Design of discotic liquid crystal enabling complete switching along with memory of homeotropic and homogeneous alignment over a large area. Issue 34 (2nd August 2022)

• Record Type: Journal Article
• Authors: Shoji, Yoshiaki; Kobayashi, Miki; Kosaka, Atsuko; Haruki, Rie; Kumai, Reiji; Adachi, Shin-ichi; Kajitani, Takashi; Fukushima, Takanori
• Is Part Of: Chemical science. Volume 13:Issue 34(2022)
• Page Start: 9891
• Page End: 9901
• Publication Date: 2022-08-02
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d2sc03677k
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : A columnar liquid crystal consisting of a triphenylene hexacarboxylic ester mesogen and semifluoroalkyl side chains shows complete switching between homeotropic and homogeneous alignments, each of which remains persistent up to its melting point. Abstract : The alignment control of discotic columnar liquid crystals (LCs), featuring a low motility of the constituent molecules and thus having a large viscosity, is a challenging task. Here we show that triphenylene hexacarboxylic ester, when functionalized with hybrid side chains consisting of alkyl and perfluoroalkyl groups in an appropriate ratio, gives a hexagonal columnar (Colh ) LC capable of selectively forming large-area uniform homeotropic or homogeneous alignments, upon cooling from its isotropic melt or upon application of a shear force at its LC temperature, respectively. In addition to the alignment switching ability, each alignment state remains persistent unless the LC is heated to its melting temperature. In situ X-ray diffraction analysis under the application of a shear force, together with polarized optical microscopy observations, revealed how the columnar assembly is changed during the alignment-switching process. The remarkable behavior of the discotic LC is discussed in terms of its rheological properties.