Water Droplets in a Spherically Confined Nematic Solvent: A Numerical Investigation

Дата и время публикации : 1998-03-10T12:02:41Z

Авторы публикации и институты :
Holger Stark (Universitaet Stuttgart, Germany)
Joachim Stelzer (Universitaet Stuttgart, Germany)
Ralf Bernhard (Waiblingen, Germany)

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: 9 pages, RevTeX, 12 encapsulated postscript figures
Первичная категория: cond-mat.soft

Все категории : cond-mat.soft

Краткий обзор статьи: Recently, it was observed that water droplets suspended in a nematic liquid crystal form linear chains (Poulin et al., Science 275, 1770 (1997)). The chaining occurs, e.g., in a large nematic drop with homeotropic boundary conditions at all the surfaces. Between each pair of water droplets a point defect in the liquid crystalline order was found in accordance with topological constraints. This point defect causes a repulsion between the water droplets. In our numerical investigation we limit ourselves to a chain of two droplets. For such a complex geometry we use the method of finite elements to minimize the Frank free energy. We confirm an experimental observation that the distance d of the point defect from the surface of a water droplet scales with the radius r of the droplet like d = 0.3 * r. When the water droplets are moved apart, we find that the point defect does not stay in the middle between the droplets, but rather forms a dipole with one of them. This confirms a theoretical model for the chaining. Analogies to a second order phase transition are drawn. We also find the dipole when one water droplet is suspended in a bipolar nematic drop with two boojums, i.e., surface defects at the outer boundary. Finally, we present a configuration where two droplets repel each other without a defect between them.

Category: Physics