Near-Infrared PhotoInitiating Systems: Photothermal Effect vs. Triplet-Triplet Annihilation -based UpConversion Polymerization

International audienceNIR light induced polymerization has attracted more and more attention in the photopolymerization field due to the possibility to use safer and more penetrating wavelengths, reducing the hazardousness. Here, a novel perspective for the Free Radical Polymerization (FRP) of acrylate-based monomers based on Triplet-Triplet Annihilation UpConversion (TTA-UC) is proposed, avoiding the introduction of heavy metals, usually required in the TTA processes. Thermal imaging experiments and Real Time Fourier Transform Infrared (RT-FTIR) spectroscopy have been respectively used to record the temperature during NIR irradiation and measure the reactive function conversion. The competition between the TTA-UC and the NIR photothermal activation was investigated to compare the relative efficiency of both NIR processes. In view of the results obtained by the different methods, the photothermal effect seems to get the hupper hand over the photoactivation of the system