Visible Light–Induced RAFT Polymerization of Methacrylate with 4-(N,N-diphenylamino)benzaldehyde as Organophotoredox Catalyst and the Effect of Temperature on the Polymerization

With UV–vis absorption in the range of 270–435 nm, 4-( N , N -diphenylamino)benzaldehyde (DPAB) takes efficient photoreduction quench with 4-cynao-4-(phenylcarbonothioylthio)pentanoic acid (CTP). The polymerization rates of methyl methacrylate (MMA) are 0.019, 0.056, and 0.102 h −1 at 33, 40, and 50 °C, respectively, in the presence of DPAB and CTP under visible-light irradiation. Dark reaction produces no PMMA at 50 °C for 120 h. The living feature is demonstrated by linearly increasing M n with the monomer conversions and narrow polydispersity index (PDI), chain extension, and block polymerizations with benzyl methacrylate (BnMA) and poly(ethylene glycol) monomethyl ether methacrylate (PEGMA). With PMMA-CTP ( M n = 6800, PDI = 1.17), chain extension gives PMMA with M n = 15 900 and PDI = 1.15. With PMMA-CTP ( M n = 6000, PDI = 1.21) as macro-RAFT, PMMA- b -PBnMA of M n = 12 600 (PDI = 1.44) and M n = 18 500 (PDI = 1.31) are prepared. These results support that there is a positive synergistic effect between polymerization temperature and visible-light irradiation on the photo-RAFT without losing the living features.