mz8b00044_si_001.pdf (952.4 kB)
One Methylene Group in the Side Chain Can Alter by 90 Degrees the Orientation of a Main-Chain Liquid Crystal on a Unidirectional Substrate
journal contribution
posted on 2018-03-23, 18:43 authored by Yaroslav Odarchenko, Matthieu Defaux, Martin Rosenthal, Azaliia Akhkiamova, Polina Bovsunovskaya, Alexey Melnikov, Alexander Rodygin, Andrey Rychkov, Kirill Gerasimov, Denis V. Anokhin, Xiaomin Zhu, Dimitri A. IvanovThe
mechanisms of orientation of columnar liquid crystals (LCs)
on a PTFE-rubbed surface are explored on a homologous series of symmetrically
substituted poly(di-n-alkylsiloxanes) (PDAS). It
is shown that by increasing the side-chain length in steps of one
CH2 group, the orientation of PDAS switches back and forth
from perpendicular to parallel with respect to PTFE chains. These
changes are sensitive to the smallest possible variation of the macromolecular
structure (i.e., modification of the side chain length by just one
CH2 group) reflect the alteration of the alignment mechanism
identified as graphoepitaxial or epitaxial for the perpendicular and
parallel orientation, respectively. The results show that two orthogonal
LC orientations are realizable on the same rubbed substrate, which
can open new perspectives in the field of organic and printed electronics
such as multidomain LCD technology.