Design And Property Studies Of Solution-processable Porous Organic Polymers

Porous materials have undergone evolution from inorganic zeolites,activated carbon,kieselguhr,to hybrid metal-organic frameworks（MOFs）,porous coordination polymers（PCPs）,pure organic porous cages and porous organic polymers（POPs）hitherto.In comparision,POPs have inspired an increased level of research interest in recent years due to their combined advantages of low skeleton density,high surface area,good physical and chemical stability,easy to control and functionalize.The ultimate goal for the design of functional materials is to realize their practical application,while exploring the types and functionalities,the processability of POPs has also become a hot topic in this field.Till now,the study of solution-processable POPs is still at an initial stage,although the appearance of polymers of intrinsic microporosity（PIMs）and soluble conjugated microporous polymers（CMPs）has improved the solution-processability of POPs,it faces the problems of expensive monomer,harsh reaction condition and complex process,which limit the large-scale industrialization of POPs.Therefore,design of solution-processable POPs with low-cost preparation,easy accessibility in a large-scale,and expand their applications in energy and environmental fields will be a new direction.Accordingly,the main task of this dissertation is to explore new synthesis strategies for the design of solution-processable POPs with low cost,mild reaction condition and simple process.Characterization of the obtained POPs was realized by Fourier Transform Infrared（FTIR）,Nuclear Magnetic Resonance（NMR）,nitrogen adsorption-desorption and so on.The solubility was measured by high-speed centrifugation and Tyndall effect.According to the properties of the obtained POPs,they are applied to adsorption,separation,drug release and explosive detection in the form of solid powder,solution,and polymer membrane,respectively.Overall,the dissertation includes the following parts:In the first chapter,the development of porous materials and POPs is extensively summarized,and focus on the research progress of solution-processable POPs.In the second chapter,solution-processable hypercrosslinked microporous polystyrene（SHCPs）was designed and prepared by external crosslinker knitting method.Commercial polystyrene was directly employed as precursor,the crosslinking was well-controlled intramolecularly at a high dilution and by slowly adding the external crosslinker.The obtained SHCPs have high surface area as well as good organosolubility and can be coated as film on a glass substrate,which exhibited excellent H₂ and CO₂adsorption performance.The third chapter,the concepts of hyperbranched polymers（HBPs）and POPs are integrated.AB₂-type organic monomers were employed as building blocks to obtain soluble hyperbranched POPs by simple,efficient,one-step Frediel-Crafts reaction.This class of materials combines the organosolubility of HBPs with the porous structure of POPs,the dual effect of internal cavities and intrinsic nanopores endows them high loading efficiency（1.91 g/g）for ibuprofen.It can be seen from the cumulative release curve that the release of the drug from the obtained material is a sustained-release process.The fourth chapter,a method for the preparation of a solution-state fluorescent porous hybrid material is proposed.By introducing active group and inert group simultaneously on the polyhedral oligomeric silsesquioxanes（POSS）,and polymerizing with pyrene,a pyrene-based,fluorescent porous hybrid polymer（HOPS-Py）was obtained successfully.The presence of propyl groups enhances the flexibility of polymer network,making the fluorescent HOPS-Py available for processing and applying in solution.The propyl chloride group serves as active site for the crosslinking,imparting the porous property to the obtained material.HOPS-Py displayed high sensitivity in the detection of a series of nitroaromatic compounds,and the quenching efficiency to picric acid was as high as 94%.In addition,HOPS-Py has also been processed into test film and test paper,realizing simple device integration.In the last chapter,a new strategy to prepare N₂-phobic POPs is presented.Azo-POPs which contain azobenzene unit were prepared by cationic polymerization of vinyl-modiefied azo compounds.Compared with the existing methods for synthesizing azo-based POPs,this strategy has no requirement of inert gas protection and can be carried out rapidly at low temperature,which is suitable for large-scale synthesis.Due to the high surface area and N₂-phobic property,the obtained azo-POPs displayed good CO₂/N₂selectivity.In addition,azo-POPs exhibit certain photo-switching properties under UV and visible light,along with the change of pore size and pore volume.At last,swollen-type azo-SPOPs with good solution-processability were explored through the adjustment of reaction condition.