Phenylboronic acid-decorated ZrP nanosheets for enhancing fire resistance, smoke suppression, and water/acid/alkali tolerance of intumescent coatings

To enhance the integrated properties of intumescent fire-resistant coatings (IFRCs) for structural steel, multifunctional phenylboronic acid-decorated zirconium phosphate (ZrP-M) nanosheets were fabricated in this work. The ZrP-M nanosheets featured superior char-forming capacity, flame-retardant effect and hydrophobicity, which simultaneously enhanced the fire resistance, smoke suppression, thermal stability, and water/acid/alkali tolerance of IFRCs. Compared with the unmodified IFRC, the IFRC with 3 wt% ZrP-M (IFRC-4) showed 74.3%, 74.5% and 41.9% reductions in the peak heat release rate (PHRR), total heat release (THR) and total smoke release (TSR). Meanwhile, the IFRC-4 exhibited significantly improved charring capacity and water tolerance, of which the char yield and water contact angle reached 70.9% and 116.9°. The superior fire retardancy and carbonization ability of IFRC-4 enabled it to outperform previous fire-retardant coatings. The introduction of ZrP-M nanosheets also improved the acid and alkali resistance of IFRC. In a fire, the ZrP-M mainly promoted the formation of highly intumescent and compact chars in the condensed phase, thereby strengthening the fire resistance of IFRC. Thus, this work offers an integrated strategy to prepare fire-resistant, smoke-suppressive, thermally-stable and water/acid/alkali-tolerant coatings via introducing versatile ZrP nanosheets, which are expected to find ubiquitous applications in modern construction.