Towards the restoration of the liquid crystal surface anchoring potential using Grandgean-Cano wedge

GRAPHICAL ABSTRACT

ABSTRACT

We extend further the theoretical and experimental studies of the actual surface anchoring potential restoration by polarization microscope technique in a wedge-shaped cell with weak surface anchoring forces filled by a chiral nematic liquid crystal (in Grandjean-Cano Wedge). To realize the theoretically predicted options of observation of large director deviation angles from the easy axes ϕ at a wedge surfaces (up to π/2) the experimental studies of director distribution in Grandjean-Cano zones were performed. A weak surface anchoring at one wedge surface was obtained by photoalignment technique. A strong surface anchoring at the second wedge surface was obtained by rubbing. The measurements were performed using polarizing microscope. The experimentally found director distributions in Grandjean-Cano zones were compared with theoretical ones calculated for various model surface anchoring potentials. As a result of the present studies the ways to enlarge (compared to the previous studies) angular range of the actual surface anchoring potential restoration were proposed and it was found that the experimentally found surface potential is nicely fitted by a new model surface anchoring potential, the so called model D-potential W_D(ϕ) ∼ ϕ².

KEYWORDS:

• Grandjean-Cano wedge
• photoalignment
• polarization microscope technique
• surface anchoring potential restoration

Additional information

Funding

The work is supported by the RFBR grants 16–02-0295_a, 16–02-0679_a, and 18–52-05010-Arm_a.