Reconfigurable and Spatially Programmable Chameleon Skin-Like Material Utilizing Light Responsive Covalent Adaptable Cholesteric Liquid Crystal Elastomers
Reconfigurable and Spatially Programmable Chameleon Skin-Like Material Utilizing Light Responsive Covalent Adaptable Cholesteric Liquid Crystal Elastomers
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DOI：
10.1002/adfm.202003150
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发表时间：
2020-08-26
影响因子：
19
通讯作者：
Bowman, Christopher N.
中科院分区：
文献类型：
--
作者：
Martinez, Alina M.;McBride, Matthew K.;Bowman, Christopher N.
一种机械致变色的，可编程的，可编程的液晶弹性体（CLCE）的制造，并在应变后，导致通过可见光谱的蓝移，通过其各向同性相变加热时返回到其初始形状和颜色。光引发的、自由基介导的加成断裂链转移（AFT）通过可逆键交换松弛施加在应变网络上的应力来促进热可逆形状和颜色的永久编程或擦除。热可逆应变与可逆颜色变化相结合，并且可以通过光暴露和相应的AFT活化在任何期望的应变下永久化，在加热时暂时恢复几乎初始的形状和颜色。固有地连接到网络的光学特性和光子结构被测量为应变的函数，以确认反射凹口变窄，这表明通过剪切的预聚合对准是差的，从而导致当材料被拉伸时变窄的反射光的宽光谱。除了编程一个新的形状和颜色，反射凹口被擦除，并单独重新着色，以实现动态配色方案，通过加热和冷却进行切换，类似于变色龙的变色技术，该技术能够在单一材料中操纵多种颜色，也可用于应变映射。
A mechanochromic, programmable, cholesteric liquid crystalline elastomer (CLCE) is fabricated, and after straining, resulting in a blue shift through the visible spectrum, is returned to its initial shape and color upon heating through its isotropic phase transition. Light initiated, radical-mediated, addition fragmentation chain transfer (AFT), facilitate permanent programming or erasure of thermoreversible shape and color by relaxing stress imparted on the strained network through reversible bond exchange. Thermoreversible strain is coupled with reversible color change and can be made permanent at any desired strain by light exposure and corresponding AFT activation, temporarily restoring nearly initial shape and color upon heating. The optical characteristics and photonic structure, inherently linked to the network, are measured as a function of strain, to confirm the reflection notch narrowing indicating that prepolymerization alignment via shearing is poor thereby causing a broad spectrum of reflected light that narrows when the material is stretched. Beyond programming a new shape and color, the reflection notch is erased and separately, photopatterned to achieve dynamic color schemes that are toggled with heating and cooling, similar to that of a chameleon's camouflaging technique that has the ability to manipulate multiple colors in a single material, also with use for strain mapping.