Synthesis And Properties Of Quaternary Ammonium Gemini Surfactants

Exploratory work on the self-assembly mechanism and application of surfactantsare important thesis to reseachers. Gemini surfactants were composed of twohydrophilic groups, two hydrophobic groups and one spacer chain. Compared withtraditional surfactants, the hydrophilic head groups, hydrophobic chain structure andthe spacer of Gemini surfactants can be changed variedly. Gemini surfactants haveexcellent properties. Study on synthesis and properties of Gemini surfactants haveattracted cosiderable attention in chemistry domain.The main work and the results in this thsis are as follows:1. A total14kinds of Gemini surfactants were synthesized.(1)12-3(OH)-12,12-4(OH)2-12and12-4(OH)-12were synthesized from propanetriol,1,4-dibromo-2-butene and1,4-dibromo-2-butanol by a series of reactions.(2)12-2-m(m=8,10,14,16),12-6-m (m=8,10,14,16) and12-12-m(m=10，14,16) weresynthesized from tetramethylethylenediamine,1,6-dibromohexane and1,12-dibromododecane by quaternization two times. All of the above products werecharacterized by IR,1HNMR and elemental analysis.2. The interface adsorption at the air/water of the12-3-12and12-3(OH)-12aqueous solution were studdied. The results show that abilities of micelle formation,the capacity and efficeiency of reducing surface tension of water of12-3(OH)-12arebetter than that of12-3-12. The rheological properties of12-3(OH)-12,12-3-12,12-4-12,12-4(OH)-12and12-4(OH)2-12were studied. experimental resultsshow that Gemini surfactants with spacer chain containing hydroxyl can formworm-like micelles in relatively lower concentrations. the increasing number ofhydroxyl, the viscoelasticity of the solution became more obvious, owing to theinteraction of intermolecular hydrogen bonding.3. The interface adsorption at the air/water of Gemini surfactant series (m-6-m)and the corresponding monomers (CmTABr) were studdied. experimental results showthat the surface activity of m-6-m is obviously higher than that of CmTABr. Thethermodynamic calculations results confirmed the existence of the hydrophobic synergism between the alkyl tails of Gemini surfactants. Furthermore, the effect ofdissymmetric structure of gemini surfactants on the micellization and the adsorption isalso discussed and the result shows that the symmetric Gemini surfactants are morefavorable for their association and adsorption in comparison with the dissymmetricGemini surfactants. The micellization and the adsorption of these compounds aremainly driven by the hydrophobic effect of the long alkyl chain, a very smallcontribution of increasing the number of carbon atoms in the short chain to both themicellization and the adsorption. Additionally, the micellization and the adsorption of12-s-m(s=2,12) were investigated. Aggregation competed with absorption, theformation of premicellar aggregation at concentrations below the cmc result in doubleinflection point on the surface tension curve of12-12-m (m=10,14,16), whichreflect the strong interaction between the surfactant molecules.