Bio-based epoxy resin demonstrating high breakdown strength and low dielectric loss via intrinsic molecular charge traps construction

Abstract

In the ultra-high voltage, ultra-high capacity and high frequency energy systems, epoxy-based dielectric materials demonstrating high breakdown strength and low dielectric loss are urgently needed. This work reports a strategy to modulate the charge trap depth in bio-based epoxy dielectric materials by tailoring the local molecular chain structures, ultimately leading to the significant suppression of high-field conductivity and dielectric loss. With the introduction of octa (dimethylsiloxy)octasilsiloxane (POSS) as the intrinsic molecular charge traps, our synthesized epoxy dielectric material exhibits a high breakdown strength of Eb-DC = 81.5 kV/mm, 37 % higher than the traditional bisphenol A epoxy resin (DGEBA), and low dielectric loss of tan δ = 0.0022, 45 % lower than that DGEBA. Furthermore, simulation results give the structure-property relationships, guiding the molecular design. Specifically, the dielectric properties are positively correlated with the LUMO energy difference and charge separation index of the polymer molecular chains. This work provides a promising pathway to enhance the dielectric properties of polymers by building intrinsic molecular charge traps, which is prospective for practical electronics and electrical power systems.