Heat-resistant bio-based superhydrophobic coating from lycopodium powder skeletons for liquid food residue reduction

Facing the increasingly serious problems of plastic waste pollution and food waste, edible superhydrophobic coatings have received extensive attention from researchers because of their excellent anti-adhesion performance, which can effectively prevent liquid food from adhering to the inner wall of containers. In this study, we designed a heat-resistant and edible superhydrophobic coating by leveraging the unique and robust hierarchical structure of lycopodium spore powder (LSP) and utilizing natural low surface energy carnauba wax as the binder. The focus was to evaluate the hydrophobicity, heat resistance, and mechanical properties of the coating and to further demonstrate its application on liquid food packaging surfaces. The results confirmed that the lycopodium spore powder-carnauba wax superhydrophobic coating (LCW) exhibited excellent superhydrophobic properties (WCA > 150°, SA < 4°) and excellent self-cleaning function. It also has excellent anti-adhesion properties toward liquid foods with high viscosity and complex composition, such as honey, yogurt, <i>etc.</i> (it only takes 5170 ms and 2930 ms to completely slip on a surface with about 10° tilt, respectively). The incorporation of lycopodium spore powder notably enhanced the thermal stability of the coating, allowing it to retain a contact angle of 150° even after being subjected to high-temperature treatment at 120 °C for 2 hours. We posit that this Lycopodium-coated water-repellent material offers a promising avenue for the efficient production of biodegradable superhydrophobic coatings and holds significant potential for applications in functional food packaging.