Colloidal stability of model polymer colloids with different functional groups

Abstract

In this work we describe the colloidal stability of different functionalized latexes: four monodisperse latexes were prepared by surfactant-free emulsion polymerization. The particle sizes of the samples varied between 276 and 350 nm, when measured by TEM. The surface charge densities were determined by conductimetric and potentionmetric titrations, the lowest and highest values being 1.3 and 19.2 µC/cm². The relative hydrophobicity of latexes was estimated by adsorption of a non-ionic surfactant onto their surfaces. The critical coagulation concentration (ccc) was determined in the presence of 1:1 electrolyte (K Br) at several different pH. By means of the DLVO theory the characteristic parameters A and ψ _d were calculated. We have employed the Eversole and Boardman equation for calculating Δ and, using this factor, we can find the best argeement between the theoretical and experimental Hamaker Constant values for latexes with the most hydrophobic character.