Preparation and performance study of thermally conductive coatings with mixed fillers

The increasing demand for effective thermal management has led to a growing need for composite coatings with high thermal conductivity (TC). In this work, we developed a novel approach to enhance the TC of polymer coatings by incorporating hybrid fillers composed of hexagonal boron nitride (h-BN) and graphitic carbon (GC). The process involved the creation of hybrid fibers through wet spinning, combining biomass polysaccharide sodium alginate with bulk h-BN, followed by controlled carbonization at varying temperatures. During carbonization, the in-situ generation of small-molecule compounds facilitated the preparation of BN nanosheets and the formation of a unique BN and graphitic carbon (BN-GC) preassembled  heterostructure. By adjusting the carbonization temperature, the degree of graphitization was controlled in the hybrid fillers. Subsequently, these hybrid fillers were blended with a polymer matrix to create photocurable coatings. Leveraging the intrinsic high thermal conductivity of BN nanosheets and the low interfacial thermal resistance between BN and GC, our composite coatings demonstrated a remarkable enhancement in TC. Notably, with a filler content of 20 wt%, the resulting composite coating exhibited an impressive in-plane and out-of-plane TC of up to 2.34 and 0.41 W/(m K), respectively. This innovative approach holds significant promise for improving the thermal performance of polymer coatings in various applications.