COPOLYMERIC SYSTEMS WITH PENDANT THIOXANTHONE AND ALPHA-MORPHOLINOACETOPHENONE MOIETIES AS PHOTOSENSITIZING AND PHOTOINITIATING AGENTS FOR UV-CURABLE PIGMENTED COATINGS

The synthesis and structural characterization of copolymers of 1-[(2-a cryloyloxy) ethoxycarbonyl] thioxanthone (ATX) with hylthio)phenyl]-2- methyl-2-morpholino-propan-1-one (AMMP), as well as ATX, AMMP and n-bu tyl acrylate (BA) terpolymers, is reported. These copolymeric systems have been checked in the photoinitiated polymerization in film matrix of the 1,6-hexanediol diacrylate (HDDA)-BA equimolar mixture under UV irradiation over 380 nm, i.e., under conditions simulating a TiO2-pigm ented acrylic coating formulation, and compared with the corresponding mixture of low-molecular-weight structural. models 1-[(2-isobutyroylo xy)ethoxycarbonyl]thio (ITX) and hylthio)phenyl]-2-methyl-2-morpholino -propan-1-one (IMMP). The much higher photoinitiation activity shown b y the copolymers is discussed in terms of close vicinity of thioxantho ne and alpha-morpholinoacetophenone moieties along the backbone, which favors the excitation energy transfer from the former to the latter p hotosensitive group. (C) 1995 John Wiley & Sons, Inc.