Aggregation-State Tailored Insulation Robustness by Spherulite Size Control in Semicrystalline Poly(vinylidene fluoride) Film

Predicting dielectric failure in semicrystalline polymers, e.g., poly(vinylidene fluoride) (PVDF) under extreme electric fields (>300 MV/m) remains impeded by the disconnection from the spatial structure, which can be attributed to a fundamental schism where reciprocal-space band models fail to capture real-space aggregated states control of carrier dynamics. Herein, this dichotomy is resolved through an aggregation-state framework where crystalline spherulites and amorphous domains deterministically control electronic behavior. To address this, engineered spherulite dimensions directly modulate the entire field-dependent band models of carrier injection, trapping, detrapping, and enabling field-driven intertrap hopping via amorphous free-volume channels. Moreover, space-charge-limited current and thermally stimulated current measurements map carrier trapping to chain-end defects at spherulite edges, while electrical treeing visualization identifies these interfaces as breakdown initiation sites. As a consequence, by correlating band structure modification, and carrier kinetics, this paradigm transforms aggregation states into design variables for high-field insulation robustness in semicrystalline polymers.