Study On The Preparation And Performance Of Polyphenols Based Hydrogels With High Strength And High Healing Efficiency

The self-healing hydrogel with the ability to repair damage automatically can prolong the life of the materials and reduce the cost of repairing or replacing.It is widely used in soft tissue recovery,biological tissue substitute and other fields.Mechanical performance and self-healing performance are two basic properties.But the high healing efficiency usually accommanied by the poor mechanical strength.As such,the tensile strength of reported hydrogels is relatively low.Based on the high activity of phenolic hydroxyl groups in polyphenol compounds(dopamine,tannic acid),here,the hydrogels with high healing efficiency,high tensile strength,and good biocompatibility were developed by the formation of hydrogen bonds and electrostatic interactions between phenolic hydroxyl groups and polymer chains.The specific research work is as follows:The polydopamine-polyacrylamide(PDA-PAM)self-healing hydrogel has been applied in soft tissue recovery,because of its good biocompatibility,tissue adhesion,and self-healing properties.But the low tensile strength restricts its applications.By adjusting the p H during the dopamine polymerization and introducing the oxidant ammonium persulfate,the content of polydopamine in PDA-PAM hydrogel is increased to as high as 5%(mass percentage of dopamine/acrylamide).The tensile strength of the prepared hydrogel can reach 16 k Pa,which is 2 times high of the reported PDA-PAM self-healing hydrogel.Infrared spectroscopy indicates the dopamine polymerization and the acrylamide polymerization.The tensile and self-healing experiments show that,after tensile fracture,the tensile strength can restore to96% after healing for 2 h.In vitro cellular experiments indicate the biocompatibility of the hydrogel.In current reports,the tensile strength of self-healing hydrogels with high healing efficiency(healing efficiency ≥80%)is below 63 k Pa,which is difficult to meet the requirements of load-bearing tissue substitution materials(such as cartilage and muscle implants).In order to manufacture self-healing hydrogels with higher strength,based on hydrogen bonds between the polyvinyl alcohol(PVA)and the tannic acid(TA),the PVA-TA self-healing hydrogels is prepared by optimizing the ratio of PVA and TA.The tensile strength of hydrogel can reach 224 k Pa with the healing efficiency of 87% after 2 h.This tensile strength is significantly higher than the reported self-healing hydrogels with high healing efficiency.Its biocompatibility is also supported by in vitro cellular experiments.To further increase the tensile strength,the chitosan(CS)is introduced into the former PVA-TA hydrogel.Based on the electrostatic interactions and hydrogen bonds among the CS,TA,and PVA,the PVA-CS/TA hydrogel with the tensile strength of 447 k Pa and the healing efficiency of 84% after 2 h is prepared.The tensile strength is 7 times of the highest strength of reported self-healing hydrogels(healing efficiency ≥80%).The infrared spectroscopy analysis results exhibit the existence of hydrogen bonds among the CS,TA,and PVA.The resonance light scattering analysis shows that the introduction of CS promotes the aggregation of polymer chains in the hydrogel.The in vitro cellular experiments suggest its biocompatibility.