Structure of styrene grafted poly(vinylidene fluoride) membranes investigated by solid-state NMR

The poly(vinylidene fluoride), PVDF, membranes that have been radiation gra fted with polystyrene, PS, producing PVDF-g-PS membranes, are intermediates in the synthesis of PVDF-g-polystyrenesulfonic acid (PSSA) polymer electro lyte membranes. Solid-state NMR measurements were carried out to study the structure of the PVDF-g-PS membranes. The previous investigations by therma l methods and by X-ray scattering showed phase separation of the two polyme ric components. The extent of phase separation and the mobility of the comp onents in the membranes were investigated by NMR relaxation time measuremen ts and by 2-D wide-line separation (WISE) experiments. It was shown that th e amorphous PVDF and PS are phase separated into domains larger than severa l nanometers. The amorphous PVDF component also retained higher mobility th an the PS. Information on the structure of the intermediate product can be used when interpreting the properties of the final polymer electrolyte memb rane.