| Surfactants are widely used in many yields, and Gemini surfactants have higher surface activity, the researches on Gemini surfactant have recently attracted increasing attention. In this paper, the seven alkylbetaine zwitterionic gemini surfactants (ZS Cn–m–Cn where n represents the hydrocarbon chain length of aliphatic amine, the values of n are 6, 8, 12, 14) were synthesized from cyanuric chloride, aliphatic amine, N,N–dimethylpropane–1,3–diamine and sodium chloroacetate. The chemical structures of the prepared compounds were confirmed by 1H NMR, 13C NMR, ESI–MS and elemental analysis and the surface activity and applied properties were determined.Their critical micelle concentrations (CMC) in the aqueous solutions were determined by surface-tension and steady-state fluorescence methods. The results indicate that the gemini surfactants ZS Cn–m–Cn have a lower cmc, a greater efficiency in lowering the surface tension than those of corresponding conventional N–alkylbetaine (BS-12), the values of CMC andγCMC are 2.9×10-5mol/L and 30.4mN/m respectively and their cmc values are generally one to two orders of magnitude lower than for the corresponding conventional (monomer) surfactants.The wetting ability, emulsification stability and lime soap dispersing power of ZS Cn-m-Cn and BS-12 were measured respectively, ZS C6-2-C6 exhibits better wetting than BS-12, but the others are less than BS-12; the emulsification stability and lime soap dispersing power of ZS Cn-m-Cn are better than BS-12, so ZS Cn-m-Cn is suitable for use as emulsification and dispersant. In additions, ZS Cn-m-Cn has lower Krafft temperature and melting point, so as to ZS Cn-m-Cn have better applications.
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