Abstract
Formation of microdomain structures in concentrated systems of irregular (stochastic) copolymers with weak composition asymmetry is considered theoretically. The study is focused on the weak segregation regime for infinitely long copolymer chains near the disorder-to-order transition. It is shown that the transition occurs below the spinodal (at ) and that it results in the formation of micelles rather than in a superposition pattern of a few harmonic composition waves. The micelle size is inversely proportional to . For small the micelles are like large nearly uniform droplets with “reflected” composition, . As increases the micelle composition profile develops oscillations. A first-order transition from spherical-wave micelles to micelles with internal bcc structure is predicted at . Interaction of micelles is also considered. It is shown that micelles always tend to form a fcc superlattice. The micellization in the weak segregation regime is controlled by the so-called nonlocal free energy. The classical fourth order (in composition parameter ) approximation for this energy is significantly generalized in the regime of low volume fraction of micelles. It is shown that the nonlocal energy strongly (exponentially) increases with near and above a certain critical value .
- Received 13 May 2005
DOI:https://doi.org/10.1103/PhysRevE.73.041803
©2006 American Physical Society