Adsorption of dispersants at a polyester resin-alkane interface

Abstract

Non-aqueous colloidal dispersions form the basis of many real-world applications, including electro-rheological fluids in automotive assemblies and inks in printing devices. The dispersion of particles within the non-aqueous liquid is typically stabilised by the use of dispersants, which adsorb to the particle/liquid interface and provide steric and/or electrical forces to prevent their aggregation. Importantly, the selection of the dispersant influences not only the inter-particle forces, but also their summation across many particles then defines the bulk properties of the suspension. Tailoring of these bulk properties is important in an industrial context, as each application will demand different bulk properties. In this study, the adsorption of three dispersants onto a polyester resin surface from a simple alkane is investigated. It is shown that the competition between the rates of adsorption from the bulk relative to that of the internal relocation of the functional groups of already adsorbed material defines the total adsorbed mass and structure of the film. Dispersants that have a slow rate of adsorption and a relatively fast rate of internal reorganisation produce soft visco-elastic layers with less total adsorbed mass. Conversely, dispersants with fast rates of adsorption and relatively low rates of reorganisation produce stiffer more elastic films and a greater total adsorbed mass.