Properties of PVDF Films Blended with Zwitterionic Copolymers

Poly(vinylidene fluoride), PVDF, is a semicrystalline polymer used as a membrane for filtration and separation applications. Its properties can be enhanced by blending together with zwitterionic co-polymers which alter the hydrophobicity. In this work, we study the structure and electrical properties of PVDF blended with the random copolymer poly(methylmethacrylate-r-sulfobetaine-2-vinylpyridine). Solutions in dimethylacetamide/ acetone are prepared by varying the concentration of the blend components. Doctor-blading is used to make films of uniform thickness for further investigation by wide angle X-ray scattering, calorimetry, scanning electron microscopy, and dielectric relaxation spectroscopy. The crystalline and glassy structure of these films is determined by the manner in which the solvent is removed from the film, either by slow and continuous evaporation of the solvent, or rapid solvent removal by water immersion. These casting methods create different pore size and distribution which affect the structure and dielectric properties of the films.