Phytic acid-chitosan/silicone polyurethane composite coating: A versatile strategy for flame-retardant,...

In this study, an assembly technique based on phytic acid-modified chitosan (PA-CS) and silicone-containing waterborne polyurethane (SiWPU) was developed to construct of a multifunctional hemp fabric integrating flame retardancy, hydrophobicity, and antibacterial properties. A stable multilayer structure was constructed via hydrogen bonding interactions between the phosphate groups of PA-CS and the urethane groups (-NHCOO-) of SiWPU. Research shows that PA-CS significantly enhances the fabric's thermal stability and decomposes at high temperatures to form a dense carbon layer, raising the limiting oxygen index (LOI) of the hemp fabric to 35.1%, achieving a UL-94 V-0 rating. Compared with the original fabric, the PHRR, HRC, and THR of the PA-CS/SiWPU coated hemp fabric were reduced by 80.7%, 80.7%, and 65.8%, respectively. Simultaneously, the silicon component in SiWPU migrates to the fabric surface, resulting in a water contact angle of 133.10°, demonstrating excellent hydrophobicity and antifouling performance. Furthermore, the coating exhibits remarkable antibacterial activity against S. aureus and E. coli. Following the coating treatment, the breaking strength of the fabric increased by 41.6% (warp) and 40.7% (weft), while the elongation at break improved by 28.6% (warp) and 27.9% (weft). Concurrently, the bending rigidity decreased from 4.93 cN/mm to 3.20 cN/mm, accompanied by a reduction in both static and dynamic friction factors. After 10 washing cycles, the fabric exhibited breaking strength retention rates of 94.2% (warp) and 89.1% (weft). This study opens a new avenue for the high-value-added and multifunctional utilization of hemp fabrics, demonstrating great application potential in fields including home, biomedical, and smart textiles.