The effects of processing method on conductivity and dielectric relaxations in PVDF blended with a zwitterionic copolymer

The conductivity and relaxation dynamics of poly(vinylidene fluoride) (PVDF) blended with a random copolymer of methyl methacrylate and sulfobetaine-2-vinylpyridine (PMMA-r-SB2VP) were investigated. Films were prepared using two processing methods, compression molding and doctor blading from solution. Scanning electron microscopy revealed morphological differences between the films, with the doctor bladed films demonstrating a porous microstructure, while FTIR revealed the presence of different crystallographic phases for the films. Dielectric relaxation in the temperature range from 30 ^oC to 140 ^oC showed several relaxations in compression molded films due to the motion of dipoles in the PVDF crystal phase, segmental relaxations of PMMA, as well as a unique relaxation seen only in the blends. Blends demonstrated higher conductivity then the neat PVDF and copolymer. Doctor bladed films showed a large decrease in the dielectric constant and conductivity as well as different relaxation behavior compared to the compression molded films. These differences suggest that influence of the different processing techniques on the molecular environment plays a significant role on the dielectric properties of these PVDF zwitterionic copolymer blends.