Durable Electro-Photothermal Superhydrophobic Coatings Based on Liquid-Like Functionalization of Nanoparticles: Improved Water Repellency and Droplet Rebound

This study reports on durable electro-photo-thermal superhydrophobic (SHS) coatings using nanomaterials functionalized with slippery liquid-like brushes. Hydroxylated multi-walled carbon nanotubes (CNTs) are functionalized with non-reactive linear polydimethylsiloxane (LPDMS) by heating at 200 °C for 24 h, a method previously applied only to inorganic oxides. These are incorporated into an epoxy-silicone hybrid resin and spray-coated onto various substrates. Compared to traditional rigid alkyl-functionalized CNTs, the LPDMS-coated CNTs show superior water repellency, demonstrated by lower contact angle hysteresis (from 4.9° to 3.1°), reduced roll-off angles (from 7.6° to 3.4°), and enhanced rebound behavior of impacting droplets (reduced contact times and increased number of rebounds). The coatings feature multiscale roughness and maintain superhydrophobicity after abrasion, outperforming surface-textured coatings. The approach is compatible with both hydrophobic and hydrophilic resins, indicating broad applicability. While the anti-icing performance is limited due to a temperature-induced wetting transition, this is effectively addressed by electrothermal (up to 129.4 °C under 100 V) or photothermal (99.92% light absorption) surface heating, restoring the coating's superhydrophobicity. This is the first in-depth, systematic comparison of nanocomposite coatings incorporating nanoadditives functionalized with liquid-like PDMS brushes versus rigid alkyl brushes, evaluated in terms of water repellency, droplet rebound, and anti-icing properties.