Tannic Acid Physically Cross‐Linked Responsive Hydrogel

Tannic acid (TA) is a polyphenol‐rich compound found in many natural plants. There are large numbers of phenolic hydroxyls at the terminal of the TA molecule, being capable of forming hydrogen bonds with hydrogen‐bonding donating polymers such as polyvinylpyrrolidone (PVP) and then engineering a hydrogel network. The reversible switch between phenolic hydroxyls and quinones tuned by pH affords the dynamic nature of the resultant hydrogen bonds. The gels exhibit excellent shear‐thinning and self‐recovery properties. Moreover, the polyphenols can form coordinates with Fe(III) that link different TAs to form a hydrogel network. Hence, adding Fe(III) solution to the TA‐PVP sol can form additional interactions inside the TA‐PVP gel. The easy preparation of the dual‐responsive gels with nontoxic raw materials may allow for its application in the biomedical field. A physically crosslinked responsive hydrogel is prepared using tannic acid (TA) and polyvinylpyrrolidone (PVP). The hydrogen bonds between the phenolic hydroxyls of the TA molecule and carbonyl group play a vital role in the formation of the obtained hydrogel which exhibits responsibility, self‐recovery, and self‐healing properties. The easy preparation of the dual‐responsive gels with abundant raw materials may allow for its application in the biomedical field.