Self-healing hydrogels based on complex formation between a sugar and metal ions

Abstract

Self-repairing gels utilize reversible bonds at cross-linking points, which are repaired by the reformation of these bonds. On the other hand, such reversible bonds can be dissociated by exchange reactions with competing agents under the presence of contaminants. In this study, hydrogels with stable self-healing properties in the presence of various metal ions were prepared by using metal coordination bonds between sugars and monovalent metal ions as cross-linking points. Water-insoluble polymer complexes were formed by mixing polymers possessing a sugar side chain with poly(sodium 4-styrenesulfonate) (PSS) in water. This result indicates that the hydroxyl group of the sugar chain interacted with sodium ions, which are the counter ions of PSS. The hydrogels prepared by utilizing the complex formation exhibited self-healing ability and good stability in the presence of mono- and multivalent metal ions.