Constructing epoxy polymer with significantly increased dielectric strength through molecular design by introducing deep trap

Abstract

The demand for epoxy resin (EP) with superior dielectric strength is critical in advanced power equipment. Here, we aimed to construct EP with enhanced dielectric strength via molecular design. Simulations indicated that substituting the CH3 groups in bisphenol A EP with CF3 significantly improved charge transfer, which mostly led to an enhanced trap level and dielectric strength. Guided by simulations, we developed a synthetic pathway to produce fluorinated EP (FEP), which was subsequently validated that the molecular structure of the synthesized polymer aligned with expectations. Compared to traditional bisphenol A EP, a deeper trap was induced by the CF3 group, and the dielectric strength improved from 366.39 to 483.62 kV/mm, representing an increase of over 30%. We elucidated that the substantial enhancement in the breakdown performance of FEP can be attributed to the trapping effect of these traps on charge migration. The increased trap levels effectively inhibit the migration of carriers, thereby reducing both conductivity and carrier mobility, resulting in a higher threshold for discharge initiation. Our research holds significant implications to construct EP polymers tailored for advanced power equipment through strategic molecular design.