Preparation And Properties Of Self-Healing,Multi-Responsive Color-Change Hydrogel Based On MHB

Smart hydrogels are widely used in drug delivery devices,wound dressings,tissue engineering,isolation materials,and sensors due to their high moisture content,high elasticity,and responsiveness to pH and temperature stimuli.As an indispensable part of biomedical materials,smart hydrogel is a hotspot that people pay close attention to and study.Self-healing is a very important way to improve the reliability and durability of hydrogels.At present,most researches of the self-healing hydrogels are reversible non-covalent bonds,such as hydrogen bonds,electrostatic interactions,host-guest interactions,and metal coordination bonds.The main research directions are single stimulus response hydrogel(like pH,heat,light),or double stimulus response hydrogel.With the development of science and technology,the demand for multiple stimuli-responsive hydrogels is becoming more and more urgent.The self-healing,high-strength,excellent performance of multiple stimuli-responsive hydrogels is still a research difficulty and challenge.In this paper,two types of double-network hydrogels were designed and prepared:hydrophobic association(HA)hydrogel and sodium alginate/polyvinyl alcohol/hydroxyapatite(SA/PVA/HAp)hydrogel.Using the structural changes of Michler's hydrol blue(MHB)before and after ultraviolet irradiation,as well as its solubility changes,were introduced into the hydrogels of the as mentioned two systems by a simple and efficient method.And the stimulus response behaviors such as pH,temperature and solvent were explored.We have successfully got a self-healing hydrogel with strong mechanical properties and multiple stimuli responsiveness.The main research contents and results obtained in this paper are as follows:1.HA hydrogel was synthesized and MHB was introduced into HA hydrogel.MH-HA hydrogel was successfully prepared.The hydrogel has multiple stimuli responsiveness,that is,it shows sensitivity to pH,light and alcohol solvents stimulus responsiveness.Excellent swelling performance by 2010%of the hydrogel was confirmed by measurements of swelling,time-dependent rewetting data and differential scanning calorimeter(DSC).Through tensile testing,we verified that the introduction of MHB did not affect the mechanical properties of the hydrogel matrix,and the tensile strength of the hydrogel reached up to 0.9 MPa with loading MHB by 2.0%.MH-HA hydrogel also shows excellent self-healing performance,and can complete self-healing at room temperature without any external stimulus,which ensures its stability and longevity.2.The SA/PVA/HAp hydrogel was designed and successfully synthesized,and it was proved by infrared that the added HAp and SA formed an "eggshell"structure.Through the swelling rate test,the optimum freezing-thawing times was determined to be 4 times.And through TGA,DSC,tensile test and SEM,it was demonstrated that with the increase of HAp content,the cross-linking network density of the hydrogel system increased.The performance has also been improved:Among them,the mechanical properties of the hydrogel with 3%HAp can reach 0.28 MPa,and the residual weight at 400? reaches 57%.Then,MHB was successfully introduced into the SA/PVA/HAp hydrogel system by a simple and efficient method,and its response was tested.Therefore,we verified that the method of introducing MHB into the hydrogel system is universal,and the method is easy and efficient,and provides a new idea for the preparation of multi-response hydrogels.