Liquid-like states in micelle forming diblock copolymer melts

Compositionally asymmetric diblock copolymers form micelles that pack onto an ordered lattice when the system is cooled below the order-disorder transition (ODT). At temperatures slightly above the ODT, the fluid structure is inhomogeneous and consists of fluctuating micelles. We have developed a mean-field picture of this fluctuating micelle state by seeding self-consistent field theory calculations with initial conditions generated from molecular dynamics simulations of the Kob–Anderson fluid. These calculations reveal a large number of disordered liquid-like states that are nearly degenerate with the equilibrium body-centered cubic (bcc) structure that would emerge in the ordered state. Moreover, the typical micellar spacings in the disordered liquid are slightly swollen compared to bcc. The presence of many local minima suggests the existence of a rugged free energy landscape within the disordered micelle state, which may be the origin of the anomalously slow ordering kinetics of micelle-forming systems.