Extension of the surfactant bridge model for the electrorheological effects of surfactant-activated suspensions

Young Dae Kim, Suk Woo Nam

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


Surfactants influence the electrorheological (ER) response in two ways. At low surfactant concentrations, they enhance the ER response by enhancing the particle polarizability; at high concentrations, the response degrades (nonlinear ER response). The nonlinear ER behavior arises from the formation of surfactant bridges between the particles at high surfactant concentrations. A surfactant bridge model was introduced to explain the nonlinear behavior (τ0∝En, n≈1) of surfactant-activated ER suspensions when surfactant bridges were formed between the particles. Here, the surfactant bridge model is extended for the prediction of both the linear and nonlinear ER behaviors of surfactant-activated ER suspensions over the low and high surfactant concentrations (for Brij 30, from 0 to 7 wt%), regardless of the formation of surfactant bridges between the particles. For 20 wt% neutral alumina suspensions in silicone oil activated by Brij 30, the predicted ER behaviors show almost the same Brij 30 concentration and electric field strength dependence. It predicts the linear E2 dependence of the ER response at low surfactant concentrations and the nonlinear ER behavior at high surfactant concentrations. Also, the estimated yield stresses show fairly good agreement with the experimental data.

Original languageEnglish
Pages (from-to)205-210
Number of pages6
JournalJournal of Colloid and Interface Science
Issue number1
Publication statusPublished - 2004 Jan 1

Bibliographical note

Funding Information:
This work was supported by the Korea Research Foundation Grant (KRF-2001-003-E00285).


  • ER suspensions
  • Nonlinear behavior
  • Surfactant bridge model
  • Surfactant-activated suspensions

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry


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