Superhydrophobic, Abrasion-Resistant, Thermally Stable Cardanol-Based UV-Curable Coatings for Self-Cleaning, Oil–Water Separation, and Flame-Retardant/Smoke Suppression Applications

Petroleum-based resins face limitations in superhydrophobic and flame-retardant applications, including high surface energy, poor durability under harsh conditions, low oxygen index, and high heat release. This study employs cardanol, which features a C 15 alkyl chain that confers low surface energy and char formation, along with a phenolic hydroxyl group suitable for graft copolymerization. Two rapidly UV-curable cardanol-based coatings were developed. M-PUA incorporates mesoporous SiO 2 and polydimethylsiloxane into cardanol-based polyurethane acrylate. At 3 wt% loading of mSiO 2 , it achieves water contact angle (WCA) > 151°, maintains WCA above 144° after 100 abrasion cycles, and exceeds 150° after 24 h immersion in pH = 1 or 13. The coating demonstrates efficient self-cleaning and oil/water separation, delivering over 98% separation efficiency across 20 cycles for six different oil/water mixtures, with a maximum flux of 2389.86 L m −2 h −1 . The B-PUA coating constructs a phosphorus-containing network by grafting di(2-(methacryloxy)ethyl) phosphate onto cardanol-Dicyclohexylmethane diisocyanate. It achieves a limiting oxygen index (LOI) of 28 and reduces total heat release by 67.2% and total smoke production by 52.2%. Both coatings exhibit low volatile organic compound emissions and rapid curing, providing an integrated and practical strategy for functionalizing cotton fabrics. These materials show strong potential for self-cleaning, oil/water separation, and flame-retardant applications.