Synthesis And Properties Of Gemini Surfactants With Polarity Group

Gemini surfactant has a unquie structure, mainly composed of two hydrophobicchain, two hydrophilic groups, and one spacer chain. The special parts of Geminisurfacant-the spacer chain and two hydrophobic chains-can be changed variedly,which have an important effect on the adsorption and aggregation behavior of Geminisurfacant. The spacer chain can be controled by the structure, length, flexibility orrigidity, hydrophilicity or hydrophobicity, which make Gemini surfactant possesspecial and excellent properties. So the synthesis and properties of Gemini surfactantshave attracted cosiderable attention in chemistry domain.The main work and results in this thesis are as follows:1. Six kinds of carboxylate Gemini surfactants with benzene group and threekinds of quaternary ammonium Gemini Surfactant with hydroxyl group weredesigned and synthesized in this thesis:(1) Carboxylate Gemini surfactants withbenzene group: α-brominated acid ester was prepared by α-bromo reaction that thestarting material is the long chain acid. Then, it was reacted with4,4’-dihydroxybenzophenone or4,4’-sulfonyldiphenol via Williamson synthesis ofether to get the intermediate diacid, which finally reacted with sodium hydroxide toget the final compound (referred to as Cm-Y-Cm).(2) Quaternary ammonium GeminiSurfactant with hydroxyl group: take propanetriol as the starting material, whichreacted with bromine via substitution reaction to get the intermediate1,3-dibromopropan-2-ol, then reacted sperately with N,N-dimethyldodecan-1-amineN,N-dimethyltetradecan-1-amine，and N,N-dim ethyl hexadecan-1-amine to getthe final compound (reffered to as m-3(OH)-m). All the above products areconfirmed by1HNMR, IR and elemental analysis.2. The surface tension of C12-OSO-C12and C12-CO-C12were measured by DuNoüy method.The results showed that all of the three Gemini surfactants have greaterAmin, because they all have a big head group and a long benzene chain, and arrangedclosely in the interface so that they have small cmc. In addition, they all have a verysmall cmc, mainly due to the spacer chain with hydrophilic polar groups. Via electricconductance techniques to determine the cmc of C12-OSO-C12.,The results showedthat cmc determination of this method was significantly higer than the cmc determination of surface tension. Last,via UV method to determine the cmc ofC14-OSO-C14, compared with the cmc of C12-OSO-C12, which determined by thesurface tension technique, is significantly smaller. so, with the increasing length of thehydrophobic chain, which largely contributed to the formation of micelles, showed asmaller cmc value.3. The adsorption properties of m-3(OH)-m at the air/water interface wasinvestigated by surface tention method. Mainly focus on the long hydrophobic alkylchain effect on the surface adsorption properties. The results showed that the cmc ofall reduced with the increasing lenth of the alkyl chain, particular of16-3(OH)-16. thiswas attributed to the significantly hydrophobic effect of the long alkyl chain, therefore,showed high surface activity.