Preparation and characterization of proton exchange polyvinylidene fluoride membranes incorporated with sulfonated mesoporous carbon/SPEEK nanocomposite

Abstract

Sulfonation of mesoporous carbon CMK-3 (sCMK-3) prepared by nano-casting technique was carried out post synthesis using one-step process. The incorporation of the acid groups was confirmed using XRD, Raman spectroscopy, FTIR, SEM, TEM and BET isotherm. The sCMK-3 was incorporated into sulfonated poly(ether ether ketone) to form a nanocomposite which was introduced into polyvinylidene fluoride matrix to form a proton exchange membrane. The physicochemical characteristics of the nanocomposite incorporated membranes were characterized using FTIR, ionic exchange capacity, water uptake, swelling ratio, mechanical stability and TGA. The nanocomposite incorporated membranes showed greater surface wettability and higher ion-exchange capacity. The presence of the –SO3H acid groups plays a major role in improving the proton conductivity through the Grotthuss-type mechanism. M4 membrane was identified to be a suitable replacement in the DMFC as it had sufficiently high tensile strength (862.2 MPa), high proton conductivity (0.081 S cm−1) at 45 °C and ultra-low methanol permeability (2.17 × 10−8 cm2 s−1). No evident hydrolytic damage could be identified and had sufficiently high thermal stability and hence can be proposed as a suitable alternative for Nafion membranes in high temperature, low humidity DMFC applications.