Chemical imaging of functional coatings with thermal release of encapsulated ingredients

Abstract

Aqueous dispersions of organic nanoparticles with encapsulated oils can be used in the formulation of barrier coatings for packaging materials. Through thermal stimulation of the coating material, the oil release can be triggered depending on the synthesis conditions of the nanoparticles and the degree of saturation of the encapsulated oil. The resulting surface properties after oil release will increase the surface hydrophobicity. In particular, the amount of oil and homogeneity of the oil distribution over the surface should be monitored as a function of temperature to detect different mechanisms of oil release, which largely depend on the type of ‘core-shell’ encapsulation: are induced by either diffusion through the porous polymer shell or softening of the polymer shell. The Raman microscopy and ATR-FTIR microscopic techniques are used to visualize the different states in oil release as a function of time and temperature.