Mechanical Properties and Photomechanical Fatigue of Macro- and Nanodimensional Diarylethene Molecular Crystals
Mechanical Properties and Photomechanical Fatigue of Macro- and Nanodimensional Diarylethene Molecular Crystals
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DOI：
10.1021/acs.nanolett.0c02631
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发表时间：
2020-09-09
期刊：
影响因子：
10.8
通讯作者：
Tivanski, Alexei, V
中科院分区：
文献类型：
--
作者：
Lansakara, Thiranjeewa, I;Tong, Fei;Tivanski, Alexei, V
二芳基乙烯衍生物，1，2-双（2，4-二甲基-5-苯基-3-噻吩基）全氟环戊烯，在固态下经历其开环和闭环形式之间的可逆光异构化，并具有作为照相制版材料的应用。宏观晶体，纳米线单晶，和非晶薄膜作为一个功能的多个连续的紫外线和可见光曝光的机械性能已被量化使用原子力显微镜纳米压痕。异构化反应对各固体的弹性模量没有影响。但是从宏观到纳米线晶体导致弹性模量显著降低超过3倍。宏观晶体和无定形固体是高度耐光机械疲劳的，而纳米线晶体显示出归因于从晶体到无定形形式的转变的光机械疲劳的明显证据。这项研究提供了第一个实验证据的光反应分子晶体固体的尺寸依赖性的光机械疲劳，并建议晶体形态和尺寸必须考虑未来的光机械应用。
The diarylethene derivative, 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)perfluorocyclopentene, undergoes a reversible photoisomerization between its ring-open and ring-closed forms in the solid-state and has applications as a photomechanical material. Mechanical properties of macrocrystals, nanowire single crystals, and amorphous films as a function of multiple sequential UV and visible light exposures have been quantified using atomic force microscopy nanoindentation. The isomerization reaction has no effect on the elastic modulus of each solid. But going from the macro- to the nanowire crystal results in a remarkable over 3-fold decrease in the elastic modulus. The macrocrystal and amorphous solids are highly resistant to photomechanical fatigue, while nanowire crystals show clear evidence of photomechanical fatigue attributed to a transition from crystal to amorphous forms. This study provides first experimental evidence of size-dependent photomechanical fatigue in photoreactive molecular crystalline solids and suggests crystal morphology and size must be considered for future photomechanical applications.