Study On Synthesis And Mechanism Of Mesoporous Silica With Organosilane Ionic Liquids As Template

Ordered mesoporous silica materials are silica mesoporous with narrow pore size distribution between 2-50 nm and uniform pore structures.One of the routes for the preparation of silica mesoporous is usually on the basis of the self-assembly behaviors of surfactants which act as template.Ordered mesoporous silica materials have attracted much attention due to their potential applications of ordered mesoporous materials in biocatalysis,adsorption,drug delivery,environmental protection and many other areas.This thesis focused on the synthesis of mesoporous silica nanospheres by using the organosilane ionic liquids as template.The partical size and pore structure of such mesoporous silica nanospheres were controllable.The possible synthesis mechanism of such mesoporous was investigated with combination of adsorption kinetic properties and molecular dynamic results of organosilane ionic liquids in aqueous solutions.1.The dynamic surface tension(DST)of organosilane ionic liquids,trisiloxanepyridinium ionic liquids([Si(3)Py]Cl)and trisiloxaneimidazolium ionic liquids([Si(3)Mim]Cl),in aqueous solution were measured using bubble pressure tensiometer.The effects of concentration and temperature on DST were discussed in detail.On the basis of Word-Tordai equation,the diffusion coefficients were calculated in short time stage and long time stage of adsorption,respectively.The results indicated that the adsorption mechanism of both above ionic liquids was mixed diffusion-kinetic controlled adsorption.2.The aggregation behaviors of[Si(3)Py]Cl and[Si(3)Mim]Cl in water had been investigated by coarse-grained(CG)molecular dynamics simulation on the basis of MARTINI force field.The new CG model was developed from the optimized molecule computed by using density functional theory.The CG model was validated by comparing with all-atom(AA)simulations.The results of long time CG simulation indicated that both ionic liquids self-assembled into vesicles in aqueous solutions.3.Highly thermostable mesoporous silica nanospheres were synthesized using trisiloxanepyridinium as template and partial silica source in the basic conditions at room temperature.With the transmission electron micrographs(TEM),fourier transform infrared spectrometer(FT-IR),N2 adsorption-desorption,low angle X-ray diffraction(LAXRD),the effects of calcination,amounts of tetraethyl orthosilicate,crystallization time on the particle morphology and pore structure were investigated in detail.The results showed that the particle sizes were nearly same,pore size distribution was narrow and the structure of such materials were highly thermostable;with the amounts of tetraethyl orthosilicate increasing,the particle size of nanosphers and pore volume increased,but BET surfaces and average pore size decreased.The possible synthesis mechanism was proposed on the basis of the results of above characterizations.4.Yolk-shell silica spheres were also prepared using trisiloxanepyridinium ionic liquids as template and partial silica source under pH=11 at 100 ? in a Teflon bottle.The effects of pH,calcination,concentration of template on the particle morphology and pore structure were discussed with the characterizations of TEM,FT-IR,N2 adsorption-desorption.It was found that the obtained Yolk-shell silica spheres possessed high thermostabilities.The particle size,void space,and shell thinkness increased with the increase of the concentration of template,indicating that the obtained nanostructure was controllable.The possible synthesis mechanism was also proposed on the basis of the results of above characterizations.