Phototunable, Reconfigurable, and Complex Shape Transformation of Fe³⁺-Containing Bilayer Polymer Materials

Abstract

The design of materials that can mimic the complex shape-morphing phenomena in nature is important for applications in soft robotics, biomedical devices, and sensors. Yet, morphing a two-dimensional thin plate into a programmed complex threedimensional (3D) shape is still challenging. Herein, we demonstrate a new paradigm for designing a photothermal shape-transformable Fe 3+ -containing polymer film (FePF) coated with a patterned inactive black-tape strip layer. The near-infrared (NIR) light-triggered dehydrative shrinkage of the FePF layer drives the bending of the inactive layer toward the FePF layer. Various reversible 3D shapes, including a complex "human face" and gripping-force-tunable soft grippers, are fabricated by the experimental pattern design of the inactive layer with the aid of theoretical simulations. The white-light sensitive dynamic coordination of Fe 3+ −Alanine (Ala) enables tunability of the deformation degree under white-light irradiation. The deformation rate is also tunable by adjusting the Fe-to-Ala mole ratio, humidity, NIR light intensity, and FePF thickness. These shape transformations are reconfigurable through the simple peeling off and repatterning of the black-tape strip layers. Our simple and scalable design strategy without an intricate heterogeneity design in material properties provides guidance for fabricating new soft robotics and biomimetic systems.

Dual-Mechanism-Driven Environmental-Friendly Fast Self-Healing Ionic Hydrogels with Excellent Sensitivity to Strain Responsiveness

“…However, the self-healing efficiency of the CMC/PDA@Fe 3+ -3 hydrogel was only 67.86% at 3 h under a shorter wavelength and a higher energy ultraviolet light irradiation. It might be because Fe 3+ could be reduced to Fe 2+ under ultraviolet light irradiation and lost the ability to coordinate with oxygen atoms. , Infrared light had a strong thermal effect, which prompted the hydrogel to increase in temperature and lose water rapidly. The reduced water content led to a decrease of the self-healing efficiency to only 51.70% under infrared light irradiation.…”

Biomorphogenesis-Inspired Three-Dimensional Shape Transformation of Bilayer Polymer Sheets

“…In contrast to the bilayer-structured design, the in-plane design can achieve 3D shapes that exhibit both Gaussian curvature and mean curvature variations. When triggered by external stimuli, the shape-morphing materials with an in-plane swelling/dehydration pattern ,− or liquid-crystalline molecule orientation pattern − can be shaped into various 3D morphologies with multicurvatures. Nevertheless, in most cases, the shape-morphing materials required complex inhomogeneous or discontinuous design of materials, such as patterned cross-linking distribution, patterned orientation of the liquid crystal phase, and cutting cracks.…”

Reversible White-Light-Driven Photochromic Polymer Hydrogels with High Stretchability and Adhesiveness

“…Smart materials, which respond to heat, − light, , electric, , force, − humidity, − and chemical inputs, , have been developed and demonstrated in many applications, such as sensors, , probes, and optoelectronics . Among these smart materials, photochromic materials, which change color reversibly by the light stimulus, have attracted great research interest and are extensively developed. − In recent years, enormous efforts have been devoted to integrating photochromism in hydrogels since hydrogels can be soft as skin and stretchable as rubbers or elastomers. − Therefore, photochromic hydrogels have great potential to be used in soft wearable electronics, − biomedical sensors, − and soft robotics. − …”