Tough Hydrogels with Programmable and Complex Shape Deformations by Ion Dip‐Dyeing and Transfer Printing

Abstract

Stimuli-responsive hydrogels with high mechanical strength, programmable deformation, and simple preparation are essential for their practical applications. Here the preparation of tough hydrogels with programmable and complex shape deformations is reported. Janus hydrogels with different compositions and hydrophilic natures on the two surfaces are first prepared, and they exhibit reversible bending/unbending upon swelling/deswelling processes. More impressively, the deformation rate and extent of the hydrogels can further be easily controlled through an extremely simple and versatile ion dip-dyeing (IDD) and/or ion transfer printing (ITP) method. By selectively printing proper patterns on 1D gel strips, 2D gel sheets and 3D gel structures, the transformations from 1D to 2D, 2D to 3D, and 3D to more complicated 3D shapes can be achieved after swelling the ion-patterned hydrogels in water. The swelling-deformable Janus and ion-patterned hydrogels with high mechanical strengths and programmable deformations can find many practical applications, such as soft machines. www.afm-journal.de www.MaterialsViews.com Figure 6. Various 2D and 3D shapes deformed from ion printed 1D, 2D, or 3D hydrogels. a) 1D to 2D shapes; b-d) 2D to 3D shapes; e,f) 3D to complicated 3D shapes. Hydrogel synthesis conditions were: C AAm = 3.0 mol L −1 , C NaAAc = 0.5 mol L −1 , C PVP = 43 mg mL −1 , thickness: 1 mm, or diameter: 14 mm. All scale bars are 5 mm. full paper 8 wileyonlinelibrary.com

Study of extrudability and standoff distance effect during nanoclay-enabled direct printing

“…Then the hydrated 1D pattern was submerged in a 60 • C hot water bath to induce the deformation from a line to a triangle at 0.5 and 5.0 min as shown in Fig. 7f and g, which is similar to that as reported in a previous study [32]. This three-layered 1D pattern printing and deformation case demonstrates the good extrudability and print quality during nanoclay-enabled printing under optimal printing conditions, which may facilitate more nanoclay-based printing applications.…”

“…Due to the shrinking ratio difference between the pNIPAAm-Laponite and pNIPAAmLaponite-GO layers, an interfacial stress develops between adjacent layers, leading to the deformation of the printed 1D pattern to a 2D shape. In this study, the design of the 1D pattern was based on a previous study [32]. During printing, two independent dispensing pumps (Pumps 1 and 2) were utilized to sequentially deposit corresponding Laponite nanoclay-based NIPAAm nanocomposite hydrogel precursors to form the first layer as shown in Fig.…”

Synthetic self-assembled homogeneous network hydrogels with high mechanical and recoverable properties for tissue replacement

“…However, the translucent or even non-transparent hydrogels were obtained using similar compositions by other synthetic methods. 35,36 The asobtained hydrogels maintained their transparency irrespective of the concentration of PVP (Fig. 1b).…”

Sequentially Controlled Deformations of Patterned Hydrogels into 3D Configurations with Multilevel Structures

“…Morphing materials with programmable deformations have promising applications in biomedical devices, soft robotics, deployable aircrafts, etc . Scientists have developed bioinspired systems with through‐thickness and/or in‐plane gradient structures to realize typical deformations, including bending, folding, and twisting . Reversible shape transformations or step‐by‐step deformations can be realized by incorporating different responsive polymers into one composite hydrogel .…”