Size control of polymeric nanoparticles from polystyrene-b-poly(2-vinylpyridine)

We describe size control of polymeric nanoparticles prepared from an amphiphilic block copolymer, polystyrene-b-poly(2-vinylpyridine) (PS-P2VP). During the progress of quaternization between poly(2-vinylpyridine) block and methyl iodide, ionic interactions lead to strong aggregations of reverse micelles in methyl ethyl ketone (MEK). The size of the PS-P2VP nanoparticles with molecular weight of 12.6×104 was around 109 nm in MEK. When the dispersing medium of the nanoparticles was changed from MEK to toluene, the size of the nanoparticles was reduced from 109 to 73 nm. In addition, as the molecular weight of the PS-P2VP block copolymers was decreased, the size of the PS-P2VP nanoparticles was brought down up to 21 nm.