Competing micellar and cylindrical phases in semi-dilute diblock copolymer solutions

Abstract

We develop a “first principles” coarse-graining procedure based on a soft effective segment representation of an athermal AB diblock copolymer model in selective solvent, to map out the self-assembly phase diagram for several asymmetry ratios f using Monte Carlo free energy calculations. We find that the free energy per unit volume is surprisingly insensitive to the aggregation number of monodisperse cubic and cylindrical phases for a given polymer volume fraction. The cylindrical phase is found to pre-empt the cubic micellar phases for nearly symmetric (f ≃ 0.6) copolymers.