The present invention provides a multi-layer polymeric film comprising a core layer; a first skin layer; and at least one intermediate layer between the core layer and the first skin layer; wherein the at least one intermediate layer comprises a cavitating agent such that it is cavitated; and wherein the first skin layer side of the film exhibits a roughness level (Rz) of greater than 2 m, measured in accordance with ISO 4287.

A method includes forming a polymer solution having a crystallizable PVDF-family polymer and a liquid solvent, forming a gel from the polymer solution, forming a polymer thin film from the gel by calendering or solid state extrusion, stretching the polymer thin film, and applying an electric field to the polymer thin film to form a poled polymer thin film, where an electromechanical coupling factor (k.sub.31) of the poled polymer thin film is at least approximately 0.1. The polymer thin film may include up to approximately 90 wt. % of an additive and may be characterized by a bimodal molecular weight distribution of a crystallizable polymer where the molecular weight of the additive is less than the molecular weight of the crystallizable polymer. In some examples, the polymer(s) and the additive(s) may be independently selected from vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, hexafluoropropene, vinyl fluoride, etc.

A toothbrush filament preparation method, a prepared toothbrush filament, and a toothbrush. The toothbrush filament preparation method comprises: melting and extruding a piezoelectric polymer, and executing a corona polarization step and an annealing step, such that the piezoelectric constant of a toothbrush filament in a standing state is greater than or equal to 0.4 pC/N, and some polarization charges stably exist on the surface of the toothbrush filament. The problem of bacteria breeding on a toothbrush filament in a standing state can be effectively relieved by utilizing the action principle of physical electrical stimulation for an antibacterial purpose, thereby improving the antibacterial properties of the toothbrush filament.