Synthesis Of Quaternary Ammonium Cationic Gemini Surfactants With Hydroxyl In Head Groups And Study Of Its Micellization In Aqueous Solution

With molecules made up of two identical amphiphilic moities, gemini surfactants are covalently connected at the level of the headgroups by a spacer group, which notably inhibits the separation between the polar headgroups within Gemini surfactants when they aggregate and greatly enhances the surface activity at the same time. Compared with conventional surfactants, Gemini surfactant is reputed as a new generation of surfactant not only because of its breakthrought on concept, but also attributes to its unique properties, such as lower krafft point, cmc is generally at least one order of magnitude lower than that of the corresponding conventional surfactants,10-100times more efficient at reducing the surface tension of water and the interfacial tension of the oil-water interface than convetional surfactants, and so on. Therefore, studies on the novel surfactants become hotspots in surface chemistry research.In this paper, tetradecyl alcohol, cetyl alcohol and stearyl alcohol, used as synthon components, are firstly reacted with bromine and red phosphorus, then treated with diethanolamine to obtain tetradecyldiethanol-ammonium bromide, which finally resulted in the corresponding tertiary amine by alkali-treatment. Using1,2-dibromo-ethane(1), epichlorohydrin(2), epichlorohydrin derivatives(3), anti-1,4-dibromo-2-butene(4), a, a’-di-bromo-p-xylene (5) as the linking group, and reacting with tertiary, this paper is trying to develop a new type of quaternary ammonium Gemini surfactant, which is characterized by quaternary ammonium Gemini surfactant in the introduction of the ethyl alcohol.The structure of some intermediates, linking group and Gemini surfactants are identified by FT-IR and1H-NMR.The purity of the synthetic Gemini surfactant G16-4and G16-5are tested by Titration, whose krafft point, conductivity and viscosity of solution are tested as well, and which are compared with one cationic surfactant G31656. The result shows that the krafft point and CMC of G16-4and G16-5are a little higher than G31656. The thermodynamic parameters caculated by conductivity show that the micellization of G16-4, G16-5and G31656are driven by entropy. The G16-4and G16-5’s thickening effect on aqueous solution are better than G31656. That may because hydroxy on the head group associated to form hydrogen bonds between the micelles and increased the interaction between the micelles. The test results show that hydroxyl on the head group can increase the viscosity of aqeous solution of Gemini surfactants.