Effects of Chain Dispersity on the Stability of Frank–Kasper Phases Self‐Assembled from Diblock Copolymers

Abstract The effect of chain dispersity on the relative stability of Frank–Kasper (FK) phases self‐assembled from diblock copolymers (DBCPs) is studied using self‐consistent field theory applied to DBCPs with one disperse block obeying the Poisson or Schulz–Zimm distributions. The results demonstrate that the chain dispersity enhances the relative stability of the FK phases. For DBCPs with small conformational asymmetry, the FK phase can be stabilized by dispersity and the stability window of the FK phases widens with the increase of dispersity. For DBCPs with large conformational asymmetry, the Laves C14 and C15 phases, which are metastable in monodisperse DBCPs, can be stabilized by dispersity. An analysis of the spatial organization of polymers reveals that the enhanced stability of the FK phases originated from intra‐ and inter‐domain segregation of chains with different lengths.