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Block Copolymers in Electric Fields: A Comparison of Single-Mode and Self-Consistent-Field Approximations
 

Summary: Block Copolymers in Electric Fields: A Comparison of Single-Mode
and Self-Consistent-Field Approximations
Yoav Tsori*
Department of Chemical Engineering, Ben Gurion UniVersity, P.O. Box 653, Beer SheVa 84105, Israel
David Andelman
School of Physics and Astronomy, Raymond and BeVerly Sackler Faculty of Exact Sciences,
Tel AViV UniVersity, Ramat AViV 69978, Tel AViV, Israel
Chin-Yet Lin and M. Schick
Physics Department, Box 351560, UniVersity of Washington, Seattle, Washington 98195
ReceiVed August 2, 2005; ReVised Manuscript ReceiVed October 22, 2005
ABSTRACT: We compare two theoretical approaches to diblock copolymer melts in an external electric field.
The first is a relatively simple analytic expansion in the copolymer composition and includes the full electrostatic
contribution consistent with that expansion. It is valid close to the order-disorder transition point, the weak
segregation limit. The second employs self-consistent-field (SCF) theory and includes the full electrostatic
contribution to the free energy at any copolymer segregation. It is more accurate but computationally more intensive.
Motivated by recent experiments, we explore a section of the phase diagram in the three-dimensional parameter
space of the block architecture, the interaction parameter, and the external electric field. The relative stability of
the lamellar, hexagonal, and distorted body-centered-cubic (bcc) phases is compared within the two models. As
function of an increasing electric field, the distorted bcc region in the phase diagram shrinks and disappears
above a triple point, at which the lamellar, hexagonal, and distorted bcc phases coexist. We examine the deformation

  

Source: Andelman, David - School of Physics and Astronomy, Tel Aviv University

 

Collections: Materials Science; Physics