Robust Superhydrophobic Flame‐Retardant Coating on Polyester Fabrics Based on Polyphosphazene Nanospheres

ABSTRACT Developing surface coatings with both superhydrophobic and flame‐retardant properties for polyester (PET) fabrics is crucial yet challenging. A novel, environmentally friendly coating based on polyphosphazene nanospheres (PNSs) was introduced to address this challenge. The PNSs were synthesized via polycondensation of hexachlorocyclotriphosphazene and branched polyethyleneimine, followed by surface modification with stearic acid to enhance hydrophobicity. The modified PNSs are applied to PET fabric through a facile dip‐coating process and co‐cured with a binder and silicone resin. The resultant fabric demonstrates superior superhydrophobicity (water contact angle > 150°) and significant flame retardancy, characterized by a reduced peak heat release rate and inhibited melt dripping. The coating exhibits robust mechanical stability, maintaining its performance after 120 abrasion cycles, 250 tape peel‐off cycles, and 10 washing cycles. Additionally, the treated fabric retains adequate air permeability at optimal coating concentrations. This approach enhances the functionality and safety of polyester textiles, with potential for industrial scale‐up due to its cost‐effectiveness and straightforward preparation process.