Optical coatings exhibiting photochromic effects were prepared by UV-curing of a coating formulation that incorporates a hexa-functional monomer, DPHA, and an organic dye, spironaphthooxazine. Spectroscopic studies of the coatings indicated efficient photochromic activities in response to UV irradiation. The depth of color and the rate of bleaching at 610 nm were found to depend on the UV dosage and the dye content; specifically, the transmittance returned from 42 to 82% and from 38 to 67% in 60 s. for the coating containing 3.7 wt% dye that received 0.45 and 3.6 of J/cm2 of UV exposure, respectively. Furthermore, the coatings were very hard (7H, pencil hardness) and adhered perfectly (100%, peel test) on poly (methyl methacrylate) substrates.
Journal of Applied Science and Engineering 17(2), pp.167-174