Modulating cross-linked network structure of epoxy resin blends towards concurrently high intrinsic thermal conductivity and dielectric properties

High thermal conductivity (k) epoxy resin (EP) composites are widely used in electronic devices and power equipment where timely heat dissipation is urgently desirable. However, achieving a balance between high-k values and excellent dielectric properties such as breakdown strength (Eb) is challenging, which subsequently affects their applications in high-voltage fields. Enhancing the intrinsic k of cured EP is the key to addressing this dilemma. Along this line, in this work, a liquid crystal (LC) epoxy (LCE, BE) with biphenyl mesogenic unit was synthesized and introduced into commonly used EP E-51 to currently promote the k and Eb of the blends. The findings demonstrate that the EP blends' k increases with the BE loading due to the formation of multi-scale ordered domains resulting from the self-assembly of biphenyl mesogenic units, which establish the heat-conductive channels for phonon transport. These ordered domains further induce charge traps and efficiently impede the migration of charge carriers. So, the simultaneous enhancement of k and Eb along with low dielectric permittivity and loss are achieved in the E-51/BE blends. Moreover, two curing agents also affect the structure, thermal and dielectric performances of the blends. The prepared BE/E-51 blends with enhanced k and Eb showcase potential applications as thermal management materials in microelectronic devices and electrical power systems.