Simulation of diblock copolymer melts by Dissipative Particle Dynamics

Abstract

Dissipative Particle Dynamics (DPD), a recently developed mesoscopic simulation technique, is used to model the morphology and dynamical behavior of short-chain diblock copolymer melts. The two blocks, A and B, of the copolymer chain are represented by particles of different DPD “phases”, and composition is varied by varying the number of beads in each block. As composition is varied from 0–50% A, the predicted morphology changes, progressively, from a disordered system to BCC spherical domains of A, and then to cylindrical domains and lamelae. These predicted phase structures are in agreement with experimental and theoretical results from the literature. Steady shear flow is simulated by means of Lees–Edwards boundary conditions to investigate the effect of shear flow on morphology, and to evaluate viscosity and normal stresses under shearing. The predicted effects of shear flow include flow-induced microstructural transitions, and enhanced rheological properties for systems having the BCC equilibrium microstructure.