Abstract
A long-persistent phosphorescent surface coating was developed from a simple inorganic/organic nanocomposite towards the simple industrial manufacture of glow-in-the-dark products. This glow-in-the-dark smart coating is able to continue to emit light for proloned time periods. The organic/inorganic nanocomposite consisted of an organic polyester resin and inorganic europium- and dysprosium-doped strontium aluminate oxide nanoparticles. The phosphorescent lanthanide-doped strontium aluminate oxide pigment nanoparticles were added to the synthetic polyester resin in a generated pigment-loaded viscous solution that could then be harden in a few minutes using a cross-linking process in the presence of methylethyl ketone peroxide as a catalyst. The transparency of the produced glow-in-the-dark coating was accomplished simply by homogenous dispersion of the phosphorescent lanthanide-doped strontium aluminate nanoparticles into the sticky polyester resin before adding the catalyst to prevent pigment accumulation. This translucent long-persistent phosphorescent polyester nanocomposite can be simply applied under ambient conditions onto different surfaces such walls, textiles, tiles and glasses, ceramics, paper sheets, metals, and wood. The photoluminescent film displayed durable long-persistence emission with high reversibility. An optimum excitation wavelength was monitored at 360 nm, while the emission was monitored at 525 nm. Both the blank and the luminescent coating exhibited a transparent white colour in normal visible light. Conversely, the photoluminescent coating generated a bright green colour under an ultraviolet light lamp, a bright white colour after maintaining the sample for 10 sec in the dark, and a green phosphor after maintaining the sample for 100 min in the dark. The coloration parameters were explored using Commission Internationale de l'eclairage CIELAB colour coordinates. The hardness, as well as photophysical properties including emission, excitation, and life-time were studied. The surface morphology and elemental content were investigated using scanning electron microscopy, wavelength dispersive X-ray fluorescence, elemental mapping, and energy-dispersive X-ray spectroscopy. The films displayed an enhanced superhydrophobic activity without negatively influencing its native physico-mechanical properties.