Cylindrical morphologies in asymmetric ABC triblock copolymers

In asymmetric ABC triblock copolymers with C being the matrix-forming majority component, the formation of cylindrical morphologies is governed by the sum of the volume fractions of the components A and B (phi(A) + phi(B)) as well as by their ratio (phi(B)/phi(A)). The paper describes the morphologies of various polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (SBM) and polystyrene- block-poly(ethylene-co-butylene)block-poly(methyl methacrylate) block copolymers (SEEM) in dependence on these parameters. In addition to previously reported cylinder in cylinder (cic, core shell) and helical (hel) morphologies, new microphase separated structures as cylinders at cylinder (c(a)c), undulated/perforated cylinder in cylinder (uc(i)c) and spheres on cylinder (s(o)c) are discussed. Based on a simple theoretical approach the transitions between these various morphologies are predicted, especially focusing on the transition between the c(i)c and c(o)c morphologies.