Effect of a Mixed Anionic−Nonionic System of Surfactants on the Entry and Exit of Free Radicals into Polystyrene Particles

Abstract

Seeded emulsion polymerizations of styrene were conducted with various ratios of the anionic surfactant sodium lauryl sulfate and the nonionic surfactant Triton X-405 adsorbed on the polystyrene latex particles. The polymerization kinetics were monitored utilizing the Mettler RC1 reaction calorimeter and subsequently analyzed to determine the effects of the adsorbed surfactants on the entry of free radicals into the particles and the desorption of radicals from the particles. All the reactions were run in interval III at 50 °C, and “zero−one” conditions were determined to exist in order to analyze the data by the “slope−intercept” method. Using the RC1, the start of the polymerization could be determined within 4 s. No significant effect of the surfactant ratio (40% surface coverage) was noted on the pseudo-first-order entry rate coefficients within experimental error. Larger experimental errors were noted in the determination of the pseudo-first-order exit coefficients with no discernible effect of the s...