Phase transformations in a mixture of two mesomorphic cyclolinear siloxanepolymers miscible in isotropic melt1

The phase state of mixtures of two mesomorphic cyclolinear polyorganosiloxa nes with different structures was studied by the DSC, optical microscopy, a nd optical interferometry methods. In the mixtures prepared by mixing using a common solvent, both polymers were found to produce mesophases, which we re typical of these polymers in a pure state. When the mixtures were cooled from the isotropic melt; that is, at temperatures above the isotropization temperature of the highest temperature mesophase, when the polymers are co mpletely miscible, the ability of both polymers to develop mesophases drama tically decreases, especially in the region of intermediate compositions. O n prolonged existence at room temperature, the above mixtures are likely to develop a mixed mesophase.