M Muhammed Rasi, Pujala Ravi Kumar, Dhara Surajit
School of Physics, University of Hyderabad, Hyderabad, 500046, India.
Indian Institute of Science Education and Research, Tirupati, India.
Sci Rep. 2019 Mar 15;9(1):4652. doi: 10.1038/s41598-019-40198-1.
Robust control over the position, orientation and self-assembly of nonspherical colloids facilitate the creation of new materials with complex architecture that are important from technological and fundamental perspectives. We study orientation, elastic interaction and co-assembly of surface functionalized silica nano-rods in thin films of nematic liquid crystal. With homeotropic boundary condition, the nano-rods are predominantly oriented perpendicular to the nematic director which is different than the mostly parallel orientation of the micro-rods. The percentage of perpendicular nano-rods are significantly larger than the parallel nano-rods. The perpendicular nano-rods create very weak elastic deformation and exhibit unusual, out-of-plane, attractive interaction. On the other hand, the nano-rods oriented parallel to the director create strong elastic deformation and shows anisotropic, in-plane, dipolar interaction. In both orientations, the induced defects reside in the nano-rods. With the help of a dynamic laser tweezers and using nano-rods as building blocks we demonstrate colloidal analogues of linear polymer chains, ribbons and two-dimensional binary crystals.
对非球形胶体的位置、取向和自组装进行稳健控制，有助于创造出具有复杂结构的新材料，这些材料从技术和基础角度来看都很重要。我们研究了向列型液晶薄膜中表面功能化二氧化硅纳米棒的取向、弹性相互作用和共组装。在垂直排列边界条件下，纳米棒主要垂直于向列型指向矢取向，这与微棒大多平行的取向不同。垂直纳米棒的百分比明显大于平行纳米棒。垂直纳米棒产生非常微弱的弹性变形，并表现出异常的、面外的吸引相互作用。另一方面，平行于指向矢取向的纳米棒产生强烈的弹性变形，并表现出各向异性的、面内的偶极相互作用。在这两种取向下，诱导缺陷都存在于纳米棒中。借助动态激光镊子并使用纳米棒作为构建块，我们展示了线性聚合物链、带和二维二元晶体的胶体类似物。
