[论文解读] Printing Mosaics of Magnetically Programmed Liquid Crystal Directors for Reversibly Morphing Soft Matter

Yueping Wang, Jongwon An+7 more|arXiv (Cornell University)|Jan 12, 2024

Advanced Materials and Mechanics被引用 5

一句话总结

该论文展示了一种用于液晶弹性体（LCE）的数字光投射（DLP）成像打印方法，可以在制造过程中通过磁场定向，从而实现可逆热致执行和可编程的LC取向马赛克在打印结构中。

ABSTRACT

Liquid crystal elastomer (LCE) has been intensively utilized in 4D printing techniques to fabricate smart structures with reversible actuation on the basis of appropriate alignment of liquid crystal (LC) molecules. As a non-contact alignment strategy with a controllability of orientation, magnetic-field alignment has been rarely adapted in 4D printing of LCE because of its poor printing efficiency and demand on large field strength. Here, we report a digital light projection (DLP) system integrated with reorientable magnetic field to facilely print smart LCE structures. We propose a new LCE precursor solution that maintains a liquid crystalline nematic phase and an adequate flowability at room temperature. The resin prior to photopolymerization can be sufficiently aligned by a magnetic field with a strength of 500 mT in seconds without temperature elevating or cycling. Consequential printed structures are capable of presenting an impressive reversible thermal actuation of more than 30 %. The local and arbitrary magnetic-field alignment in layers during DLP printing is characterized, which renders us the ability to construct smart structures with more delicate LC alignments. Furthermore, we introduce the selective deformation of LCE structures with programmed molecular orientation using the photo-thermal effect. Our reported approach reveals the significant potential for fabricating morphing structures in various fields, including soft robotics, biomedical structures, and microelectronics. (†These authors contributed equally.)

研究动机与目标

• 实现液晶导向在4D打印LCE过程中的非接触、快速定向。
• 开发在室温下保持向列相且可打印的LCE前体，以便磁场定向。
• 展示在打印层内通过磁场辅助定向LC取向的模式化。
• 在磁场定向的LCE结构中显示>30%的可逆热致驱动。
• 引入使用光热效应的选择性变形以实现结构形变。

提出的方法

• 将可再定向磁场与数字光投射（DLP）打印系统集成。
• 制定在室温下保持液晶相且可流动的LCE前体以实现磁场定向。
• 在打印过程中施加磁场（约500 mT），在不进行温度循环的情况下使每层的LC导向定向。
• 表征打印层内的局部与任意磁场定向，以实现细腻的LC取向。
• 通过光热效应演示对LCE结构的选择性变形。

实验结果

研究问题

• RQ1 是否可以在LCE中使用DLP系统可靠地打印出磁场定向的LC导向？
• RQ2 哪些磁场强度和处理窗口能够在不需加热循环的情况下实现快速室温定向？
• RQ3 层状LCE结构是否能通过编程的导向马赛克实现可控形变与可逆热致驱动？
• RQ4 选择性光热激活如何与磁场编程的取向相互作用，以实现目标部位的变形？

主要发现

• 所打印的LCE结构显示出超过30%的可逆热致驱动。
• 在打印过程中以500 mT的磁场定向，在数秒内就能将LC导向定向，而无需升温或循环温度。
• 层内实现局部和任意的LC导向定向成为可能，从而实现细腻的马赛克图案。
• 该方法支持适用于软体机器人、生物医学设备和微电子学的形变结构。
• 该方法在磁性编程的基础上结合光热效应，促进选择性变形。