COLL 407 |
| Maria Buleva, Alexandar M. Zhivkov, and Stoyl P. Stoylov. Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria |
| Electric birefringence measurements on the highly advanced electro-optic instrument of Dietmar Pörschke have confirmed electron microscopy, neutron scattering and quasielastic light scattering results that primary laponite particles may be approximated by thin discs of 30-50 nm diameter. Further studies on composite b-FeOOH needle-like particles covered with laponite particles allowed us to investigate their interfacial electric properties by electric light scattering. Moreover this made possible to measure the electrophoretic mobility of the laponite particles by the classical method of microelectrophoresis. In contrast to composite b-FeOOH-Ludox particles, in this case the rotational relaxation time and the electric polarizability considerably increase at pH=5.5. At higher pH (=9.5), the electric polarizability of b-FeOOH-Laponite is almost twofold higher than that of b-FeOOH-Ludox, and the saturated electric light scattering effect is 30% higher. The authors acknowledge the great help of D. Pörschke in the electric birefringence measurements. |
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Colloidal and Molecular Electro-Optics
Division of Colloid and Surface Chemistry |