Benzene ring structural design strategy toward well-balanced thermal and electrical properties in epoxy dielectric polymers

The increasing demand for high power density and compact size devices in modern electrical and electronic systems requires polymer materials with excellent high-temperature electrical properties. However, electrical properties and thermal stability are often mutually exclusive in current polymer dielectric materials. Here, we report a strategy to achieve a well balance between thermal and dielectric properties by tailoring the molecular structure of epoxy resin (EP) curing agents. With the rigid benzene ring providing high thermal stability, the carrier density is controlled by modulating the non-localized electron density through substitution with strong electron-withdrawing groups and aliphatic structures, while the intermolecular charge conjugation transport is blocked by altering the conformation between molecular chains through grafting of side chain groups. By synergistically combining the two strategies within the same curing agent, the resultant polymer exhibits a volume resistance of 3.76 × 10¹³ Ω m and a direct current breakdown strength of 243.23 kV mm⁻¹ at 120 °C. It also demonstrates potential applications in DC transmission systems and power electronics packaging, providing a new direction for the development of next-generation insulating polymers for harsh environments.