Convenient patterning and precisely programmable shape deformations are crucial for the practical applications of shape deformable hydrogels. Here, a facile and versatile computer‐assisted ion inkjet printing technique is described that enables the direct printing of batched, very complicated patterns, especially those with well‐defined, programmable variation in cross‐linking densities, on one or both surfaces of a large‐sized hydrogel sample. A mechanically strong hydrogel containing poly(sodium acrylate) is first prepared, and then digital patterns are printed onto the hydrogel surfaces by using a commercial inkjet printer and an aqueous ferric solution. The complexation between the polyelectrolyte and ferric ions increases the cross‐linking density of the printed regions, and hence the gel sample can undergo shape deformation upon swelling/deswelling. The deformation rates and degrees of the hydrogels can be conveniently adjusted by changing the printing times or the different/gradient grayscale distribution of designed patterns. By printing appropriate patterns on one or both surfaces of the hydrogel sheets, many complex 3D shapes are obtained from shape deformations upon swelling/deswelling, such as cylindrical shell and forsythia flower (patterns on one surface), ding (patterns on both surfaces), blooming flower (different/gradient grayscale distributive patterns on one surface), and non‐Euclidean plates (different/gradient grayscale distributive patterns on both surfaces).

Nonconventional poly(maleic anhydride-alt-vinyl pyrrolidone) copolymers exhibit distinct AIE characteristics, as well as molecular weight-dependent and excitation-dependent fluorescence. They can emit blue to red colours under different excitation wavelengths.

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

Nonconventional luminescent copolymers poly(itaconic anhydride-co-vinyl caprolactam) (PIVC) and poly(itaconic anhydride-co-vinyl pyrrolidone) (PIVP) emit strong orange-red and bright white emissions, respectively.

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Small aliphatic oximes produced by the oxidation of primary and secondary amines are confirmed to be AIE luminogens.

A novel type of polymeric material with tunable mechanical properties is fabricated from polymers and small molecules that can form hydrogen-bonded intermolecular complexes (IMCs). In this work, poly(vinyl alcohol) (PVA)-glycerol hydrogels are first prepared, and then they are dried to form IMCs. The tensile strengths and moduli of IMCs decrease dramatically with increasing glycerol content, while the elongations increase gradually. The mechanical properties are comparable with or even superior to those of common engineering plastics and rubbers. The IMCs with high glycerol content also show excellent flexibility and cold-resistance at subzero temperatures. Cyclic tensile and stress relaxation tests prove that there is an effective energy dissipation mechanism in IMCs and dynamic mechanical analysis confirms their physical crosslinking nature. FTIR and NMR characterizations prove the existence of hydrogen bonding between glycerol and PVA chains, which suppresses the crystallization of PVA from X-ray diffraction measurement. These PVA-glycerol IMCs may find potential applications in barrier films, biomedical packaging, etc., in the future.

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