Structure of laponite-styrene precursor dispersions for production of advanced polymer-clay nanocomposites

Rui Fartaria, Nadeem Javid, Richard Pethrick, John Liggat, Jan Sefcik, Martin Sweatman

Research output: Contribution to journalArticle

6 Citations (Scopus)
151 Downloads (Pure)

Abstract

One method for production of polymer-clay nanocomposites involves dispersal of surface-modified clay in a polymerisable monomeric solvent, followed by fast in situ polymerisation. In order to tailor the properties of the final material we aim to control the dispersion state of the clay in the precursor solvent. Here, we study dispersions of surface-modified Laponite, a synthetic clay, in styrene via large-scale Monte-Carlo simulations and experimentally, using small angle X-ray and static light scattering. By tuning the effective interaction between simulated laponite particles we are able to reproduce the experimental scattering intensity patterns for this system, with good accuracy over a wide range of length scales. However, this agreement could only be obtained by introducing a permanent electrostatic dipole moment into the plane of each Laponite particle, which we explain in terms of the distribution of substituted metal atoms within each Laponite particle. This suggests that Laponite dispersions, and perhaps other clay suspensions, should display some of the structural characteristics of dipolar fluids. Our simulated structures show aggregation regimes ranging from networks of long chains to dense clusters of Laponite particles, and we also obtain some intriguing ‘globular’ clusters, similar to capsids. We see no indication of any ‘house-of-cards’ structures. The simulation that most closely matches
experimental results indicates that gel-like networks are obtained in Laponite dispersions, which however appear optically clear and non-sedimenting over extended periods of time. This suggests it could be difficult to obtain truly isotropic equilibrium dispersion as a starting point for synthesis of
advanced polymer-clay nanocomposites with controlled structures.
Original languageEnglish
Pages (from-to)9157-9166
Number of pages10
JournalSoft Matter
Volume7
Issue number19
Early online date17 Aug 2011
DOIs
Publication statusPublished - 2011

Keywords

  • surface-modified clay
  • polymerisation
  • dispertion
  • Monte Carlo simulation
  • light scattering
  • TIC - Bionanotechnology

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