High toughness, flexible and thermally conductive fluorine rubber composite films reinforced by hexagonal boron nitride flakes for thermal management

The rapid advancement of electronic information technology has generated a substantial demand for polymer-based thermal management materials. In order to address the challenges of heat dissipation and avoid signal interference, it is essential to develop polymer-based thermal management materials with both high thermal conductivity and low dielectric properties. Herein, hexagonal boron nitride flakes (h-BNFs) with a high aspect ratio and some hydroxyl groups were prepared using the high pressure homogenization technique. Subsequently, h-BNF/fluorine rubber (h-BNF/FKM) composite films were fabricated through a simple and scalable blade coating method. During the blade coating process, most of the h-BNFs can align with their (002) crystal planes paralleling to the horizontal direction. In addition, the rest of the h-BNFs will randomly distribute and overlap with each other, combining with the horizontally aligned h-BNFs to form a distinctive three-dimensional packing network. This unique network structure enables the h-BNF/FKM composite films to have thermal conductivities of up to 0.44 W/(m·K). Moreover, the introduction of h-BNFs can effectively reduce the dielectric constants and dielectric losses of FKM films. More importantly, the h-BNF/FKM composite films also exhibit outstanding mechanical toughness, excellent flexibility, good adhesion and improved flame-retardancy, providing promising applications in the electronic device thermal management.