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Planar Alignment of Columnar Discotic Liquid Crystals by Isotropic Phase Dewetting on Chemically Patterned Surfaces
Author(s) -
Bramble Jonathan P.,
Tate Daniel J.,
Revill Derek J.,
Sheikh Khizar H.,
Henderson James R.,
Liu Feng,
Zeng Xiangbing,
Ungar Goran,
Bushby Richard J.,
Evans Stephen D.
Publication year - 2010
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200902140
Subject(s) - materials science , dewetting , columnar phase , discotic liquid crystal , planar , liquid crystal , triphenylene , phase (matter) , perpendicular , isotropy , anisotropy , silicon , microcontact printing , lyotropic , optics , mesophase , nanotechnology , optoelectronics , thin film , liquid crystalline , geometry , computer graphics (images) , organic chemistry , chemistry , mathematics , physics , computer science
A novel method of creating planar aligned columnar discotic liquid crystals (cDLCs) on surfaces, which also gives control over the azimuthal angle, is presented. Surfaces are chemically patterned with stripes via microcontact printing of organothiol self‐assembled monolayers (SAMs) on gold, or via deep UV patterning of organosilane SAMs on silicon. These are then used to isolate long droplets of cDLCs by dewetting in the isotropic phase. Upon cooling from the isotropic into the hexagonal columnar phase, polarizing microscopy reveals that the cDLC aligns in a planar orientation. Results for three triphenylene derivatives (HAT‐6, HHTT, H7T) and for a phthalocyanine derivative (8H 2 Pc) are presented. H7T and HAT‐6 are found to align with the director perpendicular to the stripe direction, but HHTT and 8H 2 Pc align parallel to the stripe direction. This relatively simple new method for creating planar aligned columnar phases of DLCs gives control over the azimuthal angle: a condition required for organic field‐effect transistor applications of cDLCs.