Charge Transfer Complexes as Pan-Scaled Photoinitiating Systems: From 50 μm 3D Printed Polymers at 405 nm to Extremely Deep Photopolymerization (31 cm)

Charge transfer complexes (CTC) between N-aromatic amines (donors) and iodonium salts (acceptors) are used here as photoinitiating systems (PIS) for the polymerization of clear methacrylate formulations under a 405 nm LED irradiation. Outstandingly, a complete spatial and temporal resolution is kept for 50 μm resolved 3D printed photopolymers at 405 nm (50 μm being the size of the printing laser used here). Photocuring of a high thickness (31 cm) is also possible. The photopolymerization propagation is rationalized and interpreted from both experimental (using thermal imaging experiments) and predicted data. An experimental/molecular modeling study also attempts to rationalize the CTC structure/reactivity/efficiency relationships. These systems are commercially available, stable, and metal-free and have a low toxicity.