Method of Uniformly Orienting Magnetic Particles in a Dispersion
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
Magnetic particles are enveloped in a spherical coating by bead polymerization. If dispersed in a liquid and exposed to an outer homogeneous magnetic field, the spherical droplets thus obtained line up, with their magnetic moments pointing essentially in the same direction. There are two stable positions that acicular magnetic particle overlapping magnetic fields may assume relative to each other: a position where the magnetic moments point in opposite directions (twin position; Fig. 1) and a position in which the magnetic moments point in the same direction (chain position; Fig. 2). If the acicular magnetic particles are enveloped in a spherical coating, the twin position is destabilized, i.e., the particles, if freely rotatable, assume the chain position (Fig. 3). The spherical coating is formed as follows.