Department of Physics, Material Science and Engineering Program, Department of Electrical, Computer, & Energy Engineering, and Liquid Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA.
Nanoscale. 2018 Mar 1;10(9):4218-4227. doi: 10.1039/c7nr06663e.
Monodisperse rod-like colloidal particles are known for spontaneously forming both nematic and smectic liquid crystal phases, but their self-assembly was typically exploited from the fundamental soft condensed matter physics perspective. Here we demonstrate that depletion interactions, driven by non-adsorbing polymers like dextran and surfactants, can be used to enrich the self-organization of photon-upconversion nanorods into orientationally ordered nematic and smectic-like membrane colloidal superstructures. We study thermodynamic phase diagrams and demonstrate polarization-dependent photon upconversion exhibited by the ensuing composites, which arises from the superposition of unique properties of the solid nanostructures and the long-range ordering enabled by liquid crystalline self-organization. Finally, we discuss how our method of utilizing self-assembly due to the steric and electrostatic interactions, along with attractive depletion forces, can enable technological uses of lyotropic colloidal liquid crystals and mesostructured composite materials enabled by them, even when they are formed by anisotropic nanoparticles with relatively small aspect ratios.
单分散棒状胶体颗粒以自发形成向列相和近晶相液晶相而闻名，但它们的自组装通常是从基础软凝聚态物理的角度来利用的。在这里，我们证明了由非吸附性聚合物（如葡聚糖和表面活性剂）驱动的耗散相互作用可用于丰富光上转换纳米棒的自组织，使其进入各向有序的向列相和类似近晶相的膜胶体超结构。我们研究了热力学相图，并证明了由此产生的复合材料表现出偏振依赖性的光上转换，这是由固体纳米结构的独特性质和由液晶自组织实现的长程有序的叠加引起的。最后，我们讨论了我们如何利用由于空间和静电相互作用以及吸引力耗散力引起的自组装的方法，即使它们是由具有相对较小纵横比的各向异性纳米颗粒形成的，也可以使溶致胶体液晶和介孔复合材料的技术应用成为可能。
