Topology Regulation And Properties Of Polymers Based On Highly Efficient Chemical Reactions

Polymer synthetic chemistry not only expands the types of polymerization reaction and enriches the types of polymers,but also provides a solid theoretical foundation for the preparation and application of functional materials.The design and development of novel polymerization reaction,the regulation of polymer topological structure and synthesis of multifunctional polymers have been the research hotspots of polymer synthetic chemistry.High efficiency chemical reaction has the characteristics of high reaction efficiency,selectivity and atom utilization,mild reaction conditions,and can be used to regulate the topological structure of polymers and functionalize polymers.Hyperbranched polymers and porous polymers with unique physical and chemical properties have attracted extensive attention in recent years.In recent years,the design and synthesis of fluorescent polymers is also an important research direction of multifunctional polymer.This paper is mainly to design efficient chemical reactions and apply them to regulate the topological structure and synthesize functional polymers.Novel hyperbranched polymers were synthesized by Friedel-Crafts reaction and amino-yne click reaction respectively.And nitrogen-rich porous organic polyamine was synthesized by Schiff base reaction.Its application as organic carrier in the synthesis and catalysis of metal nanocomposites was also explored.In addition,fluorescent initiators were constructed based on amino-yne click reaction,and a series of fluorescent polymers were synthesized.The main research contents are summarized as follows:Chapter 2:100%hyperbranched polymers were synthesized via Friedel-Crafts aromatic substitution reaction of the novel AB₂ monomer catalyzed by trifluoromethanesulfonic acid.Firstly,the rate constant（K₂）of the second step is much larger than that of the first step（K₁）（K₂>>K₁）,which provides a theoretical basis for the synthesis of 100%hyperbranched polymers.At the same time,the regioselectivity of the reaction was determined by the model reaction,which provided a basis for the accurate structure characterization of hyperbranched polymer.The molecular weight of the synthesized hyperbranched polymer can be adjusted by controlling the polymerization temperature and time because of the mechanism of gradual polymerization.Next,the precise structure of the polymer was determined by FT-IR and NMR,and DB of the synthesized hyperbranched polymer was proved to be100%.Chapter 3:Hyperbranched poly（ester enamine）（hb-PEEa）were synthesized by amino-yne click reaction.Gelation is an intrinsic problem in an ideal A₂+B₃polymerization system.By controlling the polymerization conditions,the gelation of the polymerization system was avoided,and hb-PEEa with good solubility was synthesized.Due to abundant unreacted alkynyl groups in periphery,amphiphilic hyperbranched polymer PEG-hb-PEEa was synthesized by further functionalization of NH₂-polyethylene glycol monomethyl ether.The synthesized PEG-hb-PEEa not only has a highly branched topological structure,but also contains a large number of amino and ester functional groups.It can enrich metal ions by complexation,control the nucleation and growth of metal nanoparticles.AuNPs@PEG-hb-PEEa has good dispersion in water and high stability,and show high catalytic activity in the catalytic reduction of nitrobenzene compounds in water.Chapter 4:A novel fluorescent molecular framework was constructed by amino-yne click reaction.On this basis,a series of fluorescent compounds（NBKI3a-3i）,fluorescent initiators（i-NBKI）and fluorescent polymers were prepared.First,the terminal ketone alkynyl compounds with higher reactivity were designed and synthesized,and a series of ketoamine ligands were synthesized by click reaction with amino compounds（alkyl amine or aromatic amine）,and then coordinated with boron trifluoride ether to construct novel fluorescent compounds.On this basis,we explored the synthesis of fluorescent initiators（i-NBKI 1-4）for atom transfer radical polymerization（ATRP）,and studied the polymerization of different monomers,so as to synthesize fluorescent polymers with different chemical composition and fluorescence properties.The synthesis of chain transfer agents（i-NBKI 5）for reversible addition fragmentation chain transfer polymerization（RAFT）was explored,and its application in the synthesis of amphiphilic block fluorescent copolymers was studied.Polyethylene glycol fluorescent polymer（PEG-i-NBKI）and fluorescent block copolymer（i-NBKI-5-P（DBA-PEG））have good water solubility and fluorescence properties.Chapter 5:Organic porous polyamines（POPa）were synthesized by using Schiff base chemistry of melamine and used to prepare highly stable metal nanoparticles supported catalysts（Au NPs@POPa and Pd NPs@POPa）.The strong nucleophilic activity of melamine can avoid the formation of unstable imine bonds,thus improving the chemical and thermodynamic stability of POPa.POPa has large surface area,abundant pore structure and a large number of nitrogen functional groups.It can effectively control the size and dispersion of metal nanoparticles in materials,and obtain high metal loading and stability.Au NPs@POPa and Pd NPs@POPa exhibit remarkable catalytic activity and good cycle stability in reduction of nitrobenzene compounds and organic dyes,and Suzuki-Miyaura coupling reaction,respectively.