Luminescent elastomeric Janus particles

We report on a low-cost and low-tech method for the preparation of luminescent micro- and millimeter elastomeric particles with asymmetric morphology. The method of fabrication consists in UV-irradiating soft urethane/urea fluorescent spheres, which are then extracted in toluene and dried. Wrinkles appear on the irradiated portions of the particles surfaces, and the spatial periodicity can be controlled with variation in UV irradiation time and the amount of the luminescent compound. The spheres are thus composed of an urethane/urea network in which the tris(8-hydroxyquinolinato)aluminum (Alq3) fluorescent compound was incorporated. The asymmetric morphology and the optical properties of the resultant particles have been confirmed by scanning electron microscopy, atomic force microscopy, optical microscopy, and UV-Vis spectrophotometry. The system shows negligible leaching, and the encapsulation of the Alq3 without recourse to covalent bonding to the polymeric matrix has the advantage of allowing the tuning of the spheres morphology and fluorescence.