Cyanoethyl cellulose can form lyotropic liquid crystal in some organic solvents above a certain concentration C1*. When phase transition occurs
the optical properties of the solutions very. The existence of the liquid crystalline phase depends on the concentration and temperature of the solutions. The effect of solvent on the formation of lyotropic liquid crystal for the cyanoethyl cellulose is that the critical concentration C*1 decreases with decreasing the polymersolvent interaction parameter x12.