SYNTHESIS OF SPHERICAL MICROCAPSULES BY PHOTOPOLYMERIZATION IN AEROSOLS

The preparation of polymer microcapsules of well defined size in the r ange of 10-50 mu m with different shell thickness to core diameter rat ios is described. An aerosol of monodisperse droplets of a homogeneous ternary liquid system which contained a hydrophobic component and a h ydrophilic component dissolved in a high-volatile mutual solvent, was produced by dispersing with a vibrating-orifice aerosol generator. Aft er the evaporation of the solvent in a nitrogen atmosphere the particl es demix and form a two-phase droplet of core-shell type. These drople ts were illuminated with UV light and polymerized to highly monodisper se microcapsules with a solid polymer shell and a liquid core. The pro perties of the resulting particles (size, size distribution, shell thi ckness, shape and surface characteristics) were investigated by scanni ng electron microscopy, Raman spectroscopy on single optically levitat ed particles, and confocal Raman micro spectroscopy. The microcapsules were highly monodisperse and have spherical shape.