Effect of a mixed anionic-nonionic system of surfactants on the entry and exit of free radicals into polystyrene particles

Seeded emulsion polymerizations of styrene were conducted with various rati os of the anionic surfactant sodium lauryl sulfate and the nonionic: surfac tant Triton X-405 adsorbed on the polystyrene latex particles. The polymeri zation kinetics were monitored utilizing the Mettler RC1 reaction calorimet er and subsequently analyzed to determine the effects of the adsorbed surfa ctants 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 degrees C, and "zero-one" conditions were determined to exist in orde r to analyze the data by the "slope-intercept" method. Using the RC1, the s tart of the polymerization could be determined within 4 s. No significant e ffect of the surfactant ratio (40% surface coverage) was noted on the pseud o-first-order entry rate coefficients within experimental error. Larger exp erimental errors were noted in the determination of the pseudo-first-order exit coefficients with no discernible effect of the surfactant ratio being observable.