Van Der Waals attraction between stöber silica particles in a binary solvent system

Z. Király, L. Turi, I. Dékány, K. Bean, B. Vincent

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Hydrophilic Stöber silica particles are stable in ethanol, but flocculation may be induced by the addition of sufficient cyclohexane. Low-shear rheological measurements indicated non-Newtonian behaviour beyond the critical cyclohexane concentration. The thickness and composition of the solvation layer around the particles were calculated from the adsorption excess isotherm on the basis of a multilayer adsorption model. The composition dependences of the Hamaker constants of the dispersion medium and the adsorption layer were obtained from optical dispersion measurements. A single-sheet, hard-sphere model predicted a weak van der Waals attraction in the ethanolic regime, but a strong attraction in the cyclohexane-rich region, in good accordance with the rheological properties of the dispersions and visual observations.

Original languageEnglish
Pages (from-to)779-787
Number of pages9
JournalColloid and Polymer Science
Issue number8
Publication statusPublished - Aug 1 1996



  • Adsorption
  • Colloid stability
  • Hamaker constant
  • Rheology
  • SAXS
  • Silica particles
  • Van der Waals potential

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Colloid and Surface Chemistry
  • Materials Chemistry

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