Tunable, reagent‐loaded polyurethane nanocapsules cleavable by NIR light.

Dual response polyurethane nanocapsules consisting of a hydrophilic core are synthesized via interfacial polyaddition of the diisocyanate monomers and different diols (VA‐060 and glycols) in inverse miniemulsion process. The presence of the water‐soluble NIR dye in the core and azo‐bonds in the polymer shell allows the selective release of encapsulated material triggered by temperature or NIR light. The capsules are characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The capsule degradation under external stimuli, like temperature and NIR light, is confirmed microscopically by TEM. Macroscopic evidence of the capsule cleavage was achieved by the incorporation of the chemical into the capsule core, and subsequent treatment of the capsules with NIR laser in the presence of the suitable reagent outside the capsules. A color‐forming chemical reaction occurred after the shell opening. The reactions were easily detected by visual observation of a color change and by UV–Vis spectroscopy. [ABSTRACT FROM AUTHOR]