Discrete Linear–Branched Block Copolymer with Broken Architectural Symmetry

Abstract

Rationally introducing chain length heterogeneity, such as binary blending, is a robust approach to regulate phase behavior of block copolymers. This work designed a library of discrete linear–branched block copolymers bearing two unequal branches. Diverse ordered nanostructures, including complex Frank–Kasper phases and quasicrystalline phase, were captured by tuning the compositional and architectural asymmetry. The precise chemistry rules out the interferences associated with statistical distribution, while the discrete feature decouples the intertwined variables. Compared with the symmetric counterparts, the synergies between the long and short chains effectively release the packing frustration during the formation of ordered structures, leading to a significant increase of lattice dimension and phase stability. The “built-in” chain length heterogeneity circumvents the shortcomings encountered by the conventional blending strategy, providing an excellent alternative for quantitatively assessing the effect of molecular symmetry on the self-assembly behaviors of block copolymers.