Thermomechanically active electrodes power work-dense soft actuators
Thermomechanically active electrodes power work-dense soft actuators
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DOI：
10.1039/d0sm01399d
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发表时间：
2021-02-14
期刊：
影响因子：
3.4
通讯作者：
Shankar, M. Ravi
中科院分区：
文献类型：
--
作者：
Martinez, Angel;Clement, Arul;Shankar, M. Ravi
研究了扩链剂结构和组成对硫醇-丙烯酸酯迈克尔加成法合成液晶弹性体（LCE）热机械性能的影响。硫醇扩链剂的固有分子刚度及其与丙烯酸酯基主体介晶的相对摩尔比决定了热机械应变的大小、它们实现的温度和机械功含量。出现非线性结构-性质关系，其中较高浓度的柔性扩展剂首先放大热机械敏感性，但持续增加导致较弱的致动。理解这种相互作用导致复合材料平台，使用类似于在2 V下供应的115 mW的电功率实现类似于2 J kg（-1）的峰值比功生产。制备LCE与eGaIn液态金属（LM）的复合材料，其充当加热器，同时能够自身致动。热机械活性电极将电功率转换成焦耳热，它们有效地与它们所结合的纯LCE耦合。这个系统利用LCE的新生反应，使用与它们一起工作的电极，而不是对抗它们（或被动地站在路上）。当受到增加的载荷水平时，产生的比功增加，在类似于260倍致动器重量的载荷下达到峰值。这些想法被扩展到三层致动器，其中具有正交分子取向的LCE膜夹持LCE-LM复合加热器。扭转致动模式用于在负载下扭转。
The effect of chain extender structure and composition on the thermomechanical properties of liquid crystal elastomers (LCE) synthesized using thiol-acrylate Michael addition is presented. The intrinsic molecular stiffness of the thiol chain extender and its relative molar ratio to acrylate-based host mesogens determine the magnitudes of the thermomechanical strains, temperatures at which they are realized and the mechanical work-content. A non-linear structure-property relationship emerges, wherein higher concentrations of flexible extenders first magnify the thermomechanical sensitivity, but a continued increase leads to weaker actuation. Understanding this interplay leads to a composite material platform, enabling a peak specific work production of similar to 2 J kg(-1) using similar to 115 mW of electrical power supplied at 2 V. Composites of LCE with eGaIn liquid metal (LM) are prepared, which act as heaters, while being capable of actuation themselves. The thermomechanically active electrodes convert the electrical power into Joule heat, which they efficiently couple with the neat LCE to which they are bound. This system harnesses the nascent responsiveness of the LCE using electrodes that work with them, instead of fighting against them (or passively standing in the way). Specific work generated increases when subjected to increasing levels of load, reaching a peak at loads similar to 260x the actuator weight. These ideas are extended to tri-layered actuators, where LCE films with orthogonal molecular orientations sandwich LCE-LM composite heaters. Torsional actuation modes are harnessed to twist under load.