Synthesis And Surface Activity Of Quaternary Ammonium Gemini Surfactants

Because surfactants play a very important role in industry and agriculture production and daily life, exploring novel surfactants with high surface activity is an important thesis to research werkers.At present, a kind of novel surfactant--oligomeric surfactant which havehigh surface activity have become one of focus on surfactant research. A typical example of them is dimeric or Gemini surfactant. Quaternary ammonium Gemini surfactants exhibit peculiar properties because of its novel molecular structure.In this paper, through a series of experiments, two series of quaternary-ammonium Gemini surfactants were synthesized. Their critical micelle concentration(cmc ) values, the surface tension at their cmc( γ cmc) values , the efficiency of decreasing the surface tension(C2o) and the micelle aggregation number were measured; and the factor affected the results were also discussed. The properties of the system of C12-s-C12 2Br/SDS have been investigated. Meanwhile, the use of C12-s-C12 2Br was discussed in this paper. The main results are as follows:1 Two series of quaternary-ammonium Gemini surfactants have been synthesized with their structures testified. The optimized methods of synthesis were determined by discussing the factors affecting reactions.2 Their critical micelle concentration(cmc ) values, the surface tension at their cmc( γ cmc) values and the efficiency of decreasing the surface tension(C20) of the two series surfactants were measured. Results show that Gemini surfactants have much lower cmc and stronger surface activity comparing with the corresponding common surfactants.3 The excess absorption amount at surface and the area of molecule were discussed. A conclusion can be drawn that the excess absorption amount increases and the area of molecule decreases with the increase of space group carbon number. In the foaming properties of the Gemini surfactants synthesized in this paper, β has shown excellent foaming quality and its foam has the most stable properties.4 The micelle aggregation number were measured by the technique time-resolved fluorescence quenching (TRFQ) and fluorescence polarization. The concentration of quaternary-ammonium Gemini surfactants has greatinfluences on the micelle aggregation number. The micelle aggregation number increases with the length of spacer group decreased; and the micelle aggregation number decreases with the temperature increasing.5 The Mixtures of Gemini surfactants and SDS can lower the surface tension of water solutions more effectively, compared with those of the corresponding common surfactants. Their critical micelle concentration(cmc ) values are more small than those of mixtures of common surfactants.6 Compared with DTAB, C12-3-C12 2Br can promote the rate of the alkali reduction on terylene more efficiently. So it can be used as textile auxiliaries.