Recent advances on push–pull organic dyes as visible light photoinitiators of polymerization

International audience; Photoinitiators activable under visible light and low light intensity are actively researched as it can advantageously address the safety concerns raised by the traditional UV-light photopolymerization process as well as the light penetration issue. Among dyes strongly absorbing in the visible range, one of the most promising family of photoinitiators are push-pull dyes based on an electron-donating and an electron-accepting moiety connected at both ends of a polyenyl-type spacer. By acting on both the strength of the electron donor and the electron accep-tor, position of the intramolecular charge transfer (ICT) band can be easily tuned from the near-UV to the near infrared region. In this review, an overview of the different D-π-A push-pull dyes used as visible photoinitiators of polymerization is presented. Over the years, a clear evolution in the chemical structure of the electron accep-tors can be clearly observed, evidencing the strong activity existing around these structures.