| Porous organic polymers are a class of lightweight porous materials made of organic block molecules connected by covalent bonds.Because of its large specific surface area,high porosity,good stability,adjustable pore size and skeleton,easy functionalization and metal-free features,they were widely used in catalysis,sensing,adsorption,biomedicine and other fields.In this thesis,we used organic monomers（2,1,3-benzothiadiazole and 4-dimethylaminopyridine）as functional blocks,alkyne-like monomers as linkers,and Si O2 nanospheres and ZIF-8as templates by a bottom-up strategy which porous organic polymers were constructed on their surfaces.The effects of the one-pot and stepwise synthesis methods about the heterogeneous and homogeneous growth of the polymers were discussed.The template of above core-shell polymers was removed by solution etching,hollow porous shell polymers containing a large number of catalytic active sites with uniform size and complete morphology were obtained.The photocatalytic oxidation of thioethers was investigated by using benzothiadiazole-functionalized hollow porous polymers as visible light catalysts,and the relationship all over photocatalytic performance and morphology and pore channel conformation was explored.The research of this dissertation is divided into two main parts as follows:（1）Synthesis and photocatalytic properties of BT and DMAP functionalized hollow conjugated microporous polymersUsing Si O2 nanospheres and ZIF-8 as templates,1,3,5-triethynylbenzeneasthealkynylmonomer,4,7-dibromo-2,1,3-benzothiadiazole（4,7-dibromo-BT）or3,5-dibromo-4-dimethylaminopyridine（3,5-dibromo-DMAP）as the block molecules by a stepwise dropwise addition method bottom-up construction of BT or DMAP functionalized porous polymer shell layers（Si O2@CMP-3-BT,ZIF-8@CMP-3-BT,Si O2@CMP-3-DMAP）on the template surface by the Sonogashira-Hagihara coupling reaction.Using10%HF etching of Si O2 nanospheres and 5%HCl etching of ZIF-8 to obtain functionalized hollow conjugated microporous polymers HCMP-3-BT,Z-HCMP-3-BT,HCMP-3-DMAP.The hollow morphology of the material was confirmed by scanning electron microscopy（SEM）and transmission electron microscopy（TEM）.HCMP-3-BT has a specific surface area of 290 m2/g,a shell layer thickness of 11 nm,and a bandgap of 2.43 e V,and its efficient and highly selective oxidation of anisole to methyl phenyl sulfoxide under room temperature,oxygen atmosphere,and visible light irradiation（425 nm,3 W）.Compared with the one-pot synthesis of CMP-3-BT,the unique cavity structure of HCMP-3-BT facilitates the mass transfer process and multiple reflections of light inside the cavity,which enhances the contact probability between the substrate and the catalytic active site,thus improving the catalytic efficiency.（2）Constructing BT functionalized hollow nanospheres based on TEPB and TEPM and exploration of their photocatalytic activitiesUsing Si O2 nanospheres as template,Si O2@CMP-TEPB-BT and Si O2@PAF-BT were synthesized by 1,3,5-tris（4-ethynylphenyl）benzene（TEPB）and tetrakis（4-ethynylphenyl）methane（TEPM）as alkynyl monomers respectively and 4,7-dibromo-BT as the block molecules,using a stepwise dropwise addition method by the bottom-up assembly strategy to guide organic monomers constructing on the surface of Si O2nanospheres via the Sonogashira-Hagihara coupling reaction.The hollow BT-functionalized nanospheres HCMP-TEPB-BT and HPAF-BT with different pore size were further obtained by etching the template using low concentration HF.The hollow morphology of the materials was confirmed by SEM and TEM.HCMP-TEPB-BT has a specific surface area size of 204 m2/g,a shell layer thickness of 23 nm,and a bandgap of2.35 e V.HCMP-TEPB-BT can efficiently and selectively catalyze the oxidation of anisole to methyl phenyl sulfoxide under room temperature,oxygen atmosphere and visible light irradiation（425 nm,3 W）,and the catalyst retains efficient catalytic activity after four cycles.Combined with the electron paramagnetic resonance spectra（EPR）,a possible reaction mechanism for the HCMP-TEPB-BT photocatalytic oxidation of anisole was proposed.The performance of BT nanocatalysts constructed with different alkyne-based monomers for photocatalytic oxidation of thioether was compared in terms of catalyst morphology and pore size,and it was found that the hollow morphology has the advantages of faster mass transfer and greater exposure of active sites,which confer excellent catalytic performance.Compared with HCMP-3-BT,HCMP-TEPB-BT has a higher percentage of mesoporous structure,which facilitates the rapid diffusion of substrates and thus has superior photocatalytic activity. |
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