Construction And Properties Study Of Fluorescent Supramolecular Star-shaped Polymers

Star polymer refers to a central unit with three or more arms radiating from the core.The unique topology structure of the star polymer makes it have a compact structure,high arm density and unique rheology,and it has broad application prospects in the fields of drug delivery,catalysis,biological imaging and nanoreactors.Supramolecular chemistry mainly refers to complex and ordered molecular conjugates with different structures and functions that are interconnected by non-covalent weak interaction forces between different chemical species.Supramolecular star polymers refer to a class of new polymers constructed through the interaction of non-covalent bonds.In particular,the introduction of metal coordination bonds into star polymers can construct a class of supramolecular stars polymers with unique properties and functions.In this thesis,through the combination of supramolecular star polymers and fluorescent moieties,a series of supramolecular star polymers with porphyrin and tetraphenylethylene fluorescent groups were successfully constructed,and further investigations on their properties such as aggregation-induced emission?AIE?,CO₂stimulus responsiveness,self-assembly behaviours,and applications in photodynamic therapy?PDT?and antibacterial were performed.The research content of this thesis is mainly divided into the following parts:In Chapter one,the concepts of organic fluorescent materials,star polymer,and supramolecular star polymer,respectively,are introducted with a focus on the rescent research progresses in these fields.On this basis of the literature reveiw,the research topics of this paper are proposed.In Chapter two,two types of endo-and exo-functionalized tetraphenylethylene modified metallacycles were first synthesized by coordination driven self-assembly.Then the“post-assembly polymerization”strategy was used to precisely construct the two types of amphiphiles supramolecular star polymers with aggregation-induced emission?AIE?properties.The structure of these supramolecular star polymers was characterized and determined by proton nuclear magnetic resonance,mass spectrometry,infrared spectroscopy and other characterization methods.The self-assembly behavior of these two types of star polymers in the aqueous phase was then studied by transmission electron microscopy and dynamic light scattering,and it was proved that these two types of supramolecular star polymers can be assembled into nano-spherical structures.The phenomenon of their aggregation-induced emission was further studied by fluorescence spectroscopy,and it was proved that with endo-functionalized tetraphenylethylenes supramolecular star polymer had better aggregation-induced emission capacity.In Chapter thee,a bipyridine donor with a porphyrin group was first synthesized,and then a porphyrin-functionalized metallacycle was constructed by its self-assembly with a platinum acceptor through coordination bonds.Subsequently,the"post-assembly polymerization"strategy was used to precisely construct a porphyrin-functionalized supramolecular star polymer.The structures of metallacycle and supramolecular star polymers were characterized by proton nuclear magnetic resonance,mass spectrometry,infrared spectroscopy,gel permeation chromatography and other techniques.The self-assembly behavior of the star polymer in the aqueous phase was studied by scanning electron microscopy,transmission electron microscopy and dynamic light scattering.The cytotoxicity and other biological properties of the resultant star polymer were then studied by confocal microscopy,singlet oxygen measurement compatibility and photocytotoxicity.We expect that such supramolecular star polymers can be used in the fields of biological imaging and photodynamic therapy.In Chapter four,based on the research in Chapter three of this thesis,the polymer segment was replaced with polymethacrylate N,N-dimethylaminoethyl chain?PDMAEMA?which had CO₂ stimuli-responsive properties.Through the"post-assembly polymerization"strategy,three PDMAEMA chains were introduced into the metallacycles to construct a class of supramolecular star polymers with CO₂ stimuli-responsive properties.The structure of the resultant supramolecular star polymer was characterized by means of nuclear magnetic resonance,infrared spectroscopy,gel permeation chromatography and so on.The star polymer can spontaneously self-assemble into a nano-spherical structure in water.The CO₂stimulus response properties of this star polymer were studied by proton nuclear magnetic spectroscopy,dynamic light scattering and transmission electron microscopy,which proved the changes of the morphology and the size of the aggregation before and after CO₂ stimulation.Pseudomonas aeruginosa was used to study the antibacterial properties of the star polymer.Through the combination of confocal microscopy,singlet oxygen testing and in vitro antibacterial experiments,the star polymer was proved to have good antibacterial properties.