Effect of Isomeric Amine Chain Extenders and Crosslink Density on the Properties of Liquid Crystal Elastomers
Effect of Isomeric Amine Chain Extenders and Crosslink Density on the Properties of Liquid Crystal Elastomers
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DOI：
10.3390/ma13143094
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发表时间：
2020-07-01
期刊：
影响因子：
3.4
通讯作者：
Ahn, Suk-kyun
中科院分区：
文献类型：
--
作者：
Lee, Yoojin;Choi, Subi;Ahn, Suk-kyun
在各种类型的形状变化材料中，液晶弹性体（LCE）因其可以进行程序化和可逆的形状变换而受到了极大的关注。 LCE 的分子工程是操纵其相变、机械性能和驱动性能的关键。在这项工作中，合成了侧链中含有三种不同类型的丁基（正丁基、异丁基和仲丁基）的LCE，并研究了异构胺扩链剂对所得LCE的热、机械和驱动性能的影响。由于仲丁基对液晶单体中的二丙烯酸酯的反应性相当低，因此仅合成了致密交联的LCE。最有趣的是，包含异丁基的LCE的机械性能、致动温度和粘连应力高于包含正丁基的LCE。这种差异归因于 LCE 中存在带有异丁基的支链，这导致分子堆积更紧密并减少了自由体积。我们的研究结果提出了一种通过选择扩链剂来合成具有定制机械和驱动性能的LCE的简便有效的方法，这可能会促进软驱动器在航空航天、医学和光学领域各种应用的开发。
Among the various types of shape changing materials, liquid crystal elastomers (LCEs) have received significant attention as they can undergo programmed and reversible shape transformations. The molecular engineering of LCEs is the key to manipulating their phase transition, mechanical properties, and actuation performance. In this work, LCEs containing three different types of butyl groups (n-, iso-, and sec-butyl) in the side chain were synthesized, and the effect of isomeric amine chain extenders on the thermal, mechanical, and actuation properties of the resulting LCEs was investigated. Because of the considerably low reactivity of the sec-butyl group toward the diacrylate in the LC monomer, only a densely crosslinked LCE was synthesized. Most interestingly, the mechanical properties, actuation temperature, and blocking stress of the LCEs comprising isobutyl groups were higher than those of the LCEs comprising n-butyl groups. This difference was attributed to the presence of branches in the LCEs with isobutyl groups, which resulted in a tighter molecular packing and reduced the free volume. Our results suggest a facile and effective method for synthesizing LCEs with tailored mechanical and actuation properties by the choice of chain extenders, which may advance the development of soft actuators for a variety of applications in aerospace, medicine, and optics.