The synthesis and structural characterization of copolymers of 1-[(2-acryloyloxy) ethoxycarbonyl] thioxanthone (ATX) with 1-[4-(2-acryloyloxyethylthio)phenyl]-2-methyl-2-morpholino-propan-1-one (AMMP), as well as ATX, AMMP and n-butyl 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-pigmented acrylic coating formulation, and compared with the corresponding mixture of low-molecular-weight structural. models 1-[(2-isobutyroyloxy)ethoxycarbonyl]thio (ITX) and 1-[4-(2-isobutyroyloxyethylthio)phenyl]-2-methyl-2-morpholino-propan-1-one (IMMP). The much higher photoinitiation activity shown by the copolymers is discussed in terms of close vicinity of thioxanthone and alpha-morpholinoacetophenone moieties along the backbone, which favors the excitation energy transfer from the former to the latter photosensitive group.