Benzoxazinone-Based Dual Cationic and Radical Photoinitiating Systems for VPP 3D Printing

The development of 3D printing technology has revolutionized manufacturing, enabling the precise creation of complex structures and functional components. A key aspect of this technology is the development and use of new photosensitizers, which play a key role in photopolymerization processes. These innovative photosensitizers improve the efficiency and accuracy of light-induced polymerization, enabling the production of high-resolution 3D printed materials. The number of compounds commonly used as polymerization initiators is vast. The most common photoinitiators are phosphine compounds such as TPO (diphenyl(2,4,6-trimethylbenzoylo)phosphine oxide) and BAPO (phenylbis(2,4,6-trimethylbenzoylo)phosphine oxide). However, despite their many advantages, there are concerns about their toxicity, especially potential reproductive toxicity. As a result, they are subject to increasingly stringent regulations aimed at phasing them out completely. Therefore, increasing attention is being paid to multi-component systems as an alternative. Herein, we report sixteen new benzoxazinone derivatives as promising photoinitiators for 3D printing processes. Spectroscopic studies and kinetic measurements were performed using Fourier transform infrared (FT-IR) spectroscopy. Two- and three-component photoinitiating systems comprising new benzoxazinone derivatives and MDEA and EDB amines have been developed. In addition, various objects were printed to identify favorable substitutions and modifications that would provide the highest performance. The presented results provide insight into the impact of a properly selected photoinitiating system on the radical and cationic photopolymerization processes in 3D printing, which leads to better sharpness of printed objects and can significantly reduce the time of the entire printing process.