Thermally Conductive, Superhydrophobic, and Flexible Composite Membrane of Polyurethane and Boron Nitride Nanosheets by Ultrasonic Assembly for Thermal Management

Thermal management is of significance for modern electronic products, and it remains challenging to keep the cooling performance of thermal management materials in multi-environment applications from being unaffected by external contamination. Herein, we constructed thermally conductive, superhydrophobic, and flexible composites using thermoplastic polyurethane electrospun membrane as a nano-fibrous substrate, hexagonal boron nitride nanosheets as a conducting filler, and polydimethylsiloxane/SiO2 nanoparticles for hydrophobization. The composite membrane demonstrated outstanding thermal management performance with an ultrahigh thermal conductivity (TC) of 7.193 W/m K. The membrane is flexible with durable TC even after 500 bending and stretching cycles and possesses superhydrophobicity with a water contact angle greater than 165° and a slide angle lower than 2.7°, which prevents the surface from being stained and protects its excellent TC for long-term applications, favoring thermal management of modern electronic products.