Martensitic organic crystals as soft actuators

Li, Liang; Commins, Patrick; Al‐Handawi, Marieh B.; Karothu, Durga Prasad; Halabi, Jad Mahmoud; Schramm, Stefan; Weston, James; Rezgui, Rachid; Naumov, Panče

doi:10.1039/c9sc02444a

Cited by 62 publications

(59 citation statements)

References 32 publications

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“…Therefore they can only be considered as single‐stroke thermal actuators, similar to some of the other “smart” systems such as shape‐memory alloys (Table S1, Supporting Information). Cycling is at least in principle, possible, however the actuating force in subsequent cycles is expectedly reduced due to disintegration, and measurements of cyclic operation normally include significant data scatter. Performance attributes related to time‐dependent operation (e.g., frequency) or operational cycling (e.g., efficiency, resolution, etc.)…”

Section: Resultsmentioning

confidence: 99%

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Global Performance Indices for Dynamic Crystals as Organic Thermal Actuators

Karothu

Halabi

et al. 2020

Advanced Materials

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same basic thermodynamic principles of energy transduction and are collectively referred to as actuators. [1][2][3][4][5][6][7][8][9][10] While complex natural biomechanical systems have evolved to aid functions such as dispersal and survival, the artificially manufactured actuators are specifically designed for integration in mechatronic or adaptronic systems that range from miniature devices such as navigation and positioning systems in flying machines, to complex systems that can perform tasks in specific environments, such as humanoid robots and spacecraft. The current applications of actuators are many and diverse; they include sensors, [11,12] artificial muscles, [13] soft robotics, [14] and energy-harvesting materials. [15] Simple or complex actuating motions can be induced by heat, light, electricity, pressure, and moisture, among other stimuli, and can be realized with shape-memory polymers, [16] conductive fibers, [17] liquid crystal elastomers, [18] piezoelectric, [19] magnetostrictive, [20] and electromagnetic materials. [21] The energy supplied to the artificial actuators can vary from fluid pressure or flow in the pneumatics, to current, charge or voltage in the electromagnetic, piezoelectric and magnetostrictive actuators, to heat in shape memory and thermal expansion actuators.The active media in actuators include fluids, hard solids such as metals, and even complex soft matter such as tissuesensembles of cells with similar structure that act together to perform a specific function. While molecular crystals do not immediately appeal as working actuating medium, their dynamic properties have recently transpired as an alternative to other materials and they are thought to hold an untapped potential for miniature, soft actuating devices, quickly shaping up into a new research field, crystal adaptronics. [22,23] Smallscale demonstrations of the usefulness of molecular crystals as microscale devices, including cantilevers, [24,25] ratchets, [26] optical waveguides, [27][28][29][30][31][32][33][34][35][36] and other "crystal gears" [37] that can move or reshape are occasionally reported for dynamic crystals. Although being very illustrative, these demonstrations have thus far remained limited to a laboratory scale and have not been implemented in actual, functional devices. Some of the obstacles toward wider applications are difficulties with reproducible growth of crystals of predictable size without the use Crystal adaptronics is an emergent materials science discipline at the intersection of solid-state chemistry and mechanical engineering that explores the dynamic nature of mechanically reconfigurable, motile, and explosive crystals. Adaptive molecular crystals bring to materials science a qualitatively new set of properties that associate long-range structural order with softness and mechanical compliance. However, the full potential of this class of materials remains underexplored and they have not been considered as materials of choice in an engineer's toolbox. A set of general performance metric...

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Section: Resultsmentioning

confidence: 99%

“…With the ever‐increasing reports on adaptive crystals, there have been several attempts to compare the performance of individual dynamic molecular crystals to those of other materials . These efforts have been limited with the amount of available data and have been focused on specific examples of dynamic materials.…”

Section: Conclusion and Perspectivementioning

confidence: 99%

Global Performance Indices for Dynamic Crystals as Organic Thermal Actuators

Karothu

Halabi

et al. 2020

Advanced Materials

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“…Further cooling of complex 2 leads to diffusionless transformation, similar to martensitic phase transitions. 20 − 23 The low-temperature phase is refined as a twin in the triclinic system using the twin matrix [1 0 0 1 −1 0 1 0 −1]. After the phase transition, two domains are clearly visible in the temperature range 210–100 K. Each domain gives approximately 35% reflexes ( Figure S2c,d ).…”

Section: Resultsmentioning

confidence: 99%

Single Crystal X-ray Diffraction Studies of Two Polymorphic Modifications of the Dicarbonyl-o-Semiquinonato Rhodium Complex at Different Temperatures. Destruction Stimulated by Cooling Versus Stability

et al. 2020

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It was found that the dicarbonyl-rhodium- o -semiquinonate complex (which thread-like crystals can bend reversibly under light/warm activation) can form two polymorphic modifications: isometric prisms ( 1 ) and sticks ( 2 ). Some thin sticks can bend as mentioned above. X-ray diffraction studies of polymorphic modifications at different temperatures were carried out. It was found that crystals 1 are destructed after cooling to 110 K as opposed to crystals 2 . In turn, the reversible phase transition is detected in 2 . In both polymorphic modifications, stack packaging motifs through the direct Rh–Rh bond are observed. The principal difference between packages of polymorphic modifications is that molecules 1 in the adjacent stacks are shifted relative to each other along the stack, in contrast to crystal 2 . It was found that different packing of stacks leads to different anisotropic compression of crystals 1 and 2 during cooling, which is a key factor of their stability. Using the molecular invariom approach, the nature of the chemical bonds and charge distribution was investigated; the energy of the Rh–Rh bonds was estimated.

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“…Therefore, we consider that the thermal phase transition of 1oRR is a martensitic-like transformation. [33][34][35] As the temperature decreased, the volume of a molecule gradually decreased due to thermal contraction. As shown in Table 2, comparing 20 K with 173 K, all axes contracted (see Fig.…”

Section: Thermal Phase Transitionmentioning

confidence: 99%