Fluorine-free and breathable self-cleaning superhydrophobic CS/PDMS/PLA coatings on wearable cotton fabric with light-induced self-sterilization

Developing textiles with self-sterilization and self-cleaning properties for microbial deactivation in the medical sector and high-risk areas is becoming a hot research topic. Compared with traditional methods like chemical, UV irradiation, and heat sterilization for disinfection of microbials, photothermal self-sterilization combined with superhydrophobic self-cleaning has gained considerable attention. In this study, we have developed layered coatings of candle soot/polydimethylsiloxane (CS/PDMS) and polylactic acid (PLA) on cotton fabric to achieve photothermal self-sterilization and superhydrophobic self-cleaning properties. The CS nanoparticles generate heat when exposed to light, facilitating the photothermal effect. Meanwhile, the CS nanoparticles are integrated into the polymer network, creating a hierarchical rough structure that traps air and reduces the water contact area. PDMS is a vital binder for CS nanoparticles on cotton fabric, enhancing the durability of the composite layer and reducing surface energy. The photothermal and superhydrophobic effects of the developed coating successfully demonstrated self-sterilization and self-cleaning capabilities, respectively. The as-prepared coating exhibits high water repellence with a water contact angle of 159 ± 2° and a low sliding angle of 6°. Moreover, the surface temperature of coated cotton fabric rose to 70.2 °C within 60 s under 1 sun solar illumination. Furthermore, the coating demonstrated excellent mechanical stability by maintaining its superhydrophobicity even after 55 sandpaper abrasion cycles, 12 adhesive tape peeling cycles, 140 min of ultrasound and 90 min of washing treatment. Additionally, the coated cotton exhibited excellent flexibility, breathability, air permeability, water vapor transmission, self-sterilization against gram-positive Staphylococcus aureus and gram-negative Pseudomonas aeruginosa bacteria, and self-cleaning against dust contamination. The present results have high potential for developing advanced self-cleaning cotton fabrics with contactless sterilization of microbials for commercial applications.