Encapsulation of microgels with polystyrene (PS): A novel method for the preparation of hollow PS particles

Novel core-shell particles with polystyrene (PS) as the shells and thermosensitive poly(N-isopropylacrylamide) (PNIPAM) microgels (i.e. submicrometer-sized hydrogel particles) as the cores were prepared by a seeded emulsion polymerization of styrene using a PNIPAM microgel suspension as the seed latex. It was found that upon the dehydration of microgels inside the core-shell particles, hollow PS particles were obtained. The morphology and size of the hollow particles were observed by transmission electron microscopy and light scattering. It was also found that the shell thickness of the hollow particles increases apparently with the increase of the amount of PS. The merit of this method is that the microgel templates need not to be removed by calcination or etching to obtain hollow particles.