Abstract
Miniemulsion stability of threeβcomponent disperse phase systems comprising styrene [ST (1)], methyl methacrylate [MMA (2)], and stearyl methacrylate [SMA (3)] was investigated. The Ostwald ripening rate (Ο) increases with increasing MMA content in the monomer mixture. The empirical equation 1/Ο = k(Ο~1~/Ο~1~ + Ο~2~/Ο~2~) + Ο~3~/Ο~3~ was proposed to adequately predict the miniemulsion stability data. The empirical parameter k was determined to be 555.77, and the Ostwald ripening rate (Ο~3~) and water solubility of SMA were estimated to be 8.77 Γ 10^β21^ cm^3^/s and 1.90 Γ 10^β9^ mL/mL, respectively. A waterβinsoluble dye was used as a molecular probe to study particle nucleation mechanisms in the miniemulsion copolymerizations. In addition to the primary monomer droplet nucleation, homogeneous nucleation also plays an important role in the formation of particle nuclei, and this mechanism becomes more important for the polymerization systems with higher MMA contents as a result of the enhanced aqueous phase polymer reactions. The polymer composition data suggest that, during the early stage of polymerization, MMA is consumed more rapidly by free radical polymerization compared with ST. The final latex particle surface potential data also support this conclusion. Β© 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009