Competitive Absorption of Free Radicals by Micelles and Particle Nuclei

Nomura and co-workers [20] studied the competitive absorption of free radicals by micelles and particle nuclei. In addition to the basic assumptions made in the Harkins-Smith-Ewart theory, the bimolecular termination reac- 

Based on this particle nucleation mechanism, the mole balance of free radicals in the continuous aqueous phase and the rate of particle nucleation can be described by the following equations. 

Applying the pseudo-steady-state assumption to Eq. (3.9) because of the extremely reactive free radicals and substituting the resultant expression for [R ]. into Eq. (3.10), the rate of particle nucleation then becomes 

The ratio kepNpKJce m) signifies the competitive absorption of free radicals by micelles and particle nuclei. Only those kinetic events involving the entry of free radicals into micelles contribute to the formation of particle nuclei. Eq. (3.11) is reduced to Equation (3.3) when the ratio kepNpl(ke i) is much smaller than one. On the other hand, the rate of particle nucleation can be written as 

Taking into account the effect of desorption of free radicals out of the particle nuclei, the following equation was developed to predict the rate of particle nucleation in the emulsion polymerization of relatively hydrophilic monomers. 

---