Electrothermally driven structural colour based on liquid crystal elastomers
Electrothermally driven structural colour based on liquid crystal elastomers
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基于液晶弹性体的电热驱动结构色
DOI：
10.1039/c2jm30176h
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发表时间：
2012-01-01
影响因子：
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通讯作者：
Li, Guangtao
中科院分区：
文献类型：
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作者：
Jiang, Yin;Xu, Dan;Li, Guangtao
提出了一种基于液晶弹性体的新型电热驱动光子晶体，并对其在电压驱动下的光学特性（结构色）进行了研究。将石墨纳米颗粒旋涂在玻璃衬底上，作为一个反乳白色转换层，在其上安装所制备的基于LCE的反乳白色薄膜。当施加电压时，石墨层产生的热量将引起涂覆的反蛋白石膜的变形，从而实现电热驱动的光子系统或结构色。我们发现，当这些薄膜的玻璃化转变温度（Tg）以上的第一，并在此重新排列的过程中，弱交联反乳白色薄膜的结构颜色消失，可能是由于崩溃的周期性有序的多孔结构存在的重新排列行为。用于产生具有可逆响应的基于LCE的反蛋白石的阈值交联密度（Cx）为25摩尔%。有趣的是，它被发现，通过使用硅油的制备的光子薄膜的处理可以降低阈值Cx到15摩尔%，和LCE为基础的反蛋白石具有广泛的可调光学性能的制造是可能的。当所使用的液晶转换层的温度接近LCE膜的向列-各向同性（N-I）转变温度（TNI）时，反蛋白石结构中的液晶部分变为各向同性，导致布拉格衍射峰的快速移位和相应的结构颜色变化。关闭电压后，它们可以恢复到初始状态。随着交联密度的降低，光致伸缩弹性体的布拉格衍射位移变大。值得注意的是，这些薄膜对电压的响应速度快，可逆性好。
In this article, a new type of electrothermally driven photonic crystal based on liquid crystal elastomers (LCEs) was developed, and its optical properties (structural colour) driven by voltage were described. Graphite nanoparticles were spin-coated on glass-substrates and acted as an electrothermal conversion layer, on which the prepared LCE-based inverse opaline films were mounted. When voltage is applied on the fabricated system, the heat produced by the graphite layer will induce the deformation of the coated inverse opaline film and thus the electrothermally driven photonic system or structural colour is realized. We found that realignment behaviour existed when these films were first above their glass transition temperatures (Tg), and during this realignment process, the structural colour of weakly crosslinked inverse opaline films disappeared, probably due to the collapse of the periodically ordered porous structure. The threshold cross-linking density (Cx) for producing LCE-based inverse opalines with reversible response is 25 mol%. Interestingly, it is found that the treatment of the prepared photonic films by using silicone oil could reduce the threshold Cx to 15 mol%, and the fabrication of LCE-based inverse opaline with widely tunable optical properties is possible. When the temperature of the used electrothermal conversion layer is close to the nematic–isotropic (N–I) transition temperature (TNI) of the LCE films, the liquid crystal moieties in inverse opaline structure became isotropic, leading to rapid shift of the Bragg-diffraction peak and corresponding structural colour change. After turning off the voltage, they could regain to the initial state. With the decrease of the cross-linking density of the photonic-structured elastomers, the degree of Bragg-diffraction shift became larger. Remarkably, the response of these films stimulated by electric voltage is fast and the reversibility is perfect.