Surfactant characteristics of random block polyelectrolyte polyester emulsifier (SMTAPE) in aqueous solution and on polystyrene latex particles

Abstract

The surfactant characteristics of novel random block polyelectrolyte polyester emulsifiers, SMTAPE, were investigated by analyzing the surface tension of a variety of SMTAPE with different molecular weights and different hydrophilicities in aqueous solution, and also by studying the change of surface tension of polystyrene (PS) latex with increasing SMTAPE emulsifier concentration. The SMTAPE emulsifier was found to lower the surface tension of water by about 15 mN/m at the CMC. All of the investigated SMTAPE emulsifiers show two CMC break points, which were attributed to their broad molecular weight distribution. A Langmuir type adsorption isotherm was observed in this system. The surface area occupied by an SMTAPE molecule on a PS latex particle at 25°C was found to be 187 Å2 at saturation. The conformation of SMATAPE emulsifier molecule adsorbed on a PS latex particle is thought to be a hydrophobic segment ″trains″ anchored to the polymer surface. (C) 2000 Elsevier Science Ltd. All rights reserved.