Stability of parallel/perpendicular domain boundaries in lamellar block copolymers under oscillatory shear

Zhi Feng Huang, Jorge Viñals

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

We introduce a model constitutive law for the dissipative stress tensor of lamellar phases to account for low frequency and long wavelength flows. Given the uniaxial symmetry of these phases, we argue that the dissipative stress tensor must be similar to that of nematics/smectics but with the local variable being the slowly varying lamellar wave vector. This assumption leads to a dependence of the effective dynamic viscosity on orientation of the lamellar phase. We then consider a model configuration comprising a domain boundary separating laterally unbounded domains of so called parallel and perpendicularly oriented lamellae in a uniform, oscillatory, shear flow, and show that the configuration can be hydrodynamically unstable for the constitutive law chosen. It is argued that this instability and the secondary flows it creates can be used to infer a possible mechanism for orientation selection in shear experiments.

Original languageEnglish (US)
Pages (from-to)99-123
Number of pages25
JournalJournal of Rheology
Volume51
Issue number1
DOIs
StatePublished - 2007
Externally publishedYes

Bibliographical note

Funding Information:
This work has been supported by the National Science Foundation under Grant No. DMR-0100903 and by NSERC Canada.

Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.

Keywords

  • Block copolymers
  • Deformation and flow
  • Hydrodynamic instability

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