STUDIES ON LYOTROPIC LIQUID CRYSTAL OF ETHYL-ACETYL CELLULOSE
乙基醋酸纤维素溶致性液晶的研究

Ethyl-acetyl cellulose ((E-A)C) could dissolve in organic acid solvent such as trifluoro-acetic acid (TFA), dichloroacetic acid (DCA) and acetic acid (AA) and form lyotropic liquid crystal above the critical concentration C1. With increasing concentration the solutions transformed form isotropic to anisotropic phase through a biphasic range. When the an-isotropic solutions were heated, they changed first to the biphase and then to the isotropic phase. The mesomorphic phase could form again when the solutions were cooled. There was a supercooling phenomenon for the solutions in the process of forming the liquid crystal. Birefringence of the solutions varied greatly at the transition between biphasic and anisotropic phases. In some conditions there were spherulitic liquid crystals in the anisotropic solutions. The rigidity of the chains of (E-A)C increased with increasing acidity of the organic acid solvent systems. It caused the critical concentration C1 to decrease with increasing the acidity of the solvents.