Effect of the number of seed polymer particles on the kinetic behavior of the seeded emulsion copolymerization of styrene and acrylamide

Abstract

The seeded emulsion copolymerizations of styrene and acrylamide were carried out at 50°C using polystyrene latex particles as the seed and potassium persulfate as the initiator, respectively. It was found that the change in the number of seed particles initially charged causes a drastic change in the kinetic behavior of this seeded emulsion copolymerization system: when the number of seed particles initially charged was less than a certain critical value, both styrene and acrylamide started polymerization from the beginning of the reaction. However, when the number of seed particles was higher than this critical value, an apparent induction period suddenly emerged only for acrylamide polymerization, that is, acrylamide did not start polymerization until the styrene conversion exceeded around 75%, while the styrene polymerization started and continued very smoothly from the beginning of the reaction. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2689–2695, 1997