Molecular dynamics simulation reveal the N–Cl/N–H cycling mechanism: Long-lasting and regenerable N-halamine antibacterial cotton fabrics

Cotton, as one of the world’s most crucial economic crops, suffers from a markedly shortened service life of its fabrics due to microbial degradation. In this study, N-isopropylacrylamide (NIPAM) containing amide bonds was grafted onto cotton fibers via atom transfer radical polymerization (ATRP) to develop a heat-resistant and wash-durable N-halamine functionalized cotton fabric (PN@CF-Cl). The resulting material exhibited rapid and potent antibacterial activity, killing over 85 % of bacteria within 1 min of contact and achieving > 99.9 % inactivation of Staphylococcus aureus and Escherichia coli within 10 min. After 50 washing cycles at 75 °C, the antibacterial activity retention remained above 97 %. Following storage for 30 days, rechlorination restored the active chlorine content to its initial level. Even after 10 consecutive chlorination–reduction cycles, the active chlorine recovery reached 98.9 %. In addition, the fabric demonstrated high hydrophobicity, air permeability, and moisture vapor transmission. Molecular dynamics (MD) simulations further validated the dynamic interconversion between N–Cl and N–H in the material, elucidating the underlying mechanism for its regenerative performance. Functionalized cotton fabrics based on the N–Cl/N–H dynamic cycling mechanism can extend product lifespan and hold significant promise for applications in medical protective equipment and smart home textiles. • Precise ATRP creates highly efficient and durable N-halamine antibacterial cotton. • Withstands 50 hot wash cycles at 75 °C and can be renewed through simple chlorination. • Kills 99.9 % of bacteria within 10 min for rapid antibacterial action. • MD simulations show N-Cl and N-H conversion mechanism explaining regeneration.