How Far Can We Push the Rigid Oligomers/Polymers toward Ferroelectric Nematic Liquid Crystals?
How Far Can We Push the Rigid Oligomers/Polymers toward Ferroelectric Nematic Liquid Crystals?
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DOI：
10.1021/jacs.1c09594
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发表时间：
2021-10-18
影响因子：
15
通讯作者：
Huang, Mingjun
中科院分区：
文献类型：
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作者：
Li, Jinxing;Xia, Runli;Huang, Mingjun
新兴的铁电向列 (N-F) 液晶是一种新型的 3D 有序液体，表现出宏观电极化。超高介电常数、强非线性光信号和对电场的高灵敏度的结合使得N-F材料在先进液晶电光器件的开发中具有广阔的前景。此前，所有研究都集中在长度（l）范围和偶极矩（mu）值有限的棒状小分子上。在这里，通过精密合成，我们将芳香族棒状介晶扩展到低聚物/聚合物（重复单元高达12，具有单分散分子量分散），并将μ值提高到30德拜（D）以上。 N-F相的广泛存在远远超出了我们的预期，并且可以在所有低聚物/聚合物长度范围内观察到。值得注意的是，N-F相经历了一条非平凡的演化途径，传统的非极性向列相完全受到抑制，即N-F相直接从各向同性液相成核。低聚物/聚合物棒的铁电堆积的发现不仅提供了将N-F态扩展到低聚物/聚合物的概念，而且还提供了一些以前被忽视的基于苯氧基苯甲酸酯的液晶聚合物材料的见解。
The emerging ferroelectric nematic (N-F) liquid crystal is a novel 3D-ordered liquid exhibiting macroscopic electric polarization. The combination of the ultrahigh dielectric constant, strong nonlinear optical signal, and high sensitivity to the electric field makes N-F materials promising for the development of advanced liquid crystal electroopic devices. Previously, all studies focused on the rod-shaped small molecules with limited length (l) range and dipole moment (mu) values. Here, through the precision synthesis, we extend the aromatic rod-shaped mesogen to oligomer/polymer (repeat unit up to 12 with monodisperse molecular-weight dispersion) and increase the mu value over 30 Debye (D). The N-F phase has a widespread existence far beyond our expectation and could be observed in all the oligomer/polymer length range. Notably, the N-F phase experiences a nontrivial evolution pathway with the traditional apolar nematic phase completely suppressed, i.e., the N-F phase nucleates directly from the isotropic liquid phase. The discovery of thte ferroelectric packing of oligomer/polymer rods not only offers the concept of extending the N-F state to oligomers/polymers but also provides some previously overlooked insights in oxybenzoate-based liquid crystal polymer materials.