Non-dispersive Production Strategy of Binder-Free Boron Nitride Slurry via Differentiation of Exfoliation, Amorphization and Functionalization

Miniaturization and high-power consumption of modern electronic devices have led to local heat generation and accumulation issues, and as a result, demand for thermal dissipation technology has increased recently. Hexagonal boron nitride (BN) is recently highlighted as a material for thermal regulation due to excellent thermal conductivity (750Wm^-1K^-1) with electrical insulation and thermal stability. In spite of the great advantages of superior thermophysical properties, poor interfacial interaction between BN nanosheets often degrades the collective functionality, and conventional approaches inevitably used an additive to compensate for the formability, but this severely diluted the BN’s thermophysical properties. In this study, we report a highly effective non-dispersive binder-free BN slurry production method. The method is totally conversive without loss of materials, immediately applicable, and shows wide morphology variability by virtue of excellent dispersity and rheological characteristics. By adjusting hydrodynamic stress regimes and mechanochemical reaction conditions, we strategically differentiate the functionality of BN nanosheets into a physically exfoliated BN (p-BN) as a thermal conductive component and a mechanochemically treated BN (m-BN) as an interfacial adhesive component. Via finding an optimal ratio of p-BN and m-BN that maximize the thermophysical functionality and mechanical stability, the casted BNs exhibit excellent thermal conductivity (> 40Wm^-1K^-1,) with high adhesion energy over 3.8J/m² without any additive incorporation. Owing to systematically ordered microstructures with rich hydrogen bonding component, the casted BN is well-adhered to the heat exchange unit and successfully reduce working temperatures of the various device modules including high power LED, central processing unit (CPU) and Peltier module. Furthermore, confirmed by high temperature combustion and neutron radiography, the binder-free characteristic with rich boron contents in the casted BN film gives superior flame retardancy (> 900^oC) and thermal neutron absorption (>1.3x10³cm^-1).