Kim Dahin, Ndaya Dennis, Bosire Reuben, Masese Francis K, Li Weixingyue, Thompson Sarah M, Kagan Cherie R, Murray Christopher B, Kasi Rajeswari M, Osuji Chinedum O
Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA.
Department of Chemistry, University of Connecticut, Storrs, CT, 06269, USA.
Nat Commun. 2022 May 6;13(1):2507. doi: 10.1038/s41467-022-30200-2.
Reconfigurable arrays of 2D nanomaterials are essential for the realization of switchable and intelligent material systems. Using liquid crystals (LCs) as a medium represents a promising approach, in principle, to enable such control. In practice, however, this approach is hampered by the difficulty of achieving stable dispersions of nanomaterials. Here, we report on good dispersions of pristine CdSe nanoplatelets (NPLs) in LCs, and reversible, rapid control of their alignment and associated anisotropic photoluminescence, using a magnetic field. We reveal that dispersion stability is greatly enhanced using polymeric, rather than small molecule, LCs and is considerably greater in the smectic phases of the resulting systems relative to the nematic phases. Aligned composites exhibit highly polarized emission that is readily manipulated by field-realignment. Such dynamic alignment of optically-active 2D nanomaterials may enable the development of programmable materials for photonic applications and the methodology can guide designs for anisotropic nanomaterial composites for a broad set of related nanomaterials.
二维纳米材料的可重构阵列对于实现可切换和智能材料系统至关重要。原则上，使用液晶（LC）作为介质是实现这种控制的一种有前景的方法。然而，在实践中，这种方法受到难以实现纳米材料稳定分散的阻碍。在此，我们报告了原始CdSe纳米片（NPL）在液晶中的良好分散，以及使用磁场对其排列和相关各向异性光致发光的可逆、快速控制。我们发现，使用聚合物液晶而非小分子液晶可大大提高分散稳定性，并且相对于向列相，所得体系的近晶相中的分散稳定性要高得多。排列好的复合材料表现出高度极化的发射，可通过场重新排列轻松操控。这种光学活性二维纳米材料的动态排列可推动用于光子应用的可编程材料的开发，并且该方法可为一系列相关纳米材料的各向异性纳米材料复合材料的设计提供指导。
