Conductive, self-healing, and adhesive hydrogels are of great significance in wearable electronic devices. The most important properties of conductive self-healing hydrogels are the efficient recovery of both electrical and mechanical properties at room temperature and prolonged durability. In this work, we developed a novel double-network hydrogel consisting of poly(4styrene sulfonate-co-methyl-uracil-imidazolium) chloride (PSS-MUI), gelatin, and ferric ions (Fe 3+ ). Here, the MUI serves as a supramolecular crosslinker, while ferric ions act as ionic crosslinkers between gelatin and PSS functional groups. The hydrogel demonstrated excellent stretchability and outstanding ionic conductivity. The reversible nature of dynamic hydrogen bonding and ionic and metal coordination interactions rendered the hydrogel selfhealing ability, strong adhesion, and rapid electrical performance recovery. Variation in the Fe 3+ concentration proved to influence the time window of hydrogel processability and allowed tuning the hydrogel mechanical and ion-conducting properties. The optimal Fe 3+ ion concentration for use in a processable, ion-conducting hydrogel was found to be 2 wt %. During repeated stretching, the hydrogel showed only small changes in its electrical resistance. An electric circuit was successfully assembled onto a flexible polyurethane (PU) substrate where the power supply, light-emitting diode, and resistor were connected with the hydrogel, serving as a conductive wire. Upon breakage of the wire, simple extrusion of the hydrogel precursor into the gap yielded instant repair of the circuit. Thus, the hydrogel demonstrated suitability for use in flexible electronic devices.

Wrought by nature's wondrous hand, surface topographies are discovered on all length scales in living creatures and serve a variety of functions. Inspired by floral striations, here we developed a scalable means of fabricating custom-tailored photonic cellulose films that contained both cholesteric organization and microscopic wrinkly surface topography. Free-standing films were prepared by molding cellulose nanocrystal ink onto an oriented wrinkled template through evaporation-assisted nanoimprinting lithography, yielding morphology-induced light scattering at a short wavelength as well as optically tunable structural color derived from the helical cellulose matrix. As a result, the interplay between the two photonic structures, grating-like surface and chiral bulk, led to selective scattering of circularly polarized light with specific handedness. Moreover, the wrinkled surface relief on cholesteric cellulose films could be precisely controlled, enabling engineered printing of microscopic patterned images.

The study of colloidal liquid crystals (LCs) reveals fundamental insights into the nature of ordered materials, giving rise to emergent properties with fascinating applications in soft matter nanotechnology. Here we investigate the shape instabilities, layer undulations, dynamic assembly, and collective behaviors in evaporating a cellulose nanocrystal-based cholesteric LC drop. During the drying process, the drop edges are pinned to the substrate with spontaneous convective flow occurring along the drop, which leads to nonequilibrium sliding of the individual cholesteric fragment with active ordering as well as hydrodynamic fluctuations and flow transitions in the bulk cholesteric phase.

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It is of great interest to dynamically manipulate the optical property by controlling nanostructures under external stimuli. In this work, chiral photonic cellulose nanocrystal (CNC) and elastic polyurethane (PU) composite films demonstrate reversible optical tunability arising from structural transition between the chiral nematic and layered pseudonematic order. The composite films exhibit impressive water resistance and mechanical adaptability. Reversible modulation of the optical property of the composite CNC/PU film is enabled during mechanical stretching and water absorption. Film stretching is accompanied by CNC transition from a chiral nematic to layered pseudonematic structure. After fixation, shape recovery takes place when exposed to water, and the CNC structure reverts to the initial chiral nematic order. These reversibly switchable shape and optical properties further advance the study and design of smart optical and mechanical sensors.

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The p.o. and i.v. formulations of pantoprazole (40 and 20 mg) are equivalent in their ability to suppress gastric acid output. The i.v. form of pantoprazole offers an alternative for gastroesophageal reflux disease patients who are unable to take the p.o. formulation.