Photoinitiating systems for acrylate and thiol-ene photopolymerisation
Owing to their unique photodynamics, phenothiazine (PTZ) can be used to form charge-transfer complexes (CTCs), which serve as effective visible-light photoinitiating systems (PIS) for acrylate and thiol-based click polymerisation. In this study, seven PTZ structures and their corresponding CTCs with iodonium salt (Iod) were evaluated by calculated spectra and polymerization kinetics. The effectiveness of the initiator decreased in the order of N-substituted polycyclic aromatic hydrocarbons > electron-donating aromatics > electron-withdrawing aromatics ≈ aliphatic alkanes.
Substituted dimethylaminophenyl derivatives exhibited a lower energy gap and higher photoinitiation efficiency in CTCs. Moreover, PTZ-based CTCs as PIS rendered increased thermal stability to the photosensitive resin systems due to the mild free-radical quenching of PTZ. Such characteristic demonstrates potential versatility in the 3D printing of high-performance and high-precision materials.
The study has been published in Progress in Organic Coatings, Volume 166, May 2022.