Structure and properties of biodegradable self-healing starch/PVA/chitosan hydrogels
Kai Lu, Cornelis Post, Jintao Hu, Dina Maniar, Rudy Folkersma, Vincent S.D. Voet, Katja Loos
Abstract
In this study, a biodegradable and self-healing starch-based hydrogel (starch/polyvinyl alcohol (PVA)/chitosan/borax) was synthesized via a one-pot method. The effects of the chitosan concentration on the resulting hydrogel properties were systematically investigated. An increase in the chitosan concentration increased the gel fraction and decreased the swelling ratio. The addition of chitosan and borax significantly increased the strength of the hydrogel, as the maximum storage modulus increased by 10 times, from 441 Pa to 4276 Pa. In addition, the hydrogel showed self-healing ability and thermal responsiveness due to the dynamic borate ester between the hydroxyl groups of PVA and starch and the hydrogen bonding between the hydroxyl or amino groups of chitosan and the hydroxyl groups of starch and/or PVA. The synergistic dual reversible crosslinking of hydrogen bonds and borate ester bonds imparts hydrogel with self-healing capabilities. The hydrogel demonstrated excellent recovery behavior under continuous step strain. Furthermore, the prepared hydrogels are prone to biodegradation in activated sludge, with a relatively high degree of biodegradation between 23 and 32 % after 28 days, demonstrating their good biodegradability. We expect that the present research could broaden the application of biodegradable starch-based hydrogels, such as those used in agriculture and sensors. • A novel starch-based hydrogel was synthesized. • The addition of chitosan and borax significantly reinforced the strength of the hydrogel. • The hydrogel exhibited excellent recovery behavior and thermal responsiveness. • The hydrogel demonstrated a biodegradable character in activated sludge.