Synthesis and antibacterial activity of Schiff base-pyridine quaternary ammonium salt-halamine compounds on cotton fabrics

The incorporation of a single antimicrobial agent on textiles has been proven to be effective to enhance the antibacterial efficacy against single bacteria family. However, the daily usage of textile products face challenges from multiple microbes, i.e., bacterial, fungal, or/and viral, which threaten human's safety and health. A "combination" of antimicrobial agents could be efficient and accessible to against several microbes at one time. In this study, a Schiff base-pyridinium quaternary ammonium salt-halamine precursor compound (E)-3-(((2,4-dioxoimidazolidin-1-yl)imino)methyl)pyridin-1-ium (4-DMPY) was synthesized and grafted onto MPTES-treated cotton fabric by thiol-ene click chemistry. The results of NRM, FTIR, Raman, EDX, XPS and SEM tests showed that 4-DMPY was synthesized and grafted onto cotton fabrics. The antibacterial test results showed that 4-DMPY had antibacterial activity against both Staphylococcus aureus and Escherichia coli. The antibacterial activity of 4-DMPY-finished cotton fabric was significantly enhanced after chlorination treatment, which could kill 98% of S. aureus and 98.9% of E. coli at a concentration of 5 g/L, confirming the enhanced synergistic effect between 4-DMPY and N-chloramine. The antimicrobial substance on the cotton fabric is non-soluble, which kills 98.4% E. coli and 98.3% S. aureus within 1 min by a direct contact. In addition, the produced fabric retained 81% and 63% of active chlorine content after 30 washes and 30 days of storage, indicating a good antimicrobial durability. Herein, we anticipate the technology can be used to enhance antibacterial function of cellulose products and thus resist the potential threats from microbes to ensure human's health.