Synthesis And Properties Of Novel Gemini Imidazolium Surfactants

In this dissertation, two series of Gemini imdazolium surfactant with imidazole, 1-Bromoalkane,2,2’-dichlorodiethyl ether and 1,2-Bis (chloroacetoxy) ethane as raw materials are synthesized under solvent-free conditions. Molecular structures of objective products are characterized by FT-IR,1HNMR and thermogravimetric analysis.Surface activity of Gemini imdazolium surfactants are investigated using surface tension. The results show that the critical micelle concentration(cmc) decreases with the increasing carbon atoms of hydrophobic groups, however the area per molecule(Amin) and the efficiency of adsorption of surfactant(PC20) increase. Two series of A and B own high surface activities and tendency to form aggregates. The cmc of former are roughly one orders of magnitude lower than the latter. It demonstrates the better interfacial activity than corresponding single surfactant. The surface tension of a solutions still decreases when concentrations of series A exceed the cmc, which is an unusual behavior.Degree of counterion binding to micelles(β) and thermodynamic properties of micellization of Gemini imdazolium surfactants are determined by the conductivity measurements. It is found that the cmc values obtained by the conductivity method are slightly different from those obtained by the surface tension method. As the temperature increase, the conductivity and the cmc values increase with the same long hydrophobic chains. At the same temperature, the value of β decreases with the increasing of hydrophobic chain length. Combining the related thermodynamics formula. It can be obtained these thermogravimetric parameters ΔGm(?) s ΔHm(?) and ΔSm(?). It is found that ΔGm(?) and ΔHm(?) are all negative, indicating that the formation of micelles is spontaneous and exothermic. The value of ΔGm(?) of series A is smaller than that of series B, which suggests that the micelle formation of series A is more feasible.The foaming and emulsification of the two series are investigated, which indicates that the emulsifying of the two series increase with the increasing of hydrophobic chains length. There was an initial increase and then an decrease in the foam volume and half foam life period with the increase of hydrophobic alkyl tail. As the concentration increase, there was an initial increase and then an decrease in the foam volume and half foam life period. Because of the difference of spacer length and hydrophilicity, the foaming power and emulsifying capacity of series A are better than series B and the foam stability of series B is better than series A.Thermal properties of the series A and B are studied with thermogravimetric analysis(TGA) and differential scanning calorimetry(DSC). The decomposition temperature(Tstart) of two series increases with the increasing of hydrocarbon chain length and the order of them is A>B.