Simulation of diblock copolymer melts by Dissipative Particle Dynamics

Dissipative Particle Dynamics (DPD), a recently developed mesoscopic simula tion technique, is used to model the morphology and dynamical behavior of s hort-chain diblock copolymer melts. The two blocks, A and B, of the copolym er chain are represented by particles of different DPD "phases", and compos ition is varied by varying the number of beads in each block. As compositio n is varied from 0-50% A, the predicted morphology changes, progressively, from a disordered system to BCC spherical domains of A, and then to cylindr ical domains and lamelae. These predicted phase structures are in agreement with experimental and theoretical results from the literature. Steady shea r flow is simulated by means of Lees-Edwards boundary conditions to investi gate 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 propert ies for systems having the BCC equilibrium microstructure. (C) 2000 Publish ed by Elsevier Science B.V. All rights reserved.