Preparation and Antibacterial Activity of Copolymer of Methacryloxyethyldimethyl Dodecyl Ammonium Bromide/Acrylamide

Copolymers PMDAB-co-AA with excellent antibacterial activity were designed and prepared (MDAB/AA=methacryloxyethyldimethyl dodecyl ammonium bromide with acrylamide). The chemical structures of the copolymers were characterized by Fourier transform infrared(FTIR), ¹H NMR, ¹³C NMR and chemical titration. The antimicrobial activities and kinetics of the copolymer against E. coli and S. aureus were examined by viable cell counting method. The compositions of the copolymers could be easily controlled by the feed molar ratio of MDAB to AA. Furthermore, the highest antibacterial activity was achieved when the molar fraction of MDAB was in a range of 5%-20%, and the killing rate reached 100% under the test conditions. In addition, the antibacterial activity of PMDAB-co-AA was maintained and stable without any loss after 15 times of repeated usage. It was proved that the PMDAB-co-AA samples targeted at cell membrane, and caused serious damage to cell integrity and inner membrane permeation. The surrounding conditions, such as pH and inorgainc salts concentrations(CaCl₂ or NaCl), also affected their antibacterial activities.