Morphology Control And Application Of Mesoporous Silica Nanoparticles

Mesoporous nanomaterials,including silica(SiO₂),polystyrene,phenolic(RF),metal oxides,etc.,are of vital importance use values in our daily lives,so they have received enormous attention in recent years.Among them,SiO₂nanoparticles are favored by scientific researchers because of their excellent thermal stability and biocompatibility.Compared with dense SiO₂nanoparticles,mesoporous bring extra surface area and pore volume for nonporous SiO₂nanoparticles.This makes mesoporous silica nanoparticles(MSNs)play an irreplaceable role in adsorption-desorption,catalysis,energy storage-release and biomedicine.So,it is highly interesting to impart dense SiO₂nanoparticles with different porous architecture.Up to now,despite tremendous efforts have been devoted to tailoring architecture,large pore size,and morphology of MSNs,there are still complicated steps,time-consuming and environmental pollution issues in the synthesis process.In addition,the fabrication of monodisperse MSNs with various structures in a single oil-water microemulsion system is still difficult to achieve.Therefore,it is still a challenge to synthesize monodisperse MSNs with tailoring pore size,diverse structures and transition between different structures.Based on the above issues,this thesis conducted a detailed study on the following four aspects of the fabrication and application of MSNs with various pore sizes and morphological structures based on extensive investigation and reading of the literature:(1)Utilizing unique CTAB/cyclohexane/pentanol/TEOS microemulsion system,monodisperse MSNs with different pore sizes and morphologies were successfully prepared,and discussed the influence of the volume of pentanol,the volume of isopropanol,the comcentration of CTAB and the amount of ammonium bicarbonate on the particle diameter,pore size and morphology of MSNs.The results show that MSNs exhibit a uniform wrinkle-like spherical structure in the absence of pentanol,while MSNs have a smaller pore size and a larger specific surface area.As the volume of pentanol increase,the morphology of MSNs gradually translation from dendritic,walnut to mulberry.The particle size does not change significantly,the pore size first increase and then decrease,and the specific surface area is significantly reduced compared with the sample lacking pentanol.With the increase of the volume of isopropanol,MSNs showed a typical mulberry-like structure,the particle size was significantly reduced,the pore size and specific surface area did not change.The amount of CTAB has no obvious effect on the morphology,particle diameter,pore size and surface area.With the increase of the amount of ammonium bicarbonate,the morphology of MSNs is still mulberry-like,but the particle size and specific surface area show a decreasing trend.(2)Based on the classic St?ber system,the innovative introduction of resorcinol(R)and formaldehyde(F),and successfully prepared silica/RF(SiO₂/RF)composite nanoparticles.First synthesize RF nanoparticles,then add TEOS,under the catalysis of ammonia,TEOS hydrolysis and condensation to form primary SiO₂nanoparticles,these small particles will gradually deposit on the surface of the preformed RF nanoparticles to further obtain SiO₂/RF composite nanoparticles,and finally obtain SiO₂nanoparticles with different morphologies after high temperature calcination.The effects of ethanol-water volume ratio,ammonia water volume,reaction temperature,RF dosage and reaction time on the results were explored.The results show that with the decrease of ethanol-water volume ratio,the particle size and cavity of MSNs gradually decrease and the surface becomes rough.With the increase of ammonia water volume,the constant particle size of MSNs cavity decreases gradually,and the surface is also rough.With the increase of temperature,the particle size,cavity and surface of MSNs did not change significantly.When the amount of RF increased,the particle size and cavity of MSNs did not change significantly,but the surface appeared obvious mesoporous structure.As the reaction progresses,the interior of the RF nanoparticles gradually dissolves and finally forms a hollow structure.(3)In the classic St?ber system,while innovatively introducing of RF as pore formers,using tetrapropyl orthosilicate(TPOS)instead of TEOS,because TPOS has a lower hydrolysis and condensation rate than TEOS under the same conditions,therefore,successfully controlled the structural transformation of MSNs.The influence of ethanol-water volume ratio,ammonia volume,reaction temperature,and RF dosage on MSNs was explored.The results show that as the volume ratio of ethanol to water decreases,the particle size of MSNs gradually increases and the morphology gradually changes from mesoporous to nuclear@mesoporous SiO₂nanoparticle structure(CM-SNs);as the volume of ammonia increases As the temperature increases,the particle size of MSNs gradually decreases,and the morphology gradually changes from CM-SNs to rough mesoporous SiO₂nanoparticle structure(RM-SNs);with the increase of temperature,the particle size of MSNs gradually decreases and The morphology is core@mesopore@shell SiO₂nanoparticle structure(CMS-SNs);when the amount of RF is further increased,the structure of MSNs is mesoporous.(4)The MSNs with different morphologies obtained by the above method were subjected to gold catalysis and bovine serum albumin adsorption experiments.In the catalysis experiment,MSNs were firstly amination treated,and then gold nanoparticles were grafted.The results show that gold nanoparticles with a size of about 3 nm can be well loaded in the mesopores of MSNs,and the wrinkle-like MSNs with smaller particle diameters exhibit excellent performance in the reduction of4-nitrophenol(4-NP).In the adsorption experiment,the results showed that,compared with the hollow MSNs with rough surface,the hollow MSNs with the mesoporous surface showed a better adsorption effect in the adsorption experiment of bovine serum albumin.