RIGID BACKBONE POLYMERS .16. RANDOM COPOLYAMIDES

In the reported experiments, several homologous families of random copolyamides containing aromatic rigid elements and aliphatic or aralkyl flexible elements were prepared and characterized. Lyotropic liquid crystallinity was observed in all such polymers where over 50% of the aromatic residues belonged to rigid elements whose axial ratio surpassed a critical value of 5 less than x less than 6. The point where 5 less than x less than 6 is reached depends on the nature of the flexible comonomers. The higher their basicity or flexibility, the higher the concentration of rigid monomers in the copolymer at the point of 5 less than x less than 6. In concentrated ternary systems of polymer 1/polymer 2/solvent, a single anisotropic phase containing both polymers can be obtained when each polymer can form an anisotropic solution in the solvent. When either polymer is too flexible to form an anisotropic solution by itself, it will then separate from the ternary system into an isotropic phase, leaving the more rigid polymer in the coexisting anisotropic solution.