Pullulan-Based Polymer Surfactants for Vinyl Acetate Miniemulsion Polymerization: Kinetics and Colloidal Stability Investigations

Various pullulan-b-Jeffamine block copolymers (Jeffamine is a PEO-b-PPO copolymer (PEO = poly(ethylene oxide), PPO = poly(propylene oxide)) are used as surfactants for vinyl acetate miniemulsion polymerization. Their influence on the kinetics, average molecular weights and colloidal stability, is compared with that of Pluronic F68, when using either organosoluble or hydrosoluble initiators. In the first case, conversions and molecular weights are not affected by the polymer surfactant, in contrast to what is observed when using the hydrosoluble system, that may be due to a reaction between the incoming radicals and the sugar units of the pullulan chain. Long-term colloidal stability between 4 degrees C and 40 degrees C over more than 4 months is observed and is not affected by the addition of salts when using pullulan-based surfactant.