Fabrication and properties of modified PVDF dielectric films with high ductility

Dielectric polymeric thin films are widely used in electronics, energy storage equipment, and biotechnologies owing to their merits of low cost, light weight, ease of transportation, and ease of processing. Among them, PVDF films have an increasingly wide range of applications in energy generation, storage, transfer and monitoring due to their flexibility, high electroactive response and non-toxicity. In this study, modified PVDF films were produced by doctor-blading PVDF solutions containing additives of amphiphilic copolymers, which have both hydrophobic polyoxypropylene chain segments and hydrophilic polyoxyethylene chain segments. Compared to pure PVDF, the modified PVDF films have substantially increased ductility while maintaining a higher dielectric constant and breakdown strength enhancement. For example, a 11.5-μm-thick modified PVDF film with 3 wt.% amphiphilic copolymers could be extended up to 495% before break (6.24 μm in thickness after break), which is over 40 folds of the extensionality of pure PVDF film (~12%). At the same time, its breakdown strength is improved by 73 kV/mm. This method provides a strategy to make easy-to-process highly ductile dielectric thin films.