Morphology Control And Application Of Silica Nanoparticles

Silica(SiO₂)nanoparticles have low toxicity,low thermal conductivity,high stability,better plasticity and environmental friendliness.These advantages enable them to have a wide range of uses in various industries,so they have always been hot spots of materials research.At the same time,after in-depth research,it is found that SiO₂nanoparticles with different morphologies often have unique properties and uses.First of all,hollow silica nanoparticles(HSPs)have a large load space and are good carrier materials in the chemical,pharmaceutical and biological fields.Secondly,SiO₂nanoparticles with rough surface(RSPs)have a larger specific surface area and easy modification of surface groups,which determines their wide application in the field of catalysis.Therefore,the advantages of SiO₂nanoparticles in structure and performance have attracted many scientists to study them.So far,although there have been many preparation methods,designing a greener and simpler method is still an urgent problem to be overcome.On the basis of reading and researching a large amount of literature,this thesis understands the current research status of HSPs and RSPs,and makes the following explorations and improvements:(1)This article systematically studied the formation process of the H₂O-TEOS-EtOH three-component system,expanded the scope of the applicable system in the St(?)ber method.A series of H₂O-TEOS-EtOH three-component systems were prepared by visual titration,and the corresponding phase diagrams of the three-component systems were drawn.The traditional St(?)ber method was improved,and the influence of the ratio of the H₂O-TEOS-EtOH three-component system on the morphology and uniformity of the synthesized SiO₂nanoparticles was further explored.The results show that only by controlling the ratio of the three components,a series of SiO₂nanoparticles with different degrees of condensation can be prepared under low-concentration ammonia conditions.The successful preparation of SiO₂nanoparticles with a low degree of condensation is the basis for the later morphology control of the particles.(2)The H₂O-TEOS-EtOH three-component system mixture with a molar ratio of124 H₂O:1 TEOS:45.8 EtOH was selected as the reaction liquid,,and low-concentration ammonia solution was used to prepare microporous SiO₂nanoparticles with a low degree of condensation.Without the use of surfactants,block copolymers,strong bases,and high-temperature hydrothermal reaction conditions,monodisperse HSPs with a controllable hollow structure can be obtained through mild experimental treatments.In the experiment,polydiallyl dimethyl ammonium chloride(PDDA)was selected as the protective agent to protect the surface of the particles.Subsequently,the interior of the low-condensed nanoparticles can be preferentially etched by ammonia solution to obtain HSPs.At the same time,an experiment for HSPs immobilization of bovine serum albumin was designed,and a UV spectrophotometer was used to detect the peak changes to verify the good immobilization performance of HSPs.(3)The H₂O-TEOS-EtOH three-component system mixture with a molar ratio of 124 H₂O:1 TEOS:45.8 EtOH is continuously selected as the reaction solution.Without the use of surfactants,it innovatively regulates the reaction process Temperature-prepared monodisperse silica particles(RSPs)with controllable surface morphology and rough surface.Specifically,the reaction liquid first reacts with ammonia water at room temperature to form soft primary particles with a very low degree of condensation.Subsequently,the reaction temperature is quickly lowered so that the loose matrix inside the primary particles dissolves and deposits on the surface of the particles to form silica nanoparticles(RSPs)with rough surfaces.At the same time,an experiment was designed to use Au@RSPs as a catalyst,NaBH₄to reduce4-nitrophenol to 4-aminophenol,verifing the excellent performance of RSPs as a catalyst carrier.