPAEK solution onto porous PTFE films that contain different concentrations of Triton surfactant to reinforce their mechanical properties. The properties of the composite membranes, including their mechanical properties, proton conductivities, oxidative stabilities, water uptake, thermal stabilities and swelling ratios, are investigated experimentally. The tensile strength of BSPAEK/PTFE-7 (7 wt% Triton as a surfactant) is 26.0 MPa, which is 2.1 times higher than that of a pristine membrane. In addition, the BSPAEK/PTFE composite membranes exhibit excellent dimensional and oxidative stabilities. The BSPAEK/PTFE-5 (5 wt% Triton as a surfactant) composite membrane is tested in a direct methanol fuel cell (DMFC), and it can yield a peak power density of 69.70 mW cm⁻² at 60 °C, which is somewhat comparable to those using Nafion membranes.