Study On The Construction And Optical Properties Of Polyarylene Ether Nitrile Micro-nano Materials With Metal Ion Coordination

Polymer micro-nano materials have larger specific surface area,higher surface activity,and exhibit basic properties（such as optical properties,melting point,etc.）that are different from the corresponding macroscopic materials.It has huge application potential in the fields of catalysis and sensors.Micro-nano materials based on polymer metal complexes combine the unique properties of polymer micro-nano materials and the photoelectromagnetic properties of inorganic metal ions,and have been widely used in materials technology and engineering.Polyarylene ether nitrile（PEN）is a high performance engineering polymer with a large number of aromatic rings in the main chain,so it can emit intrinsic blue fluorescence,however,because the alternate existence of benzene ring and ether bond affects the conjugation degree of polyarylene ether nitrile,its luminous efficiency is low.At the same time,the molecular structure of polyarylene ether nitrile is easily programmable and adjustable.It is facile to introduce active functional groups such as carboxyl and sulfonic acid groups into the side chain of PEN,so it can be used as an excellent macromolecular ligand for metal ions.In order to improve the weaknesses of low luminous efficiency and single color fluorescence of polyarylene ether nitrile,this thesis will focus on the construction and optical properties of metal ion-coordinated polyarylene ether nitrile micro-nano materials.Firstly,a series of amphiphilic polyarylene ether nitrile block copolymers（am PENs）containing active functional groups and a double hydrophilic polyarylene ether nitrile block copolymer（dh PEN）donated as D5S5were synthesized.Next,the self-assembly of the transition metal ions coordinated am PEN to blue fluorescence-enhanced composite microspheres was induced by emulsion solvent evaporation.Then,the self-assembly of the Tb³⁺coordinated D5S5 to strong green light emitting composite microspheres Tb-D5S5 was induced by the solvent displacement.The composite microspheres enriched the optical properties of polyarylene ether nitrile.Finally,a ratiometric fluorescence sensor was constructed on the basis of Tb-D5S5,which can detect Cr³⁺,p H and K₂CO₃.The detailed research contents are as follows:（1）Using bisphenol A and 2,6-dichlorobenzonitrile as raw materials for the hydrophobic section,4,4-bis（4-hydroxyphenyl）valeric acid/potassium hydroquinone sulfonate and 2,6-dichlorobenzonitrile as raw materials for the hydrophilic segment,a series of amphiphilic polyarylene ether nitrile block copolymer（am PEN）were synthesized via nucleophilic substitution polycondensation reaction.Next,using4,4-bis（4-hydroxyphenyl）valeric acid/and 2,6-dichlorobenzonitrile as the raw materials of a hydrophilic section,potassium hydroquinone sulfonate and 2,6-dichlorobenzonitrile as the raw materials of another hydrophilic section,a dh PEN containing both carboxylic acid and sulfonic acid was synthesized via the same reaction mechanism.Experimental results have shown that as the content of sulfonic acid groups with stronger polar in the amphiphilic block polyarylene ether nitrile increases,the fluorescence intensity of the polymer solution increases,and the corresponding thermal stability is better.The amount of hydrophilic groups in the dual-hydrophilic block polyarylene ether nitrile D5S5 is far more than am PEN,and the fluorescence intensity of D5S5 is far stronger than am PEN.（2）In order to improve the defect of low luminous efficiency of polyarylene ether nitrile aggregates,（post）transition metal ions were introduced to participate in the self-assembly process of am PEN in the emulsion to prepare composite microspheres.Experimental results have shown that the fluorescence intensity of metal ion-coordinated composite microspheres is significantly greater than that of uncoordinated polymer microspheres,and the structure of the polymer and the introduction of metal ions can effectively adjust the morphology of the microspheres.In addition,the composite microspheres also have crystallization ability in some extent.This method of metal ion coordinated with polymer provides a simple and effective way to enhance the fluorescence of polyarylene ether nitrile polymers under aggregation.（3）In order to enrich the optical properties of polyarylene ether nitrile and broaden its application fields,the double hydrophilic polyarylene ether nitrile block copolymer D5S5 with more active functional groups was used as the macromolecular ligand for Tb³⁺to prepare water-dispersed Tb³⁺coordinated PEN composite nanospheres Tb-D5S5by solvent replacement method.Experimental results have shown that the composite microspheres emit strong green light.On this basis,taking advantage of the adsorption capacity of Tb-D5S5,the red-emitting Rhodamine B was introduced as an internal standard to construct a ratiometric fluorescence probe Tb-D5S5/RB.Experimental results have shown that the fluorescence probe shows specific fluorescence quenching to Cr³⁺,and has a linear response to Cr³⁺in the range of 5×10^-6-0.04 mmol/L.At the same time,the probe has a linear response to p H in the range of 1.88-5.77 and7.51-11.09,showing a visual p H response.In addition,the probe also has a linear response to K₂CO₃in the concentration range of 0.05-7.41 mmol/L and shows the visual detection.Finally this probe realized the detection of residual potassium carbonate in the polyarylene ether nitrile produced by factory.