Using styrene as typical monomer

polyvinyl alcohol PVA as dispersant

hexadecane HD as co-stabilizer

NaNO2 as water-soluble polymerization inhibitor

a series of submicron polystyrene particles were prepared by micro-suspension polymerization with the help of ultrasonic homogenization. The formation of submicron droplets during homogenization and the variation of particles size and size distribution of disperse phase during polymerization were investigated. It was found that the combination of ultrasonic homogenization and polymer dispersant was conducive to reducing the size of monomer droplet and stabilizing the micro-suspension. The synergistic effect of PVA adsorbed on the surface of droplets

HD dispersed in the droplets phase and NaNO2 dispersed in the water phase facilitated maintenance of disperse phase size during polymerization. Thus the size of colloidal particles could be controlled by varying ultrasonic intensity. Comparing with the conventional micro-suspension polymerization using shear homogenization

the micro-suspension polymerization using ultrasonic homogenization was more suitable to fill the particle size gap between (mini-)emulsion polymerization and suspension polymerization

and more likely to encapsulate the submicron target contents.