Tactoids of Plate-Like Particles: Size, Shape, and Director Field

被引:48
作者
Verhoeff, A. A. [1 ]
Bakelaar, I. A. [1 ]
Otten, R. H. J. [2 ,3 ]
van der Schoot, P. [2 ,4 ]
Lekkerkerker, H. N. W. [1 ]
机构
[1] Univ Utrecht, Debye Inst NanoMat Sci, Vant Hoff Lab Phys & Colloid Chem, NL-3584 CH Utrecht, Netherlands
[2] Eindhoven Univ Technol, Eindhoven Polymer Labs, Grp Theory Polymers & Soft Matter, NL-5600 MB Eindhoven, Netherlands
[3] Dutch Polymer Inst, NL-5600 AX Eindhoven, Netherlands
[4] Univ Utrecht, Inst Theoret Phys, NL-3584 CE Utrecht, Netherlands
关键词
LIQUID-CRYSTALS; FINE-STRUCTURE; DEFORMATION; DISPERSIONS; TRANSITION; ALGORITHM; DEFECTS;
D O I
10.1021/la104128m
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
We studied; by means of polarized light microscopy, the shape and director field of nematic tactoids as a function of their size in dispersions of colloidal gibbsite platelets in polar and apolar solvents. Because of the homeotropic anchoring of the platelets to the interface, we found large tactoids to be spherical with a radial director field, whereas small tactoids turn out to have an oblate shape and a homogeneous director field, in accordance with theoretical predictions. The transition from a radial to a homogeneous director field seems to proceed via two different routes depending in our case on the solvent. In one route, the what presumably is a hedgehog point defect in the center of the tactoid transforms into a ring defect with a radius that presumably goes to infinity with decreasing drop size. In the other route, the hedgehog defect is displaced from the center to the edge of the tactoid, where it becomes virtual again going to infinity with decreasing drop size. Furthermore, quantitative analysis of the tactoid properties provides us with useful information on the ratio of the splay elastic constant and the anchoring strength and the ratio of the anchoring strength and the surface tension.
引用
收藏
页码:116 / 125
页数:10
相关论文
共 54 条