Charge Transfer Complexes as Dual Thermal and Photochemical Polymerization Initiators for 3D printing and Composites Synthesis

Photoinitiators and thermal initiators are two important and distinct classes of molecules for polymer synthesis. In the present paper, dual initiators able to initiate both thermal and photochemical polymerization are presented. Very few structures are reported with this unusual dual behavior. Here, a series of Charge Transfer Complexes (CTCs) formed between phosphines (donors) and iodonium salt (acceptor) are investigated as dual thermal and photochemical free radical polymerization (FRP) initiators. The CTCs exhibit excellent photo and/or thermal initiating properties for the benchmarked methacrylate resin and can be efficiently used for the curing of glass fibers or carbon fibers composites. This represents, to the best of our knowledge, the first access to high-tech carbon fibers composites using dual photo/thermal initiators. The formations of the CTCs were confirmed by several techniques, such as 31P NMR, UV-vis, and Molecular Orbitals (MO) calculations. Laser write experiments @405 nm show excelle...