Efficient and durable cotton fabric surface modification via flame retardant treatment

A halogen-free, highly efficient, and durable flame retardant containing both phosphonate and ammonium phosphonate groups, ammonium salt of diethylenetriamine pentamethylene phosphonate glycol ester (ADTPMPAEG), was synthesized and applied to cotton fabrics by surface grafting modification. Fourier-transform infrared spectroscopy (FT-IR) and energy-dispersive X-ray spectroscopy (EDS) analyses indicated that ADTPMPAEG was grafted onto the surface of cotton fiber by a P–O–C covalent bond. The limiting oxygen index (LOI) of ADTPMPAEG-treated cotton with 18.92% weight gain was 45.1%, and after 50 laundering cycles (LCs), the LOI was 32.7%. Thermogravimetric analysis, conical calorimetry, and vertical combustion measurements revealed that treated cotton possessed outstanding flame retardancy and excellent durability. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results showed that ADTPMPAEG had little influence on the surface morphology and crystal structure of cotton fibers. It was observed that ADTPMPAEG had no obvious effect on the mechanical properties of the cotton fabrics.