Phase transitions in liquid-crystalline cyanoethyl cellulose solutions in magnetic field

The cloud-point method and polarization microscopy have been used to investigate the phase transitions and the phase state of cyanoethyl cellulose-dimethylacetamide and cyanoethyl cellulose-dimethylformamide systems in the presence and absence of magnetic field with the help of polarization photoelectric and magnetic setups. The temperature-concentration region of the existence of the liquid-crystalline phase in solutions widens in the magnetic field; the higher the field strength and polymer concentration, the more pronounced this widening. Cyanoethyl cellulose solutions are found to possess “memory”: after the magnetic field is switched-off, the orientation of macromolecules and the increased phase transition temperature are preserved for many hours.