Design, Synthesis And Characterizations Of Functional Mesoporous Composite Material

Mesoporous materials with highly ordered pore structure, high specific surface area,large pore volume, uniform pore size distribution have large application foreground incatalysis, sorption, separation, optical devices, sensor and so on. Over the past twodecades, various mesoporous materials with different mesostructure, frameworkcompositions, morphologies and properties have been obtained by different methods.However, for the sake of future development of mesoporous materials, there are stillmany research need to be developed, expecially the sythesis and application ofmesoporous functional materials. In this thesis, firstly, we improved the originalexperimental route and designed new synthetic methods, made the experimentalmethods facile and reduced the synthetic cost. Secondly, we prepared several newfunctional mesoporous composite materials and studied their application property.In the chapter2, a novel method has been developed to fabricate well dispersedsilver nanoparticles inside the channels of mesoporous silica. In this method, themesoporous host （SBA-15）, filling agent （toluene） and the Ag precursor（Ag（NH₃）₂NO₃solution） can be regarded as a system. Cooperative assembly amongthe system restricted the growth of Ag nanoparticles, in which Ag（NH₃）₂NO₃solutionadsorbed on surfaces of mesoporous host in the form of nano-layer played a key role.The particle size and loading amount of Ag nanoparticles in the mesoporous silicacould be easily tuned by altering the concentration of Ag（NH₃）₂NO₃solution. Themesoporous composite materials show an excellent catalytic activity toward thereduction of dye molecules by sodium borohydride.Owing to the unique physical and chemical properties, extensive studies have beenfocused on using mesoporous carbon materials to remove pollutants in the water.Unfortunately, the inert and hydrophobic natures of mesoporous carbon materials result in poor wettability and dispersibility in water, which would limit their potentialin adsorption. In addition, the separation of carbon materials from the final system isnotoriously difficult, even causing secondary pollution. In order to solve theseproblems, in the chapter3, highly ordered mesoporous carbon CMK-3functionalizedwith carboxylate groups and magnetic nanoparticles has been successfully synthesized.By oxidative treatment of （NH₄）₂S₂O₈and H₂SO-4mixed solution, numeroushydrophilic groups were created in the mesopores without destroying the orderedmesostructure of CMK-3. Through the in situ reduction of Fe³⁺, magneticnanoparticles were successfully introduced into the mesopores, resulting in themultifunctional mesoporous carbon composite. The obtained mesoporous compositematerial possesses ordered mesostructure, high specific surface area, large porevolume, carboxylic surface and excellent magnetic property. When used as anadsorbent, this material exhibits excellent performance for removing toxic organiccompounds from waster-water, with a high adsorption capacity, an extremely rapidadsorption rate and an easy magnetically-separable process. In the case of requiringemergency removal of large amount of organic pollutants in aqueous, the hybridcarbon adsorbent would be an ideal choice.The precise control of the surface chemistry, assembly process, and size of eachcomponent is crucial to the construction of integrated functional nanocomposites.Inspired by this view, in the chapter4, we have prepared mesoporous Agnanoparticle/carbon composites by two different methods. First, a novel in situauto-reduction route has been developed, by which well dispersed silver nanoparticlescan be easily fabricated in ordered mesoporous carbon. The mesoporous carbonfunctionalized with carboxylate groups was used to anchor glycol to form novelreducing species （COOCH₂CH₂OH）, on which Ag（NH₃）₂NO₃could be in situ reduced.Highly dispersed and small-sized Ag nanoparticles were thus obtained. The welldesigned composite has large surface area, highly open mesopores, and stablyconfined but accessible Ag nanoparticles and, as a result, shows high performance incatalytic reduction of4-nitrophenol. Without stabilizing agent, reductant orcalcination, the preparation method reported here is easy and energy-saving for thesynthesis of Ag supported mesoporous carbon materials. Second, ordered mesoporoussilver nanoparticle/carbon composites have been produced by a "one-pot" synthesis method. They have open mesopores, large specific surface areas, high pore volumes,and well dispersed Ag nanoparticles. The mesostructure and particle size as a functionof Ag content were studied and correlated with the performance in catalytic reduction.The ordered mesoporous carbon framework and highly dispersed Ag nanoparticlesmake the material a novel system for effective contacting with the reactants andcatalysis of the reaction, increase the usefulness of functional mesoporous materials,and promote them toward the practical application.In many practical applications, the mesoporous material should not only have awell-defined mesostructure but also a well-defined morphology for operation.Mesoporous materials with defined morphology, like films or monoliths, can be usedas good host materials. In the chapter5, polymer resin and polymer-silica films withhighly ordered mesostructure have been used as host materials to encapsulatefluorescent dye molecules through evaporation-induced self-assembly method. Afterencapsulation, the composites show significant blue-shift in photoluminescencespectra. Particularly, by changing the excitation wavelength, the samples showdifferent emission bands. These phenomena are related to the mesostructure and thepositions of dye molecules in the host.In this thesis, we fabricate several new functional mesoporous composite materialsby improving the original experimental route and investigating new synthetic methods.Based on optimizing the structure and properties of the materials, we improve thedisadvantages of the components in composite materials and strengthen theiradvantages, investigate the application performance of functional mesoporouscomposite materials, provide new route for the synthesis of mesoporous compositematerials, and expand the application of these materials in the catalysis, water...