Synthesis And Performance Of Asymmetric Gemini Alkyl Polyglycosides

With the increasing of the amount of surfactant all over the world and the enhancing awareness of environmental protection, the environmental problems caused by surfactant have attracted people more and more attention. Some surfactants who are difficult to degrade when adsorbing in the soil, will significantly change the physical and chemical properties of the soil. In addition, some surfactants will reduce body’s immune ability, and affect organisms’ nervous system. Therefore, it is imperative to develop some safe and efficient environment friendly surfactants.Green surfactants and their derivatives, which are derived from natural renewable resources, represent the development tendency of the new generation of green surfactants. They not only exhibit good surface activity but also possess good biodegradability and biocompatibility. As a typical representative of the green and mild surfactants, alkyl polyglucoside has been modified by several chemical methods in order to improve their surface properties.In this paper, a novel green surfactant with high surface efficient, namely asymmetric Gemini alkyl polyglycoside(AGAPG), was formed by bonding a Gemini structure to a synthetic biomass surfactant alkyl polyglycoside(APG). The surface properties of the resulted samples were characterized and compared with symmetric Gemini alkyl polyglycosides(SGAPG). Subsequently, the surface properties of AGAPG and that of the compound system composed by AGAPG and commercial surfactant were also studied in detail.The conclusions are as follows:(1) In the synthesizing process for a series of AGAPG, the optimal conditions for getting intermediate 2, namely glycosidic base tertiary amine is n(diethylamine): n(chlorinated alkyl glycoside)=1.25 at 50℃ for 8h, and the yield is 57.7%. Meanwhile, the optimum synthesis process of a series of AGAPG is n(intermediate 1): n(intermediate 2) =1.4, wherein the intermediate 1 is N, N-dimethyl-(3-chloro-2-hydroxypropyl)-dodecyl/tetradecyl/hexadecyl ammonium chloride. And the yield of C12-、C14-、C16-AGAPG is 52.4%, 50.1%, and 49.7% respectively.(2) Critical micelle concentration(CMC) of the series of AGAPG is near 0.025g/mL. The surface tension of C12-、C14-、C16-AGAPG is 22.8mN/m, 23.0mN/m, and 23.2mN/m respectively. Their corresponding HLB value range varies from 10 to 13, indicated that they are of good hydrophilicity. If AGAPG is used as detergent, it only produces little amount of foam, and the foam is stability. That means it is applicable to low foam operation. Though its wetting performance is not outstanding, AGAPG shows excellent emulsifying properties. Compared with commercially available detergent Diaopai, the detergency of resulted sample is relatively weak, but better than that of the raw material APG. Its Kraft point is below 0℃. Moreover, it can maintain high surface activity when pH ranges from 3.470 to 12.521, which shows a wide range of applications.(3) The combination of a series of AGAPG surfactants and commercial anionic surfactant(LAS), cationic surfactant(CTAB) and nonionic surfactant(Tween 80) can bring about strong synergistic effect on foaming, emulsifying and wetting properties. The surface tension of compound solution system was further reduced compared to single sample solution. While the foaming, emulsifying and wetting property of compound solution system are improved, reflecting a good application prospect.(4) Compared with the raw material alkyl polyglycoside, symmetric and asymmetric Gemini alkyl polyglycoside can form larger vesicles at lower concentration(0.025g/mL), showing the high performance of Gemini structure once again.