Poly(Vinyl Alcohol)/ N-Methylene Phosphonic Chitosan/ 2-Hydroxyethylammonium Formate (PVA/NMPC/2-HEAF) Membrane for Fuel Cell Application

The cost of conventional membrane, Nafion® used in the current proton exchange membrane fuel cell (PEMFC) is high. Thus different alternatives are being proposed as an option of Nafion® membrane in PEMFC application. In this study, poly(vinyl alcohol)/ N-methylene phosphonic chitosan/ 2-hydroxyethylammonium formate (PVA/NMPC/2-HEAF) proton exchange membrane was prepared using the solution casting technique. The effects of 2-HEAF concentrations (0 – 20 wt.%) on crosslinked and non-crosslinked PVA/NMPC/2-HEAF membrane were studied. The characterizations of PVA/NMPC/2-HEAF membrane were done by Fourier transformation infrared spectroscopy (ATR-FTIR), water uptake test, ion exchange capacity (IEC) analysis and electrochemical impedance spectroscopy (EIS). The crosslinkages (-O-CH2-O-) formed using formaldehyde crosslinking agent were confirmed through the formation of new peak by –CH2- stretching at around 2863 cm-1 and the increased intensity of C-O stretching absorption. Crosslinked PVA/NMPC/5 wt.% 2-HEAF membrane showed the highest percentage of water uptake and IEC value. The EIS result agrees with the water uptake and IEC analysis where crosslinked PVA/NMPC/5 wt.% 2-HEAF showed the highest ionic conductivity of 5.44 × 10-5 S cm-1. This is due to the plasticization effect of 2-HEAF that softened the polymer chains and which it also provided more charge carriers to increase the ion mobility in the membrane.