Shear ordering in thin films of spherical block copolymer

Gaurav Arya, Jörg Rottler, Athanassios Z. Panagiotopoulos, David J. Srolovitz, Paul M. Chaikin

    Research output: Contribution to journalArticle

    Abstract

    We have investigated shear-induced alignment of a bilayer of spherical diblock copolymer micelles within thin films using molecular dynamics simulations at two different levels of coarse-graining. At the microscopic level, the copolymers are modeled as bead and spring chains with specific interaction potentials which produce strongly segregated spherical micelles. The simulations qualitatively reveal that long-range shear-induced ordering of hexagonally arranged micelles arises because of the tendency of micelles to pursue trajectories of minimum frictional resistance against micelles in the opposing layer. This influences their alignment in the direction of shear without them breaking apart and reforming within the time scale of the simulations. As observed in experiments, the ordering is shown to be very sensitive to the film thickness and shearing rates. To access larger lengths and longer time scales, we further coarse-grain our system to a mesoscopic level where an individual micelle is represented by a spherical particle, which interacts with other micelles through an effective potential obtained from the microscopic simulations. This approach enables us to follow the time evolution of global order from locally ordered domains. An exponentially fast growth of the orientational correlation length of the hexagonal pattern at early times, followed by a crossover to linear growth, is found in the presence of shear, in contrast to the much slower power-law scalings observed in experiments without shear.

    Original languageEnglish (US)
    Pages (from-to)11518-11527
    Number of pages10
    JournalLangmuir
    Volume21
    Issue number24
    DOIs
    StatePublished - Nov 22 2005

    Fingerprint

    Micelles
    block copolymers
    Block copolymers
    micelles
    shear
    Thin films
    thin films
    copolymers
    simulation
    alignment
    Scaling laws
    Reforming reactions
    shearing
    Shearing
    beads
    scaling laws
    Particles (particulate matter)
    Film thickness
    Molecular dynamics
    crossovers

    ASJC Scopus subject areas

    • Physical and Theoretical Chemistry
    • Colloid and Surface Chemistry

    Cite this

    Arya, G., Rottler, J., Panagiotopoulos, A. Z., Srolovitz, D. J., & Chaikin, P. M. (2005). Shear ordering in thin films of spherical block copolymer. Langmuir, 21(24), 11518-11527. https://doi.org/10.1021/la0516476

    Shear ordering in thin films of spherical block copolymer. / Arya, Gaurav; Rottler, Jörg; Panagiotopoulos, Athanassios Z.; Srolovitz, David J.; Chaikin, Paul M.

    In: Langmuir, Vol. 21, No. 24, 22.11.2005, p. 11518-11527.

    Research output: Contribution to journalArticle

    Arya, G, Rottler, J, Panagiotopoulos, AZ, Srolovitz, DJ & Chaikin, PM 2005, 'Shear ordering in thin films of spherical block copolymer', Langmuir, vol. 21, no. 24, pp. 11518-11527. https://doi.org/10.1021/la0516476
    Arya G, Rottler J, Panagiotopoulos AZ, Srolovitz DJ, Chaikin PM. Shear ordering in thin films of spherical block copolymer. Langmuir. 2005 Nov 22;21(24):11518-11527. https://doi.org/10.1021/la0516476
    Arya, Gaurav ; Rottler, Jörg ; Panagiotopoulos, Athanassios Z. ; Srolovitz, David J. ; Chaikin, Paul M. / Shear ordering in thin films of spherical block copolymer. In: Langmuir. 2005 ; Vol. 21, No. 24. pp. 11518-11527.
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