Emulsion polymerization of styrene using a reactive surfactant and its polymeric counterpart: Kinetic studies

Emulsion polymerizations of styrene using the reactive surfactant sodium do decyl allyl sulfosuccinate (TREM LF-40) and its polymeric counterpart, poly (TREM), were studied. The critical micelle concentrations (cmc) and the ads orption behaviors on polystyrene latex particles were determined. The polym erization kinetics obtained via reaction calorimetry showed that the emulsi on polymerization of styrene using the reactive surfactant behaved similarl y to those reported for the conventional surfactant sodium lauryl sulfate ( SLS) in that the rate of polymerization (R-p) profiles showed the same thre e distinct regions: a rapid rise in rate, attributed to micellar nucleation (interval I); a moderate rise in rate to a maximum where droplets disappea r, attributed to homogeneous nucleation (stage 2); and the decreasing rate period (interval III). However, with varying TREM LF-40 concentration (cons tant initiator concentration), R-p was not found to be proportional to the first power of N-p as reported for the SLS system, but 0.7 instead (i.e., R -p proportional to N-p(0.67)). In contrast, by varying the initiator concen tration, the kinetics were found to have the same dependencies as the conve ntional surfactant (R-p proportional to N-p(1.0) proportional to [I](0.4)). These differences are attributed to the participation of the surfactant in the reaction. The kinetics using poly(TREM) differed from those of the rea ctive counterpart in several ways. The R-p profiles indicated a longer homo geneous nucleation stage 2 in comparison to interval I. Larger (fewer) part icles were produced for equivalent weights of the surfactants. This was exp ected. Although R-p was found to be proportional to the first power of N-p, the dependencies on the surfactant and initiator concentrations varied dep ending on concentration of the component held constant (R-p proportional to N-p(1.0) proportional to [E](0.2-0.5) and R-p proportional to N-p(1.0) pro portional to [I](0.4-0.8)). The lower dependencies on the surfactant concen tration and higher dependencies on the initiator concentration are attribut ed to the ionic strength and the longer nucleation period.