Preparation and characterization of proton exchange membranes from polystyrene grafted poly(vinylidene fluoride) powder

Proton exchange membranes(PEMs)were prepared in three steps:grafting of polystyrene onto PVDF powder using pre-irradiation graft polymerization technique,processing the grafted PVDF powder into membranes of around 50-μm thickness,and sulfonating them with cholorosulfonic acid to form poly(vinylidene fluoride)-g-poly(styrene sulfonic acid)membranes.Kinetics of the graft polymerization was studied.The existing of polystyrene side-chains in the grafted PVDF powders,and PSSA groups in PEMs,were proved by FT-IR.Properties of the PEMs,i.e.the ion exchange capacity,water uptake,proton conductivity,thermal property and oxidative stability, were characterized.Dependence of properties on the degree of grafting was investigated,too.