COAGULATION KINETICS IN POLYMER COLLOIDS DETERMINED BY LIGHT-SCATTERING

Aqueous polymethyl methacrylate colloids were formed by flash photoinitiation followed by polymerization and nucleation. The primary particles are estimated to have a radius of 1.9 nm. The kinetics of the coagulation of these colloids has been followed by measuring the time dependence of the Rayleigh light-scattering intensity over a time period of about 100 sec. The rate of coagulation depends strongly on the concentration of sodium dodecyl sulfate [SDS]; the range of [SDS]used was 0 to 8.8 × 10-4 M. In terms of the Fuchs stability factor, W, this dependence was W ≈ 2.1 × 105 [SDS]. The results suggest that coagulation may be important during the earliest stages of emulsion polymerization in determining particle number kinetics. © 1979.