Synthesis And Properties Of Carboxylate And Quaternary Ammonium Gemini Surfactant With Amide Group

The Spacer chain in a Gemini surfactant molecule plays an important role in theadsorption and aggregation process of Gemini surfactants. The arrangement atinterface and aggregate morphology of surfactants are also influenced by the chemicalstructure, length, flexibility or rigidity, hydrophilicity or hydrophobicity and linkingposition and so on of the Spacer chains.Three routes have been obtained from the summarization of the syntheticmethods of the Gemini surfactants so far, and carboxylate quaternary ammoniumGemini surfactant with amide group are designed and synthesized. All the targetmolecules are confirmed by1HNMR, IR and elemental analysis.1）For the carboxylate Gemini surfactant (referred to as C12CsC12(cb)), α-brominated tetradecanoic acid was prepared through the Hell-Volhard-Zelinskyreaction by the starting molecule, tetradecanoic acid. Then, it was reacted withalkanediol via Williamson synthesis of ether to gain the intermediatealkoxypolymethylene diacid, which was finally neutralized with sodium hydroxide inethanol to give the final compound C12CsC12(cb), however, some of them have a badwater-solubility such as s=6，8，12.2） For the quaternary ammonium Gemini surfactant with amide group(symbolized as Sn), the Gemini surfactants was prepared by chlorization ofchloroactic acid with thionyl chloride, and subsequently ammonolysis with diamineand finally quaternization with N,N-Dimethyldodecylamine.The properties of quaternary ammonium Gemini surfactant with amide groupwere investigated by surface tension and electric conductance techniques. The resultsshowed that with the increasing length of spacer the volume of the headgroup areaincreased, however, the activity characters cmc，γcmcchanged little compared with thatof the traditional quaternary ammonium Gemini surfactants. These were attributed tothe hydrophilic property of amide group in the headgroup.The properties of the anionic Gemini surfactant abbreviated as C12CsC12(cb)were studied also. The C12CsC12(cb) showed a lower cmc and smaller γcmcand C20,contrast to those of the quaternary ammonium Gemini surfactant (C12CsC12(aq)), exhibiting stronger aggregate ability and higher surfactant activity. The effects of pHin the solution were investigated.