Pigment-Polyelectrolyte Interaction and Surface Modified Particle Characterization by Electrokinetic Sonic Amplitude Measurements

摘要

Detailed information about the interaction of copolymers with the pigment surface, e.g., adsorption/desorption phenomena as reflected from the dynamic mobility UD of the dispersed particle, can be obtained by applying the electrokinetic sonic amplitude (ESA) technique. With this method, a potential is measured from pressure waves generated by the movement of charged particles in an oscillating electric field. The variation of this potential with frequency can be used for determining UD of particles with a thin double layer and for calculating the zeta potential as well as the particle size. For fixed low frequencies as applied in this work, μ_D is effected by the surface charge of the particle only. The study of the change of the dynamic mobility μ_D of aqueous TiO_2 dispersion upon addition of amphipolar polyelectrolytes revealed that ESA is a powerful method to reveal the course of polymer-pigment interactions and how this is related to the molecular architecture of the employed polyelectrolytes. A model of initially competitive polymer micelle formation and mono-/bilayer polymer coating of the pigment surface is proposed.