Shape morphing of anisotropy-encoded tough hydrogels enabled by asymmetrically-induced swelling and site-specific mechanical strengthening

This communication reports a dual regulation strategy, i.e., swelling and stiffness mismatch, for the shape morphing of calcium-alginate/polyacrylamide (PAAm) tough hydrogels enabled by site-specific patterning of ferric ions. Complex 3D or even 4D folding of tough hydrogels is achieved by sequentially applying the dual regulation.