Preparation and Investigation of Reinforced PVP Blend Membranes for High Temperature Polymer Electrolyte Membranes

Poly(vinylpyrrolidone) (PVP), as the low-cost and commercial material, exhibits superior phosphoric acid doping capability due to the presence of heterocycle and carbonyl groups in the repeat unit. However, it can't be used as the high temperature polymer electrolyte membrane (HT-PEM) alone because of its significant hydrophilicity and poor mechanical stability. In the present work, polyethersulfone (PES), polysulfone (PSU), polyetherketone-cardo (PEK-c), polyvinylidene fluoride (PVDF) and poly(vinylidene fluoride-co-hexafluoropropylene) (PHFP), five kinds of engineering thermoplastics with excellent mechanical properties and chemical inertness, are chosen to prepare a series of PVP blend membranes by the polymer blending method in order to enhance the dimensional and mechanical stabilities of PVP based membranes. The influence of structures of enhanced polymers on properties of HT-PEMs was investigated systematically. PVP blend membranes with aromatic polymers (i.e. PES, PSU and PEK-c) exhibited decreased volume swellings, increased acid doping contents, superior conductivities and improved mechanical strengths, which determined that they are more suitable for electrolytes of fuel cell applications comparing with PVP/PVDF and PVP/PHFP membranes blended with aliphatic polymers.