The Construction Of A New Type Of Surfactant-free Microemulsion System And Its Application In The Preparation Of Nanomaterials

The thesis consists of four parts.The first part is the introduction.The second partisasurfactant-freemicroemulsionconsistingofwater/acetic acid/1-butyl-3-methylimidazolium hexafluorophosphate and its application for titania synthesis.The third part is the phase behavior and properties of a surfactant-free microemulsion containing water/ethanol/dichloromethane.The last part is the preparation and characterization of silica nanoparticles in surfactant-free microemulsions containing water/ethanol/dichloromethane.? IntroductionThe definition,microstructures and properties of microemulsions were introduced.The surfactant-free microemulsion systems and their characterizations were summarized.The construction,properties and applications of surfactant-free microemulsion systems were reviewed.? A surfactant-free microemulsion consisting of water/acetic acid/1-butyl-3-methylimidazolium hexafluorophosphate and its application for titania synthesis.Ionic liquid,1-butyl-3-methylimidazolium hexafluorophosphate?BmimPF₆?was synthesized.A new type surfactant-free microemulsion system consists of water/acetic acid/BmimPF₆ was constructed.1.The phase behavior of the surfactant-free microemulsion system consists of water/acetic acid/BmimPF₆ were investigated at 25°C,35°C,45°C,respectively.Single-phase microemulsion and multi-phase region were distinguished in the ternary phase diagram.The effect of temperature on the phase behavior of the ternary system was examined.2.The microstructure and structural transition of the microemulsion system were investigated by electrical conductivity and cyclic voltammetry at 25°C.Water-in-BmimPF₆?W/IL?,bicontinuous?B.C.?and BmimPF₆-in-water?IL/W?microemulsions were obtained.3.Using potassium ferricyanide?K₃Fe?CN?₆?as probe,the solubility of salts in the W/IL microemulsion was studied by the UV-Vis spectroscopy.It was found that the solubility of K₃Fe?CN?₆ in the microemulsion is consistent with Lambrt-Beer law.4.Using TiCl₄ as a titanium source,titanium dioxide?TiO₂?nanoparticles with different morphologies and sizes were synthesized in the different regions of the microemulsion systems.TiO₂ nanoparticles,TiO₂ nanorods and TiO₂ nanoflowers were synthesized in W/IL region,B.C.region and IL/W region,respectively.? The phase behavior and properties of water/ethanol/dichloromethane surfactant-free microemulsionA new type surfactant-free microemulsion system consists of water/ethanol/dichloromethane was constructed.1.The microregions,that is,water-in-dichloromethane,bicontinuous and dichloromethane-in-water were divided by conductivity.2.Using methyl orange as a probe,the polarity of the microenvironment was studied by UV-vis spectroscopy.It was found that the polarity of the microenvironment was between pure water and ethanol.Importantly,the intersections of the three segments by UV-vis spectroscopy coincide well with the intersections of the three microregions of the microemulsions using conductivity.3.Potassium ferricyanide?K₃Fe?CN?₆?was chosen as a probe to investigate the dissolution of metal salts in the water droplets of the W/O microemulsions using UV-vis spectroscopy.The solubility of K₃Fe?CN?₆in the W/O SFME is similar to SBMEs and is well consistent with Lambrt-Beer law.? The preparation and characterization of silica nanoparticles in surfactant-free microemulsions containing water/ethanol/dichloromethaneSilica nanoparticles?SNs?were synthesized and characterized in the water/ethanol/dichloromethane surfactant-free microemulsion template.1.The effect of different template?the mixtures of water and ethanol,O/W,B.C.and W/O?on the morphology and size of the SNs were investigated.It is found that under the same experimental conditions,only in O/W SFME template,can the uniform spherical SNs obtained.2.The effects of tetraethylorthosilicateconcentration(C_TEOS),ammonia hydroxideconcentration(C_NH3?H2O)anddichloromethanecontenton themorphologyand size of the SNs were investigated.The average diameters of the SNs increased with increasing C_TEOS and C_NH3?H2O.However,the effect of increasing C_NH3?H2Oon the particle size is more significant.3.The growth mechanism for the SNs synthesized in the O/W SFMEs can be elucidated by the time evolution of the morphology and size of the SNs.A mechanism for the growth process of the SNs synthesized in the O/W SFMEs was proposed.?I?The induction period for the nucleation;?II?Nucleation burst and growth by diffusion-coalescence stage;?III?Slowdown of growth stage.