Construction And Application Of Catalytic System Based On Organic Porous Materials

The application of catalysts in the chemical industry plays an irreplaceable role in the development of human society which makes it of great significance to construct a cheap,simple preparation,the high efficient and stable catalytic system.Organic porous materials show great application potential in catalysis due to their high specific surface area,tunable pore size,and various synthesis strategies.Among them,organic porous catalytic systems based on hyper-crosslinked polymers（HCPs）and porous organic cages（POCs）have achieved certain progress in the fields of small molecule catalytic reactions,photocatalysis and free radical polymerization,but there are still some challenges:the synthesis methods of the HCPs are still complex and need long reaction time;it’s impossible to obtain ultra-high molecular weight polymersu by free radical polymerization,etc.Traditional free radical polymerization has a wide range of application in polymer engineering due to its mild reaction conditions,fast polymerization speed,water resistance,abundant monomer sources and large-scale production.However,the microstructure,molecular weight,and molecular weight distribution of the polymer cannot be controlled.The reversible deactivation radical polymerization（RDRP）technology represented by atom transfer radical polymerization（ATRP）has solved the above-mentioned problems to a certain extent,but some problems caused by this method have restricted its application in industry.For example:（1）the low polymerization rate in the polymerization reaction makes it difficult to prepare ultra-high molecular weight polymers（UHMWP）;（2）the use of metal catalysts result in the problem of residual metal catalysts,which limits The application of polymer products in the fields of biology and electronics.This article intends to study the preparing strategy of organic porous materials under mild conditions and the free radical polymerization controlled by organic porous materials are studied in order to solve the problems faced by traditional methods.The main contents are as follows:In chapter 1,the research progress of porous catalytic systems and the key scientific issues facing ATRP at this stage are summarized and analyzed.The focus is on the synthesis strategy of hyper-crosslinked microporous polymers（HCPs）,the catalysis application of porous organic cages（POCs）,the research progress of preparation of ultra-high molecular weight polymers and the removal of metal catalysts by ATRP technology.In chapter 2,a new strategy for the preparation of HCPs by cationic polymerization under mild conditions is proposed.The obtained HCPs can be applied to the preparation of heterogeneous catalytic system.In an open system and room temperature,vinyl monomers are polymerized by cationic polymerization under acid catalysis to obtain HCPs with high specific surface area.The polymerization process is very fast,the BET specific surface area of the product can reach 730 m² g^-1 in 5 minutes.The specific surface area of HCPs is tunable by changing the polymerization time and the highest specific surface area is 1477m² g^-1.HCPs with high specific surface area exhibit good CO₂ and H₂ adsorption performance:the porphyrin structure-containing polymer（PTVPP）has better carbon dioxide adsorption performance due to the presence of N element in the framework structure（the CO₂ adsorption capacity 13.90 wt%at 273 K,the CO₂ adsorption capacity is 8.41 wt%at 298 K）;the hydrogen adsorption performance is mainly related to the specific surface area of the material,the hydrogen adsorption capacity of PTVP-2（constructed by pyrene building unit catalyzed by the aluminium trichloride）reached 1.3 wt%at 77 K and 1.13 bar.The above-mentioned HCPs materials can be used in heterogeneous catalysis after loading the metal catalysts.PTVP has good visible light absorption capacity.It can be used for photocatalytic water splitting to produce hydrogen after being loaded with Pt,and the hydrogen production rate can reach 308μmol h^-1 g^-1.The porphyrin structure in PTVPP is a good metal ligand for stabilizing Au nanoparticles.Au NPs@PTVPP can be used to efficiently catalyze the reduction reaction of 4-NP with a rate constant of 1.62×10^-3 s^-1.The catalyst still has high catalytic activity after five cycles.In chapter 3,a kind of HCPs heterogeneous catalytic system for tuning the free radical polymerization,and prepared ultra-high molecular weight polymers is developed.The HCPs（POP-Bpy）with a hierarchical pore structure are constructed by the vinyl-modified bipyridine.CuBr@POP-Bpy catalytic system is obtained after loading cuprous bromide（CuBr）,which is used to regulate free radical polymerization reaction.The segregation effect of the pores of HCPs limits the diffusion of chain radicals in the pores and reduces the probability of double radical termination.At the same time,the nano-confinement effect of the pore structure greatly increases the polymerization reaction speed,and ultra-high molecular weights are prepared under mild conditions.Wherein,the molecular weight of prepared polymethyl methacrylate（PMMA）1991100 g mol-1,and a molecular weight distribution（PDI）of 1.16.Subsequently,by adjusting the pore structure of the HCPs material and the conditions of the polymerization reaction,the preparation mechanism of ultra-high molecular weight polymers was explored.After the reaction,the residual Cu catalyst in the polymer can be removed by simple filtration,and the residual amount in PMMA is only 0.003 mg ^g-1.In chapter 4,a kind of organic cage catalytic system applied to the regulation of ATRP reaction is proposed.Taking the flexible weak ligand cyclohexanediamine（DACHEX）as the skeleton,the rigid components are gradually introduced to increase the rigidity of the ligand.The reduced imine cage（RCC3）ligand has the highest rigidity.After CuBr or CuBr₂is loaded,Cu@RCC3 catalytic system is obtained.The experimental results show that as the rigidity of the ligand increases,the ATRP rate increases.At the same time,the controllability of the molecular weight and molecular weight distribution of the obtained polymer is also improved.When the used as a ligand after loaded with 100 ppm of Cu,Cu@RCC3 can catalyze the polymerization of MMA and nBA（n-butyl acrylate）.The conversion rate of MMA monomer in 4h is 60%,and the PDI is 1.14.The conversion rate of nBA monomer in 4h is above 80%,showing that the Cu@RCC3 catalytic system has super high catalytic activity.Subsequently,Cu@RCC3 was used to catalyze the ATRP reaction of low-activity vinyl acetate（VAc）.The conversion rate of VAc in 5h was 50%,and the PDI was 1.36.