Preparation And Property Analysis Of Stimuli-responsive Polymers

Stimulating responsive luminescent polymers are a class of intelligent macromolecular systems that accept physical(temperature,optical radiation,electromagnetic fields,stress,etc.)and chemical(p H,ionic strength,redox agents,biomolecules,etc.)stimulating signals from external environmental inputs,causing changes in polymer unit configuration,chain structure,and assembly morphology,resulting in the sudden change of macroscopic properties of the system,which is also known as environmentally sensitive polymer.Light-emitting polymers usually use quantum dots,metal complexes or organic fluorescent monomers as the source of light emission.The introduction methods are usually divided into two types,one is physical doping(the interaction mode is mainly non-covalent bonds);the other is the formation Covalent bond(covalent and non-covalent bonds exist in the interaction mode).Although quantum dots have good fluorescence properties,their application is limited due to their toxicity.At the same time,metal complexes are faced with the difficulties of high cost,high toxicity,limited resources and easy precipitation due to the inclusion of metals;therefore,selecting organic fluorescent monomers as the luminous source and introducing them into the polymer structure in the form of covalent bonds will solve the above problems problem.The luminous properties of stimuli-responsive polymers are endowed,and the construction of stimulus-responsive luminescent polymers is widely used in the fields of controlled release of drugs,fluorescent probes,and biological scaffolds.Therefore,this paper synthesized five fluorescent small molecule monomers and three types of stimuli-responsive luminescent polymers.First,using carbazole,rhodamine B,benzaldehyde,pyrrole and acryloyl chloride as raw materials,through the means of organic synthesis,we successfully prepared five kinds of small-molecule fluorescent monomers with different luminescent properties;then the synthesized small molecules Fluorescent monomer as the light source,with ethylenediamine ethyl methacrylate(DEAEMA)as the carbon dioxide-responsive monomer,trifluoroethyl methacrylate(FMA)as the oxygen-responsive monomer,and methacrylic acid In order to adjust the water-soluble monomers of the polymer,three types of stimulus-responsive luminescent polymers were synthesized by means of free radical random copolymerization and reversible addition-fragmentation chain transfer polymerization(RAFT).They are oxygen or carbon dioxide single-response light-emitting random copolymer,oxygen and carbon dioxide double-response light-emitting diblock copolymer,and carbon dioxide and temperature double-response light-emitting diblock copolymer with critical phase separation temperature.The stimulus-responsive luminescent polymer synthesized in this paper has a low polydispersity index and a high molecular weight.By conducting sensitivity experiments on it,it was found that the synthesized stimulus-responsive luminescent polymer has high sensitivity to both carbon dioxide and oxygen;in response to the double-responsive fluorescent diblock copolymer of oxygen and carbon dioxide in aqueous solution,carbon dioxide Switching with the stimulation of oxygen can make the polymer form micelles in the aqueous solution and realize the reversal of the polymer micelles;through the change of the fluorescence intensity,the reverse process of the polymer micelles can be visually observed;The change of absorbance at a certain wavelength can indirectly reflect the inversion process of polymer micelles.The excellent biocompatibility of the polymer synthesized in this thesis and the cyclic reversibility of the response to stimuli make this type of polymer widely applicable to the fields of controlled release of drugs,fluorescent probes and biological scaffolds.Through the fluorescence performance and spectrum research of the five newly synthesized fluorescen tmonomers,it was found that the fluorescent monomers have good fluorescent properties in the polymer,and they can still be independent of other covalent monomers and maintain their excellent light-emitting characteristics.Therefore,it can be tried to be applied to various types of polymers to give them luminescent properties,which is of great significance to the development of the field of optical functional polymers.