From two-dimensional to three-dimensional structures: A superior thermal-driven actuator with switchable deformation behavior

Inspired by origami, 3D structures constructed from 2D structures have increasingly attracted attention, which have potential applications in many fields. Herein, a novel double-layered actuator was fabricated by adding different thermo-responsive thermal expansion microspheres, expanding at low temperature (L-TEMs) and at high temperature (H-TEMs), into different silicone rubber layers. Due to the expansion of L-TEMs and H-TEMs at 120 and 170 degrees C, respectively, the active and passive layers could exchange at different temperatures, showing switchable deformation behavior. Compared with traditional double-layered actuators, the actuator with the switchable active layers is capable of providing additional functionality. The two layers were assembled by crosslinking the silicone rubber at the interface of the two layers, which endows the good stability of the double-layered actuator. The 2D double-layered structures of the actuators could be transformed into complex 3D structures by heating. In addition, the actuation time was shortened by adding 50 phr alumina due to the enhancement of thermal conductivity and the limited increase in Young's modulus. This work could pave a way to the design and preparation to high-performance actuators with multiple functions.