Study On The Preparation Of Cellulose Graft Copolymer And Its Photochromic Functionalization

Cellulose is the most abundant biological organic raw material on earth,with the rich sources,biodegradable and environmentally friendly advantages.However,due to the existence of intramolecular and intennolecular hydrogen bonds,cellulose is insoluble in water and common organic solvents.The poor solubility limits the application of cellulose in many fields.Therefore,it is imperative to improve the solubility of cellulose in conventional solvents by chemical modification,and to give cellulose photochromic function to expand its application field.Based on the above research ideas,the research content of this paper mainly includes the following three aspects.Firstly,cellulose was used as raw material to react with 2-bromo-2-methylpropionyl bromide to prepare macromolecular initiator,and cellulose graft copolymers with different branched chain structures were prepared by the method of atomic transfer radical polymerization technique(ATRP).FT-IR,1H NMR and XPS test results show that the copolymers have been successfully prepared.The solubility tests show that the sampes have good solubility than pure cellulose and can dissolve in common organic solvents.TG and DSC results prove that the copolymers have good thermal stability.Secor,ndly,spiropyran derivative was grafted onto the cellulose backbone via esterification and the cellulose graft copolymers with photochromic function were prepared through the method of ATRP.FT-IR and IH NMR results show that the target plobucts have been suceessfully prepared.UV-VIS absorption spectra and fluorescence tests show that the samples have good photochromic function and can display different colors excited by ultraviolet light of different wavelengths.Finally,the photochromic cellulose graft copolymers prepared above were configured into a casting film solution with a certain mass concentration,and the photochronmic cellulose films were prepared by nonsolvent induced phase separation(NIPS).The surface morphology of cellulose films were observed by microscope.The results of ultraviolet test show that the cellulose films can show differernt corlors under ultraviolet excitation.The mechanical property analysis show that cellulose films have the mechanical properties,which provide the good foundation for wide application in different fields.