Synthesis,Structural Characterization And Properties Of Photoluminescent Mesoporous Silica

Mesoporous silica plays an increasingly important role in the field of optics and medicine,especially in drug delivery because of its large specific surface area,large pore volume as well as adjustable pore size.As an excellent doping matrix,mesoporous silica can obtain luminescent properties by doping dyes,quantum dots and rare earth metals.However,the introduction of luminescent centers still has some restrictions in practical application,such as dye leakage,complex preparation and biological toxicity.In recent years,carbon doping has become a research hotspot of luminescent mesoporous silicon dioxide because it does not need to dope fluorescent groups or metal ions,and its luminescent center comes from hybrid materials.In this paper,mesoporous silica SBA-15 with good hydrothermal stability and ordered structure was synthesized by using P123 as a common template.Carbon-doped mesoporous silica was synthesized by introducing CTAB as a common template.Ethanol was added to adjust the sphericity of mesoporous materials.In addition,in order to obtain mesoporous materials with superior sphericity,hexadecylamine was used as a template to synthesize spherical mesoporous silica,and the feasibility of adding 3-aminopropyl triethoxysilane(APTES)as an auxiliary structure guide agent to enhance the luminescent properties of the materials was evaluated.The synthesized mesoporous silica was analyzed by X-ray diffraction(XRD),fluorescence spectroscopy(FL),nitrogen isothermal desorption specific surface area analysis(BET),elemental analysis(EA),electron microscopy(SEM,TEM),thermogravimetric(TG)-differential scanning calorimetry(DSC),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR).The photoluminescence properties,mesoporous structure and surface morphology were characterized by analytical methods in order to analyze the mechanism of photoluminescence properly.In the second chapter,mesoporous silica SBA-15 was prepared by using P123 as a template,hydrochloric acid as a catalyst and tetraethyl orthosilicate(TEOS)as a precursor.On this basis,CTAB was added as an auxiliary structure directing agent.The mesoporous materials using CTAB as a template were also synthesized for comparison.The effects of CTAB content,calcination temperature and time,heat treatment temperature and time on the mesoporous structure,luminescence properties and surface morphology of the samples were investigated.After adding CTAB,the synthesized SBA-15 has good dispersibility and good photoluminescence properties,which laid a foundation for the later modification.In the third chapter,based on the synthesis of SBA-15 using CTAB as an auxiliary structure directing agent metioned in the previous chapter.Ethanol,an additive,can improve the degree of sphericity of mesoporous silica.The amount of ethanol has a great effect on the pore structure and fluorescence properties of mesoporous silica.Mesoporous silica materials synthesized by hexadecylamine have homogeneous spherical and good dispersion properties under electron microscope observation.The high calcination temperature is beneficial to the fluorescence properties of mesoporous materials.The temperature is optimal at 450 °C.The fluorescence properties of the material are improved by introducing APTES as a common silicon source,while the degree of sphericity can be kept.The mesophase structure is destroyed with introducing APTES.The prepared mesoporous silica was used for ibuprofen absorption and sustained release.The loading relationship of several mesoporous silicas is: P-0.2C-400-2>P-C0.2et-1-350-2>SBA-15>PLMS-he0.The loading property of mesoporous silica was investigated by the sustained release experiment of ibuprofen.The ibuprofen release rates of the prepared mesoporous materials are as follows: P-0.2C-400-2 > P-C0.2et-1-350-2 > SBA-15 > PLMS-he0.The release rate of ibuprofen for several mesoporous materials is as follows: P-0.2C-400-2 > P-C0.2et-1-350-2 SBA-15 > PLMS-he0.Therefore,the type of pore structure in the mesoporous material has an effect on the amount and the rate of drug release.