Vinyl monomers bearing chromophore moieties and their polymers. VII. Synthesis, photochemical, and initiation behavior of acrylic monomers bearing phenothiazine oxide moieties and their polymers

Abstract

Four acrylic monomers bearing phenothiazine oxide moieties, that is, N-acryloyl-phenothiazine-5-oxide (APTO), N-acryloyl-2-chlorophenothiazine-5-oxide (ACPTO), N-acryloyl-phenothiazine-5,5-dioxide (APTDO), and N-acryloyl-2-chlorophenothiazine-5,5-dioxide (ACPTDO) were synthesized by oxidation of corresponding N-acryloyl-phenothiazine (APT) and N-acryloyl-2-chlorophenothiazine (ACPT) using sodium perborate as an oxidant. These monomers could easily be polymerized by initiation of AIBN. The emission fluorescence spectra of the monomers and their polymers were recorded, and the results indicated that these 4 new monomers possess a fluorescence structural self-quenching effect (SSQE), as we have reported previously. Moreover, with the change of the electronic structure of sulfur atom in the phenothiazine chromophore, that is, from sulfide to sulfoxide and sulfone groups, the tendency of SSQE of these monomers is in the order of APT > APTO > APTDO. This would be ascribed mainly to the decrease of electron-donating abilities of monomers in a sequence of sulfide, sulfoxide, and sulfone groups; that is, at the sulfur atom of these monomers, APT has 2 lone-pair electrons, APTO has 1 lone-pair electrons, and APTDO completely loses its lone-pair electrons. Based on the exciplex formation, the monomers APTO, APTDO, ACPO, and ACPTDO could act as sensitizers for the photopolymerization of acrylonitrile (AN). The combination of APTO or ACPTO with organic peroxides such as BPO could also initiate the polymerization of vinyl monomers, such as AN, by redox nature. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1191–1199, 1998