High performance dyes based on triphenylamine, cinnamaldehyde and indane-1,3-dione derivatives for blue light induced polymerization for 3D printing and photocomposites

In this research, high performance dyes based on triphenylamine, cinnamaldehyde and indane-1,3-dione derivatives have been designed/synthesized and evaluated as photoinitiators for visible light photopolymerization. The introduction of light-emitting diodes (LEDs) as low-cost and secured sources of irradiation is one of the major purposes in this study, where a LED at 405 nm was used for both the cationic polymerization (CP) of thin epoxide samples and the free radical polymerization (FRP) of thin TMPTA films. The proposed dyes showed very high efficiencies in the presence of the two-component photoinitiating systems based on Dye/Iodonium salt (Iod) couples or Dye/Amine (such as N-Phenylglycine (NPG) or ethyl 4-(dimethylamino)benzoate (EDB)) couples for the FRP and/or CP, highlighting their importance through a photo-oxidation (with Iod) process but also through a photo-reduction (with amine) process. The examined dyes are also able to initiate the FRP of thin acrylate films in the presence of the three-component (Dye/Iod/NPG) systems where very high rates of polymerization (Rp) and great final reactive function conversions (FCs) were achieved. A new dye (Dye 4) is proposed here for the first time (never synthesized before) and a new synthetic pathway for Dye 3 is also established. Objectives of this work concern the study of the photoinitiating abilities of the different photoinitiating systems using FTIR technique but also the study of the chemical mechanisms which was mainly examined in solution. The use of the investigated systems for 3D printing experiments (using LED projector or laser diode @405 nm) is particularly outlined. Finally, the production of thick glass fiber photocomposites presenting excellent depth of cure is also accomplished in the presence of these dyes (using near-UV conveyor: LED@395 nm).