TY - JOUR
T1 - Synthesis of Goethite as a Model Colloid for Mineral Liquid Crystals
AU - Thies-Weesie, D.M.E.
AU - de Hoog, J.P.
AU - Henar Hernandez Mendiola, M.
AU - Petukhov, A.V.
AU - Vroege, G.J.
PY - 2007
Y1 - 2007
N2 - We describe the synthesis and modification of lathlike goethite (R-FeOOH) model colloids, where we focused on the reduction of the size polydispersity (determined from transmission electron microscopy pictures.) The length polydispersity could be strongly reduced from 55% down to 17% using a combination of a forced hydrolysis method and an improved centrifugation procedure. Preliminary small-angle X-ray scattering experiments demonstrated the potential of these model particles to study the influence of the
length polydispersity on the occurrence of different liquid crystalline phases. A coating of polyisobutene was applied on the goethite surface to obtain a stable dispersion of hard-core laths in toluene, which retained the peculiar magnetic alignment behavior of aqueous goethite particles (changing from parallel to perpendicular orientation at increasing field strength.) The goethite laths could further be coated with a silica layer of tunable thickness which also allowed the incorporation of a fluorescent dye. Finally, the goethite core of silica-coated goethite was dissolved with acid to obtain hollow silica laths. These
modifications give additional possibilities for the use of goethite as model colloids.
AB - We describe the synthesis and modification of lathlike goethite (R-FeOOH) model colloids, where we focused on the reduction of the size polydispersity (determined from transmission electron microscopy pictures.) The length polydispersity could be strongly reduced from 55% down to 17% using a combination of a forced hydrolysis method and an improved centrifugation procedure. Preliminary small-angle X-ray scattering experiments demonstrated the potential of these model particles to study the influence of the
length polydispersity on the occurrence of different liquid crystalline phases. A coating of polyisobutene was applied on the goethite surface to obtain a stable dispersion of hard-core laths in toluene, which retained the peculiar magnetic alignment behavior of aqueous goethite particles (changing from parallel to perpendicular orientation at increasing field strength.) The goethite laths could further be coated with a silica layer of tunable thickness which also allowed the incorporation of a fluorescent dye. Finally, the goethite core of silica-coated goethite was dissolved with acid to obtain hollow silica laths. These
modifications give additional possibilities for the use of goethite as model colloids.
M3 - Article
SN - 0897-4756
VL - 19
SP - 5538
EP - 5546
JO - Chemistry of Materials
JF - Chemistry of Materials
ER -