Morphological Control Over Three- and Four-Phase Superstructures in Blends of Asymmetric ABC and BAC Triblock Terpolymers

Abstract

The versatile and simple attainment of complex superstructures through binary blends of asymmetric polyisoprene‐block‐polystyrene‐block‐poly(methyl methacrylate) (ISM) and polystyrene‐block‐polyisoprene‐block‐poly(methyl methacrylate) (SIM) triblock terpolymers is shown. Different well‐ordered core–shell morphologies with three or four microphases as well as interchanged core‐ and shell‐forming blocks are achieved by different spatial superposition during mixing. Superstructures with three microphases are obtained by antiparallel chain orientation, when ISM and SIM chains align in opposite directions. Similarly, the respective PS, PI, and PMMA blocks are in direct superposition and mix into each other. In contrast, with parallel chain orientation, ISM and SIM chains align in the same direction. It gives rise to four microphases because here, both PI blocks do not assemble into one microdomain, but form two isolated microdomains. These observations are attributed to inverse molecular weight ratios between both blends.