Expanding spherical regions of block copolymers via designed chain architectures

Recently, the self-assembly of block copolymers into spherical phases has attracted renewed interest due to the discovery of Frank-Kasper spherical phases. Experiment and theory unravel that the formation of Frank-Kasper phases mainly results from the expansion of spherical region. However, it is generally believed that the spherical domains self-assembled from AB-type block copolymers are composed of the minority blocks. Breaking this generic rule so that the spherical domains are formed by the majority blocks requires new mechanisms to drastically expand the stable region of spherical packing phases. Herein, we propose a useful mechanism, and thus we design a series of dendron-like AB-type block copolymers. Our self-consistent field theory calculations predict that all these dendron-like copolymers exhibit a spherical region extending to f>0.5. In particular, the maximal spherical region even approaches f∼0.7. Interestingly, such a phase diagram exhibits multiple reentrant transitions of Frank-Kasper phases.