Liquid crystalline (LC) materials are especially suited for the preparation of active three-dimensional (3D) and 4D microstructures using two-photon laser printing. To achieve the desired actuation, the alignment of the LCs has to be controlled during the printing process. In most cases studied before, the alignment relied on surface modifications and complex alignment patterns and concomitant actuation were not possible. Here, we introduce a strategy for spatially aligning LC domains in three-dimensional space by using 3D-printed polydimethylsiloxane-based microscaffolds as confinement barriers, which induce the desired director field. The director field resulting from the boundary conditions is calculated with Landau de Gennes theory and validated by comparing experimentally measured and theoretically predicted birefringence patterns. We demonstrate our procedures for structures of varying complexity and then employed them to fabricate 4D microstructures that show the desired actuation. Overall, we obtain excellent agreement between theory and experiment. This opens the door for rational design of functional materials for 4D (micro)printing in the future.

中文翻译：

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通过 3D 限制和双光子激光打印实现液晶的对准和驱动


液晶 (LC) 材料特别适合使用双光子激光打印制备活性三维 (3D) 和 4D 微结构。为了实现所需的驱动，必须在打印过程中控制液晶的对齐。在之前研究的大多数情况下，对齐依赖于表面修改和复杂的对齐模式以及伴随的驱动是不可能的。在这里，我们引入了一种在三维空间中空间排列液晶域的策略，通过使用 3D 打印的聚二甲基硅氧烷基微支架作为限制势垒，从而产生所需的指向矢场。由边界条件产生的指向矢场是用朗道德热尼斯理论计算的，并通过比较实验测量和理论预测的双折射图案进行验证。我们演示了不同复杂性结构的程序，然后利用它们来制造显示所需驱动的 4D 微结构。总的来说，我们在理论和实验之间获得了很好的一致性。这为未来 4D（微）打印功能材料的合理设计打开了大门。