Preparation And Properties Of Schiff Base Intelligent Fluorescent Hydrogels Containing Acylhydrazone Structure And Pyridine Ring

Smart fluorescent hydrogels have both the characteristics of traditional hydrogels and fluorescent materials,and can produce stimulus responses to the external environment.They have been widely used in soft light-emitting devices,biosensors,tissue engineering and other fields.At present,most smart fluorescent hydrogels face problems such as unstable luminescence,single performance,poor mechanical properties,etc.,and it is difficult to expand and apply to more fields.Based on this,this thesis successfully designed and prepared two Schiff base smart fluorescent hydrogels containing pyridine ring acyl hydrazone structure.The Schiff base containing pyridine ring acyl hydrazone structure gives the hydrogels stable luminescence and fluorescence performance.Tonal,external stimulus response ability,self-repair and shape memory functions,while improving the micellar copolymerization method,breaking through the mechanical properties of smart fluorescent hydrogels.（1）The problem of how to introduce the pyridine-containing acylhydrazone structure into the hydrogel network is solved,and the types of Schiff base hydrogels are broadened.The Schiff base self-healing fluorescent hydrogel P（AM-PEGA-PEPMA）hydrogel and Zn²⁺-P（AM-PEGA-PEPMA）containing the pyridine ring monoacylhydrazone structure were successfully prepared by the micellar copolymerization method.Excellent ductility,fluorescence adjustability,p H responsiveness,self-healing function and shape memory function.The prepared hydrogel containing the pyridine ring monoacylhydrazone structure can achieve 98%self-healing within 50 s,it can emit strong blue-green fluorescence,and it can be quenched during H+/OH-alternating titration At the same time,the fluorescence intensity can be adjusted by the external Zn²⁺ion concentration.While adopting the micellar polymerization method,the soft monomer PEGA is introduced to improve the flexibility of the material,so that the hydrogel can be extended to 900%of the original length.（2）Designed and prepared Schiff base fluorescent hydrogels As-prepared hydrogel and Eu-hydrogel containing pyridine ring diacylhydrazone structure.On the basis of the micellar polymerization method,the hydrophobic monomer EA is added to increase the density of the hydrophobic association in the hydrogel system,and the crosslinking agent PDCH containing the pyridine ring diacylhydrazone structure is introduced at the same time,thus breaking through the intelligent fluorescent hydrogel In terms of mechanical properties,in the tensile test,it can be stretched to≈800%of the original length,and the breaking strength can reach 1.55MPa.With the same formula,it is easy to prepare a large stretch-resistant size（side length of10 cm）.)Hydrogels.The introduction of temperature-sensitive monomers PEGA and MEA also endows the hydrogel with temperature response performance.After the hydrogel is complexed with Eu³⁺,it will undergo a more easily identifiable change in fluorescence color,and its fluorescence intensity will also be regulated by the concentration of the added Eu³⁺ion and pH.