Monte Carlo phase diagram for diblock copolymer melts
T. M. Beardsley* and M. W. Matsen**
Department of Mathematics, University of Reading, RG6 6AX, Whiteknights, Reading, UK
Accepted: 15 June 2010
Published online: 28 July 2010
The phase diagram for diblock copolymer melts is evaluated from lattice-based Monte Carlo simulations using parallel tempering, improving upon earlier simulations that used sequential temperature scans. This new approach locates the order-disorder transition (ODT) far more accurately by the occurrence of a sharp spike in the heat capacity. The present study also performs a more thorough investigation of finite-size effects, which reveals that the gyroid (G) morphology spontaneously forms in place of the perforated-lamellar (PL) phase identified in the earlier study. Nevertheless, there still remains a small region where the PL phase appears to be stable. Interestingly, the lamellar (L) phase next to this region exhibits a small population of transient perforations, which may explain previous scattering experiments suggesting a modulated-lamellar (ML) phase.
© EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg, 2010