Synthesis of a phosphorylated bio-derivative for multifunctional polyamide 6 via a self-polymerization strategy

A highly efficient and reactive flame retardant (FR) agent was developed and in situ self-polymerized on polyamide 6 (PA6) fabrics, yielding a durable and multifunctional textile. The FR agent, designated DOPO-pCA, was synthesized using bio-based p-coumaric acid and DOPO. The treated PA6 exhibited outstanding flame retardancy and anti-dripping performance, with a limiting oxygen index of 31.0% and a reduced damaged length of 12.3 cm. Cone calorimetry confirmed significant fire-safety improvements, with the peak heat release rate and total heat release reduced by 30.7% and 23.8%, respectively. The superior fire resistance should be attributed to the enhanced quenching effect of phenoxy and phosphoroxy radicals. Owing to its self-polymerization and reactivity, DOPO-pCA imparted durable FR functionality, with only slight deterioration observed after 30 laundering cycles. Moreover, the treated PA6 fabrics exhibited excellent resistance to UV resistance and antibacterial activity against S. aureus. The PA6 fabrics treated with 40 g/L DOPO-pCA achieved a high UV protection factor (UPF) of 52.4 and an antibacterial rate of 92.3%. Here, this work proposes a cleaner and novel strategy for developing durable and multifunctional PA6 fabrics.