Long-Term Anti-Wetting Superhydrophobic Surface Under High-Temperature Exposure via the Anisotropic Structure

The superhydrophobic surfaces inspired by nature demonstrate potential applications in outdoor facilities shields, advanced energy harvesters, and flexible wearable devices but may fail from harsh working conditions. In this article, we design a fish-scale-like structure with anisotropic heat dissipation, enhanced flame resistance, and long-term anti-wetting performance under high-temperature exposure. The microstructure, anisotropic thermal conductivity (TC), high temperature/long-term superhydrophobicity, and flame-retardant characteristics of the composites were studied. Results show that the silicone rubber (SiR) composites loaded 30 wt% of hexagonal boron nitride (hBN) platelets demonstrate an anisotropic TC ratio of 2.2, with an enhanced parallel TC of 3.387 W/(
$\text{m}\cdot \text{K}$
) and a lower perpendicular TC of 1.532 W/(
$\text{m}\cdot \text{K}$
). The water contact angle of SiR composites loaded with 30 wt% of hBN platelets reached 161° after 20-s flame treatment. Also, the ultrashort flame-treated superhydrophobic surface demonstrates high-temperature and long-term anti-wetting duration for above 300 h at 180°. The prevention of the SiR from flames with a fish-scale-like dense hBN barrier and the instant heat dissipation from flames by parallel hBN network with high TC contributes to the flame-resistant and long-term superhydrophobicity under high-temperature exposure. This study provides a facile and versatile approach for fabricating flame-retardance and superhydrophobic structured composites for applications in electrical equipment, energy harvesters, or the Internet of Things (IoT) sensors under high-temperature working conditions.