Sedimentation stability and aging of aqueous dispersions of Laponite in the presence of cetyltrimethylammonium bromide

V. Savenko, L. Bulavin, M. Rawiso, M. Loginov, E. Vorobiev, and N. I. Lebovka
Phys. Rev. E 88, 052301 – Published 4 November 2013

Abstract

This work discusses the sedimentation stability and aging of aqueous suspensions of Laponite in the presence of cetyltrimethylammonium bromide (CTAB). The concentration of Laponite was fixed at a constant level Cl=2 %wt, which corresponds to the threshold between equilibrium gel IG1 and glass IG2 states. The concentration of CTAB Cs was within 0–0.3 %wt. In the presence of CTAB, the Laponite aqueous suspensions were unstable against sedimentation and separated into the upper and bottom layers (U and B layers, respectively). The dynamic light-scattering technique has revealed that addition of CTAB even at a rather small concentration, Cs=0.0164 %wt (0.03 cation exchange capacity), induced noticeable changes in the aging dynamics of the U layer. It was explained by equilibration of CTAB molecules that were initially nonuniformly distributed between different Laponite particles. Accelerated stability analysis by means of analytical centrifugation with rotor speed ω=500–4000 rpm revealed three sedimentation regimes: continuous (I, Cs<0.14 %wt), zonelike (II, 0.14<Cs<0.2 %wt), and gel-like (III, Cs>0.2 %wt). It was demonstrated that the B layer was “soft” in the zonelike regime. The increase of ω resulted in its supplementary compressing and collapse of “soft” sediment above certain critical centrifugal acceleration. The physical nature of the observed behavior, accounting for enhancement of hydrophobic interactions between Laponite particles, is discussed.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
5 More
  • Received 29 May 2013

DOI:https://doi.org/10.1103/PhysRevE.88.052301

©2013 American Physical Society

Authors & Affiliations

V. Savenko1, L. Bulavin1, M. Rawiso2, M. Loginov3,4, E. Vorobiev4, and N. I. Lebovka3,4,*

  • 1Taras Shevchenko Kiev National University, Department of Physics, 2, av. Academician Glushkov, Kyiv 031127, Ukraine
  • 2Institut Charles Sadron, UPR22-CNRS, Universite de Strasbourg, 23 rue du Loess, BP 84047-67034 Strasbourg Cedex 2, France
  • 3Institute of Biocolloidal Chemistry named after F.D. Ovcharenko, NAS of Ukraine, 42, blvr. Vernadskogo, Kyiv 03142, Ukraine
  • 4Departement de Genie Chimique, Universite de Technologie de Compiegne, Centre de Recherche de Royallieu, B.P. 20529-60205 Compiegne Cedex, France

  • *Corresponding author: lebovka@gmail.com

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 88, Iss. 5 — November 2013

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review E

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×