Photochemical initiated polymerization of single microdroplets

The production of polymeric microspheres via aerocolloidal processing is explored. A droplet consisting of a mixture of 1,6-hexanediol diacrylate and trimethylolpropane ethoxy triacrylate monomers was levitated electrodynamically in the path of an argon ion laser beam (=488 nm). The laser beam served as the source of illumination for elastic and inelastic light-scattering measurements. The reaction was followed by Raman spectroscopy, and polymerization was initiated with an -amino acetophenone derivative which undergoes -cleavage upon exposure to the laser light. The diameters of the suspended droplets were typically 20–80 m, producing polymeric microspheres of approximately the same size. The size and refractive index of the product microspheres were determined by elastic light-scattering. The Raman data show the elimination of carbon-carbon double bonds and the formation of C–H bonds as rapid polymerization proceeded.