Research On Preparation Of Stimuli-responsive Organic Materials And Application Of Erasable Information Storage

Stimulation-responsive materials,as intelligent materials that can change their physical and chemical properties and be reused after being stimulated by external environments,have been widely used in basic research and practical engineering.Azobenzene and its derivatives,as functional units of stimulus responsive materials,can respond to different stimulus sources:under light stimulation,azobenzene has trans and cis structures with significant differences in molecular size and dipole moment,leading to changes in surface morphology;and under acid-base stimulation,azobenzene undergoes a protonation/deprotonation process,and achieves a reversible transformation with quinone structure,thus affecting the macro performance.In the process of constructing stimulus responsive smart materials,the introduction of azobenzene as a stimulus responsive switch is feasible and efficient.In this paper,azobenzene derivatives,azobenzene polymers,and azobenzene covalent organic framework(COF)materials were prepared using the light/acid base dual response characteristics of azobenzene groups.Combined with bilayer film/substrate surface wrinkling technology and paper surface impregnation technology,various stimulus responsive materials were constructed and applied in fields such as information storage,information encryption,and moisture sensing.This mainly includes the synthesis of bio-based azo polymers and the construction of multiple stimulus responsive materials,the synthesis of fluorinated azo polymers and the study of p H/light changing mechanisms,and the preparation and performance of azo covalent organic frameworks(COF).The specific research contents are as follows:(1)Construction and application of a biobased azo polymer dual stimulation response system: Starting from molecular design,a new type of epoxy functional monomer was synthesized using itaconic acid as raw material,and a new photo-responsive bio-based epoxy resin containing azobenzene was further prepared.The structure,light response and acid-base response were characterized by FT-IR,NMR and UV vis spectra.The results show that the new photosensitive polymer has excellent photo responsiveness and acid-base responsiveness,visible light induced surface stress relaxation of polymer wrinkled film system,achieving dynamic regulation of surface microstructure,and acid/alkali induced protonation/deprotonation of azo polymer realized a significant visual color change from orange to purple red.Based on the dual responsiveness mentioned above,the application of new polymer film materials in erasable information storage has been achieved.(2)Study on the preparation and information storage application of fluorinated azo polymer: Four types of azobenzene polymers with different substituents were synthesized by reacting fluorinated and non-fluorinated monomers with small molecule derivatives of azobenzene.The structure,acid-base response,and rate of the polymers were systematically characterized using testing methods such as NMR,FT-IR,and UV-vis spectroscopy.The results show that the acid base induced protonation/deprotonation of azobenzene groups based on azobenzene polymer forms a quinone structure to produce visual color transformation characteristics.The information storage and anti-counterfeiting encryption are widely used by using strategies such as paper impregnation,film/substrate system construction and so on.Fluorine substituted polymers among the four azo containing polymers are suitable for long-term surface information storage,and fluorinated substituted azobenzene polymers and non-fluorinated substituted azobenzene polymers achieve high efficiency,convenience,and fine regulation in the field of information encryption.(3)Preparation and performance study of azo covalent organic framework(COF): firstly,two bifunctional azobenzene small molecular derivatives were synthesized by coupling method,and then azobenzene COF structure was prepared with trifunctional trimesoyl chloride through nucleophilic addition elimination process,and the structure and performance of azobenzene COF were characterized by FT-IR,XPS,BET,SEM and other methords.The results showed that two types of azobenzene based COFs were successfully prepared,and the relationship between the formation process of azobenzene COF and the preparation method and condition control was further systematically studied through scanning electron microscopy.In addition,azobenzene COF achieves significant visual color transformation characteristics through acid-base induced protonation/deprotonation,which has good applications in information storage,environmental monitoring steam sensing and so on.