title: Universality of block copolymer melts.
abstract: Simulations of five different coarse-grained models of symmetric diblock copolymers are compared to demonstrate a universal (i.e., model-independent) dependence of the free energy and order-disorder transition (ODT) on the invariant degree of polymerization N̄. The actual values of χN at the ODT approach predictions of the Fredrickson-Helfand (FH) theory for N̄ ≳ 10(4) but significantly exceed FH predictions at lower values characteristic of most experiments. The FH theory fails for modest N̄ because the competing phases become strongly segregated near the ODT, violating an underlying assumption of weak segregation.
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, USA.
authors.forename: Jens
authors.initials: J
authors.lastname: Glaser
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, USA.
authors.forename: Pavani
authors.initials: P
authors.lastname: Medapuram
authors.affiliation: School of Mathematical and Physical Sciences, University of Reading, Whiteknights, Reading RG6 6AX, United Kingdom.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Beardsley
authors.affiliation: School of Mathematical and Physical Sciences, University of Reading, Whiteknights, Reading RG6 6AX, United Kingdom.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Matsen
authors.affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Morse