The use of reactive surfactants is a promising way of avoiding the deleterious effects on film properties caused by the segregation of conventional surfactants. In this work, the distributions of conventional and reactive anionic surfactants in acrylic latex films are compared. Atomic force microscopy was used to examine the surface of the films cast from high solids content acrylic latexes, and Rutherford backscattering spectrometry provided depth profiles of the surfactants. It was proven conclusively that the use of surfmers is an effective way of eliminating unwanted surfactant exudation. The amount of conventional surfactant (sodium lauryl sulfate (SLS)) exuded to the surface increased with the temperature at which the films were annealed (60, 90, and 125 °C), but the migration of the surfmer (sodium tetradecyl maleate) was very minimal and only weakly dependent on temperature. An unexpectedly large amount of conventional surfactant was exuded to the film surface when annealed at 125 °C. This result suggests that its transport to the surface might be facilitated by the enhanced mobility of poly(acrylic acid) shells at temperatures above the polymer's glass transition temperature (ca. 106 °C).

The water sensitivity of films obtained from high solids content acrylic latexes was investigated, with special focus on the role of the surfactant used in the synthesis step. The performance of films obtained from latexes stabilized by nonionic surfmers was compared to that of the acrylic latexes stabilized with conventional nonionic and anionic surfactants. It was seen that the latexes stabilized with reactive surfactants exhibited a remarkably better resistance to both water permeability and water vapor permeability and therefore enlarged the durability of the films. Atomic force microscopy images suggested that the defects created by surfactant migration in the latexes stabilized with conventional surfactants promoted the permeation of water by capillarity.

SYNOPSISThe effect of the monomer/water ratio on the rate of polymerization per polymer particle in both seeded emulsion polymerizations and miniemulsion polymerizations was used in an attempt to elucidate the main locus of radical formation in emulsion polymerization initiated by an oil-soluble initiator ( AIBN) . It was found that, for the rest of conditions constant, the polymerization rate per polymer particle increased when the monomer/water ratio increased, namely when the amount of initiator dissolved in the aqueous phase per polymer particle decreased. This is an evidence against a dominant aqueous phase formation of radicals. On the other hand, these results are consistent with a mechanism in which the radicals are mainly produced in the oil-phase with significant aqueous phase termination.