Fluorescent melamine-formaldehyde/polyamine coatings for microcapsules enabling their tracking in composites

This study aimed the development of fluorescent melamine-formaldehyde (MF)/polyamine coatings for labelling of prefabricated microcapsules and their tracking in composites. The composition of the fluorescent MF coatings was studied by FTIR spectroscopy, thermogravimetric analysis, and elemental analysis. The characteristics of the coatings and its deposition on different surfaces were investigated using optical and fluorescence microscopy and fluorescence spectroscopy. MF prepolymers were polymerised with tri- and polyamines yielding in fluorescent coatings without addition of fluorescent dyes. Both, MF/poly(ethylene imine) and MF/poly(vinyl amine) (PVAm) coated glass beads showed maximum fluorescence at an excitation wavelength of λ_max = 360 nm with the emission maxima at λ_max = 490 nm and λ_max = 410 nm, correspondingly. The MF/PVAm polymer was coated on diuron-poly(methyl methacrylate) microcapsules and tracked in highly filled composites (water-based plaster/paint) to show its applicability. MF/polyamine coatings were identified as promising materials for the fluorescent labelling of prefabricated microcapsules.