POLYMERIZATION IN NONAQUEOUS MICROEMULSIONS

Nonaqueous microemulsions containing formamide, the anionic surfactant AOT (bis(2-ethylhexyl)sulfosuccinate sodium salt), sodium bromide (Na Br), and either of the monomers hexyl methacrylate or styrene are poly merized at 60 degrees C. For both monomers, the final product is a sta ble, bluish dispersion of particles of ca. 80 nm diameter. Based on ph ase behavior studies as a function of NaBr concentration, we describe how a systematic variation of composition and monomer causes changes i n reaction rates and latex characteristics. The monomer solubility in the continuous phase plays an important role in determining the final polymer characteristics. Decreasing monomer solubility shifts the mech anism from one similar to solution polymerization to one closer to tra ditional emulsion polymerization.