Synthesis Of N-halamine Antimicrobial Agents And Preparation Of Antimicrobial Nanofibers

N-halamine compounds are one of the most important antimicrobial agents due to its effectiveness against a broad spectrum of microorganisms, regenerability and environmentally friendly properties. Electro-spinning is an important technique to prepare continuous nanofibers. The antimicrobial activity of the nanofibers produced by electro-spinning technique will be greatly improved due to the large surface area of nanofibers. However, most antimicrobial nano-fibers containing N-halamine compounds are electro-spun by physically mixing N-halamines and host polymers nowadays. The biocides might release from the nanofibers during wearing and washing since no covalent bonds were formed between boicides and fibers.In this thesis, several types of N-halamine precursor were synthesized, and they were mixtured with PVA or cellulose acetate and spun via electro-spinning. Fibers containing N-halamine precursor were cured to form covalent bonds to avoid the release ofbiocides from the nanofibers. The preparation of antibacterial materials was explored and the surface morphology of the nano-fibers was characterized by SEM. Thermal properties, antibacterial properties and UVA stability were also tested.PVA nanofibers containing3-(2,3-dihydroxypropyl)-5,5-dimethylhydantoin (DH) was first prepared through electro-spinning. In order to form covalent bonds with fibers, PVA was cured with proper temperature after electro-spinning and the optimum curing temperature and curing time was150℃and1min, respectively. The nanostructure of the PVA nanofibers was greatly affected by the high temperature curing.The second type nano-fiber prepared through electro-spinning was cellulose acetate (CA) containing poly[5,5-dimethyl-3-(3’-triethoxysilylpropyl)hydantoin](PBA). N-halamine compound can also be coated onto the fiber with covalent bonds through curing. The optimum curing temperature was only110℃which was much tower than that of PVA and the curing time was40min. The nanostructure of the coated fiber was still affected by the curing process.The third type nano-fiber was CA crosslinked with diphenyl-methane-diisocyanate (MDI) through electro-spinning. The nanofiber didn’t need curing since the covalent bonds have formed before electro-spinning. The nanostructure of the CA crosslink MDI fibers maintained well before and after use.Antibacterial test showed an excellent antimicrobial ability of all chlorinated fibers which can completely inactivated Staphylococcus aureus (Gram-positive) and E. coli O157.H7(Gram-negative) within30min of contact time. All of the three types of chlorinated fibers showed a good thermal stability compared with the pure fibers according to the TG and DSC data. The concentrations of chlorine on the three fibers decreased slowly under UVA light After exposure to UVA light for24hours and exposure to an aqueous solution of sodium hypochlorite, about71-85%of the chlorine on the the fibers was recovered. Cytocompatibility testing demonstrated the good biocompatibility of the chlorinated CA fibers.