Multifunctional antimicrobial and flame retardant cotton fabrics modified with a novel N,N-di(ethyl phosphate) biguanide

A multi-functional antimicrobial and flame retardant, N,N-di (ethyl phosphate) biguanide (DPG) was synthesized for cotton fabrics. The Fourier transform infrared spectroscopy showed that DPG was successfully grafted onto the cotton fabrics by generating covalent bonds (P–O–C). The cotton fabrics treated with 250 g/L DPG obtained the limiting oxygen index value (LOI) of 31.2%, and the antibacterial radios of Staphylococcus aureus ( S. aureus ) and Escherichia coli ( E. coli ) were 96.4% and 99.2%. After 20 times laundering cycles, the antimicrobial radio remained at 96.0%, and the LOI still had a value of 26.1%. These results proved that DPG not only had excellent antibacterial property and flame retardancy, but also had excellent durability. Scanning electron microscopy showed that the surface morphology of residues remained intact. Energy dispersive spectroscopy showed that the DPG had infiltrated into the inner space of the fibers. Thermogravimetry exhibited the thermal degradation properties of samples and the results showed DPG played a great role on lessening the degradation of cotton fabrics. The combustion properties of the cotton fabrics were assessed by cone calorimetry and the curves demonstrated that the cotton fabrics treated with DPG had lower total heat release, heat release rate and effective heat combustion compared with the control fabrics. The time to ignition showed DPG treated cotton fabrics didn’t burn easily. These results confirmed that DPG was a durable and effective antimicrobial and flame retardant for cotton fabrics, and the tensile of treated cotton fabrics reduced slightly. Graphical Abstract