In this article, the influences of ortho‐fluoroazobenzenes (o‐Fbs) on liquid crystalline (LC) phase stability and actuation properties of liquid crystalline elastomers (LCEs) are presented. Such o‐Fbs find interest because they allow full photoswitching with visible light (no ultraviolet (UV) radiation). Novel o‐Fb monomers and crosslinkers are synthesized and characterized. Different amounts of an LC mixture are replaced with synthesized o‐Fbs successively and their influences on the LC phase stability in the cis and trans forms are observed through measuring the related clearing temperatures via polarized optical microscopy. LCE precursors containing 0, 1, 3, 5, 7, and 10 mol% o‐Fb monomer or crosslinker are aligned in a magnetic field and polymerized as films in the LC phase. Thermal and visible light–controlled photochemical 2D (planar) actuation properties of LCE samples are investigated and compared to LCEs containing a liquid crystalline non‐fluorinated azobenzene monomer as reference. It is shown that, while the favorable photochemistry is obtained, the integration of o‐Fbs is less effective for photoswitching of the LC phase, because i) less o‐Fbs can be integrated without destroying the LC phase and ii) the trans–cis isomerization is less effective in destroying the LC phase.

中文翻译：

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邻氟偶氮苯对液晶弹性体的液晶相稳定性和二维（平面）驱动性能的影响

本文介绍了邻氟偶氮苯（o-Fbs）对液晶（LC）相稳定性和液晶弹性体（LCEs）的驱动性能的影响。这种o-Fb引起人们的兴趣，因为它们允许在可见光（无紫外线（UV）辐射）下进行完全的光开关。合成并表征了新型o-Fb单体和交联剂。依次用合成的o-Fb替换不同量的LC混合物，并通过偏振光学显微镜测量相关的清除温度，观察它们对顺式和反式LC相稳定性的影响。含有0、1、3、5、7和10 mol％o-Fb单体或交联剂的LCE前体在磁场中排列并在LC相中成膜聚合。研究了LCE样品的热和可见光控制的光化学二维（平面）驱动特性，并将其与包含液晶非氟化偶氮苯单体的LCE进行了比较。结果表明，尽管获得了良好的光化学性质，但o-Fbs的积分对LC相的光转换效果较差，因为i）在不破坏LC相的情况下可以整合较少的o-Fbs和ii）反式-顺式异构化在破坏LC相方面不太有效。