Our Facebook account

E. N. Vasilchikova¹, M. S. Konstantinov¹, V. I. Mashchenko^1,@, R. N. Kucherov¹, D. N. Chausov^1,2, ¹

Author affiliations
¹Moscow Region State University,
24 Very Voloshinoy St., Mytishchi, 141014, Russia
²National University of Science and Technology «MISIS»,
4 Leninsky Pr., Moscow, 119049, Russia
E-mail: mashchenko@genebee.msu.su

Abstract
Crystallization of 4,4'-azoxyanisole (N-4) upon solvent evaporation from a droplet surface located on a glass substrate was investigated by polarization optical microscopy and gravimetry. It was shown that a metal ball placed in the center of the droplet leads to the formation of multiple «coffee rings» consisting of microcrystals of N-4. It is assumed that the ball changes the geometry of the initial droplet, which leads to an increase in the number of «coffee rings». A geometric model of this phenomenon is proposed that correlates well with experimental data. The developed new approach to the formation of the microstructure of functional materials with a thermotropic liquid crystal phase on a glass substrate can be used to create devices for nano- and microelectronics and optical technology.

Keywords: «Coffee ring» effect, 4,4'-azoxyanisole, crystallization, microstructure