Conformationally asymmetric block copolymers

Authors

  • M. W. Matsen,

    Corresponding author
    1. Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455
    Current affiliation:
    1. Polymer Science Centre, University of Reading, Whiteknights, Reading RG6 6AF, UK
    • Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455
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  • F. S. Bates

    1. Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455
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Abstract

The standard parameters controlling AB diblock copolymer phase behavior are χN and fA, where χ is an A-B segment interaction parameter, N is the overall degree of polymerization, and fA is the volume fraction of the A block. Recently, it has been recognized that the ratio of the A and B statistical segment lengths αAB also represents another important parameter. Here, we theoretically examine the effects of this latter parameter on the phase behavior using the standard Gaussian chain model. Calculations are performed using both self-consistent field theory (SCFT) and strong segregation theory (SST). The ratio αAB is shown to have strong effects on order-order phase boundaries. Furthermore, it significantly affects the relative stability of the complex phases. In particular, it enhances the metastability of the perforated lamellar phase and may actually cause it to become an equilibrium structure. We also illustrate that varying αAB produces large changes in the relative domain spacings at order-order phase boundaries, which could strongly affect the kinetics of these transitions. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 945–952, 1997

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