Lin Xueyan, Zou Weike, Terentjev Eugene M
Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, U.K.
State Key Laboratory of Chemical Engineering, Zhejiang University, Hangzhou 310027, P.R. China.
Macromolecules. 2022 Feb 8;55(3):810-820. doi: 10.1021/acs.macromol.1c02065. Epub 2022 Jan 28.
Liquid-crystalline elastomers (LCEs) are frequently used in soft actuator development. However, applications are limited because LCEs are prone to mechanical failure when subjected to heavy loads and high temperatures during the working cycle. A mechanically tough LCE system offers larger work capacity and lower failure rate for the actuators. Herein, we adopt the double-network strategy, starting with a siloxane-based exchangeable LCE and developing a series of double-network liquid-crystalline elastomers (DN-LCEs) that are mechanically tougher than the initial elastomer. We incorporate diacrylate reacting monomers to fabricate DN-LCEs, some of which have the breaking stress of 40 MPa. We incorporate thermoplastic polyurethane to fabricate a DN-LCE, achieving an enormous ductility of 90 MJ/m. We have also attempted to utilize the aza-Michael chemistry to make a DN-LCE that retains high plasticity because of several bond-exchange mechanisms; however, it failed to produce a stable reprocessable LCE system using conventional ester-based reactive mesogens. Each of these DN-LCEs exhibits unique features and characteristics, which are compared and discussed.
液晶弹性体（LCEs）常用于软致动器的开发。然而，其应用受到限制，因为在工作循环中，当LCEs承受重负荷和高温时，容易出现机械故障。一种机械韧性良好的LCE系统可为致动器提供更大的工作能力和更低的故障率。在此，我们采用双网络策略，从基于硅氧烷的可交换LCE开始，开发了一系列机械韧性比初始弹性体更强的双网络液晶弹性体（DN-LCEs）。我们引入二丙烯酸酯反应性单体来制备DN-LCEs，其中一些的断裂应力为40MPa。我们引入热塑性聚氨酯来制备一种DN-LCE，实现了90MJ/m的巨大延展性。我们还尝试利用氮杂迈克尔化学来制备一种由于多种键交换机制而保持高可塑性的DN-LCE；然而，使用传统的基于酯的反应性液晶基元未能制备出稳定的可再加工LCE系统。这些DN-LCEs中的每一种都表现出独特的特性，我们对其进行了比较和讨论。
