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Surface Aligned Main-Chain Liquid Crystalline Elastomers: Tailored Properties by the Choice of Amine Chain Extenders
Macromolecules ( IF 5.5 ) Pub Date : 2018-01-18 00:00:00 , DOI: 10.1021/acs.macromol.7b02514
Hyeong-Ho Yoon 1 , Dae-Yoon Kim 2 , Kwang-Un Jeong 2 , Suk-kyun Ahn 1
Affiliation  

A promising way to induce shape transformation in soft materials is via spatial variation in the orientation of the alignment of liquid crystalline elastomers (LCEs). Here, we improve the nascent thermomechanial shape transformation in main-chain LCEs prepared via aza-Michael addition reactions. Specifically, increasing the alkyl length in the n-alkylamine chain extender effectively reduces the actuation temperature by destabilizing the nematic phase as well as reduces the glass transition temperature (Tg) by increasing the free volume. In addition, incorporating a hydroxyl end-group in the amine chain extender (i.e., n-alkanolamine) increases the actuation strain and improves the film quality by preventing side-chain aggregates of n-alkylamine-functionalized LCEs. Interestingly, uniaxially aligned n-alkanolamine-functionalized LCEs exhibit an unprecedentedly large elongation and an enhanced toughness even along the loading direction likely due to hydrogen bonding between chains. Thus, our study highlights that the choice of amine chain extender during LCEs synthesis can be an efficient strategy to tailor the properties as well as to provide a new functionality in the LCEs which may expand their range of applications in shape morphing devices, smart coatings, and dynamic substrates.

中文翻译:

表面排列的主链液晶弹性体:通过胺扩链剂的选择获得量身定制的性能

诱导软材料中的形状转变的一种有前途的方法是通过液晶弹性体(LCE)排列方向的空间变化。在这里,我们改善了通过aza-Michael加成反应制备的主链LCE中新生的热机械形状转变。具体地,在增加烷基长度Ñ烷基胺扩链剂有效地去稳定化的向列相,以及降低了玻璃化转变温度(降低了致动温度Ť通过增加自由体积)。此外,在胺扩链剂中掺入羟基端基(即烷醇胺)可通过防止n的侧链聚集而增加驱动应变并改善薄膜质量。-烷基胺官能化的LCE。有趣的是,单链排列的链烷醇胺官能化的LCE甚至由于沿链之间的氢键作用,即使在沿装载方向的情况下,也表现出前所未有的大伸长率和增强的韧性。因此,我们的研究强调,在LCE合成过程中选择胺扩链剂可以是一种有效的策略,可在LCE中调整其性能并提供新的功能,这可能会扩展其在形状变形设备,智能涂料,和动态基材。
更新日期:2018-01-18
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