1. The Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065, China 2. The Center of Medical Experiment, Zhengzhou University, Zhengzhou 450052, China
Abstract：Nano-fumed silica reacted with γ-chlopropyltrimethoxysilane as a coupling agent, and then by quaternization with N,N-dimethyl-n-tetradecylamine, finally the nano-fumed silica derivative with quaternary ammonium salts was obtained. The nano-fumed silica derivative was investigated by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), and Zeta sizer nano series. The antimicrobial properties of the nano-fumed silica derivative against selected microorganisms were tested by the quantitative suspension method. The results revealed that (1) γ-chlopropyltrimethoxysilane can be bound to the surface of the nano-fumed silica. With increasing the amount of γ-chlopropyltrimethoxysilane, the amount of surface hydroxyl groups of nano-fumed silica decreases. (2) The Zeta potential showed that the isoelectric point of the nano-fumed silica and the modified nano-fumed silica is pH 4.8 and pH 10.5, respectively. The shift of the isoelectric point is due to the quaternary ammonium groups. (3) The obtained nano-fumed silica derivative has significant inhibition effect on the growth of microorganisms，and the bactericidal rates in 15 min for E.coil (8099), S. aureus (ATCC6538) and C. albicans(ATCC10231) were 99.99％, 99.99％ and 94.12％, respectively.
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