The Synthesis and Practical Applications of Novel N-Halamine Biocides

Abstract

A novel set of N-halamine siloxane precursors were synthesized for the purpose of coating various substrates to determine the factors, which are the most dominant influences of the overall stability of the newly modified surfaces. Examination of both the coating, as well as the chlorine stability under varying conditions, has been performed. The number and types of bonds to the surface have been examined using several techniques to simulate the most stringent circumstances envisioned for the practical use of the newly modified materials. The siloxane moiety used in the design of these new halamine precursors proved to be extremely versatile demonstrating the capability of attaching to a variety of surfaces under a wide range of conditions. Factors such as solvent and curing temperatures were also evaluated to emphasize the versatility of these coatings and to demonstrate the potential usefulness of these materials as future commercial products. This dissertation will discuss the following specific projects. The first project was the design of a novel N-halamine siloxane precursor, 5,5’-ethylenebis[5-methyl-3-(3-tri-ethoxysilylpropyl)hydantoin], which possessed the capability of forming numerous chemical bonds to a large variety of surfaces such as cellulose. This enabled the coating to be considerably more durable than the previously developed siloxane monomer, 3-triethoxysilylpropyl-5,5-dimethylhydantoin. The second project was to develop a series of more industrially friendly water soluble siloxane copolymers incorporating both N-halamine and quaternary ammonium salt moieties. The copolymers with greater portions of N-halmine moieties proved to provide more efficient log reductions for both Gram-positive and Gram-negative bacteria in much shorter time intervals than in the instances in which the ratios were reversed, respectively. These copolymers showed great potential for commercial applications for which an aqueous media is preferred. Projects three and four both focused on the design of a new series of more stable N-halamine siloxane monomer precursors, 4-[3-triethoxysilylpropoxy]-2,2,6,6-tetramethyl-piperdine, and 4-[3-diethoxymethylsilylpropoxy]-2,2,6,6-tetramethyl-piperdine, which will be referred to as HAM-Sil and HAM-Sil1’, respectively. In project three these new amine siloxane monomers were employed in the treatment of cellulose. The HAM-Sil and HAM-Sil1’-treated fabrics, once chlorinated, demonstrated sufficient bactericidal activities against both Gram-positive and Gram-negative bacteria, as well as increased stability during simulated laundering tests. Project four is the chemical modification of silica gel with both HAM-Sil and HAM-Sil1’ to create an inexpensive antimicrobial filter media which could have various industrial applications