Controllable Preparation Of Double-shell Hollow Composite Microspheres And The Research Of Properties

In recent years,with the deepening of the research on micro/nano materials with different morphologies,hollow microspheres have attracted widespread attention.The special physical and chemical properties of hollow microspheres are not only related to the types of components,but also affected by the combination,morphology,size and structure of materials.Therefore,it is of great significance to study how to fabricate micro/nano hollow microspheres with controllable morphology and outstanding properties by simple and feasible methods.Based on the above research ideas,a series of double-shell hollow composite microspheres consisting of different components were prepared,and their catalytic or adsorption properties were studied,which provided some experimental and theoretical basis for the preparation and application of double-shell hollow materials.The main contents of this paper are as follows.?1?Controllable preparation and research on catalytic properties of PANI/Au/SiO₂composite microspheresA simple and controllable strategy was designed to prepare PANI/Au/SiO₂ composite microspheres.Specifically,polystyrene?PS?microspheres with uniform particle size were prepared,and then polystyrene/polyaniline?PS/PANI?composite microspheres were prepared using PS microspheres as template by"swelling-diffusion-interfacial polymerization"?SDIPM?.Subsequently,the loading of Au NPs and the deposition of SiO₂ on the surface of PANI shell were successively realized,to obtain PS/PANI/Au/SiO₂ composite microspheres.Finally,the PANI/Au/SiO₂ composite microspheres can be obtained by removing the PS template.In the process of preparation,the loading of Au NPs is realized by electrostatic adsorption.The traditional St?ber method is used for the coating of SiO₂,and no modification of template and shell materials is needed.In addition,the thickness of SiO₂ shell can be controlled by changing the amount of tetraethyl orthosilicate?TEOS?.The preparation method can also realize the loading of Au NPs with different particle sizes and other noble metal nanoparticles?NMNPs?.The PANI/Au/SiO₂ composite microspheres showed good catalytic activity and cyclic stability in the catalytic reduction of p-nitrophenol?4-NP?.?2?Controllable preparation and research on catalytic properties of RGO/Pd/m-SiO₂composite microspheresA simple and controllable preparation method was used to successfully obtain the RGO/Pd/m-SiO₂ composite microspheres with double-shell hollow structure.The preparation process is as follows.Firstly,PS microspheres were prepared by dispersion polymerization,and GO was coated on the surface of PS microspheres by means of ultrasound.After that,PS/RGO composite microspheres were obtained after reducing GO.Then Pd NPs and SiO₂were deposited on the surface of RGO shell in turn,and PS/RGO/Pd/SiO₂ composite microspheres were obtained.Finally,the RGO/Pd/m-SiO₂ composite microspheres with mesoporous shell were obtained after removing PS and pore-forming agent in one step by calcining at high temperature in inert atmosphere.In the experiment,the shell thickness and porosity of SiO₂ can be adjusted by changing the total volume and volume ratio of TEOS and porogen,respectively.The catalytic activity and stability of the catalyst for the reduction of4-NP by NaBH₄ were also studied in this chapter.The experimental results show that the structure effectively improves the catalytic activity of Pd NPs,and the existence of double-shell effectively limits the aggregation and leaching of Pd NPs.?3?Controllable preparation and research on adsorption properties of PANI/ZIF-8composite microspheresHerein we prepared PANI/ZIF-8 composite microspheres with double-shell hollow structure by hard template method with PANI as inner shell and ZIF-8 as outer shell.First,PS/PANI composite microspheres were prepared and dispersed in methanol solvent.Then,2-Hmim and Zn?NO₃?₂·6H₂O were added into the methanol dispersion of PS/PANI composite microspheres successively,which resulted in heterogeneous nucleation at the interface of PS/PANI composite microspheres and methanol,and the PS/PANI/ZIF-8 core/shell/shell composite microspheres grew up gradually.Finally,the double-shell hollow PANI/ZIF-8composite microspheres were obtained by removal of the intermediate PS template.The thickness of ZIF-8 shell can be regulated by seed growth method.The structure exhibits good adsorption performance for Congo red dyes,and the adsorption process conforms to Langmuir equation and pseudo-second order kinetics.In addition,the adsorption capacity did not decrease significantly during the five reuses,showing good structural stability.