Design and Development of a 3D Network Hybrid Polymeric System for Enhanced Dielectric Properties through Selective γ-Crystal Growth of Poly(PVDF-CTFE) and Reduced High-Frequency Relaxation

The selective growth of polar crystals, such as gamma and beta forms, during melt molding of poly(vinylidene fluoride) (PVDF) and its copolymers is expected to provide a wide range of applications. In particular, PVDF materials with gamma crystals exhibit high Curie temperatures and are suitable for use under harsh conditions. In this study, poly(MMA-co-VA) composed of methyl methacrylate, vinylphosphonic acid(VA), silica, and tetrabutylphosphonium chloride (TBPC), was added to poly(vinylidene fluoride-co-chlorotrifluoroethylene) (PVDF-CTFE). This system created melt-formable three-dimensional (3D) networks of poly(methyl methacrylate) and silica in the amorphous regions of PVDF-CTFE. TBPC enhanced the dispersibility of silica nanoparticles, promoting the selective growth of gamma ' crystals in the presence of silica nanoparticles, leading to improved mechanical properties, heat resistance, and dielectric constant. Furthermore, the 3D network suppressed the relaxation of poly(MMA-co-VA) and poly(PVDF-CTFE) and the high-frequency dielectric loss. This method creates melt-formable multifunctional materials with high dielectric constants by using inorganic nanoparticles.