Organic Acid Ester/Ethanol/Water Surfactant-Free Microemulsion System And Its Application In Solubilization And Material Synthesis

Traditional surfactant-based microemulsions（SBMEs）are isotropic and thermodynamically stable dispersion systems containing water,oil,surfactant and cosurfactant.At present,microemulsion technology has penetrated into the fields of material science,petrochemical industry,biotechnology and daily chemical industry,and has great application potential.However,SBMEs contain large amounts of surfactant and cosurfactant and the preparation cost of SBMEs is high,which is not environmentally friendly.In recent years,surfactant-free microemulsions（SFMEs）containing water,oil and an"amphi-solvent"have attracted people’s attention.SFMEs do not contain any surfactants.Thus the environmental and cost problems caused by surfactants are avoided.In this thesis,novel SFME systems with organic acid esters（amyl acetate and ethyl benzoate）as the oil phase and ethanol as the"amphi-solvent"were constructed,and the microstructures and phase behaviors of the SFME systems were investigated.The solubilization of some inorganic salts and biomolecules in the SFME systems were determined.ZnO material was synthesized using the SFME system as templates.The main contents and conclusions are as follows:1.A novel SFME containing amyl acetate/ethanol/water was constructed.The ternary phase diagram of the system at 25°C was plotted,and the SFME single-phase region was divided into O/W,B.C.and W/O phase regions using conductivity method and UV-Vis spectroscopy.The microstructures of the SFME were observed under transmission electron microscope（TEM）using the negative staining method.In the W/O and O/W phase regions,the droplets showed a spherical structure,while in the B.C.phase region they showed a pipe-like structure.Dynamic light scattering（DLS）experiments show that there is an ordered structure in the W/O phase region.With the increase in water content,the size of the W/O droplets gradually increases.The state of water in the SFME system was studied using Fourier transform infrared spectroscopy（FT-IR）spectroscopy.The solubilization of various inorganic salts（Co Cl₂,Cu Cl₂,K₃Fe（CN）₆）and biomolecular riboflavin in the W/O SFME system were investigated.2.Using the SFME system as a template,wurtzite-type ZnO was synthesized by the microemulsion-hydrothermal method.The ZnO synthesized in the W/O phase region has a regular structure and uniform size,while the ZnO materials synthesized in the O/W and B.C.phase regions are larger and have irregular shapes.In the W/O SFME system,with the increase in hydrothermal reaction time,the morphology of the ZnO changes from a spherical structure to a sheet-like structure,and finally grows into a hexagonal dumbbell-like structure.As the temperature of the hydrothermal reaction increases,the crystallinity of the ZnO crystals gradually increases.The synthesized ZnO was characterized by scanning electron microscope（SEM）,UV-spectroscopy,FT-IR and X-ray powder diffraction（XRD）.The electronic structure,surface composition and oxidation state of the ZnO were investigated by XPS and EDX spectroscopy.The EPR and XPS spectra show that there are oxygen vacancies on the surface of ZnO,which is helpful to understand the photocatalytic mechanism of the ZnO product.3.A novel SFME system of ethyl benzoate（EB）/ethanol/water was constructed.The ternary phase diagram of the EB/ethanol/water system was drawn at 25°C.The single-phase region of the SFME was divided into O/W,B.C.and W/O phase regions by the conductivity method.The morphologies of the microstructures were observed by TEM.The DLS,Fluorescence spectroscopy（FS）,FT-IR and UV-visible spectroscopy were used to investigate the ordered microstructures,micropolarity,and solubilization of the SFME.The solubilization of curcumin in the O/W SFME was investigated,and the maximum solubilization amount of curcumin was measured to be 17.54 mg/m L.The experiments on the in vitro stability and antioxidant capacity show that when curcumin is embedded in the O/W SFME,its storage stability,light stability,thermal stability and antioxidant activity are significantly improved.