Orientational order in cylinder-forming block copolymer thin films

Andrew P. Marencic, Paul M. Chaikin, Richard A. Register

    Research output: Contribution to journalArticle

    Abstract

    Shear can impart a high degree of orientational order to supported block copolymer thin films containing one or more layers of cylindrical microdomains, leading to a striped pattern with a period of tens of nanometers extending over macroscopic (centimeter-squared) areas. Though the as-deposited films have a polygrain structure, after shearing at sufficiently high stresses the only defects which remain are isolated dislocations, and the orientational order can be quite high (nematic or twofold orientational order parameter >0.99, as measured by tapping-mode atomic force microscopy). The effect of isolated dislocations on orientational order is adequately captured by an isotropic elastic continuum model of the structure surrounding the dislocation, producing a linear decrease of order parameter with dislocation density. Even at zero dislocation density, however, the order parameter does not quite reach unity, due to small-amplitude undulations of the cylinders about their axes which persist in the transverse direction over several cylinder periods.

    Original languageEnglish (US)
    Article number021507
    JournalPhysical Review E - Statistical, Nonlinear, and Soft Matter Physics
    Volume86
    Issue number2
    DOIs
    StatePublished - Aug 24 2012

    ASJC Scopus subject areas

    • Statistical and Nonlinear Physics
    • Statistics and Probability
    • Condensed Matter Physics

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