Synthesis and characterisation of PVDF-co-HFP/sTiO2 composites polymer electrolyte membranes

Abstract

The Polyvinylidene fluoride (PVDF) can be combined with hexafluoropropilene (HFP) as to manifest a co-polymer called PVDF-co-HFP polymer. The PVDF-co-HFP polymer can be used as a proton exchange membrane due to its excellent mechanical strength, chemical resistance and thermal stability. It is, however, necessarily to modify the PVDF-co-HFP polymer, as an alternative to Nafion polymer membrane, by adding sulphonate groups via sulfonation and inorganic oxides such as TiO2 via oxide mixture. The research aimed to make a fuel cell membrane using PVDF-co-HFP polymer and study the effect of sulfonated TiO2 (sTiO) on the membrane to increase proton conductivity. PVDF-co-HFP membrane was prepared by which adding sTiO2 particles before it was sulfonated using 97% H2SO4. The sulfonation degree value was determined using the titration method while the proton conductivity was determined using the four-line probe. The membranes were characterised using SEM-EDX to see surface morphology and membrane composition, FTIR to confirm the presence of the -SO3H group. The results of SEM show that TiO2 particles are scattered on the surface of the membrane. EDX and FTIR results showed that sulfonation was successful in the presence of S elements by 0.77% and wavelengths 1143.2 and 1208.8 cm-1 by confirming the presence of the S=O group. The PVDF-co-HFP membrane with the addition of 3% sTiO2 particles with a sulphonation time of 6 h at 80 °C gave the best result with a proton conductivity value of 4.3 × 10-3 S cm-1 and a saturation grade of 19.37%. Thus, the PVDF-co-HFP/sTiO2 membrane can be used as a proton exchange membrane in the fuel cell.