A two-step method to construct a superhydrophobic, ceramicizable intumescent fire-retardant coating suitable for steel and RPU

As the demand for flame-retardant materials grows, intumescent fire-retardant coatings (IFC) have attracted significant attention due to advantages such as ease of application, minimal impact on substrate properties, and high flame-retardant efficiency. However, conventional IFC exhibit limitations including low char strength and hygroscopic components. To address these issues, this study introduced low-melting-point glass powder (LMGP) as a ceramic-forming filler into IFCs, preparing a ceramicizable IFC (C-IFC) with higher char layer strength. Furthermore, TiO 2 was surface-modified with 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTS) to produce superhydrophobic PFDTS@TiO 2 powder. By combining the aforementioned coating and modified powder through a two-step process, a superhydrophobic ceramicizable IFC (C 20 -IFC/ PFDTS@TiO 2 ) was successfully developed. This coating demonstrated excellent fire-retardant and thermal insulation performance on steel structures and rigid polyurethane foam (RPU).Additionally, the coating surface exhibited exceptional hydrophobicity, with a water contact angle (WCA) of 157.5 ± 0.7° and a water roll-off angle(WRA) of 4 ± 0.3°. This hydrophobic surface gives the coating excellent water resistance. This work provides a universal and efficient solution for developing high-performance, durable fire-retardant protective coatings integrating ‘fire and water non-invasion’ and self-cleaning capabilities.