Study Of A New Gemini Zwitterionic Of Asymmetric Surfactant

Gemini surfactant is a new kind of high effective surfactant which is composedof two ordinary surfactant molecules connected by chemical bond on the hydrophilichead group or nearby. Due to its excellent surface performance, unique morphologyof aggregation and cooperatives with other types of surfactants, it becomes a hot areaof research in recent years.In this paper, a novel heterogemini zwitterionic surfactant containing quaternaryammonium group and sulfonate group was synthesized with long-chain fatty acids,long-chain fatty alcohol, N, N-dimethyl-propanediamine, epichlorohydrin and1,3-propane sulfonic acid lactone through routine organic reaction such asetherification,condensation, quaternization and sulfonation. With orthganol andmono-factor analytical methods, the process technologies of the reactions weresystemically investigated, and the optimum reaction conditions are obtained.70℃,1.0:1.8(mole ratio of fatty alcohol to epichlorohydrin) and5h are foretherification;140℃,1.0:1.2(mole ratio of fatty acid to amine) and10h are forcondensation,50℃, water and alcohol(1:4, v/v) as mixture solvent and4h are forquaternization and60℃,4h, NaH/1,3-propane sulfonic acid lactone/productⅢ was2:2:1for sulfonation. Five products obtained were characterized by IR, ESI-MS andion qualitative analysis, it showed that the structures of the samples synthesized fromthe experiments are identical with the target molecular designed, and theirphysicochemical properties were obtained as below.Critical micelle concentration (c.m.c) of the target products were determined bysurface tension scanning method. As results showed that all the c.m.c of fiveheterogemini surfactants reached down to10-4~10-5, the minimum value of c.m.c andcorresponding γc.m.cwere respectively3.75×10-5mol/L and28.9mN/m.Emulsification properties were measured by watershed time method, and thefoam properties were studied using the Waring-Blender method. The experimentalresults show that, this type of surfactant has less foam than ordinary single-chain surfactants, but the foaming stability is superior to the single one; half-life can reachto380min; furthermore the heterogemini surfactants synthesized have betteremulsifying ability than ordinary single-chain surfactant in high concentrationmineralized water at50oC.