Preparation And Performance Study Of Fluorescent Aqueous Polyurethane With Schiff Base Zinc Complexes

Conventional polymer fluorescent materials are produced by blending fluorescent organic small molecules and inorganic fluorescent substances into a polymer base material.However,the blended polymer fluorescent materials are susceptible to fluorescence migration and mechanical strength degradation of the substrate,which can be avoided by bonding the fluorescent materials into the polymer chain segments.However,there are few fluorescent organic small molecules with suitable groups for bonding,and it is very difficult to modify fluorescent small molecules by adding suitable functional groups.To solve the above problems.These problems can be solved by bonding fluorescent transition metal complexes,which can be easily modified by changing ligands,to aqueous polyurethane substrates to obtain green,non-polluting fluorescent polymers.Transition metal complexes have excellent fluorescence properties,good chemical stability,easily modifiable structures and are cost effective.Since Schiff base complexes are easy to synthesise and have excellent fluorescence properties,this paper prepares Schiff base transition metal complexes with suitable groups and bonds them to aqueous polyurethanes.The result is a fluorescent aqueous polyurethane with fluorescent properties of the transition metal complexes.The main research elements of this paper are as follows:（1）Fluorescent aqueous polyurethanes Zn L₂were prepared by reacting salicylaldehyde with ethanolamine to form the Schiff base salicylaldehyde ethanolamine（HL）,with zinc ion as the central ion and salicylaldehyde ethanolamine as the ligand,and using it as a chain extender to bond to aqueous polyurethane chain segments.WPU and characterized its structure and properties.The results show that Zn L₂-WPU has a strong blue fluorescence,a homogeneous film texture with no precipitation of complexes,and a twofold increase in fluorescence lifetime compared to Zn L₂due to the improved rigidity of the bonded structure.It also has excellent antibacterial properties.This study provides an avenue for the development of new polymer fluorescent materials.（2）The transition metal complex Zn（L₂）₂with blue fluorescence emission was synthesized by reacting salicylaldehyde with trihydroxy aminomethane to form the Schiff base salicylaldehyde trihydroxy methane（HL₂）,using zinc ion as the central ion and salicylaldehyde trihydroxy methane as the ligand,which was used as a cross-linking agent to bond to the chain segments of the aqueous polyurethane to prepare the salicylaldehyde trihydroxy methane fluorescent aqueous polyurethane[Zn（L₂）₂-WPU].[Zn（L₂）₂-WPU]was prepared as a cross-linking agent and bonded to the chain segments of the aqueous polyurethane to produce a fluorescent aqueous polyurethane[Zn（L₂）₂-WPU].The results show that the Zn（L₂）₂complex was successfully bonded to the aqueous polyurethane chain segments.The fluorescence lifetime is significantly enhanced.It also has excellent antibacterial properties.（3）The Schiff base salicylaldehyde condensed with p-amino benzyl alcohol（HL₃）is formed by the reaction of salicylaldehyde with p-amino benzyl alcohol.1,4-dihydroxybenzaldehyde reacts with p-phenylenediamine to form the Schiff base bis 1,4-dihydroxybenzaldehyde condensed with p-phenylenediamine（HL₄）.1,4-dihydroxybenzaldehyde reacts with ethylenediamine to form the Schiff base bis1,4-dihydroxybenzaldehyde condensed with ethylenediamine（HL₅）.The three Schiff base fluorescent aqueous polyurethanes HL₃-WPU,HL₄-WPU and HL₅-WPU were used in combination with zinc ions to produce three transition metal complexes fluorescent aqueous polyurethanes Zn L₃-WPU,Zn L₄-WPU and Zn L₅-WPU.These six fluorescent polyurethanes were characterized in terms of structure and properties.The results show that these six fluorescent aqueous polyurethanes have a wide range of fluorescence emission from blue,blue-green and green.The fluorescent aqueous polyurethane emulsions were stable and the films had a uniform texture without precipitation of complexes.The fluorescence lifetime was significantly enhanced.It also has excellent antibacterial properties.The present study of fluorescent polymeric fluorescent materials in a variety of fluorescent colours provides an avenue to.Figure[51]table[9]reference[120]...