Alignment of Chromonic Liquid Crystals: A Difficult Task

We present our recent effort on chromonic liquid crystal alignment. In particular, wereport the alignment behavior of chromonic molecules using different hydrophobicsubstrates.Different materials have been used to this purpose but in all cases ribbons texturesdevelop, indicating a slow water evaporation and/or a strong aggregation amongmolecules, that, as reported in a recent paper, give rise to threads connected through saltbridge bonds. Thin films of materials usually employed for thermotropic liquid crystalsalignment induce schlieren textures that after 10 days evolve into ribbon textures; thinfilms of materials with a low surface energy orient molecules in homeotropic configuration,but the alignment is lost after two weeks as in the case of degenerate planaralignment.