Structure And Physicochemical Properties Of W / O Microemulsion System Constructed By Imidazole Gemini Surfactant

The thesis contains four parts. Chapter I. Introduction. Chapter II. Comparison of the phase behavior of W/O microemulsion systems containing Gemini surfactant with those containing traditional surfactant hexadecyl trimethyl ammonium bromide or imidazoliums ionic liquid type surfactant. Chapter III. Phase behavior of W/O microemulsion containing Imidazoliums Ionic Liquid type and Gemini surfactant respectively. Chapter IV. The effect of temperature and oil on the thermodynamic and structural parameters of W/O microemulsion systems stabilized by Gemini imidazoliums surfactant.Chapter I. IntroductionThe composition, structure and research progress of phase behavior of microemulsion systems were introduced. The effects of surfactants, cosurfactants and temperatures on the phase behavior were particularly discussed.Chapter II. Comparison of the phase behavior of W/O microemulsion systems containing Gemini surfactant with those containing traditional surfactant hexadecyl trimethyl ammonium bromide or imidazoliums ionic liquid type surfactant.The thermodynamic and structural parameters of W/O microemulsion systems16-4-16(C16mimBr, CTAB)/alcohol (amine)/octane/5%NaCl solution (wo=20) are studied and compared.(1) Both the mole fraction of the alcohol in the interfacial layer Xia, and the mole fraction of the alcohol in the oil phase Xoa decrease in magnitude in the order:16-4-16> CTAB> C16mimBr for the microemulsions containing aliphatic alcohol or aliphatic amine as cosurfactant.The standard Gibbs free energy change of transferring alcohol from the continuous oil phase to the interfacial layer (-â–³Gooâ†'i) decreases in magnitude in the order:16-4-16> CTAB> C16mimBr for the microemulsions containing aliphatic alcohol, whereas (?) for the microemulsions containing aliphatic amine changes in the reverse order.Furthermore, compared with the microemulsion systems containing CTAB or Ci6mimBr, Rw values of the microemulsion systemscontaining16-4-16were much smaller.(2) As the carbon chain length of the cosurfactant (alcohol or amine) increases, both Xoa and Xia values would decrease, whereas (/) and Rw would increase for all microemulsion systems. However, Rw values of the microemulsions containing16-4-16never changed significantly.(3) Compared with the microemulsion systems containing aliphatic amine, both Xia and Xoa were much smaller, while (?) and Rw were larger, when alcohol was used as a cosurfactant.Chapter III. Phase behavior of W/O microemulsions containing imidazoliums ionic liquid type or Gemini surfactantThe W/O microemulsions formed by Gemini surfactant12-4-12and the corresponding mono-chain surfactant C12mimBr respectively with an isomeric alcohol as a cosurfactant at different temperatures were studied. The thermodynamic and structural parameters of these systems were obtained and compared.(1) As the number of branches of the alcohol increases, both Xia and Xoa would increase, whereas (?) and Rw would decrease for both microemulsion systems.(2) Compared with the microemulsions containing the mono-chain C12mimBr,(?) for microemulsion containing12-4-12is much lager, indicating that the transfer of alcohol from oil to the interfacial layer is more spontaneous. (3) The values of-â–³Gooâ†'i,â–³Hooâ†'i andâ–³Sooâ†'i mainly increase with temperature for the microemulsion systems containing12-4-12. Simiarly, the thermodynamic parameters of W/O microemulsions containing C12mimBr and butan-1-ol change in a same pattern. However, their pattern of change is opposite when butan-2-ol and2-methyl-propan-2-ol were used as a cosurfactant.Chapter IV. The effect of temperature and oil on the thermodynamic and structural parameters of W/O microemulsion systems containing Gemini imidazoliums surfactantsInterfacial composition and structural parameters of W/O microemulsion systems16-4-16(Ci6mimBr, CTAB)/butan-l-ol/alkane/5%NaCl solution (wo=20) containing various oils at varying temperatures.(1) Xia values decrease in magnitude in the order:16-4-16> CTAB> C16mimBr. It seems that the most amount of the alcohol was needed for the microemulsiom containing16-4-16.(2) Compared with the microemulsion containing CTAB or C16mimBr, the values of-â–³Gooâ†'i for12-4-12based microemulsion are much larger, due to the tight arrangement of hydrophobic chain of12-4-12molecules.(3) The values of Rw increases in magnitude in the order:16-4-16<C16mimBr<CTAB, which is related to the tight arrangement of hydrophobic chain of Gemini surfactant.(4) Both Xia and Xoa would increase, as the carbon chain length of the alkane molecules (nc) increase, whereas-â–³Gooâ†'i would decrease. It can be explained that with the length of carbon chain of alkane molecules increases, it is difficult for the alkane molecules to enter into the interfacial layer. （5）For the16-4-16based microemulsions, the transfer of the alcohol from oil tothe interfacial layer is a enthalpy-driven process at low temperatures, whileentropy-driven at high temperatures. Similarly, CTAB based microemulsion is the samewith the16-4-16one, whereas C16mimBr based microemulsion shows an opposite patternof change.