Blends of polybenzimidazole and poly(vinylidene fluoride) for use in a fuel cell

We report a new blend system consisting of an amorphous polymer polybenzimidazole (PBI) and a semicrystalline polymer poly(vinylidene fluoride) (PVDF). A systematic investigation of the blend pair in various compositions using Fourier transform infrared (FT-IR) spectroscopy provides direct evidence of specific hydrogen bonding interaction involving the N-H groups of PBI and the > CF2 groups of PVDF. Blending shows a maximum 30 cm(-1) frequency shift in the N-H stretching band of PBI and also the existence of a partial double bond character in the PVDF chain. Differential scanning calorimetry (DSC) study proves the miscibility of these polymers in a wider composition range. The decrease of the T-g with increasing PVDF in the blend and also the decrease of both the T-m and T-c with increasing PBI in the blend attribute the miscibility of the blend systems. The PA doping level of the blend membranes improves significantly as a result of the hydrophobic nature of the PVDF component.