DIRECT MEASUREMENT OF COLLOIDAL FORCES IN AN ANISOTROPIC SOLVENT

We present a new method to measure attractive interactions between col loidal particles, and determine the nature of the attraction between p articles suspended in a nematic liquid crystal, We confine droplets fi lled with ferrofluid to a thin layer and apply a magnetic field to ind uce dipole moments that drive the droplets apart. When the field is re moved, the attractive interactions pull the droplets back together. Th e force is determined from the velocity because the motion is viscousl y damped. We confirm the dipolar character of the interaction between droplets in a nematic solvent.