Triphenylamine-functionalized chalcones as one-component type II visible-light-absorbing photoinitiators for free radical photopolymerization

In this study, four new one-component Type II visible-light-absorbing chalcones (CY6-CY9) that include tri-phenylamine substitute in one side and dimethylaniline in another side have been prepared and applied for free radical photopolymerization. The position and methoxy-substituted of the triphenylamines demonstrate signif-icant influence on their properties. In addition, the triphenylamine-free one-component Type II photoinitiator (CYP2) was also prepared for comparing. All the new photoinitiators exhibit boarder and red-shifted absorption than did the CYP2 one. The maximum absorption peaks were in the range of 414-425 nm. The photochemical properties of the compounds were studied by the electron spin resonance (ESR), steady-state photolysis tech-niques, and theoretical calculations. Finally, all the one-component Type II photoinitiators were used to initiated the free radical photopolymerization of trimethylolpropane triacrylate (TMPTA) through a Photo-DSC experi-ment. Markedly, the double bond conversion efficiency for TMPTA in the presence of CY8 exhibits the highest values (UV for 34 % and LED@405 nm for 33 %) than other analogues (UV for 12-20 % and LED@405 nm for 8-13 %) and control sample (UV for 9 % and LED@405 nm for 9 %) under UV lamp and LED@405 nm irra-diation source. This work thus demonstrates a judicious chemical design to fine-tune the photopolymerization character in one-component Type II triphenylamine-functionalized chalcones.