Preparation And Properties Of Self-healing Hydrogel Based On Phenylboronic Acid Copolymer

Hydrogel is a soft material with a three-dimensional network structure formed by chemical crosslinking or physical crosslinking of hydrophilic polymer in water.Due to its good biocompatibility,hydrogels can be used in many fields,such as tissue engineering,drug release and soft electronics.Traditional hydrogels have defects of lacking mechanical strength,permanent cross-linking and less synthesis and utilization of functional polymer,which greatly limit the application of hydrogels.In recent years,the research and application of physical and chemical properties of hydrogels have been rapidly developed.In this paper,two kinds of self-healing hydrogels were prepared based on two weak reversible interactions of boronate ester bond and hydrogen bonds.The specific research contents are as follows:Self-healing hydrogels consisting of 3-acrylamidophenylboronic acid(AAPBA),acrylamide(AM)and hydroxypropyl guar(HPG)with double bonds and boric acid groups were prepared by photo-initiated copolymerization.In the system,AAPBA forms polymer chains by copolymerizing with AM,and the boronic acid group of AAPBA forms boronate bonds with the cis diol on the HPG macromolecular chain,therefore a stable crosslinked network comes to be formed.The excellent mechanical properties of the hydrogel are adjusted by changing the content of the monomer and the pH of the system.Through the results of characterization and test,the yielding phenomenon of the hydrogel during the tensile test and the reasons for the change of the cross-linking mode of the hydrogel network were explained.The network of hydrogels constructed from boronate ester bonds and hydrogen bonds,all of which are reversible,imparting the gel with healing property.From the previous work summary and related literature reports,it is known that the use of boronate ester bonds not able to achieve the self-healing ability all the time in the constructing of the hydrogel.The hydrogen bond strength from boronic acid group when phenylboronic acid is used as a polymer is nonnegligible.Therefore,we further explore the properties of phenylboronic acid-based hydrogels.In the second experiment,we prepared a self-healing P(AM-co-AAPBA)hydrogel with glucose responsive property by dissolving 3-Acrylamidophenyl boronic acid and acrylamide in an alkaline solution.By analyzing the results of macroscopic mechanical properties and microstructural characterization,the hydrogel network was cross-linked by hydrogen bonds and B-N interactions.The reversible hydrogen bonds between the amino group and the boronic acid group imparts good self-healing properties to the hydrogel.The hydrogel also has glucose sensitivity by fluorescence characterization.