Skip to main content
Article thumbnail
Location of Repository

Statistical model for the structure and gelation of smectite clay suspensions

By Marjolein Dijkstra, J.P. Hansen and P.A. Madden

Abstract

The sol-gel transition in a suspension of monodisperse, charged, disklike platelets ~Laponite, i.e., a synthetic\ud clay! is examined within a simplified statistical model. The initial ‘‘primitive’’ model of uniformly charged\ud disks surrounded by microscopic co ions and counterions is reduced to a model of nonintersecting disks\ud carrying a rigid point quadrupole, resulting from the electric double layers around the disks. The quadrupolar\ud interactions favor edge-to-face pair configurations that counteract the tendency of parallel ~nematic! alignment\ud of bare disks at high densities. The local structure and phase behavior of the quadrupolar disk model is studied\ud over a broad range of clay concentrations and quadrupole moments ~which depend on the concentration of\ud added salt! by extensive Monte Carlo simulations. The model suspension is found to undergo a reversible\ud sol-gel transition above a critical quadrupolar coupling. The gel phase lacks long-range order, and is reminiscent\ud of a ‘‘house-of-cards’’ structure in which most of the particles are edge-to-face to each other. The critical\ud concentration and quadrupolar coupling constant are not inconsistent with recent experimental data on the\ud gelation of Laponite suspensions

Topics: Natuur- en Sterrenkunde
Year: 1997
OAI identifier: oai:dspace.library.uu.nl:1874/19145
Download PDF:
Sorry, we are unable to provide the full text but you may find it at the following location(s):
  • http://dspace.library.uu.nl:80... (external link)
  • Suggested articles


    To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.