Phosphorylated pullulan/chitosan biguanide hydrochloride flame retardant for construction of cotton fabric surface: preparation, flame retardancy, antibacterial properties and mechanical properties

Cotton fabrics (CF), as one of the natural cellulose fabrics, are used in clothing and home decoration because of their comfort, softness and degradability. However, cotton fabrics are easy to ignite and have poor antibacterial properties, which limits their application potential in safety-critical fields. In this work, a multi-functional modification strategy for cotton fabrics was proposed: by synthesizing chitosan biguanide hydrochloride (CSG) and phosphate pullulan (P-Pullulan), a flame retardant and antimicrobial functional coating (named CP), was constructed on the surface of cotton fibers using layer-by-layer (LbL) self-assembly technology. Flame retardant properties of modified cotton fabrics (CP-CO-15.5) was significantly improved. Through the vertical combustion test, the char length was only 9 cm, resulting in a self-extinguishing behavior. Compared with those of control, the peak heat release rate (pHRR) and total heat release (THR) of CP-CO-15.5 decreased by 88.6% and 88.8%. In addition, CP-CO-15.5 had an antibacterial effect of more than 99.9% on Escherichia coli and Staphylococcus aureus. The breaking strength and elongation of CP-CO-15.5 was basically not affected, and only slightly decreased compared with the control (CO). In this work, a green and scalable multifunctional cotton fabrics modification method was developed. Furthermore, cotton fabrics with flame retardant and antibacterial properties were successfully prepared.