Observation of macro-heterogeneities in surface-stabilized smectic C* with antagonistically patterned substrates

A.A. Kudreyko1, W. Song2, D.N. Migranova3
1Ufa State Petroleum Technological University
2Shanghai University of Engineering Sciences
3East Economic-Legal Humanitarian Academy

Abstract

Geometry of the surface-stabilized FLC cell.In our recent study, we theoretically considered equilibrium states in a monolayered sample of ferroelectric liquid crystal in smectic C* phase, confined between two differently patterned substrates with strong anchoring under the applied electric field. By using the continuum theory for a “bookshelf” aligned sample for smectic C*, we derived elliptic sine-Gordon equation. The solution of the Dirichlet problem has shown that due to the antagonistic boundary conditions at the substrates, competing boundary effects in the thin film generate a stable alignment of smectic C* director. This alignment can be controlled by the electric field. Our theoretical finding was described as the system with harmonically coupled “atoms” with external potential within the framework of the Frenkel-Kontorova model. To challenge our finding, we prepared a cell with differently patterned substrates, and ferroelectric liquid crystal material CS-1024 (Chisso Co.) was injected into the empty cell by the capillarity flow. Patterned monolayers exhibiting planar alignment of CS-1024 in its smectic C* phase were created using microcontact printing of functionalized organothiols on gold films. By patterning the surface with planar alignment of monolayers, the location and formation of smectic C* director macro-heterogeneities can be controlled by the electric field. The observed macro-heterogeneities continue to exist when the electric field is turned off. Polarizing microscopy and fluorescent microscopy were used to observe the formation of macro-heterogeneities in the alignment of SmC* director field.

Received: 06 July 2017   Revised: 29 September 2017   Accepted: 02 October 2017

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