Scientists have designed a new family of molecules capable of hardening resins under simple exposure to daylight, revolutionizing the field of 3D printing. More efficient and less toxic than current photoinitiators, these compounds pave the way for greener manufacturing of objects for numerous applications, particularly in medicine.
In the rapidly expanding world of 3D printing, a crucial step is photopolymerization: the transition of a liquid material into a solid structure under the effect of light. However, to initiate this reaction, most systems use photoinitiators sensitive to ultraviolet (UV) rays—an effective technology but limited by high energy costs and environmental and health concerns related to the toxicity of these molecules.
Chemists from the Mulhouse Institute of Materials Science (CNRS/University of Haute-Alsace) and the Institute of Radical Chemistry (CNRS/Aix-Marseille University), in collaboration with Australian and Chinese scientists, have developed a new generation of photoinitiators that work with blue LEDs and even sunlight. Their secret? A hybrid molecule incorporating two active chemical structures that absorb visible light.
When illuminated, these molecules release free radicals capable of initiating the polymerization reaction. By combining a predictive theoretical approach and experiments on several candidate molecules, they were able to identify the most promising one for efficiently initiating polymerization under daylight. Dubbed "C5," it has demonstrated superior performance compared to commercial benchmarks, with an efficiency increase of 40 to 132% depending on the wavelength of light used.
Even better, this new photoinitiator is not only more effective but also less toxic than its predecessors—a critical criterion for biomedical or food applications. Cytotoxicity tests have shown better compatibility with human cells compared to other widely used initiators.
The implications of this discovery are numerous: manufacturing more eco-friendly materials, large-scale 3D printing under natural light, developing safer medical devices... in short, 3D printing that is more precise, sustainable, and accessible to all, thanks to simple daylight. This study was published in the journal
Angewandte Chemie International Edition.