Synthesis and surface activity of biquaternary ammonium salt gemini surfactants with ester bond

The synthesis and surface activity of gemini surfactants with ester bond as spacer are described. Their critical micelle concentrations (CMC) are much lower than that of conventional surfactants, i.e., 1.62×10⁻⁵, 1.38×10⁻⁵, 1.28×10⁻⁵ mol · L⁻¹ for gemini I, II and III respectively. Surface tension at the CMC of gemini I, II and III were 36.4, 38.5, 41.2 mN · m⁻¹. The physico-chemical properties such as Krafft points, foaming abilities and emulsifying power were also investigated. It is found that the title compounds have low Krafft points and show good solubility in water. The gemini surfactants synthesized also exhibit good foaming properties and excellent emulsifying power toward toluene. The foaming abilities and emulsifying power increase with the increase in carbon number of hydrophobic chain, and this might be caused by the sheer viscosity of different gemini surfactant solution. Biography: GAO Zhinong (1961–), male, Professor, Ph. D., research direction: applied chemistry.