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Article

Effect of Isomeric Amine Chain Extenders and Crosslink Density on the Properties of Liquid Crystal Elastomers

1
Department of Polymer Science and Engineering, Pusan National University, Busan 46241, Korea
2
Department of Chemical Engineering, Soongsil University, Seoul 06978, Korea
*
Authors to whom correspondence should be addressed.
Materials 2020, 13(14), 3094; https://doi.org/10.3390/ma13143094
Received: 28 May 2020 / Revised: 2 July 2020 / Accepted: 8 July 2020 / Published: 10 July 2020
(This article belongs to the Special Issue Stimuli Responsive Liquid Crystals)
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. View Full-Text
Keywords: liquid crystal elastomer; actuation; surface alignment; structure-property relationship liquid crystal elastomer; actuation; surface alignment; structure-property relationship
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MDPI and ACS Style

Lee, Y.; Choi, S.; Kang, B.-G.; Ahn, S.-k. Effect of Isomeric Amine Chain Extenders and Crosslink Density on the Properties of Liquid Crystal Elastomers. Materials 2020, 13, 3094. https://doi.org/10.3390/ma13143094

AMA Style

Lee Y, Choi S, Kang B-G, Ahn S-k. Effect of Isomeric Amine Chain Extenders and Crosslink Density on the Properties of Liquid Crystal Elastomers. Materials. 2020; 13(14):3094. https://doi.org/10.3390/ma13143094

Chicago/Turabian Style

Lee, Yoojin, Subi Choi, Beom-Goo Kang, and Suk-kyun Ahn. 2020. "Effect of Isomeric Amine Chain Extenders and Crosslink Density on the Properties of Liquid Crystal Elastomers" Materials 13, no. 14: 3094. https://doi.org/10.3390/ma13143094

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