Monodisperse cross-linked core-shell polymer microspheres by precipitation polymerization

Monodisperse cross-linked core-shell polymer microspheres having diameters in the micrometer-size range were prepared by semibatch and by two-step precipitation polymerization in the absence of any stabilizer. Commercial divinylbenzenes, containing 55% or 80% divinylbenzene, were used for the core, and several functional monomers including chloromethylstyrene, monovinyl, or divinyl methacrylic monomers were incorporated into the shell. Acetonitrile and toluene/acetonitrile mixtures were used as reaction media. Depending on the type of monomer and reaction medium used, the shell could be made nonporous or porous. The particle size distribution, surface morphology, internal texture, and porosity of the resulting core-shell particles were studied. The chromatographic properties of selected particles were evaluated.