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Study on Surface Activity and Bacteriostasis of a Series of Gemini Cationic Surfactants

N, N′-didodecyl-2-hydrxyl-N, N, N′N′-tetramethyl-dichloride has been synthesized with R (CH3)2N (R = CnH2n+1, n = 12, 14, 16), hydrogen chloride and epoxy chloropropane as raw materials. The products have been characterized by element analysis and 1H NMR spectra. Fundamental interfacial behavior of the surfactant at the air/water interface has been investigated by means of surface tension measurements to provide an insight into relationship between the structure of the hydrophobic moiety and the surfactant properties. Foam performance and bacteriostasis in aqueous solution have been investigated. The results indicate that the gemini cationic surfactants have strong surface activity. The surface activity is relevant to the number of carbon atoms in the hydrophobic tail of surfactant molecule. The longer the alkyl chain is, the stronger the surface activity and the lower the critical micelle concentration will be. G12Cl2 solution possesses the best performance of the foaming ability and foam stability at 298.15 K, but bubbly and stability efficiency is the lowest among the three systems. Bacteriostasis of the surfactants has been determined with disk diffusion on filter paper. The results show that all of the newly synthesized double quaternary ammoniums possess quite good bacteriostasis.