docusate-sodium and n-hexadecane

We study the electrostatic and hydrodynamic interactions of colloidal particles in nonpolar solvents. Using blinking optical tweezers, we can extract the screening length, kappa-1, the effective surface potential, |ezeta*|, and the hydrodynamic radius, ah, in a single measurement. We apply this technique to suspensions of polystyrene and poly(methyl methacrylate) particles in hexadecane with soluble charge control agents, aerosol sodium di-2-ethylhexylsulfosuccinate (AOT) and polyisobutylene succinimide (OLOA-1200). We find that the electrostatic interactions of these particles depend sensitively on surface composition as well as on the concentration and chemistry of the charge control agent.

Topics: Aerosols; Alkanes; Colloids; Optical Tweezers; Particle Size; Polymers; Polymethyl Methacrylate; Polystyrenes; Solvents; Static Electricity; Succinates; Succinimides; Surface Properties; Thermodynamics