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

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 three-dimensional (3D) shape is still challenging. Herein, we demonstrate a new paradigm for designing a photothermal shape-transformable Fe3+-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 Fe3+–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.