Controlled Synthesis Of Organo-Functionalized Hollow Mesoporous Silica Nanoparticles Based On One-Step Method And Adsorption Research

Organo-functionalized hollow mesoporporous silica nanoparticles（O-HMSNPs）have been extensively investigated due to their tunable physical and chemical properties.However,organic functional group in O-HMSNPs is traditionally introduced by post-grafting method and co-condensation method,so that it will appear for many questions,such as pore blockage,uneven distribution of organic and inorganic components and lower content of organic functional groups,etc.In this thesis,a simple and effective method,namely"one-step method combining template strategy"has been developed for the preparation of vinyl or thiol-functionalized hollow mesoporous silica nanoparticles,respectively.And on this basis,the formation mode and structural characteristics of O-HMSNPs have been explored.The etching mechanism and effect of O-HMSNPs under the etching reagents have been discussed.Furthermore,the effect of organic inorganic hybrid layer protected selective etching strategy on structure and property of O-HMSNPs has also been illustrated.Finally,the adsorptive property of OHMSNPs with different structures and characteristics is investigated.The implementation of this project may provide new insight for preparation of new and high-performance O-HMSNPs.This thesis consists of six chapters:Chapter 1:This chapter introduced a relative comprehensive overview of mesoporporous silica nanomaterials,organic functionalization,research progress,and application field of O-HMSNPs.Chapter 2:CTAB@V-SiO₂ can be synthesized via one-step method using cationic surfactant cetyltrimethyl ammonium bromide（CTAB）as a single template,vinyl triethoxy silane（VTES）as the silica source precursor.The formation mechanism is using the electrostatic interaction between cationic surfactant and negatively charged V-SiO₂ in alkaline conditions,which inducing the synthesis of the core-shell structure,denoted as CTAB@SiO₂.The vinyl functionalized hollow mesoporous silica nanoparticles（V-HMSNPs）have been obtained by removing CTAB core.The influence of different CTAB concentrations and different alcohol water volume ratios on the morphology and pore structure of the final samples has been surveyed.In addition,the structures and properties of materials have been analyzed by using various testing methods.Chapter 3:CTAB@TC-SiO₂ can be synthesized via one-step method using CTAB as a structure-directing agent,3-thiocyanatopropyl)triethoxysilane（TCPTES）as the silica source precursor.The formnation mechanism is using the electrostatic interaction between cationic surfactant and negatively charged TC-SiO₂,which inducing the synthesis of the core-shell structure,denoted as CTAB@SiO₂.The thiocyanato-functionalized hollow mesoporous silica nanoparticles（TC-HMSNPs）have been obtained by removing CTAB core.The effect of the different CTAB concentrations and different hydrothermal treating times on the structures and physicochemical properties of the final samples has been studied.Chapter 4:In this chapter,O-HMSNPs have been prepared by using a novel approach.V-HMSNPs/TC-HMSNPs have been synthesized mainly by organic inorganic hybrid layer protected selective etching strategy using CTAB as a pore-making agent,TCPTES and VTES as the silica source precursors,respectively.Silica spheres prepared by modified sol-gel method as template,NaCO₃ as etching agent.And the effect of the different organosilanes and different CTAB concentrations on the structures and properties of O-HMSNPs has been investigated.Chapter 5:The surface polymer protected selective etching strategy has been developed to prepare the V-HMSNPs,based on unstable and easy to be decomposed of vinyl silica in alkaline condition.The main research is focus on the grafting polymerization on the surface of outer V-SiO₂,with a monomer N-vinyl pyrrolidone（NVP）,via chemical bond to form polyvinylpyrrolidone（PVP）as the outermost shell.The purpose of this synthesis is to protect the outer V-SiO₂ shell from being etched.Meanwhile,the part vinyl groups on the outer surface have been destroyed due to polymerization,however,the inner vinyl groups are still retained.Finally,the structures and properties of V-HMSNPs are analyzed and characterized through various testing methods.Chapter 6:V-HMSNPs and TC-HMSNPs prepared by using CTAB as template are acted as adsorbent materials,respectively.The adsorption performance for Cd²⁺of these materials has been explored comparatively in aqueous solution.The effect of different Cd²⁺concentrations,different adsorption times,different pH values and reused numbers on the adsorption performance has been discussed.The adsorption capacity for Cd²⁺of the V-HMSNPs and TC-HMSNPs has been analysized via atomic absorption spectrum detection.