Study On The Effect And Application Of Methyl On The Properties Of Azobenzene Polymer

Adhesives play an essential role in the processing and use of various materials such as metals,plastics,and wood products.However,traditional adhesives are difficult to debond.It usually requires high temperature water bath or acid-base soaking to debond.A lot of waste are generated in the process.Not only cannot reuse resources,but also pollute the environment.Therefore,a material is urgently needed to solve this problem.Azobenzene is a compound with photoisomerization properties.It contains-N=N-bond in its molecule,and can undergo reversible cis-trans isomerization under ultraviolet light or visible light irradiation.Some special solid azobenzene derivatives can be converted into cis-isomers with melting points lower than room temperature when irradiated with ultraviolet light,thereby being reversibly converted from solids to isotropic liquids,thereby changing their adhesion properties.This feature satisfies the needs of adhesives,but the factors affecting the photo-induced solid-liquid transition properties of azobenzene polymers need further study.On this basis,this article has conducted in-depth research on azobenzene derivatives and their polymers containing methyl groups.As a typical electron donating group,methyl groups have a great influence on the electron cloud density and conversion free volume of azobenzene.In this paper,azobenzene and its derivatives with different methyl positions and quantities were synthesized,and their thermal stability and optical properties were explored.(1)Four acrylate-based azobenzene polymers containing no methyl group and one,two and three methyl groups were designed and synthesized respectively,and their structures were characterized by ~1H NMR.,Use gel permeation chromatography(GPC)to test the molecular weight and molecular weight distribution of azobenzene polymer;use thermogravimetric analyzer(TGA)to explore its thermal stability,and use UV-Vis spectrophotometer(UV-Vis)to respond to its light The performance is explored,and finally the solid-liquid transition behavior is observed with an optical microscope.The results show that in the solid state of the azo polymer without methyl group,no obvious photo-isomerization phenomenon is observed.When the molecule contains methyl group,the azo polymer has no obvious photo-isomerization phenomenon.The solid-liquid transition behavior also further shows that the presence of urgency promotes the cis-trans isomerization process of azo polymers.(2)Based on azobenzene derivatives containing one,two,and three methyl groups and their polymers,respectively,synthesize acrylate-based azobenzene polymers containing different methyl positions,and explore the effect of methyl positions on their properties.Impact,and characterized by the above-mentioned test methods.Three sets of experimental studies have shown that when the meta position of the phenyl ring of the carbon chain contains a methyl group,the conversion time of cis-trans isomerism can be shortened,and the photoisomerization phenomenon of azo polymers can be promoted.(3)Explore the application of the above synthesized azobenzene polymer in the field of reversible adhesives,and use a universal testing machine to test different types of azobenzene polymers and their shear strength before and after light exposure.The results show that most of the polymers have certain application potential in the field of reversible adhesives,and four azo polymer materials with better performance are obtained,E1,D1,H1,and I1.After modifying four azo polymer materials with unknown strength,E2,E3,F2,and F3,were also obtained,which are expected to be used in the field of adhesives.