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Abrupt and Reversible Stretching in an Azobenzene Single Crystal via Thermal Phase Transition
Minghao Gao1,2, Dennis Kwaria1, Emi Uchida1
1Core Electronics Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan.
None:
Mechanically responsive crystals are promising for actuators and microrobotics; however, achieving large reversible deformation with high durability remains challenging. Herein, A single-component azobenzene crystal is reported to exhibit an abrupt and reversible stretching of over 8% along its long axis, driven by a thermally induced single-crystal-to-single-crystal phase transition. Single-crystal X-ray diffraction revealed a significant change in molecular packing distance along the long axis accompanied by the reorientation of CH-π interactions, leading to large macroscopic stretching/shrinking. Furthermore, visible light (435 nm) induced rapid, localized, and reversible stretching of the crystal via the photothermal effect, enabling the remote control of microparticle motion. This study reveals a rare combination of large anisotropic deformation, reversibility, and light responsiveness in a single-component organic crystal, offering a new molecular platform for advancing micro-energy conversion and soft robotics.
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