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Disinfecting, nonbleaching compound 1-chloro-2,2,5,5-tetramethyl-4-imidazolidinone (MC) was uniformly coated onto polypropylene melt-blown nonwoven fabrics having basis-weights of 22 and 50 g/m(2) in order to impart antimicrobial properties via a pad-dry technique. The antimicrobial efficacies of the tested fabrics loaded with MC compound were evaluated against bioaerosols of Staphylococcus aureus and Escherichia coli O157:H7 utilizing a colony counting method. It was determined that both types of coated fabrics exhibited superior antimicrobial efficacy upon exposure to aerosol generation for 3 h. The effect of the coating on air permeability was found to be minimal. Samples were stable for a 6 month time period when they were stored in darkness. However, when the fabrics were exposed to fluorescent light, partial chlorine loss was observed. The MC-coated fabrics exhibited great potential for use in protective face masks and air filters to combat airborne pathogens.

A series of new N-halamine epoxide precursors, 3-glycidyl-5,5-dialkylhydantoins (GH's), has been synthesized by a very facile and economic method. Cellulose surfaces can be treated with GH's and rendered biocidal by exposure to halogen solutions after curing the treated material. The biocidal efficacy tests showed that the chlorinated treated cellulose surfaces were antimicrobial with contact times required for 6-7 log reductions of Staphylococcus aureus and Escherichia coli O157:H7 of 5-30 min. It was found in simulated washing tests that celluloses, such as cotton swatches, treated with 3-glycidyl-5,5-dimethylhydantoin were quite stable and could survive more than the equivalent of 50 repeated home launderings with very little loss. Upon loss of the biocidal property due to long-term use, the treated surfaces could be recharged by further exposure to dilute bleach to regain antimicrobial activity. In addition, since only water was used as a solvent for the synthesis of GH's at room temperature, the reaction solution could be directly used as a treatment solution. Stability tests showed that the reaction solutions were relatively stable at room temperature and more stable at 5 °C over a period of at least 30 d. Preliminary experiments have shown that polyester swatches can also be treated with GH's and be rendered biocidal upon treatment with household bleach. The entire process should be economical for commercial application.

Two N-halamine copolymer precursors, poly(2,2,6,6-tetramethyl-4-piperidyl methacrylate-co-acrylic acid potassium salt) and poly(2,2,6,6-tetramethyl-4-piperidyl methacrylate-co-trimethyl-2-methacryloxyethylammonium chloride) have been synthesized and successfully coated onto cotton fabric via a layer-by-layer (LbL) assembly technique. A multilayer thin film was deposited onto the fiber surfaces by alternative exposure to polyelectrolyte solutions. The coating was rendered biocidal by a dilute household bleach treatment. The biocidal efficacies of tested swatches composed of treated fibers were evaluated against Staphylococcus aureus and Escherichia coli. It was determined that chlorinated samples inactivated both S. aureus and E. coli O157:H7 within 15 min of contact time, whereas the unchlorinated control samples did not exhibit significant biocidal activities. Stabilities of the coatings toward washing and ultraviolet light exposure have also been studied. It was found that the stability toward washing was superior, whereas the UVA light stability was moderate compared to previously studied N-halamine moieties. The layer-by-layer assembly technique can be used to attach N-halamine precursor polymers onto cellulose surfaces without using covalently bonding tethering groups which limit the structure designs. In addition, ionic precursors are very soluble in water, thus promising for biocidal coatings without the use of organic solvents.

A new N-halamine copolymer has been prepared, characterized, and evaluated for antimicrobial efficacy, stability toward hydrolyses, and stability toward UVA degradation when covalently bound to cellulose fibers. A copolymer of 3-chloro-2-hydroxypropylmethacrylate and glycidyl methacrylate was coated onto cotton, and, after curing, was treated with an aqueous solution containing the potassium salt of 5,5-dimethylhydantoin to form a coating which became antimicrobial upon exposure to househod bleach (sodium hypochlorite). The coating inactivated S. aureus and E. coli O157:H7 within minutes of contact time and was quite stable toward washing and UVA photodegradation.

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N-halamine silane syntheses and coatings of cotton fabrics as siloxanes were addressed for a series of silanes. The coated fabrics were chlorinated by exposure to dilute sodium hypochlorite with a range of chlorine loadings from 0.20% to 0.26%. Two types of N-Cl moieties were involved in the N-halamine siloxanes, amine and amide. The siloxane-coated cotton swatches were very effective in inactivating Escherichia coli O157:H7 and Staphylococcus aureus, each in 10 min contact time. The N-Cl bond and compound stabilities under UV irradiation and ambient light exposure were also investigated. Both UV and laboratory light stability tests show that most of the chlorine on cotton coated with 3-(3-triethoxysilylpropyl)-7, 7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione could be regenerated after irradiation, while most of the lost chlorine from 5,5-dimethyl-3-(3 0 -triethoxysilylpropyl)hydantoin and 4-[3-triethoxysilylpropoxyl]-2,2,6,6-tetramethylpiperidine could not be recovered upon rechlorination.

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