Spatially dependent polarization of PVDF nanocomposites under the combined influence of an electric field and interfacial interaction

Highly polarized nanoparticles enhance the piezoelectric and mechanical properties of polyvinylidene fluoride (PVDF) by promoting the formation of its electroactive β-phase during electric poling. In this study, the polarization-formation mechanism of PVDF/Al₂O₃ nanocomposites under repeated electric field application was investigated using molecular dynamics simulations. The results revealed that the combined effects of the electric field and interfacial interactions led to spatially dependent polarization characteristics. The electric field induced unidirectional transformations of the PVDF chains, resulting in permanent and spatially independent polarization changes. By contrast, the polarization-locking effect induced by the nanoparticles varied significantly based on the relative positions of the nanoparticles. Thus, the residual polarization level and the associated structural transformations of the PVDF chains were determined by combining the electric field and nanoparticle adsorption. A detailed analysis of the dihedral angle distributions and orientational orders successfully revealed the molecular-level origin of these spatial differences in the polarization characteristics. This study offers methodological guidelines for the rational design of nanocomposites with enhanced performance by controlling synergistic nanoparticle interactions.