Rapidly Reversible Organic Crystalline Switch for Conversion of Heat into Mechanical Energy

Abstract

<div> <div> <div> <p>Solid state thermosalience—a sudden exertion of an expansive or contractive physical force following a temperature change in a solid state compound—is rare, few are reversible systems, and most of these are limited to a dozen or so cycles before the crystal degrades or they reverse slowly over the course of many minutes or even hours. In this work, we show a fully reversible actuator that is stable at room temperature for multiple years and is capable of actuation for more than two hundred cycles at near ambient temperature. Specifically, the crystals shrink to 90% of its original length instantaneously upon heating beyond 45 °C and expands back to its original length upon cooling below 35 °C. This temperature regime is important because it occurs around physiologically important temperatures. Furthermore, the phase transition occurs instantaneously, with little obvious hysteresis, allowing us to create real-time actuating thermal fuses that cycle between on and off rapidly. </p> </div> </div> </div>

Controlling Polymorphic Transitions in n-Type Organic Semiconductor Single Crystals by Alkyl Chain Engineering

“…Previously, cooperative transition mechanisms have typically involved rotational 7,11,21 or sliding motion within the crystal system. 19,23,26 In organic molecules, this motion has been facilitated by the side chains of the molecules which have been shown to go through a rotational order−disorder 11,27 transition or undergo a conformation change in the case of alkyl chains. 28 In our recent work, 28,29 we observed that 2DQTT-C 8 C 10 undergoes two thermally accessible polymorph transitions: the I−II (cooperative) and II−III (nucleation and growth) transitions.…”

“…Typically, nucleation and growth transitions exhibit large changes in molecular packing and slow kinetics, 14 making it promising for the kinetic stabilization of a particular metastable polymorph. Cooperativity, on the other hand, exhibits rapid transition kinetics 9,23,24 and low energy barriers 8,25 and is coupled with intriguing mechanical properties, 7,11,23 offering pathways to novel, reversible switching devices. By controlling the presence of these transitions, we may provide a method of rationally designing new switching devices.…”

Spectroscopic Tracking of Salicylideneaniline Photocolored Crystals: An Attempt to Quantify Polymorph-Dependent Features toward Precise Structure–Function Correlation Analysis

“…7 Light-and heat-induced phase changes can result in crystal actuation, 8 such as bending, 9,10 jumping, 7,11,12 and expansion. 13,14 Early studies regarding vapochromism or reversible color changes driven by vapor absorption and desorption were based on organometallic complexes, but in recent years, organic crystals that exhibit vapochromism have been reported. 15−17 These new achievements in molecular crystal chemistry are complementary to the concept of crystal engineering, 18 aimed at understanding molecular interactions and designing new crystalline materials with desired physical and chemical properties.…”

Near-room-temperature martensitic actuation profited from one-dimensional hybrid perovskite structure

“…Fig.6| Comparison of working temperatures of reported systems and actuation device of 1. a Response temperature deviating from room temperature of reported thermosalient molecular crystals. NBFB 39 ,[7]Helquat salt47 , TIP-P19 , HMB48 , 6-CAN49 , ditBu-BTBT19 , TPA17 , NDI derivant50 , DABCO(CZ) 2 51 , TBB52 , GN53 , [Ni II (en) 3 ] (ox)54 , [Co(NO 3 ) 2 (L)]55 , ABN40 , TCB18 . T tr and RT represent phase transition temperature and room temperature of 293 K, respectively.…”