Monte Carlo phase diagram for diblock copolymer melts

A partial phase diagram is constructed for diblock copolymer melts using lattice-based Monte Carlo simulations. This is done by locating the order-disorder transition (ODT) with the aid of a recently proposed order parameter and identifying the ordered phase over a wide range of copolymer compositio...

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Bibliographic Details
Published in:The Journal of chemical physics 2006-01, Vol.124 (2), p.024904-024904-9
Main Authors: Matsen, M. W., Griffiths, G. H., Wickham, R. A., Vassiliev, O. N.
Format: Article
Language:English
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Summary:A partial phase diagram is constructed for diblock copolymer melts using lattice-based Monte Carlo simulations. This is done by locating the order-disorder transition (ODT) with the aid of a recently proposed order parameter and identifying the ordered phase over a wide range of copolymer compositions ( 0.2 ⩽ f ⩽ 0.8 ) . Consistent with experiments, the disordered phase is found to exhibit direct first-order transitions to each of the ordered morphologies. This includes the spontaneous formation of a perforated-lamellar phase, which presumably forms in place of the gyroid morphology due to finite-size and/or nonequilibrium effects. Also included in our study is a detailed examination of disordered cylinder-forming ( f = 0.3 ) diblock copolymers, revealing a substantial degree of pretransitional chain stretching and short-range order that set in well before the ODT, as observed previously in analogous studies on lamellar-forming ( f = 0.5 ) molecules.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.2140286