Dye-grafted silica nanoparticles (GSiO2 ) were synthesized via a dual-step process involving, ﬁrst, attachment of the organic dye Disperse Red 1 (DR1) to the coupling agent, 3-isocyanatopropyltri- ethoxysilane, by means of urethane bonds, and then grafting of the silylated-DR1 onto silica nanoparticles (6 nm) prepared by hydrolysis and condensation of tetraethoxysilane in a sol–gel process. Dye-adsorbed silica nanoparticles (DSiO 2 ) were also prepared for comparison, for which DR1 was bound only physically to silica instead of covalent bonds. The thermal behaviors of the formed GSiO 2 and DSiO 2 were examined by means of differential scanning calorime- try and thermal gravimetric analysis. The results showed that both the particle size and silica content have signiﬁcant effects on the thermal behaviors of the dye-adsorbed and dye-grafted silica. Moreover, crys- talline DR1 lost signiﬁcantly its crystallinity after being adsorbed on silica, and became virtually amorphous after being grafted onto silica. The formed particles were UV-cured with a multifunctional acrylic mono- mer to yield color coatings on glass substrates. UV– visible spectra indicated that brightness and color saturation of the coating comprising GSiO 2 could be maintained better than that comprising DSiO 2 after heat treatment at 280C.
Journal of Coatings Technology and Research, 12(4), pp.731-738