Enhanced Inverse Piezoelectricity in Flexible PVDF Composites via Mesoporous Silica-Coated BST Core-Shell Submicron fillers

Polyvinylidene fluoride (PVDF)-based piezoelectric materials show strong potential for use in flexible sensors and actuators. However, increasing the proportion of the electroactive β phase and improving interfacial compatibility with inorganic fillers remain major challenges. In this work, an interfacial transition-layer strategy is proposed using mesoporous SiO2 (mSiO2) is used to coat barium strontium titanate submicron particles (BST@mSiO2 SMPs). This alleviates the organic-inorganic interface mismatch and forms a coherent BST-mSiO2-PVDF transition structure. This architecture not only strengthens interfacial adhesion but also facilitates the crystallization of the electroactive β phase. Fourier-transform infrared spectroscopy reveals that at a BST@mSiO2 loading of 0.4 wt%, the composite attains a total β- and γ-phase content of 79%, with the pure β phase contributing 69%. When an external voltage is applied, the composite film exhibits self-excited vibration with a maximum displacement amplitude of 110 μm. These results demonstrate that interfacial transition-layer engineering is an effective approach for developing high-performance PVDF-based piezoelectric composites for flexible electronic devices and smart systems.