A biomass-based "double-encapsulation structure" heightens the flame retardancy, antimicrobial effectiveness, and hydrophobicity of cotton fabric.

Due to the non-renewable nature of petroleum resources, there has been a notable shift toward utilizing biomass materials to confer flame retardant properties to cotton fabrics. However, endow solely with single function cannot meet the application requirements across various fields. Therefore, there is considerable impetus to develop multifunctional cotton fabrics integrating flame retardant, antimicrobial, and hydrophobic properties sourced from biomass. In this research, a flame retardant antimicrobial agent (β-TPDM-P) incorporating an N-halamine antimicrobial precursor was synthesized by modifying β-cyclodextrin (β-CD). Furthermore, β-CD's encapsulation capability was utilized to encapsulate calcium pyrophosphate particles. Subsequently, cotton fabrics underwent treatment through a conventional dip-dry-cure process, followed by chlorination and aminosilicone oil (ASO) spraying, resulting in multifunctional cotton fabrics that are flame-retardant, antimicrobial, and hydrophobic. Benefiting from double protection of the gas phase and the condensed phase, the LOI for the treated cotton fabrics reached 37.6 %. Moreover, the fabrics displayed self-extinguishing behavior in the vertical flame test. With reductions of 75.8 % in peak heat release rate (pHRR) and 42.9 % in total heat release (THR). Leveraging the potent antimicrobial properties of N-halamine, the multifunctional fabrics exhibited inhibition rates of 98.7 % and 99.9 % against E. coli and S. aureus. Introducing a low surface energy surface endowed the fabrics with high repellency to liquids, as evidenced by a water contact angle of 129°. Importantly, these enhancements were achieved without significantly altering the physical properties of the cotton fabrics. This study introduces a feasible strategy for realizing the multifunctionalization of cotton fabrics, thereby broadening their potential applications in various fields.