| The thesis contains four parts. Chapter â… . Introduction. Chapter â…¡. Comparison between phase behavior of Gemini imidazoliums and monomeric ionic liquid surfactants in W/O microemulsion systems. Chapter â…¢. Synergistic interactions in mixed W/O microemulsions of ionic liquid-type surfactant and SDS. Chapter â…£. Synergistic interactions in mixed W/O microemulsions of cationic Gemini and anionic SDS.Chapter â… . IntroductionThe chemical structures, properties and research progress of gemini surfactants were introduced. The cationic gemini surfactants and their micelles and microemulsion systems were discussed particularly.Chapter â…¡. Comparison Between Phase Behavior of Gemini Imidazoliums and Monomeric Ionic Liquid Surfactants in W/O Microemulsion SystemsThe composition and structural parameters of W/O microemulsions containing gemini surfactant12-4-12/alcohol/alkane/NaCl solution, and W/O systems containing ionic liquid type surfactant C12mimBr/alcohol/alkane/NaCl solution, were studied and compared.1. Compared with the corresponding mono-chain analogues C12mimBr based microemulsions, more alcohol molecules are incorporated into the interfacial layer of12-4-12-based microemulsions. This results in the greater Gibbs energy (-â–³Goâ†'io) values for12-4-12based microemulsion systems. The size of the water pool (Rw) for the12-4-12based microemulsion systems are smaller than that for their monomeric analogues CnmimBr systems.2. As molar ratios of water to surfactant (ωo) increases, Xao (the mole fraction of the alcohol in the oil phase), Xai (the mole fraction of the alcohol in the interfacial layer) and Rw (the radius of the water pool) increase, whereas-â–³Goâ†'io (the standard Gibbs energy change of transferring alcohol from the continuous oil phase to the interfacial layer) decreases.3. As the carbon chain length of the alcohol increases, both Xao and Xai would decrease, whereas-â–³Goâ†'io and Rw would increase for both microemulsion systems. As NaCl concentration increases, the parameters of Xao, Xai and-â–³Goâ†'io for both microemulsion systems have the same pattern of change as the carbon chain length of the alcohol increases. However, as the carbon chain length of alkane molecules increases, the parameters for microemulsion systems have the reverse pattern of change as the carbon chain length of the alcohol increases. With the increase of temperatures, the value of Xai and-â–³Goâ†'io increases, while the value of Xao and Rw decreases.4. The nanometer size of the microemulsion droplets can be changed to a greater degree by means of changing ωo values.Chapter â…¢. Synergistic Interactions in Mixed W/O Microemulsions of Ionic Liquid-type surfactant and SDSThe W/O microemulsions formed by mixed surfactants of ionic liquid C12mimBr and anionic sodium dodecyl sulfate (SDS) C12mimBr-SDS/alcohol/alkane/brine were investigated:1. The balanced microemulsions can be prepared within the range of the molar fractions of SDS to C12mimBr and SDS (XSDs)0-0.3and0.7-1.0.2. The synergic effect was found between C12mimBr and SDS. The values of Xai and Xao obtained from the mixed surfactants W/O microemulsions are smaller than that of the microemulsion systems containing the single surfaxtant C12mimBr or SDS, while the values of-â–³Goâ†'io are larger.3. With the increase in molar ratios (ω0) of water to surfactant, Xao and Xai increase, whereas-â–³Goâ†'io decreases. This can be attributed to the increased hydrophilic property of the system with the increase in ωo values.4. The effects of decreasing the carbon chain length of the alkane molecules and increasing NaCl concentrations are equivalent to that of increasing the carbon chain length of the alcohol molecules. With the increase of temperatures, the value of X’a and-â–³Goâ†'io increases, while the value of Xao decreases. Chapter IV. Synergistic Interactions in Mixed W/O Microemulsions of Cationic Gemini and Anionic SDSThe W/O microemulsions formed by mixed surfactants of cationic gemini imidazolium12-4-12and anionic sodium dodecyl sulfate (SDS) were investigated.1. The W/O microemulsions containing12-4-12/SDS/butan-l-ol/octane/brine can be prepared within the range of the molar fractions of SDS to12-4-12and SDS (XSDS)0-0.3and0.7-1.0.2. The synergic effect was found between12-4-12and SDS on the physicochemical properties of the W/O microemulsions, including the molar fraction of the alcohol at the interfacial layer (Xai), the molar fraction of the alcohol in the oil phase (Xao), and the Gibbs free energy change (-â–³Goâ†'io) of transferring alcohol from the continuous oil phase to the interfacial layer. The values of Xai and Xao obtained from the mixed surfactants W/O microemulsions are smaller than that of the microemulsion systems containing the single surfaxtant12-4-12or SDS, while the values of-â–³Goâ†'io are larger.3. With the increase in molar ratios (ω0) of water to surfactant, Xao and Xai increase, whereas-â–³Goâ†'io decreases. This can be attributed to the increased hydrophilic property of the system with the increase in coo values.4. Less alcohol with longer carbon chain (Xai) is needed to balance the hydrophile-lipophile property of the interfacial layer, and therefore less alcohol (Xao) is dissolved in the oil phase. Hence the spontaneous transfer ability of the alcohol from oil phase to the interfacial layer (-â–³Goâ†'io) would increase.5. The effects of decreasing the carbon chain length of the alkane molecules and increasing NaCl concentrations are equivalent to that of increasing the carbon chain length of the alcohol molecules. With the increase of temperatures, the value of Xai and-â–³Goâ†'io increases, while the value of Xao decreases. |
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