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Fully Controllable Structural Phase Transition in Thermomechanical Molecular Crystals with a Very Small Thermal Hysteresis
Author(s) -
Duan Yulong,
Semin Sergey,
Tinnemans Paul,
Xu Jialiang,
Rasing Theo
Publication year - 2021
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.202006757
Subject(s) - phase transition , materials science , hysteresis , phase (matter) , thermal , crystal (programming language) , molecular dynamics , chemical physics , mechanical energy , work (physics) , condensed matter physics , thermodynamics , chemistry , physics , computer science , computational chemistry , power (physics) , organic chemistry , programming language
The construction of a practical crystalline molecular machine faces two challenges: to realize a collective molecular movement, and to amplify this movement into a precisely controlled mechanical response in real time and space. Thermosalient single crystals display cooperative molecular movements that are converted to strong macroscopic mechanical responses or shape deformations during temperature‐induced structural phase transitions. However, these collective molecular movements are hard to control once initiated, and often feature thermal hystereses that are larger than 10 °C, which greatly hamper their practical applications. Here, it is demonstrated that the phase boundaries of the thermomechanical molecular crystal based on a fluorenone derivative 4‐DBpFO can be used to finely control its structural phase transition. When this phase transition is triggered at two opposite crystal faces, it is accompanied by two parallel phase boundaries that can be temperature controlled to move forward, backward, or to halt, benefitting from the stored elastic energy between the parallel boundaries. Moreover, the thermal hysteresis is greatly decreased to 2–3 °C, which allows for circular heating/cooling cycles that can produce a continuous work output.