Polyurea microcapsules with a photocleavable shell: UV-triggered release

We report the preparation and characterization of photocleavable polyurea microcapsules. First, an isocyanate end functionalized oligomer, bearing the photolabile 6-nitroveratroyloxycarbonyl group was synthesized. This oligomer, in combination with diethylenetriamine, was then utilized in the preparation of polyurea microcapsules. Polyurea microcapsules (50–300 μm) loaded with a hydrophobic dye solution and consisting of a dense capsule shell were prepared via an interfacial polymerization in a stable oil-in-water emulsion system. Thanks to the intra-molecular photocleavage mechanism, the UV-triggered rupture of the photocleavable capsule shell occurred both in the solution and in the solid state, leading to the successful release of the encapsulated liquid core.