Shape Shifting and Locking in Mechanically Responsive Organic‐Inorganic Hybrid Materials for Thermoelastic Actuators

• Published in: Angewandte Chemie International Edition Vol. 63; no. 33; pp. e202408247 - n/a
• Main Authors: Xu, Ke, Zhou, Zi‐Ning, Han, Xiang‐Bin, Yang, Ya‐Wen, Zhang, Wen, Ye, Qiong
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 12.08.2024
• Edition: International ed. in English
• Subjects: Actuation; Actuators; Crystals; Flexible components; Hybrids; Locking; molecular ferroelastic; Nonlinear optics; Optical properties; Optical switching; Phase transitions; Robotics; Shape memory alloys; shape-locking; shape-shifting; Single crystals; Stretchability; thermoelastic actuator; molecular ferroelastic; shape-shifting; shape-locking; thermoelastic actuator
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202408247

The construction of mechanically responsive materials with reversible shape‐shifting, shape‐locking, and stretchability holds promise for a wide range of applications in fields such as soft robotics and flexible electronics. Here, we report novel thermoelastic one‐dimensional organic–inorganic hybrids (R/S‐Hmpy)PbI3 (Hmpy=2‐hydroxymethyl‐pyrrolidinium) to show mechanical responses. The single crystals undergo two phase transitions at 310 K and 380 K. When heated to 380 K, they show shape‐shifting and expansion along the b‐axis by about 13.4 %, corresponding to a larger deformation than that of thermally activated shape memory alloys (8.5 %), and exhibit a strong actuation force. During the cooling process, the stretched crystal shape maintains and a shape‐locking phenomenon occurs, which is lifted when the temperature decreases to 305 K. Meanwhile, due to the introduction of chiral ions, the thermal switching shows a 10‐fold second‐order nonlinear switching contrast (common values typically below 3‐fold). This study presents a thermoelastic actuator based on shape‐shifting and ‐locking of organic–inorganic hybrids for the first time. The dielectric and nonlinear optical switching properties of organic–inorganic hybrids broaden the range of applications of mechanically responsive crystals. Thermoelastic organic–inorganic hybrids (R/S‐Hmpy)PbI3 (Hmpy=2‐hydroxymethyl‐pyrrolidinium) undergo two phase transitions at 310 K and 380 K. When heated to 380 K, the crystals show shape shifting and expand along the b‐axis by about 13.4 %, corresponding to a larger deformation than that of thermally activated shape memory alloys (8.5 %), and exhibits a strong actuation force. During cooling process, the stretched crystal shape maintains and a shape‐locking phenomenon occurs, which is lifted when the temperature decreases to 305 K.