Phase separation and structure in a concentrated colloidal dispersion of uniform plates
Semiconductor Physics, Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE, UK
2 European Synchrotron Radiation Facility, BP 220, 38043 Grenoble Cedex, France
3 Department of Chemistry, King's College London, Strand, London WC2R 2LS, UK
Published online: 15 October 1999
The structure and phase behaviour of a colloidal dispersion of plate-like particles are described. The plates are nickel (II) hydroxide and have short-range, repulsive interactions and a low polydispersity. As the concentration of the plates is increased, an equilibrium phase separation between a columnar phase and a less ordered phase is observed. Complementary measurements using small-angle neutron and small-angle X-ray scattering have been used to distinguish the columnar phase from other possible ordered structures. Previously isotropic-nematic phase transitions have been observed [CITE], however this dispersion forms the more highly ordered columnar phase, due to the aspect ratio and the low polydispersity of the plate-like particles. The concentration at which phase separation occurs, increases as the range of the particle interactions is reduced. This system provides an interesting model for comparison with theory and calculations of structures in liquid crystal and mesophase in which the particle interactions can be altered.
PACS: 61.30.Eb – Experimental determinations of smectic, nematic, cholesteric, and other structures / 64.70.Md – Transitions in liquid crystals
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999