Preparation of photoactive polymers and postmodification via nitroxide trapping under UV irradiation.

New types of photoactive homo and block copolymers bearing α-hydroxyalkylphenylketone (2-hydroxy-2-methyl-1-phenylpropan-1-one) moieties as backbone substituents are prepared using nitroxide-mediated radical polymerization (NMP). Such polymers can be readily activated via the Norrish-type I photoreaction to give polymeric acyl radicals. Photolysis in the presence of a persistent nitroxide, which serves as a C- radical trapping reagent, leads to chemically modified polymers conjugated with nitroxide moieties. The number-average molecular weight (M(n)) of the prepolymers and the chemically modified polymers was determined by gel permeation chromatography (GPC). Structures were further confirmed by NMR spectroscopy and by attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy.