Construction And Properities Of Fluorescent Supramolecular Waterborne Polyurethane Gel Based On Metal Coordination

In recent years,the application of fluorescent supramolecular polymer in the fields of optoelectronics,sensors and intelligent materials has received widespread concern.Among them,the self-assembly based on metal coordination as the driving force has a very important position and is widely applied in the construction of supramolecular polymer.At present,most fluorescent polymer uses organic fluorescent molecules,but organic fluorescent molecules in the aggregation state will occur fluorescence quenching or weakening(ACQ).In this paper,a fluorescent supramolecular polymer was constructed by combining waterborne polyurethane with effect of aggregation-induced emission(AIE).Various materials with different structural properties can be prepared by molecular design,therefore it can not only solve the restrictions of the application of traditional fluorescent molecule,but also give it good mechanical properties and self-healing properties.The details are as follow:1.The fluorescent chain extender with AIE tetraphenylethylene derivative (compound 3)and ligand chain extander 4'-p-N,N-Bis(2-hydroxyethyl)benzyl-2.2':6'.2"-terpyridine(P4)were designed and synthesized.Firstly,diphenylmethanone and 4,4'-dihydroxy-benzophenone were used as the raw materials,the Compou nd 2 containing tetraphenylethylene group was obtained by McMurry cross cou pling reaction,and then the long chain with ethoxyl was modified on the basis of Compound 2 to prepare Compound 3 to reduce its effect of spatial resist ance.Using Vilsmeier-Haack reaction,aldehyde group was introduced into the t ransposition of N,N-dihydroxyethylaniline to prepare 4-[N,N-Bis(2,hydroxyethyl)amino]benzaldehyde(P3).Finally,the target compound P4 was generated based on the Krohnke reaction.The structure was characterized by nuclear magnetic hydrogen spectroscopy(1H-NMR)and fourier infrared(FT-IR),the metal coor dination interaction was characterized by ultraviolet titration,and the fluorescent property of P4 was characterized by fluorescence emission spectroscopy.2.On the basis of the above,two functional chain extenders were prepared,through active hydroxyl to generate linear waterborne polyurethane.In this system,the metal coordination was added to construct the physical cross-linked three-dimensional supramolecular waterborne polyurethane with AIE effect.The fluorescence intensity of fluorescent waterborne polyurethane was tested by fluorescence emission spectroscopy,and the results showed that improvement of 20H-TPE(Compound 3)content and addition of metal ion can both significantly enhance the fluorescence.The ligand 20H-TPY also had a certain fluorescent intensity,and its fluorescent response was opposite to 20H-TPE.The tensile test showed that the formation of the physical cross-linked network can obviously improve the Young's modulus of the film,and the Young's modulus of the WPU50-1 and WPU50-2 films after the addition of Zn2+ was increased from 7.25 MPa and 33.83 MPa to 41.04 MPa and 187.13 MPa respectively.The supramolecular gel displayed multiple stimulus response,self-healing performance and good mechanical properties.Gel can convert into sol by heating or adding competitive ligand,and then it can be re-formed by cooling and re-adding the transition metal ions.After dyeing the WPU50-2 gel and cutting it into two parts,the gel was simply stretched after a 10-min self-healing,and it was not broken at the splicing.The tensile test showed that the supramolecular gel based on waterborne polyurethane had good mechanical properties,the elongation at break was up to 250%,and the elongation at break can also reach 139%after 10-min self-healing at room temperature.