Reducing the interfacial thermal resistance between liquid crystal epoxy and hexagonal boron nitride: An investigation from molecular dynamics simulations at the atomic level to macroscopic properties

Abstract

To gain a profound understanding of the interfacial heat transport mechanisms in hexagonal boron nitride (h-BN)/liquid crystal epoxy (LCE) composites, the theoretical simulation and experimental validation approaches are combined for clarifying the relationship between interfacial microstructure, interfacial thermal resistance (ITR) and macroscopic thermal conductivities of the h-BN/LCE composites. Molecular dynamics simulations (MD) show that LCE molecules can be closely packed on the h-BN surface to lower the ITR by 21 %∼42 %, in comparation to that of amorphous epoxy. Afterwards, the interfacial interactions between h-BN and LCE, and the interface phase thickness (2.305 nm) are experimentally confirmed. Meantime, the reduced ITR are examined to be 15 ∼ 65 % via laser flash method. The produced h-BN/linear LCE composites containing 95 wt% h-BN platelets exhibit excellent in-plane and through plane thermal conductivities up to 77.01 and 12.67 W m⁻¹ K⁻¹, which exceed 25.8 % and 55.8 % those of the amorphous epoxy composite. It proves that the mesogens adsorbed on h-BN surface provides a straightforward approach to reduce ITR and enhance thermal conductivities of resultant composites. Besides, non-covalent and covalent modifications of h-BN allow to further diminish the ITR and facilitate heat transfer. The outcomes are believed to promote the application of h-BN/LCE composites in thermal management materials.