Study Of Organic Microporous Polymers Supported Catalysis And Controlled-release Based Onbottlebrush Copolymers

Bottlebrush polymers are a class of shape-persistent macromolecules that possess a highly branched comblike architecture.Steric repulsion between densely grafted polymeric branches causes the backbone to adopt an extended conformation.When polymeric side chains are much shorter than the backbone,these macromolecules take on cylindrical shape.Much attention has been drawn to polymer bottlebrushes for their unique molecule morphology and facile structural design and their application in self-assembly,drug delivery,controlled release and supported catlaysis.In this work,various multicomponent polymer bottlebrushes were synthesized by reversible addition-fragmentation chain transfer?RAFT?polymerization via "graft from" method.Different bottlebrush copolymers were obtained via the RAFT polymerization and served as the precursors to obtain functional porous organic polymers for heterogeneous catalysis.Hydrophilic polymer bottlebrushes loaded with thermal-sensitive dye molecules were synthesized by RAFT polymerization and the controlled release of dye was explored under 808 nm.The work can improve the development of bottlebrush polymers and have an important significant on their potential application in various areas.Multicomponent bottlebrush copolymers were synthesized by the combination of RAFT polymerization and Ring-Opening polymerization?ROP?,which have the shell of PS and the core of PLA.The molecular structure of the copolymers was confirmed by ¹H NMR and GPC traces demonstrated the monomodal molecular weight distribution.Amino-functionalized microporous organic nanotube networks?NH₂-MONN_s?were prepared from the polymer bottlebrushes by combination of molecular templating of multicomponent core-shell bottlebrushes and hyper cross-linking via Friedel-Crafts?F-C?alkylation reaction.The morphology of NH₂-MONN_s was further characterized by TEM.The intramolecular and intermolecular cross-linking of the bottlebrush copolymers resulted in the formation of unique organic nanotube networks constructed by multi-porous architecture and robust organic frameworks.The cylindrical shape and size of the bottlebrush precursors were mostly preserved after hydrolytic removal of the PLA core.The Brunauer-Emmet-Teller?BET?surface area and total pore volume of NH₂-MONN_s determined by nitrogen adsorption-desorption isotherms were 936 m²/g and 1.67 cm³/g,respectively.Based on the high surface area and excellent hierarchical porosity structure,the NH₂-MONN_s would offer a favorable condition for the heterogeneous catalysis.The NH₂-MONN_s was used as a solid base catalyst for the Knoevenagel condensation reaction and the heck reaction.The results indicated the NH₂-MONN_s possessed excellent catalytic activity and recyclability.The NH₂-MONN_s has great potential application in heterogeneous catalysis because of good porosity and excellent chemical stability.The sulfonic/amino-protected bottlebrush copolymer precursors with triblock terpolymer side-chains were prepared by a "graft from" method via the combination of controlled radical and ring-opening polymerizations as the above described method.The structure and molecule weight of the polymer bottlebrushes were confirmed by ¹H NMR and GPC characterization.TEM images show the existence of microporous organic nanotube networks and the results of nitrogen adsorption-desorption isotherms demonstrated the good porosity of SO₃H/NH₂-MONN_s.To explore the possibility of the SO₃H-MONN_s and NH₂-MONN_s acting as catalysts for the cascade reactions,an acid-catalyzed deacetalization and the subsequent base-catalyzed Knoevenagel condensation were chosen as a model reaction.The outstanding multi-catalytic property is benefited from the unique hierarchically porous structures that can facilitate the accessibility of the active sites and molecular diffusion.More importantly,the acidic and basic active-sites in cavities were successfully isolated by the cross-linked shell in the network which can prevent from the undesirable interaction between the incompatible acid/base sites.This work can provide a general pathway to anchor incompatible catalyst systems into MONNs support for various one-pot cascade reactions.Owing to the strong reaction between amine groups and metal nanoparticles,amine-functional microporous organic nanotube frameworks supported Pt or Pd catalysts?Pt or Pd@NH2-MONFs?were synthesized by hyper cross-linking of multicomponent bottlebrush copolymers and subsequent gentle reduction.The structure and metal content of the Pt or Pd@NH₂-MONF_s were confirmed by TEM,XRD,TG,ICP and XPS.The porous architecture of the NH₂-MONF_s was still maintained after loading and the Pt NPs were well dispersed in the tubular channel of the NH₂-MONFs.The Pt@NH₂-MONF_s possesses high BET surface area and large pore volume.The presence of free amine moieties in the channel of NH₂-MONF_s is suggested to play a key role on the formation of uniform and well-dispersed Pt or Pd on the support.Owing to their high special surface area,hierarchically porous structure and high loading ability,the resultant Pt or Pd@NH₂-MONF_s show high heterogeneous catalytic activity and excellent reusability in the selective oxidation of alcohol and Heck reactions,respectively.An efficient oxidation catalyst has been synthesized by anchoring oxo-vanadium?IV?onto the amino-functional micriporous organic nanotuble frameworks?NH₂-MONF_s?.The amino groups are used to immobilize vanadium?IV?into the porous organic supporter.The prepared materials were characterized by FI-IR,TEM,ICP and nitrogen adsorption-desorption isotherms.The results show the oxo-vanadium?IV?complex has high surface area,large pore volume,robust 3D-continuous organic network and high vanadium content,which has potential application in heterogeneous catalysis.The introduction of mesoporous tubular channels in the network units improves mass transfer in the catalytic systerm and the well distribution of catalytic sites in the channels facilitates the accessibility of active sites,which will be beneficial to good catalytic performance in heterogeneous catalysis.The prepared oxo-vanadium heterogeneous catalyst show high catalytic performance and stability in the selective oxidation reactions of thiols to disulfides.In addition,high catalytic activity in various oxidation reactions shows the excellent universality of the vanadium-loaded catalyst in various substrates.Hydrophilic poly?ethylene glycol?bottlebrushes loaded with thermal-sensitive dye were synthesized by RAFT polymerization and click chemistry.Polypyrrole nanoparticles packed with the PEG shell were obtained from the bottlebrush copolymers via the oxidative polymerization of the pyrrole part.The structure and molecule weight of dye molecules and polymer bottlebrushes were confirmed by ¹H NMR?GPC?MS?FI-IR?UV-Vis and elemental analysis.TEM images show the existence of nanoparticles and the results of UV-Vis demonstrate the controlled release of the dye molecules.The polypyrrole nanoparticles have good photothermal effect and the thermal-sensitive dye can be controlled-released under near infrared?NIR?laser irritation?808 nm?.The study can enrich the synthetic methods and provide the theoretical foundation for their application in the drug delivery and controlled release.