含有动态共价键的液晶弹性体的分子设计、合成及性能研究

In 2014, we reported that dynamic covalent bonds offer a practical solution to the bottleneck of processing liquid crystalline elastomers. As this is a new area, the relationship between molecular structure and material property is unknown; other kinds of dynamic covalent bonds except dynamic ester bonds have not been explored. In this project, we are going to design and synthesis various kind of liquid crystalline elastomers with dynamic covalent bonds. It contains two part. In the first part, we will systematically investigate liquid crystalline elastomers containing ester bonds. By designing and synthesis liquid crystalline elastomers with different structures, we plan to find out the relationship between molecular design and the material properties, the reasons account for the successful preparation of monodomain liquid crystalline elastomers, and how to improve the actuation performance of the materials. In the second part, we are going to design and synthesis new liquid crystalline elastomers containing other kind of dynamic covalent bonds, to enrich the type of liquid crystalline elastomers, attempting to overcome the shortcomings inherent to the liquid crystalline elastomers containing dynamic ester bonds. Base on the above research, we are going to summarize the common features for the successful design of easy processable liquid crystalline elastomers, to provide new methods, new techniques and theoretical knowledge for the preparation of liquid crystalline elastomers.

液晶弹性体作为一种智能材料，应用前景广阔，我们两年前证实，采用动态共价键构筑液晶弹性体，可解决此领域长久以来面临的加工困难的瓶颈问题，但此类液晶弹性体的分子结构与性能之间的关系尚不明了，除了动态酯键外种类繁多的其它动态共价键尚未涉及。本项目拟从分子设计出发，以化学合成和性能表征为基础，研究两部分内容。第一部分通过系统的设计合成不同结构的含动态酯键的液晶弹性体，揭示分子结构与性能之间的关系，阐明成功加工的因素，提高材料的形变率。第二部分是利用其它的动态共价键，设计合成易加工的液晶弹性体，以期解决含动态酯键体系液晶基元选择受限的缺陷及高温稳定性差的问题。以上述研究为基础，总结其中的规律，丰富液晶弹性体的可选择范围，为液晶弹性体分子设计及制备提供理论基础和新方法、新技术。

液晶弹性体能够感知外界刺激，自发发生大幅形变，作为致动器和感应器，可应用于包括软体机器人在内诸多高科技领域。加工制备困难成为目前制约材料实际应用重要问题。采用动态交换键制备新驱动器材料，有望解决液晶弹性体加工难题，并为此材料带来焊接、愈合和再塑型等性能。本项目从分子设计合成出发，以化学合成和性能表征为基础，开展了动态共价键构筑液晶弹性体的研究。项目通过设计合成新的含动态酯键液晶弹性体，优化了单畴液晶弹性体的加工工艺，将此类液晶弹性体驱动的形变率提高到90%；利用硅氧交换反应和加成断裂链转移反应，合成了新的液晶弹性体。更为重要的是，我们采用了不同的策略，解决了含动态酯键体系液晶基元选择受限的缺陷及驱动稳定性差的问题，所得液晶弹性体可以稳定驱动1000次以上。项目研究不仅丰富液晶弹性体的可选择范围，为液晶弹性体分子设计及制备提供理论基础和新方法、新技术，而且为柔性机器人等领域的发展提供了新材料和新思路。