Field-induced clearing in sphere-sphere and rod-sphere binary mixtures of charged colloidal particles

• Published in: Physical review. E, Statistical, nonlinear, and soft matter physics Vol. 79; no. 6 Pt 1; p. 060401
• Main Authors: Fornasari, L, Mantegazza, F, Jimenez, M L, Buscaglia, M, Bellini, T
• Format: Journal Article
• Language: English
• Published: United States 01-06-2009
• ISSN: 1539-3755; 1550-2376
• DOI: 10.1103/PhysRevE.79.060401

Binary mixtures of larger and smaller colloids having charges of equal sign display unusual response to low-frequency electric fields. We show here that the previously reported negative torque acting on rodlike particles when in presence of a sea of smaller particles is accompanied by a field-induced clearing of the suspension. Measurements of transmitted intensity performed on mixtures of large (dilute) and small (semidilute) spherical particles indicate that such a clearing effect is universal and due to an anisotropic E2 -dependent redistribution of the small spheres around the large ones. We interpret this behavior as resulting from O(E2) electro-osmotic flows whose magnitude is greatly enhanced by the presence of the small particles.