Chitosan Modified With N-halamine And Its Application In Antimicrobial Coating Of Cotton Fabrics

Chitosan has gained increasing attentions because of its biodegradability, biocompatibility, safety nontoxicity and antibacterial activity. However, the water solubility and antibacterial property of chitosan is still needed to enhance through chemical modifications. These problems limit the various applications of chitosan in many fields. N-halamine compounds, as a novel kind of antibacterial agent, have been extensively studied with their inherent properties such as excellent antibacterial activity against a broad spectrum of microorganisms and rechargeability. In this study, chitosan was modified with N-halamine and coated onto cotton fabrics using chemistry cross-linking and layer by layer (LBL) technology, respectively.Firstly, the synthesized chitosan derivative, 1-hydroxymethyl-5,5-dimethylhydantoin chitosan, was attached onto cotton fabrics using 1,2,3,4-Butanetetracarboxylic acid (BTCA) as the crosslinking agent. The coated cotton fabrics were measured with SEM and FT-IR. Secondly, to avoid the use of cross-linking agent and improve the tensile strength of cotton swatches, the N-halamine chitosan derivative was further quaternized with glycidyl trimethyl ammonium chloride. It is feasible to use quaternized chitosan derivative positively charged as the cationic polyelectrolyte to treat cotton fabrics by LBL technology. In addition, PAMPAS was used as the anionic polyelectrolyte for LBL coating. The coated cotton fabrics were evaluated with SEM and FT-IR. Thirdly, to improve the water solubility of chitosan derivative, quaternary ammonium salts were grafted onto the amine groups of chitosan which possessed higher reaction activity, and the water solubility were improved. N-halamine was introduced into anionic polyelectrolyte, and they could be coated onto the surface of cotton fabrics using LBL technology. The coated cotton fabrics were characterized with SEM and FT-IR. Washing stability, storage stability and mechanical properties were also measured by standard methods. The antimicrobial efficacies against 5. aureus (ATCC 6538) and E. coli O157:H7 (ATCC 43895) were evaluated according to a modified AATCC 100-2004 Standard Method.Antibacterial test indicated the excellent antimicrobial property of the chlorinated cotton fabrics which can completely inactivated S. aureus (Gram-positive) and E. coli O157:H7 (Gram-negative) within 10 min of contact time. For both of the coated cotton fabrics using LBL technology, the chlorine content could be recharged to above 0.10% after 25 washing cycles by rechlorination, and still could keep the good antimicrobial property; the chlorine content reduced to above 0.10% after one month of storage which also possessed good antimicrobial. The treatment of cotton fabrics by LBL technology only caused a small degree loss of tensile strength and maintained original performance of cotton fabrics.