Synthesis And Performance Study Of Magnetic And Organic Functionalized Porous Polymers

Among all kinds of porous materials,POPs have attracted a particular attention due to their unique properties such as large surface area,low skeletal density and good chemical,thermal and hydrothermal stabilities,which are extensively applied in catalysis,gas storage,adsorption and separation,among many others.In particularly,hyper-crosslinked polymers?HCPs?,as one of kinds of POPs,have recently drawn wide attention due to their low-cost,high chemical and thermal stability with high surface areas and various pore structures.To date,most studies on HCPs mainly focused on the development of diverse synthetic strategies.It remains still rare for the preparation of morphology-controlled HCPs.HCPs with a hollow structure and unique morphology usually have a synergistic effect owing to their interconnected mesopores and micropores,which will beneficial for excellent pore accessibility and rapid mass transfer.Furthermore,the performances and applications of HCPs are mainly determined by their pore structure,skeleton construction and functionalities.Therefore,developing precise and facile preparation of functionalized HCPs with a hollow architecture at the nanoscale still remains challenging.Magnetic porous nanomaterials,as one of the most important class of functionzlized porous materials,have attracted great interest due to their unique features such as stable porous structure,large surface area,tunable pore size and magnetic property for fast magnetic separation and multiple recycling.A variety of synthetic methods combined with all kinds of porous materials have been developed towards the fabrication of magnetic porous nanomaterials,although these strategies have achieved great success in preparing various magnetic porous materials,developing new porous materials and easy methods that construct more diverse architectures of magnetic porous structures and provide precise control over their pore structure and functionality as well as strong magnetic property still retains a scientific challenge.Accordingly,the main task of this PhD thesis are explore different morphology-controlled HCPs and magnetic HCPs as well as their functionalization.More importantly,application of these HCPs and magnetic HCPs as heterogeneous catalysts and dye or toxic metal ion adsorbent were also exploited.Chapter?introduces the research background about hypercrosslinking polymers and magnetic porous nanocomposites,and highlights their preparation methods and applications.Chapter?presents the synthesis of magnetic microporous organic nanotube networks?Fe₃O₄-MONNs?by an in-situ hyper-crosslinking reaction between magnetic nanoparticles and core-shell bottlebrush copolymers.Due to abundant anionic carboxylate groups produced as end-groups after polylactide?PLA?core degradation in the bottlebrush copolymers,the Fe₃O₄-MONNs showed a selectively adsorption behavior for the cationic dyes.Moreover,the Fe₃O₄-MONNs possess superparamagnetism and high saturation magnetization,which allows them to be easily separated by an external magnetic field and subsequently reused.Therefore,this work provides a promising method for the design and synthesis of magnetic microporous organic nanotube networks,which can be used for the practical separation of organic dyes,as well as having other potential applications in the field of absorption,fast separation and heterogeneous catalysis.Chapter?describes the synthesis of core-shell and yolk-shell structure magnetic microporous organic nanospheres?CS-MMONs and YS-MMONs?,and study both structure of magnetic microporous organic nanospheres on adsorption for dye solution.Magnetic microporous organic nanospheres could be synthesized by the combination hyper-crosslinking mediated self-assembly and ship-in-bottle strategy by turning the amount of Fe²⁺within the spheres.The resulting YS-MMONs nanocomposites possess a hierarchically porous structure,large surface area,excellent magnetic response and good chemical inertness.Due to abundant anionic carboxylate groups produced in the cavity as end-groups after polylactide?PLA?degradation,the obtained YS-MMONs as sorbent showed a selective adsorption behavior for the cationic dyes.The results of adsorption kinetics and adsorption isotherms for adsorption of methylene blue?MB?by CS-MMONs and YS-MMONs showed that YS-MMONs performed a higher adsorption,magnetic separation and reusability.Chapter?proposes a novel method for the preparation of well-defined amino-functional core-shell magnetic multifunctional microporous spheres networks.Firstly,the diblock copolymers PLA-b-PS synthesized by a combination of ring open polymerization?ROP?and atom transfer radical polymerization?ATRP?.Subsequently,the microporous hollow spheres were synthesized by self-assembly and hyper-crosslinked of the copolymers PLA-b-PS in the anhydrous FeCl₃/CCl₄ system via Friedel-Crafts reaction.Finally,the well-defined core-shell magnetic microporous spheres were synthesized by the“ship-in-bottle”strategy.Furthermore,amino-functionalized hairy-like core-shell magnetic microporous spheres were prepared via grafting of glycidyl methacrylate using surface-initiated atom transfer radical polymerization?SI-ATRP?and following ring-opening of epoxy groups with ethylenediamine.Amino-functional core-shell magnetic multifunctional microporous spheres shows a high adsorption capacity for Cr?VI?,magnetic separation and reusability.Chapter?describes a meso-tetraphenylporphyrin iron?III?chloride?Fe?TPP?Cl?functionalized microporous organic nanotube networks?Fe?TPP?Cl-MONNs?was successfully synthesized by an in situ hyper-crosslinking reaction with core-shell bottlebrush copolymers and Fe?TPP?Cl.The obtained Fe?TPP?Cl-MONNs catalyst possesses a hierarchically porous structure,large surface area and good stability,which exhibits highly catalytic activity and excellent reusability in olefination of aldehydes and carbene insertion into N-H Bonds with ethyl diazoacetate.In Chapter?,Carboxyl group functionalized hollow microporous organic nanospheres?HMONs-COOH?were successfully synthesized by hyper-crosslinking reaction between polylactide-b-polystyrene?PLA-b-PS?copolymer and 2,4,6-tris?bromomethyl?mesitylene as well as subsequent alkaline KMnO₄ oxidation.The synthesized HMONs-COOH possesses a hierarchically porous structure,large surface area and robust organic framework,which shows well catalyst activity in the Friedel-Crafts alkylation of indole with aldehydes at room temperature and highly efficient adsorption performances toward cationic dyes.