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 γ and β 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 γ 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 γ′ 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.