Preparation Of Rattle-type Organosilica Nanospheres And Their Adsorption Performance

As an important branch of hollow mesoporous silica nanoparticles,rattle-typemesoporous silica has held researchers'attention due to its excellent performance,such as large specific surface area,tunable cavity,low density,good biological compatibility.Rattle-type organosilica nanospheres with organic group on core or shell combine the advantages of both organic group and inorganic silica and have the potential to be applied in drug loading,catalysis,fluorescence imaging,cascade reaction.In this study,the self-template method,which was based on the selective etching of organic group differences,was adopted to prepare a variety of bifunctional rattle-type silica with organic groups both on the core and shell.However,there were distinctions in the structure and properties of the rattle-type organosilica which was prepared from different methods.Here are the primary contents of research.1.The preparation of rattle-type organosilica with the co-assemble of CTAB.With the assistance of cetyl trimethyl ammonium bromide?CTAB?,the effect of the middle layer?2-cyanoethyltriethoxysilane?CTES?,3-cyanopropyltriethoxysilane?CPTES?andvinyltriethoxysilane?VTES??wasinvestigatedwithregarding3-mercaptopropyltrimethoxysilane?MPTMS?and 3-thiocyanopropyltriethoxysilane?TCPTES?as the core and shell,respectively.The experiment showed that the reaction rate and stereo-hindrance of the middle organosilane was the key to synthesize rattle-type organosilica.And only regarding VTES as the middle layer could rattle-type organosilica be acquired.As the volume of VTES increasing,the cavity in rattle-type organosilica increased.When the volume of VTES was 1.0 mL and 2.0 mL,HS@shell@NCS-RSNs with irregular ring in interior were prepared,whose core diameter was 130¹50 nm,the shell thickness was 19 nm.The specific surface area was calculated to be 57 m²/g,and the pore diameter was mainly distributed under 2 nm.2.The preparation of rattle-type organosilica with organosilane-assistance.HS-HMSNs were obtained via treating vinyl-SiO_1.5@cyano&thiol-SiO_1.5 prepared by using MPTMS as shell precursors,VTES as a sacrificial template precursor and CTES as a pore-making agent.CTES played an important role in the formation of pore structures,and when the volume ratio of MPTMS to CTES was 1:1,well-defined monodispersed thiol-HMSNs with an average surface area of 295.6 m²/g and pore volume of 0.5087 cm³/g were obtained.Bifunctional NCS@HS-RMSNs also could be synthesized through this method,whose core diameter was 150²30 nm,shell thickness was about 18 nm.The specific surface area was 147 m²/g,and the pore diameter was mainly around 5 nm.3.The preparation of rattle-type organosilica with acid-base catalysis.According to the different reaction rate,HS-SiO_1.5@CH₂=CH-SiO_1.5 was prepared in one step at high temperature,in which nitric acid and ammonia catalyzed the hydrolysis and condensation of organosilane,respectively.After subsequent addition of TCPTES,multi-layer HS-SiO_1.5@CH₂=CH-SiO_1.5@NCS-SiO_1.5 was obtained and was further converted into HS@NCS-RSNs after NaOH solution treatment.The experiment showed that the cavity of rattle-type organosilica expanded with the increasing of the temperature or V?VTES?:V?MPTMS?.Especially,when the reaction temperature was60?and the value ofV?VTES?:V?MPTMS?was 1.2:0.2,a novel tri layer rattle-type HS@shell@NCS-RSNs was formed,whose average core diameter was 420 nm,middle layer thickness was 25 nm,shell thickness was 70nm.And the surface area was calculated to be 22 m²/g,the pore diameter was mainly distributed under 2 nm.4.The adsorption performances of above as-prepared RSNs?from chapter 2 to chapter 4,denoted as A,B,C?were explored with 2,4-dichlorophenol?2,4-DCP?as the molecular model.The effects of adsorption time,initial concentration of 2,4-DCP,adsorbent mass and recycling times on the absorption performance of 2,4-DCP were investigated.The experiments demonstrated that the concentration of 2,4-DCP and adsorbent mass had great influence on the adsorption capacity.And the adsorption capacities of A,B,C were as follow:B>A>C.