Nanochitin/metal ion dual reinforcement in synthetic polyacrylamide network-based nanocomposite hydrogels

Nanocomposite hydrogels consisting of a synthetic matrix reinforced by nanosized crystalline polysaccharides offer significant potential in various fields. Different from nanocellulose, the combination of nanochitin with synthetic polymers to obtain nanocomposite hydrogels has not been extensively and systematically studied. Herein, a physically and chemically dual crosslinked nanocomposite hydrogel was successfully synthesized, where chitin nanowhiskers (ChNWs) and Zn2+ were incorporated within polyacrylamide (PAAm) matrix. Nanochitin/metal ion dual reinforcement imparts increased elasticity, enhanced mechanical properties, and improved recovery performance to PAAm network. The PAAm/ChNWs/Zn2+ hydrogel could be stretched to over 13 times its original length with tensile strength of 321.9 +/- 8.2 kPa, and restore its original shape rapidly even when compressed at a strain of 95% with a corresponding compressive strength of 6.95 +/- 0.20 MPa. The multiple crosslinks and interactions among ChNWs, Zn2+ and synthetic polymeric network were investigated. Moreover, the hydrogel was applied in drug release and soft bioelectronics.