Bio-inspired and Smart Materials, MESA+ Institute for Nanotechnology, University of Twente, 7500 AE, Enschede, The Netherlands.
Small. 2019 Sep;15(39):e1902419. doi: 10.1002/smll.201902419. Epub 2019 Aug 6.
Nanoparticles tend to aggregate once integrated into soft matter and consequently, self-assembling nanoparticles into large-scale, regular, well-defined, and ultimately chiral patterns remains an ongoing challenge toward the design and realization of organized superstructures of nanoparticles. The patterns of nanoparticles that are reported in liquid crystals so far are all static, and this lack of responsiveness extends to assemblies of nanoparticles formed in topological singularities and other localized structures of anisotropic matter. Here, it is shown that gold nanoparticles form spiral superstructures in polygonal fields of cholesteric liquid crystals. Moreover, when the cholesteric liquid crystals incorporate molecular photoswitches in their composition, the pitch of the nanoparticulate spirals follows the light-induced reorganization of the cholesteric liquid crystals. These experimental findings indicate that chiral liquid crystals can be used as chiral and dynamic templates for soft photonic nanomaterials. Controlling the geometry of these spirals of nanoparticles will ultimately allow modulating the plasmonic signature of hybrid and chiral systems.
纳米粒子一旦融入软物质中往往会聚集，因此，将自组装的纳米粒子大规模、规则、明确地并最终形成手性图案仍然是设计和实现纳米粒子有序超结构的一个持续挑战。到目前为止，在液晶中报道的纳米粒子图案都是静态的，而且这种无响应性也扩展到了在拓扑奇点和各向异性物质的其他局域结构中形成的纳米粒子组装体。在这里，研究人员展示了金纳米粒子在胆甾相液晶的多边形场中形成螺旋超结构。此外，当胆甾相液晶在其组成中加入分子光开关时，纳米颗粒螺旋的螺距会跟随胆甾相液晶的光诱导重组。这些实验结果表明，手性液晶可用作软光子纳米材料的手性和动态模板。控制这些纳米粒子螺旋的几何形状将最终允许调节混合和手性系统的等离子体特征。
