Kajiyama Satoshi, Iwase Hiroki, Nakayama Masanari, Ichikawa Rino, Yamaguchi Daisuke, Seto Hideki, Kato Takashi
Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Nanoscale. 2020 Jun 7;12(21):11468-11479. doi: 10.1039/c9nr10996j. Epub 2020 Mar 30.
Liquid-crystalline (LC) bio-inspired materials based on colloidal nanoparticles with anisotropic morphologies such as sheets, plates, rods and fibers were used as functional materials. They show stimuli-responsive behaviour under mechanical force and in electric and magnetic fields. Understanding the effects of external stimuli on the structures of anisotropic colloidal particles is important for the development of highly ordered structures. Recently, we have developed stimuli-responsive hydroxyapatite (HAP)-based colloidal LC nanorods that are environmentally-friendly functional materials. In the present study, the ordering behaviour of HAP nanorod dispersions, which show LC states, has been examined using in situ small-angle neutron scattering and rheological measurements (Rheo-SANS) under shearing force. The structural analyses and dynamic viscosity observations provided detailed information about the effects of shear force on the structural changes of HAP nanorods in DO dispersion. The present Rheo-SANS measurements unraveled three kinds of main effects of the shear force: the enhancement of interactions between the HAP nanorods, the alignment of HAP nanorods to the shear flow direction, and the formation and disruption of HAP nanorod assemblies. Simultaneous analyses of dynamic viscosity and structural changes revealed that the HAP nanorod dispersions exhibited distinctive rheological properties accompanied by their ordered structural changes.
基于具有各向异性形态（如片、板、棒和纤维）的胶体纳米颗粒的液晶（LC）生物启发材料被用作功能材料。它们在机械力以及电场和磁场作用下表现出刺激响应行为。了解外部刺激对各向异性胶体颗粒结构的影响对于高度有序结构的开发很重要。最近，我们开发了基于刺激响应性羟基磷灰石（HAP）的胶体LC纳米棒，它们是环境友好型功能材料。在本研究中，使用原位小角中子散射和流变测量（Rheo-SANS）在剪切力作用下研究了呈现LC状态的HAP纳米棒分散体的有序行为。结构分析和动态粘度观测提供了关于剪切力对DO分散体中HAP纳米棒结构变化影响的详细信息。目前的Rheo-SANS测量揭示了剪切力的三种主要作用：HAP纳米棒之间相互作用的增强、HAP纳米棒沿剪切流动方向的排列以及HAP纳米棒聚集体的形成和破坏。动态粘度和结构变化的同步分析表明，HAP纳米棒分散体表现出独特的流变特性，并伴随着其有序结构的变化。
