Bio-mimic four-dimensional printing of nanostructured interactive hydrogels

Nature has exhibited numerous soft-interactive botanical or zoological systems with self-adaptivenss or reconfigurable shape, however, artificial micro/nano materials of same merit are formidable due to material/structural limitations, posing multidimensional challenges to current chemical/physical fabrications. Here, we propose a new nanostructured hydrogel by four-dimensional (4D) printing for function integration and dimension reduction. The cross-linked matrix relaxes or contracts in robust hierarchical heterojunction to eliminate interface issues of dual-layer desgin.