An investigation of proton conductivity of PVDF based 5-aminotetrazole functional polymer electrolyte membranes (PEMs) prepared via direct surface-initiated AGET ATRP of glycidyl methacrylate (GMA)

Abstract

High performance of PVDF and design feature of glycidyl methacrylate (GMA) were combined in a graft copolymer with a goal of being used in fuel cells. PVDF-g-PGMA was obtained via atom transfer radical polymerization (ATRP) of GMA on a PVDF matrix using a grafting from approach. Specifically, AGET (activators generated by electron transfer) ATRP was employed in the surface grafting, which produced acceptable grafting degrees. Synthesized PVDF-g-PGMA copolymer was modified with 5-aminotetrazole and doped with triflic acid (TA) at different mole ratios with respect to aminotetrazole units, eventually fabricating various PVDF-g-PGMA-ATet-(TA)x membranes. The composition and the structure of polymers were characterized by Energy Dispersive X-ray spectroscopy (EDS), H-1-NMR and FTIR. Their thermal properties were examined by thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA demonstrated that the PVDF-g-PGMA and PVDF-g-PGMA-ATet-(TA)x membranes were thermally stable up to 275 degrees C, 200 degrees C (x=2.0) and 230 degrees C (x=4.0). According to EDS results, 71.35 % functionalization with 5-aminotetrazole was achieved. PVDF-g-PGMA-ATet-(TA)(4) showed a maximum proton conductivity of 0.011 Scm(-1) at 150 degrees C and anhydrous conditions.