Abstract:

This work is an innovative comprehensive experiment on the preparation of deformable hydrogels and the design as well as the adjustment of their complex shape deformations. A type of poly(N-vinylpyrrolidone)-polyacrylamide (PVP-PAAm) hydrogels with excellent mechanical properties are firstly prepared through free radical polymerization and cross-linking. Poly(sodium acrylate) (PNaAAc) contained in the hydrogels can complex with metal ions like Fe³⁺, leading to the increase of the cross-linking density of the hydrogels and hence the decrease of their swelling degrees. Through ion-transfer-printing (ITP) and newly developed ion-ink-printing (IIP) techniques, Fe³⁺ ions are introduced at different positions on one or both sides of hydrogels, changing the local cross-linking density and swelling degree of the surface of hydrogels. Upon swelling or deswelling, the hydrogels can undergo controllable and complex transformations from 1D to 2D, 2D to 3D and 3D to more complicated 3D shapes.

Key words: Deformable hydrogels, Stimuli-response, Ion-transfer-printing, Ion-ink-printing