MINIEMULSION POLYMERIZATION OF VINYL-ACETATE WITH NONIONIC SURFACTANT

The stability of vinyl acetate miniemulsions employing polyvinyl alcohol (PVOH) as the surfactant, and hexadecane and/or various polymers as the cosurfactant, were studied. Shelf lives (to phase separation) and monomer droplet sizes were measured. The results indicate that it is possible to prepare stable miniemulsions using a nonionic surfactant (PVOH) and hexadecane as the cosurfactant. Polymeric cosurfactants do not create stable miniemulsions but retard Ostwald ripening to an extent that allows predominant droplet nucleation. The polymerization behavior of these miniemulsion systems was investigated using on-line conductance measurements to differentiate droplet versus micellar/homogeneous nucleation. The effect of cosurfactant concentration on the reaction rate was compared for hexadecane and polymeric cosurfactants. (C) 1994 John Wiley and Sons, Inc.