Phase Segregation in Gradient Copolymer Melts

Michelle D. Lefebvre, Monica Olvera de la Cruz, and Kenneth R. Shull*
Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208
Macromolecules, 2004, 37 (3), pp 1118–1123
DOI: 10.1021/ma035141a
Publication Date (Web): January 16, 2004
Copyright © 2004 American Chemical Society
*

 Corresponding author:  e-mail k-shull@northwestern.edu.

Abstract

Local segregation in melts of copolymers with composition gradients along their backbones is analyzed. The transition to a lamellar periodic structure as the effective degree of incompatibility χN increases is studied for symmetric copolymers with various composition gradients. A numerical self-consistent mean-field (SCMF) technique is used to characterize the ordered lamellar state in the weak and strong segregation regimes, and the random phase approximation (RPA) is used to calculate the scattering function analytically and find the location of the critical order−disorder transition for each melt. The critical point increases from (χN)c = 10.495 for block copolymers to (χN)c = 29.25 for a fully tapered linear gradient copolymer. For broad composition gradients the equilibrium lamellar repeat length is shorter for a given value of χN, and the unit cell composition profile is more sinusoidal. The dependence of the equilibrium repeat distance on χN is nearly universal when renormalized by the critical point of each copolymer.

View: Full Text HTML | Hi-Res PDF

Tools

SciFinder Links

SciFinder subscribers: Click to sign in | Not a SciFinder subscriber? Learn more at www.cas.org

History

  • Published In Issue February 10, 2004
  • Received August 6, 2003
    Revised Manuscript Received November 14, 2003

Recommend & Share

Related Content

Other ACS content by these authors: