Synthesis And Application Of Functional Hollow Hyper-crosslinked Polymer Nanospheres And Their Carbonized Materials Supported Metals

With the rapid development of material science,the development of porous materials has become more and more important.Most of the currently prepared porous materials such as Covalent Organic Frameworks(COFs)and Metal Organic Frameworks(MOFs)have amorphous morphology,which is not conducive to the utilization of the internal pore structure of the material and the transmission of the medium.Therefore,the preparation Porous materials with specific morphologies are the main goal of our research.Among many porous materials,porous organic polymer nanomaterials show excellent performance in catalysis,dye adsorption and degradation and gas storage and separation,because of their stable low-density framework structure,unique nano-sized morphology,relatively high specific surface area and good physical and chemical stability.We adopt methods such as coordination complexation,immersion encapsulation,carbonization and etching to prepare a class of metal-based hollow porous organic polymers and carbonized nanomaterials.The metal-based hollow porous material is regarded as an efficient,convenient,and recyclable nanoreactor,so as to explore its application in the field of adsorption and catalysis.The utilization of polymer-derived hollow porous carbon materials for supporting metal catalysis is a pretty hot spot in the field.The hollow porous carbon materials with Yolk-Shell structure have achieved full development.Therefore,using hollow porous carbon nanomaterials as a unique nanoreactor to encapsulate various metal particles is a very popular method.The utilization of hyper-crosslinking hollow porous organic polymer materials as precursors to synthesize porous carbon materials with restricted encapsulation capabilities,in order to achieve their unique catalytic ability,is another important goal of our research.Based on the above research,this doctoral dissertation will study the synthesis and applications of metal-based hollow hyper-crosslinked polymer nanospheres and their carbonized materials and obtain the corresponding research results.First,from the synthesis perspective of the precursor of the hyper-crosslinked porous material,a series of block polymers are synthesized using a new Z-type chain transfer agent,as the precursor,to prepare the corresponding porous material through the method of hyper-crosslinking and self-assembly strategy.Compared with the previous preparation method using the R-type chain transfer agent,the synthesis steps are further shortened,and the method is simple and efficient.Through Friedel-Crafts alkylation or Scholl coupling reaction,as a universal strategy,Hollow Microporous Organic Nanospheres(HMONs)have a uniform morphology and can precisely control the size and pore size distribution of the hollow spheres.Secondly,by introducing functional groups,functionalized hollow porous organic nanospheres can be obtained,which can be further used to load or encapsulate metal nanoparticles.As a unique nanoreactor,it has a wide range of applications.By introducing porphyrin groups into the shell of the hollow porous organic nanospheres,zinc ions can be coordinated and complexed to the shell,thus exhibit higher catalytic performance in the catalytic reaction of the coupling of thiophenol.The introduction of pyridine groups on the inner wall of the hollow spheres is another functional method.It can interact with chloroauric acid.After the ions are coordinated and reduced,the gold nanoparticles are introduced into the inner wall of the hollow porous organic nanospheres.It exhibits high catalytic performance for the oxidation of benzyl alcohol and reduction of 4-nitrophenol.In addition,the introduction of carboxylic acid groups into the inner wall can be used as a cation dye adsorbent,the introduction of magnetic iron oxide nanoparticles into the cavity by immersion encapsulation can achieve efficiently separated and reusable abilities..We also prepare corresponding hollow porous carbon materials through carbonization,thereby improving the stability and porosity of the shells.As a nanoreactor that can encapsulate metal particles without ligands,it can achieve the goal of high-efficiency size selective catalysis.Hollow porous organic nanospheres encapsulating palladium and silicon dioxide are used as precursors,and encapsulated palladium hollow porous carbon nanospheres(Pd@HPCNs)with yolk-shell structure are prepared by high-temperature carbonization and etching.Because of its unique shell microporous channels have size selectivity for molecules of different sizes,the palladium nanoparticles encapsulated inside have stable and efficient catalytic activity,and show high activity and molecular size selectivity in catalyzing the oxidation reaction of aromatic alcohols.Through the two-solvent immersion encapsulation method,the platinum encapsulated hollow porous organic nanospheres are used as the precursor,and the hollow carbon nanospheres(Pt@HPCNs)of confined platinum metal nanoparticles with yolk-shell structure are prepared by one-step carbonization.Due to its stable rigid framework structure,compared with platinum-encapsulated hollow porous organic polymer nanospheres(Pt@HPOPNs),it has better catalytic effect and cycle performance in catalyzing the reduction reaction of 4-nitrophenol.