Miscibility of Liquid Crystalline Polymers; Mixtures of (Hydroxypropyl)cellulose and Ester Derivatives

Abstract

Abstract Heavily substituted cellulosic polymers including (hydroxypropyl)cellulose (HPC), (acetoxypropyl)cellulose (APC), and the propionate ester of HPC (PPC) form both lyotropic and thermotropic liquid crystalline phases. The miscibility of binary mixtures of these cellulosics in methanol and in film form are examined by polarizing microscopy. In methanol all of the binary polymer systems demix and segregate into distinct regions. Decreasing the molar mass of HPC and APC polymers does not inhibit the demixion in solution, but facilitates the phenomenon. Ester-ether blends once heated above the isotropization temperature, , exhibit two co-existing phases. The segregated regions do not mix even when reheated to a temperature at which both regions are isotropic. The ester-ester blends are apparently miscible since segregation was not observed. The of the ester blends (with the esters in a 1:1 ratio) is an average of the of the two esters.