Effect of UV-irradiation on fluorescence of poly(methyl methacrylate) films with photosensitive organic compounds

• Films of neat poly(methyl methacrylate) and with three photoactive compounds (photoinitiators) were prepared.
• Influence of UV light on fluorescence of the photoinitiators and poly(methyl methacrylate) with theses compounds was studied.
• Photoinitiators undergo decomposition under UV irradiation but in polymer matrix this process is low efficient due to energy transfer processes.
• Fluorescence properties of poly(methyl methacrylate) were improved by introduction of photosensitive compounds.

The simple way of physical modification of poly(methyl methacrylate) (PMMA) for the purpose of formation its photoactivity and fluorescence properties has been described. It was found that aromatic carbonyl compounds (2,2-dimetoxy-2-phenylaceto-phenone, benzoyl peroxide and tert-butyl peroxybenzoate) dispersed in PMMA matrix changed its optical properties, which was studied by absorption and emission spectroscopy. Modified PMMA exhibits fluorescence upon excitation of 220 or 270 nm. The intensity of emission band decreases after samples exposure to short wavelength UV-irradiation, which is evidence of component photolysis. The fluorescence decay is slightly smaller for the irradiated initiators in PMMA matrix, but the trend is similar to that for pure initiators exposed to UV. The protective effect of PMMA on the studied compounds after UV-irradiation, however, is accompanied by photodegradation reactions occurring in the polymer, which was confirmed by viscometric measurements.