Fabrication and performance evaluation of hydrophobic flame-retardant coatings on polyester substrates via phytic acid and siloxane

With the increasing demand for safety and practical performance in textiles, the development of polyester fabrics combining flame retardancy and hydrophobic properties has become an inevitable requirement for industry advancement. This study employed an in-situ cross-linking composite process for dual-functional flame-retardant and hydrophobic coatings. A flame-retardant base coating was constructed on polyester surfaces via blending and crosslinking of phytate‑zinc and siloxane-modified waterborne polyurethane. Subsequently, the flame-retardant layer catalyzed the hydrolysis and condensation of hexadecyltrimethoxysilane on the fabric surface, thereby forming a hydrophobic coating and yielding a polyester material with both hydrophobic and flame-retardant properties. The limiting oxygen index of the modified polyester fabric increased from 19.5 % to 27.2 %. It couldn't be ignited in combustion tests and exhibited no melting droplets. In the cone calorimeter test, the peak heat release rate (PHRR), total heat release (THR), and total smoke release (TSP) decreased by 43 %, 37.8 %, and 35.3 %, respectively. Moreover, the modified polyester fabric exhibited a static water contact angle of up to 149.4°, demonstrating self-cleaning ability, abrasion resistance, and washing durability. This work provides a facile and accessible strategy for the preparation of multifunctional textiles.