Surfactant and counter-ion distribution in styrene-butyl acrylate-acrylic acid dry latex submonolayers

styrene-butyl acrylate-acrylic acid latex submonolayers prepared using a non-reactive phosphate surfactant together with a reactive sulfonate surfactant were examined in a transmission microscope using electron energy loss spectroscopy imaging (esi-tem). phosphorus is nearly absent from the particles core but it is detected in a thick shell and in unusual, strongly scattering structures with a low carbon content, and largely made out of inorganic phosphate. p is also dispersed outside the particles, while s is uniformly distributed within then. the na and n elemental maps show that the respective monovalent ions (na+ and nh4+) have different distributions, in the latex: na signal within the particles is stronger than in the background, while n is accumulated at the particle borders. the distributions of surfactant and counter-ions are thus different from some current assumptions, but they support recent results on the distribution of ionic constituents in latex films, by scanning electric potential microscopy.