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Journal of Chemical Physics / Volume 126 / Issue 23 / ARTICLES / Polymers and Complex Systems

J. Chem. Phys. 126, 234902 (2007); http://dx.doi.org/10.1063/1.2740633 (10 pages)

Hard-surface effects in polymer self-consistent field calculations

Dong Meng and Qiang Wang

Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, Colorado 80523-1370

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(Received 26 February 2007; accepted 23 April 2007; published online 19 June 2007)

We have investigated several effects due to the confinement of polymer melts by impenetrable (hard) surfaces in the self-consistent field calculations. To adequately represent such confinement, the total (normalized) polymer segmental density (volume fraction) is usually constrained to an imposed profile that continuously decreases from 1 in the interior of confined melts to 0 at the surfaces over a short distance. The choice of this profile strongly influences the numerical performance of the self-consistent field calculations. In addition, for diblock copolymers A-B the hard-surface confinement has both energetic and entropic effects: On one hand, the decrease of polymer density from 1 reduces A-B repulsion and favors morphologies with more A-B interfaces near the surfaces. On the other hand, the enrichment of chain ends and depletion of middle segments near the surfaces favor parallel morphologies where chains orient mainly perpendicular to the surfaces. These two effects are comparable in magnitude, and for asymmetric diblock copolymers result in an entropic preference of a neutral surface for the shorter block as proposed previously [ Q. Wang et al., Macromolecules 34, 3458 (2001) ]. The hard-surface effects are weak in practice and thus manifested only when the surfaces are nearly neutral.

© 2007 American Institute of Physics

Article Outline

  1. INTRODUCTION
  2. MODELS AND NUMERICAL METHODS
    1. Confined homopolymer melts
    2. Confined diblock copolymer melts
  3. CONFINED HOMOPOLYMERS
    1. Choice of ϕ0(x)
    2. Segmental distributions
  4. CONFINED SYMMETRIC DIBLOCK COPOLYMER MELTS
    1. Surface-induced compatabilization
    2. Surface-induced entropy loss
    3. Influence of ϕ0(x) on phase behavior
  5. CONFINED ASYMMETRIC DIBLOCK COPOLYMERS
    1. Hard-surface effects
    2. Effectively neutral surface
  6. CONCLUSIONS

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KEYWORDS and PACS

Keywords

polymer melts, polymer blends, SCF calculations, entropy

PACS

  • 61.25.H-

    Macromolecular and polymers solutions; polymer melts

ARTICLE DATA

Digital Object Identifier
http://dx.doi.org/10.1063/1.2740633

PUBLICATION DATA

ISSN

0021-9606 (print)  
1089-7690 (online)

Publisher

$abstract.society.value is a Member of CrossRef American Institute of Physics

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