Study On The Properties And Mechanism Of New Cationic Surfactants In Different Systems

Gemini surfactants consist of two hydrophilic groups and two hydrophobic chains, which are connected with a spacer group. It has been reported that the interfacial properties of a Gemini surfactant in aqueous media can be orders of magnitude greater than those of the comparable conventional surfactant. Gemini surfactants can be used in such versatile products as detergents, cosmetics and flotation collectors, etc.The surfactants having amide have been widely used in cosmetics due to their biodegradability and their skin-compatibility. The Gemini surfactants with amide were synthesized and their properties were investigated in this dissertation, which can be divided into several parts.In the first section, the properties and the study progress of Gemini surfactants were summarized.In the second section, the amide-containing Gemini cationic surfactants and the corresponding Gemini cationic surfactants without amide have been synthesized, the structures of which were characterized by 1H NMR and IR.In the third section, the surface properties of the Gemini cationic surfactants were investigated by means of measuring surface tension. It was interesting that the Gemini surfactants with amide had high critical micelle concentration, high adsorption equilibrium capacity and low micellar aggregation number. This result indicated that the Gemini surfactants were easier to adsorb at air/aqueous interface than to form micellization in the aqueous solutions due to the amides, which easily form the hydrogen bonds.In the fourth section, the dilational properties of the Gemini surfactant were investigated by via oscillation barrier technique. The dilational moduli of the Gemini surfactants were remarkably influenced by the nature of the spacer group. The dilational moduli of the surfactants having long spacer group showed less dependence on the frequency at the air/water interface. The Gemini surfactants with long spacer group had lower dilational moduli than those with short spacer groups.In the fifth section, the wetting behavior of quartz surface in the aqueous solutions of the Gemini surfactants was studied by the sessile drop analysis. The influences of the spacer groups and the surfactant concentration on contact angle, adhesion tension and adhesion work were investigated. The curve of contact angle passed through a maximum with increasing concentration. The behavior of the Gemini surfactants absorbed on the surface of quartz could be divided into three steps. The amide group in the structures did not affect the maximum of the contact angle, but could change the absorption behavior of the Gemini surfactants on the surface of quartz.In the sixth section, host-guest complexations of cucurbiturils with four Gemini cationic surfactants were investigated by means of surface tension, 1H NMR, steadystate fluorescence measurements and isothermal titration calorimetry(ITC) respectively. Gemini surfactant and Q[7] could form host-guest complexations at the rate of 1:2. Amide could change the reaction position between Gemini surfactants and Q[7].In the seventh part, the influence of cucurbiturils on the surface activities of the Gemini surfactants was investigated. The cucurbiturils increased the cmc values of the Gemini surfactants but had no influence on the micellar aggregation number.In the eighth part, the influence of cucurbiturils on the the dilational properties of the Gemini surfactants was studied. The cucurbiturils increased the dilational moduli of the Gemini surfactants.There were fast relaxation process and slow relaxation process for the Gemini surfactants at air/water interface.In the last part, the effect of cucurbiturils on the the wetting properties of the Gemini surfactants was investigated. The cucurbiturils increased the the maximum of contact angles of the Gemini surfactants on the surface of quartz and also changed the adsorption behavior of the Gemini surfactants.