| Abstract: | Nucleation in finely dispersed monomer emulsions in competition with homogeneous and micellar mechanism was studied. The emulsions were prepared with a high-pressure homogenizer under varying homogenizing conditions and made stable by the addition of hexadecane to the monomer. Sodium dodecyl sulfate was used as emulsifer. The number of particles in latexes polymerized with potassium persulfate and benzoyl peroxide initiators was measured and plotted as a function of the free emulsifier concentrations. With persulfate initiator the particle number achieved a minimum in the transition region between droplet and water phase–micellar nucleation mechanisms. With very fine emulsions Smith–Ewart case II kinetics with n = 0.5 applied. The reaction rate, which differed from conventional emulsion polymerizations, decreased with time up to the point at which n began to increase. In these runs the particle size distribution became nearly monodisperse. |
