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

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. (paper)