pH Stability of Poly(urethane/urea) Capsules Synthesized from Different Hydrophilic Monomers via Interfacial Polyaddition in the Inverse Miniemulsion Process

Summary Poly(urethane/urea) capsules with different hydrophilic monomers and toluene‐2,4‐diisocyanate were prepared using a polyaddition reaction in inverse miniemulsion. The morphology and the size distribution of the prepared capsules were studied via transmission electron microscopy (TEM), scanning electron microscopy (SEM), and dynamic light scattering (DLS). Furthermore, the capsules were transferred into an aqueous surfactant containing solution and exposed to different pH values (2.5, 7 and 9). The changes in the capsule's shell stability were studied by measuring the amount of a released dye, which had previously been encapsulated, using fluorescence spectroscopy. The specific surface area of nanocapsules was calculated from nitrogen sorption measurements (Brunauer‐Emmett‐Teller (BET)).