Enhancement of intrinsic thermal conductivity of liquid crystalline epoxy through the strategy of interlocked polymer networks

Abstract

To enhance the intrinsic thermal conduction of liquid crystalline epoxy (LCE), a novel strategy based on interlocked polymer networks is proposed. Two cured versions of LCE respectively containing Schiff base bonds and Diels–Alder (DA) bonds are synthesized, and then well mixed in a co-solvent enabling topological reorganization of the single LCE networks via the reversible reactions of the built-in dynamic covalent bonds. The thermal conductivity of the interlocked LCE networks prepared according to the optimal formulation offered by orthogonal design is significantly increased in comparison with the parent single-LCE networks. Besides, although the thermal conductivity of the raw LCE employed in the current work is not that high and the mesogen monomer has the simplest structure, the interlocked networks are able to bring the liquid crystals into full play without changing the chemical structure of the mesogens, as characterized by the very high thermal conductivity per unit weight of liquid crystal. Further investigation of the underlying mechanism suggests that the synergy among the mesogens, the interlocked structure and the inter-component hydrogen bonds accounts for the promotion of heat transmission. Considering the easy access of the relevant chemicals and the simplicity of the materials preparation, the technology developed in the present work may have remarkable potential for future applications.