Solution-grown single crystals of random terpolymer liquid crystal polymers: Chain folding, morphology, and effect of annealing

Abstract

Abstract Thin (100–150 A thick) single crystals of large lateral dimensions have been grown from dilute solution in xylene of random terpolymer, thermotropic, liquid crystal polymers containing approximately equimolar amounts of C6 or C7 flexible segments, oxybenzoate, and dioxyphenyl. With both polymers having molecular lengths of 800 A or longer, electron diffraction patterns indicate chain folding. The crystal structure, hexagonal, is less perfect than found previously for thin films of the C7 (and C5) polymer crystallized from the nematic state by slow cooling (orthorhombic). Annealing of the crystals below the crystal-liquid crystal transition results in merging of overgrowths and rough crystal edges into the main crystal and a surface roughening, followed, at longer times and/or higher temperatures, by lamella thickening. Annealing in the nematic state results in the development of rosettes of lamellae. Implications of the results for crystallization mechanisms and morphology of the nematic state ar...