Characterization of the surface morphology in carboxylated methyl methacrylate‐butyl acrylate emulsion copolymers

Abstract

AbstractA series of carboxylated methyl methacrylate (MMA)‐butyl acrylate (BuA) (weight ratio 1 : 1) copolymer latexes were prepared by emulsion polymerization with varying the nature of carboxylic acid (acrylic (AA), or methacrylic acid (MAA)), the type of emulsifier (sodium dodecyl sulfate (SDS) or nonylphenyl polyoxyethylene ether (HV25®) surfactants), or the polymerization method (batch or shot process). Results of surface characterization and rheological behavior of the latexes were found to provide information on the carboxylic acid location and the interfacial layer thickness, respectively. Stability studies against different types of electrolyte and temperature showed that the surface morphology is strongly dependent upon the nature of oligomers formed during the synthesis, especially the presence of sequences rich of poly‐(carboxylic acid)s, and how they are anchored onto the particle. According to the type of emulsifier and polymerization process, stability is predominantly determined either by electrostatic or steric forces. In some cases, when surfactant HV25® is used, enhanced steric stabilization prevails.