Abstract
Materials with synchronous capabilities of color change and actuation have prospects for application in biomimetic dual-stealth camouflage and artificial intelligence. However, color/shape dual-responsive devices involve stimuli that are difficult to control such as gas, light or magnetism, and the devices show poor coordination. Here, a flexible composite film with electrochromic/actuating (238° bending angle) dual-responsive phenomena, excellent reversibility, high synchronization, and fast response speed (< 5 s) utilizes a single active component, W18O49 nanowires. From in situ synchrotron X-ray diffraction, first principles calculations/numerical simulations, and a series of control experiments, the actuating mechanism for macroscopic deformation is elucidated as pseudocapacitance-based reversible lattice contraction/recovery of W18O49 nanowires (i.e. nanostructure change at the atomic level) during lithium ion intercalation/de-intercalation. In addition, we demonstrate the W18O49 nanowires in a solid-state ionic polymer-metal composite actuator that operates stably in air with a significant pseudocapacitive actuation.
Highlights
Materials with synchronous capabilities of color change and actuation have prospects for application in biomimetic dual-stealth camouflage and artificial intelligence
A biomimetic technology derived from the reversible shift of skin colors of chameleons through controlling the lattice of guanine nanocrystals[1], has been extensively studied to improve current camouflage methods originating from pattern painting dating back to the 1940s2–4
There still exist some critical shortcomings: (i) the dual-responsive performances of these materials were stimulated by gas, light or magnetism, which are affected by environmental conditions and are weakly controllable; (ii) the color changes were not striking enough to be observed by the naked eye within all visual angles, which lead to moderate detectability
Summary
Materials with synchronous capabilities of color change and actuation have prospects for application in biomimetic dual-stealth camouflage and artificial intelligence. Kwon and colleagues fabricated a magnetochromatic microactuator through self-assembling superparamagnetic colloidal nanocrystal clusters in a photocurable polymer resin[11] Despite these achievements, there still exist some critical shortcomings: (i) the dual-responsive performances of these materials were stimulated by gas, light or magnetism, which are affected by environmental conditions and are weakly controllable; (ii) the color changes were not striking enough to be observed by the naked eye within all visual angles, which lead to moderate detectability. Hosson and colleagues developed this type of dual-responsive composite film by electrodepositing an EC material (polyaniline) on an electrochemical actuator (nanoporous gold film)[16] This dual-responsive composite film can be efficiently controlled by an input electrical signal, and exhibit many other advantages such as low driving voltage, high reversibility, and fast response rate. A symmetric ionic polymer metal composite (IPMC) actuator is built based on pseudocapacitive actuation of W18O49NWs to extend its application range in air and some other complex environments, which introduces a new approach for building IPMC and achieving enhanced properties
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