TY - JOUR

T1 - Quantification of photoinduced bending of dynamic molecular crystals

T2 - From macroscopic strain to kinetic constants and activation energies

AU - Chizhik, Stanislav

AU - Sidelnikov, Anatoly

AU - Zakharov, Boris

AU - Naumov, Panče

AU - Boldyreva, Elena

N1 - Publisher Copyright: © 2018 The Royal Society of Chemistry.

PY - 2018/2/28

Y1 - 2018/2/28

N2 - Photomechanically reconfigurable elastic single crystals are the key elements for contactless, timely controllable and spatially resolved transduction of light into work from the nanoscale to the macroscale. The deformation in such single-crystal actuators is observed and usually attributed to anisotropy in their structure induced by the external stimulus. Yet, the actual intrinsic and external factors that affect the mechanical response remain poorly understood, and the lack of rigorous models stands as the main impediment towards benchmarking of these materials against each other and with much better developed soft actuators based on polymers, liquid crystals and elastomers. Here, experimental approaches for precise measurement of macroscopic strain in a single crystal bent by means of a solid-state transformation induced by light are developed and used to extract the related temperature-dependent kinetic parameters. The experimental results are compared against an overarching mathematical model based on the combined consideration of light transport, chemical transformation and elastic deformation that does not require fitting of any empirical information. It is demonstrated that for a thermally reversible photoreactive bending crystal, the kinetic constants of the forward (photochemical) reaction and the reverse (thermal) reaction, as well as their temperature dependence, can be extracted with high accuracy. The improved kinematic model of crystal bending takes into account the feedback effect, which is often neglected but becomes increasingly important at the late stages of the photochemical reaction in a single crystal. The results provide the most rigorous and exact mathematical description of photoinduced bending of a single crystal to date.

AB - Photomechanically reconfigurable elastic single crystals are the key elements for contactless, timely controllable and spatially resolved transduction of light into work from the nanoscale to the macroscale. The deformation in such single-crystal actuators is observed and usually attributed to anisotropy in their structure induced by the external stimulus. Yet, the actual intrinsic and external factors that affect the mechanical response remain poorly understood, and the lack of rigorous models stands as the main impediment towards benchmarking of these materials against each other and with much better developed soft actuators based on polymers, liquid crystals and elastomers. Here, experimental approaches for precise measurement of macroscopic strain in a single crystal bent by means of a solid-state transformation induced by light are developed and used to extract the related temperature-dependent kinetic parameters. The experimental results are compared against an overarching mathematical model based on the combined consideration of light transport, chemical transformation and elastic deformation that does not require fitting of any empirical information. It is demonstrated that for a thermally reversible photoreactive bending crystal, the kinetic constants of the forward (photochemical) reaction and the reverse (thermal) reaction, as well as their temperature dependence, can be extracted with high accuracy. The improved kinematic model of crystal bending takes into account the feedback effect, which is often neglected but becomes increasingly important at the late stages of the photochemical reaction in a single crystal. The results provide the most rigorous and exact mathematical description of photoinduced bending of a single crystal to date.

KW - COMPLEXES

KW - DIARYLETHENE CRYSTALS

KW - ION

KW - MACHINES

KW - NITRO LINKAGE ISOMERIZATION

KW - PENTAAMMINENITRITOCOBALT(III)

KW - PHOTOISOMERIZATION

KW - POLYMER

KW - SOLID-STATE ISOMERIZATION

KW - THICKNESS DEPENDENCE

UR - http://www.scopus.com/inward/record.url?scp=85042598867&partnerID=8YFLogxK

U2 - 10.1039/c7sc04863g

DO - 10.1039/c7sc04863g

M3 - Article

C2 - 29719705

AN - SCOPUS:85042598867

VL - 9

SP - 2319

EP - 2335

JO - Chemical Science

JF - Chemical Science

SN - 2041-6520

IS - 8

ER -