Synthesis of Polymeric Yolk-Shell Microspheres by Seed Emulsion Polymerization

The convenient synthesis of polymeric yolk shell microspheres, which possess a hollow shell and an encapsulated spherical core, is both an interest and challenge in polymer chemistry. A method for the synthesis of polymeric yolk shell microspheres by seed emulsion polymerization is proposed. The present synthesis includes a procedure for swelling the seed latex particles with the hydrophobic monomer mixture, polymerizing the adsorbed and entrapped monomer mixture, forming the coated microspheres, assembling the coated microspheres into sandwichlike ones through phase separation, and removing the seed by solvent etching. Followed this proposal, two kinds of yolk shell microspheres, one of which contains an similar to 200 nm hollow shell of cross-linked poly(styrene-co-acrylamide) and a spherical core of cross-linked polystyrene and the other containing a coordinative segment, are fabricated. The parameters affecting the synthesis of yolk shell microsphercs are investigated, and the phase separation within the seed particles is deemed to play the dominant role.