Study On Multi-Phase Equilibrium Microemulsions, The Effect Of Template And Ionic Liquid Tuning Microemulsion Curvature

Microemulsions are thermodynamic self-assembly systems with wide-ranging applications in scientific research and industry because of their unique properties. Ionic liquids,as a class of chemical substance which have many special chemical and physical properties,have received much attention by chemists.In this doctoral dissertation,we studied three parts such as synthesis of nanomaterials through microemulsions,ionic liquid tuning microemulsions' curvature and synthesis of nanomaterials through ionic liquid microemulsions,and tried to combine them together,provided new pathways for correlative research fields.The outline and contents of this doctoral dissertation are as follows:Chapterâ… is a brief introduction of the research background of this work,in which the correlative knowledge and recent progress in surfactant science,ionic liquid science and their constructing microemulsion systems are reviewed from a worldwide angle of view.The objective and the scientific significance of this doctoral dissertation are also pointed out at the end of this part.In Chapterâ…¡,we prepared multi-phase equilibrium microemulsions(MPMs) systems through cationic surfactant,tetradecyltrimethylammonium bromide(TTABr) and anionic surfactant,sodium dodecyl sulfate(SDS),then studied the phase behavior of TTABr/n-butanol/iso-octane/Na₂CO₃ or CaCl₂ and SDS/n-butanol/iso-octane/ Na₂CO₃ or CaCl₂ systems when the concentration of different composition changed. We found that the phase transition follows as:WinsorⅠ→WinsorⅢ→Winsorâ…¡.For further study,we measured the interfacial tension between microemulsion and residual oil or water phase.MPMs provide a simple and versatile reaction media,i.e., upper-phase W/O,BC,and O/W structured equilibrium microemulsions to be used for synthesizing hierarchically structured CaCO₃ at the nanometer scale.The morphologies of the CaCO₃ precipitates were characterized by transmission electron microscope(TEM) and scanning electron microscope(SEM) images,it proved that hierarchically structured calcium carbonates with dendrites,ellipsoids, square-schistose cubes were synthesized through the MPM-based routes and we found that the corresponding relation between the template and the morphologies and sizes of the nanoparticles is not very close.Finally,we characterized the synthesized CaCO₃ nanoparticles through powder X-ray diffraction(XRD) and Fourier transform infrared spectroscopy(FT-IR),the shapes of the diffraction peaks show that the CaCO₃ particles were well-crystallized,demonstrating that the synthesis of nanoparticles through MPM-based routes have potential applications and we have developed a useful method of synthesizing nanometerscale inorganic particles.In Chapterâ…¢,we studied the phase behavior of TTABr/n-butanol/iso-octane/Na₂CO₃ or BaCl₂ systems when the concentration of different composition changed,and the results confirmed that the sequence of phase transition was the same as other multi-phase microemulsions.However,unlike CaCO₃ in Chapterâ…¡,we prepared BaCO₃ nanoparticles through MPMs and the effect of different aging time were obtained,so the growth mechanism of the BaCO₃ nanoparticles could be deduced.Therefore,this work can open alternative pathways to synthesize complex superstructures of inorganic materials.In Chapterâ…£,a MPMs system formed from cationic dioctadecyldimethylammonium chloride(DODMAC),anionic sodium dodecylsulfate (SDS),n-butanol,and n-heptane were studied.An ionic liquid(IL), 1-butyl-3-methylimidazolium tetrafluoroborate([bmim][BF₄]),was employed as the electrolyte in the aqueous media instead of inorganic salts usually used in microemulsion formulation.Studies have been carried out as a function of the concentrations of[bmim][BF₄],n-butanol,total suffactant(c_DODMAC+SDS),and temperature on the phase behavior and the ultralow interracial tensions in which the anionic component is present in excess in the catanionic film.Ultralow interfacial tension measurements confirmed the formation of middle-phase microemulsions and the necessary conditions for stabilizing middle-phase microemulsions.Electrical conductivity,small-angle X-ray scattering(SAXS),and smallangle neutron scattering (SANS) experiments were also performed,indicating that the typical heptane domain size has an average radius of 360(?) and the ionic liquid induces softening of the charged catanionic film.Most interestingly,the IL concentration(c_IL) is shown to act as an effective interfacial curvature-control parameter,representing a new approach to tuning the formulation of microemulsions and emulsions.The results expand the potential uses of ILs but also point to the design of new ILs that may achieve superefficient control over interracial and self-assembly systems.In Chapterâ…¤,the ionic liquid ethylammonium nitrate(EAN) formed nonaqueous microemulsion with nonionic surfactant TX-100 and cyclohexane.The phase behavior of the ternary system is investigated,and three microregions of the microemulsions-ionic liquid-in-oil(IL/O),bicontinuous,and oil-in-ionic liquid(O/IL) -are identified by conductivity measurements,according to percolation theory.The micropolarity of the microemulsions is investigated by using methyl orange(MO) as a UV/Vis spectroscopic probe.A relatively constant polarity of the microemulsion droplets is obtained in the IL microemulsion.FT-IR was performed to investigate the microstructural characteristics of the microemulsions.Finally,CaCl₂ and Na₂CO₃ were solubilized in the IL phase of IL/O microemulsions respectively,and prepared nanoparticles through mixing the IL/O microemulsions solubilized the inorganic salts. The obtained nanoparticles were characterized by TEM.It indicated that ionic liquid microemulsions may have potential applications in nanoscience.