Is Simple Cubic Spherical Phase Possible in Block Copolymers?*

The self-assembly of amphiphilic macromolecules into various mesocrystals has attracted abiding interest. Although many interesting mesocrystals have been achieved, the simple cubic mesocrystal is rarely reported. Here we purposely design an AB-type multiblock copolymer composed of an AB diblock copolymer with A-/B-block tethered by an extra B-/A-block at the middle point to target the simple cubic spherical phase based on the self-consistent field theory. Specifically, two sophisticated mechanisms are realized synergistically in the copolymer, i.e. packing frustration release and stretched bridge block, leading to the formation of the simple cubic mesocrystal in a significant parameter space. Moreover, more other unusual phase behaviors are predicted.