Micro- and Nano-technology Research Center, State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University , 28 Xianning Road, Xi'an 710049, P. R. China.
ACS Appl Mater Interfaces. 2017 Sep 27;9(38):33119-33128. doi: 10.1021/acsami.7b09246. Epub 2017 Sep 15.
A liquid crystal elastomer (LCE) can be regarded as an integration of mesogenic molecules into a polymer network. The LCE can generate large mechanical actuation when subjected to various external stimuli. Recently, it has been extensively explored to make artificial muscle and multifunctional devices. However, in the commonly adopted two-step crosslinking method for synthesizing monodomain LCEs, the LCE needs to be well-cross-linked in the first step before stretching, which increases the disorder of mesogenic molecules in the final state of the LCE and makes it very challenging to fabricate the LCE of complex shapes. In this article, we developed a new LCE with disulfide bonds, which can be reprogrammed from the polydomain state to the monodomain state either through heating or UV illumination, owing to the rearrangement of the polymer network induced by the metathesis reaction of disulfide bonds. In addition, the newly developed LCE can be easily reprocessed and self-healed by heating. Because of the excellent reprogrammability as well as reprocessability of the LCE, we further fabricated LCE-based active micropillar arrays through robust imprint lithography, which can be hardly achieved using the LCE prepared previously. Finally, we showed an excellent long-term durability of the newly developed LCE.
液晶弹性体（LCE）可以被视为介晶分子与聚合物网络的集成。LCE 在受到各种外部刺激时可以产生较大的机械致动。最近，它被广泛探索用于制造人工肌肉和多功能器件。然而，在合成单畴 LCE 的常用两步交联方法中，LCE 在拉伸之前需要很好地交联，这增加了 LCE 最终状态中介晶分子的无序性，使得制造复杂形状的 LCE 非常具有挑战性。在本文中，我们开发了一种具有二硫键的新型 LCE，它可以通过加热或 UV 照射从多畴状态重新编程到单畴状态，这是由于二硫键的复分解反应引起的聚合物网络的重排。此外，新开发的 LCE 可以通过加热轻松再加工和自修复。由于 LCE 具有出色的可重编程性和可再加工性，我们进一步通过强大的压印光刻法制造了基于 LCE 的主动微柱阵列，这是以前制备的 LCE 很难实现的。最后，我们展示了新开发的 LCE 的出色长期耐久性。
