Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH, 44242, USA.
Department of Ophthalmology and Visual Science and Department of Electrical and Computer Engineering, Ohio State University, Columbus, OH, 43212, USA.
Angew Chem Int Ed Engl. 2016 Oct 10;55(42):13090-13094. doi: 10.1002/anie.201606895.
Adding colloidal nanoparticles into liquid-crystal media has become a promising pathway either to enhance or to introduce novel properties for improved device performance. Here we designed and synthesized new colloidal hybrid silica nanoparticles passivated with a mesogenic monolayer on the surface to facilitate their organo-solubility and compatibility in a liquid-crystal host. The resulting nanoparticles were identified by H NMR spectroscopy, TEM, TGA, and UV/Vis techniques, and the hybrid nanoparticles were doped into a dual-frequency cholesteric liquid-crystal host to appraise both their compatibility with the host and the effect of the doping concentration on their electro-optical properties. Interestingly, the silica-nanoparticle-doped liquid-crystalline nanocomposites were found to be able to dynamically self-organize into a helical configuration and exhibit multi-stability, that is, homeotropic (transparent), focal conic (opaque), and planar states (partially transparent), depending on the frequency applied at sustained low voltage. Significantly, a higher contrast ratio between the transparent state and scattering state was accomplished in the nanoparticle-embedded liquid-crystal systems.
将胶态纳米粒子加入液晶介质中，已成为一种很有前途的方法，可以增强或引入新的性质，从而提高器件性能。在这里，我们设计并合成了新型的胶体杂化二氧化硅纳米粒子，其表面用介晶单层进行钝化，以提高它们在液晶主体中的有机溶解性和相容性。通过 H NMR 光谱、TEM、TGA 和 UV/Vis 技术对得到的纳米粒子进行了鉴定，将杂化纳米粒子掺杂到双频胆甾相液晶主体中，以评估它们与主体的相容性以及掺杂浓度对其电光性能的影响。有趣的是，发现掺杂有二氧化硅纳米粒子的液晶纳米复合材料能够动态地自组织成螺旋结构，并表现出多稳态，即垂直取向（透明）、焦锥（不透明）和平坦取向（部分透明），这取决于在持续低电压下施加的频率。重要的是，在纳米粒子嵌入的液晶体系中实现了透明态和散射态之间更高的对比度。
