Customizable Multidimensional Self-Wrinkling Structure Constructed via Modulus Gradient in Chitosan Hydrogels

Customizable patterning and deformation of soft matter represents a powerful tool to achieve programmable 3D configurations of soft materials. However, customizing the multidimensional self-wrinkling hydrogels for specific configuration on demand remains a challenge. This work introduces a facile, effective approach to construct self-wrinkling hydrogels with customizable geometric dimension and well-aligned wrinkle structure. By prestretching chemically cross-linked chitosan elastic hydrogel in water for a short period of time (1 min), the chitosan chains and bundles were further physically cross-linked to form aggregates, quickly creating a closely packed nanofiber layer as a shell on the hydrogel surface. The significant modulus gradient between the relatively stiff shell and the inner elastic networks of the chemically cross-linked hydrogel drives the formation of the wrinkling surface topography. This has allowed construction of 1D fiber, 2D plane, 3D tubular, and 3D scaffold self-wrinkling hydrogels with well-organized microgroove-like structure and controllable size. Moreover, the self-wrinkling hydrogel can act as an excellent matrix for fabricating multifunctional devices with customizable geometry by integrating different functional components, highlighting the possibility for constructing soft material structures to create novel biomedical and engineering devices from natural polymers.