Rheology of branched wormlike micelles

Simon A. Rogers, Michelle A Calabrese, Norman J. Wagner

Research output: Contribution to journalReview articlepeer-review

73 Scopus citations

Abstract

The topology of self-assembled surfactant solutions includes varying degrees of micellar branching, ranging from linear wormlike micelles to a micellar network. Micellar branching acts as an effective attraction between micelles such that network condensation can lead to phase separation. Unlike chemical branching in polymers, micellar branches are labile. Movement of branches along a micelle contour has therefore been proposed as a mechanism of stress relaxation that leads to a reduction in the structural relaxation time and thus, the zero-shear viscosity. Branching is also thought to suppress flow alignment, and for lower levels of branching, may also suppress instabilities such as shear banding. The suppression of shear banding can lead to a lesser degree of shear-thinning in the apparent viscosity at higher shear rates, as well as a reduction in extensional thickening. However, for higher levels of branching, shear can induce branching for samples in proximity to such a phase transition, which can result in shear banding due to shear-induced phase separation. Recent modeling and simulations of the energetics of branching, as well as experiments on model systems, show that the reduction in zero-shear viscosity is due to micelle branching. Current research includes efforts to develop a more mechanistic, quantitative understanding of micellar branching and more generally, its effects on micellar solution rheology.

Original languageEnglish (US)
Pages (from-to)530-535
Number of pages6
JournalCurrent Opinion in Colloid and Interface Science
Volume19
Issue number6
DOIs
StatePublished - Jan 1 2014
Externally publishedYes

Keywords

  • Branching
  • Rheology
  • Self-assembled
  • Surfactant
  • Viscoelasticity
  • Wormlike micelles

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