Thermal conductivity of multilayer hexagonal boron nitride nanoscrolls

The article presents a theoretical analysis of the anisotropic thermal conductivity of multilayer hexagonal boron nitride (h-BN) nanoscrolls as promising fillers for thermal interfaces in electronic devices. Traditional thermally conductive composite materials, while possessing high thermal conductivity, are prone to agglomeration within the polymer matrix; their chemical inertness hinders the formation of strong bonds with the polymer, and their high electrical conductivity significantly limits their application in electronics. The h-BN-based material combines high thermal conductivity, excellent electrical insulation properties, and high processability for integration into electronic components. An analytical model is proposed to predict the thermal conductivity values of multilayer h-BN nanoscrolls in both the longitudinal and transverse directions. The analytical model for the anisotropic thermal conductivity of multilayer nanoscrolls (scrolled 2D nanoplates) is developed based on the generalized conductivity theory. Key scientific enhancements to existing models include the capability to increase the number of calculable layers and the dimensions of the nanoscrolls. To more accurately describe size effects, an interlayer scattering parameter is introduced for the first time in such a multilayer structure to correct the effective phonon mean free path within the material. Mathematical dependences of the thermal conductivity of multilayer h-BN nanoscrolls on the number of layers were obtained for the directions longitudinal and transverse to the nanoscroll axis. It is shown that as the number of layers increases, the longitudinal thermal conductivity (along the nanoscroll axis) decreases. The transverse thermal conductivity (perpendicular to the nanoscroll axis) is significantly higher than that of their carbon-based counterparts. Due to the absence of quantitative data (both experimental and numerical) for multilayer boron nitride nanoscrolls in available scientific literature, validation of the simulation results was performed on a similar system reported in open sources — a three-layer carbon nanoscroll. The obtained predictive results allow for assessing the influence of the layer count on the thermal conductivity of h-BN nanoscrolls and for synthesizing multilayer nanoscroll structures with a predetermined thermal conductivity value. It is demonstrated that multilayer h-BN nanoscrolls represent a promising alternative to carbon nanotubes in electronics for applications where it is critically important to eliminate “thermal bottlenecks” and ensure high inter-component electrical insulation.