Coating Boron Nitride Nanosheets with a Perfluoropolyether to Improve Thermal Conductivity

For filled-type thermally conductive composites, the interfacial compatibility between inorganic fillers and the polymer matrix plays a critical role in forming efficient thermal conduction pathways. Boron nitride nanosheets (BNNS), known for their exceptional insulating properties and high thermal conductivity, are considered one of the most promising fillers. However, their strong tendency to agglomerate and poor interfacial compatibility with polymer matrices pose significant challenges for practical applications. In this study, an amphipathic (hydrophilic–hydrophobic) oligomer, perfluoropolyether (PFPE), was employed as a surface modification agent for BNNS (referred to as FBNNS) via noncovalent functionalization. The results demonstrate that PFPE effectively reduces the surface energy of BNNS by introducing sufficient fluorine atoms, thereby enhancing its compatibility with the silicone rubber (SR) matrix. This modification significantly improves BNNS nanoparticle dispersibility within the SR matrix and reduces the interfacial thermal resistance of the BNNS/SR composite from 1.54 × 105 KW–1 to 1.16 × 105 KW–1. As a result, the FBNNS/SR composite achieves a thermal conductivity of 1.97 W/m·K, reflecting a 35% improvement over the unmodified BNNS/SR composite, along with enhanced mechanical properties. This work offers valuable insights for the efficient enhancement of thermal conductivity in thermal interface materials.