Thermal Conducting Thermosets Driven by Molecular Structurally Enhanced Mesogen Interactions

Thermally conductive thermosets are greatly relevant for improving heat dissipation in advanced electronics. Although the thermal conductivities of organic materials, which are largely heat insulators, cannot be readily improved, a liquid crystal moiety can efficiently improve these properties via its self-assembling nature. Here, we report the syntheses of a series of bifunctional liquid crystal epoxy resins (LCERs) containing double mesogenic structures that are connected by aliphatic spacers to enhance their self-assembling properties. Phenyl benzoate derivatives are utilized as mesogens, and the series is chemically well-characterized. Although all the monomers exhibit clear mesomorphic properties in a wide temperature range (115-210 °C), as revealed by differential scanning calorimetry and polarized optical microscopy investigations, a slight difference is observed based on the length of the spacer. Cured LCERs are prepared by hot compression molding utilizing 4,4′-diaminodiphenylmethane, which is a suitable curing agent for the liquid crystal (LC) phases. They exhibit a glass transition temperature (Tg) of μ100 °C with a high decomposition temperature of μ350 °C. Interestingly, owing to the enhanced LC interaction, the maximum thermal conductivity attained is 0.45 W/m·K, which is remarkably high.