Thermal Conductivity in Side-Chain Liquid-Crystal Epoxy Polymers: Influence of Mesogen Structure.

Abstract

Side-chain liquid-crystal epoxy polymers (SCLCEPs) are valued for their unique properties, which combine LC side chains with epoxide-based polyether main chains for ordered molecular arrangements. They have high thermal conductivity and optical properties due to their low polydispersity and high crystallinity. Achieving optimal thermal conductivity in SCLCEPs involves addressing factors such as mesogen nature, polymer design, and alignment within the polymer structure. Balancing these factors enhances their suitability for heat dissipation in advanced materials. In this study, SCLCEPs with a polyethylene glycol backbone and laterally arranged mesogens are synthesized via anionic ring opening of mesogenic epoxides with unique LC phases. These monomers, which feature biphenyl mesogens attached to glycidyloxy ether and different alkyl chain lengths on the other side, is designed to facilitate mesogen self-assembly and interaction. The resulting polymers exhibited higher crystallinity and LC phases than the monomers. Notably, because of their LC nature, their thermal conductivity exceeds 0.48 W·m^-1 K^-1 and increases with shortened alkyl chain lengths, reaching 0.57 W·m^-1 K^-1. This research expands the applications of SCLCEPs in advanced fields requiring enhanced thermal properties.