Synthesis of antibacterial polymers from 2-dimethylamino ethyl methacrylate quaternized by dimethyl sulfate

An antibacterial quaternary ammonium acrylic monomer (1) was synthesized by quaternization of 2-dimethylamino ethyl methacrylate with dimethyl sulfate. This synthetic route to quaternary ammonium salt monomer proved to be of high yield and lower cost than that used to synthesize alkyl halide. The corresponding homopolymers (2) were then obtained by free radical polymerization using potassium persulfate as the initiator. The chemical structure was characterized by Fourier transform infrared and H-1-nuclear magnetic resonance, and molecular weights (MWs) were compared by the viscosity method. Factors influencing the synthesis of (1) and (2) were also investigated. Antibacterial activity was tested against Escherichia coli and Staphylococcus aureus using a minimum biocidal concentration test and the shaking flask method. Monomer (1) exhibited moderate antibacterial activity; however, the polymers had significantly stronger antibacterial activity than the monomer. Therefore, their potential for antibacterial application was established. Similar to other quaternary ammonium compounds, the antibacterial activity of the polymers depended on their MW, and this dependence varied with the type of testing microorganisms. Polymer Journal (2010) 42, 766-771; doi:10.1038/pj.2010.63; published online 14 July 2010