3D Printing of Thiol-Yne Photoresins through Visible Light Photoredox Catalysis

In this work, we report a visible light active thiol-yne photoresin formulation that is printable with digital light processing (DLP) 3D printer under irradiation of blue-light (lambda(max)=470 nm). The resulting objects have the Z axis resolution of 250 mu m (layer thickness) and building speed of (5 mm/h). Uniquely, our thiol-yne photoresin contains photoredox catalysts Eosin Y and fac-Ir(ppy)(3), which initiate the photopolymerization through a photoredox mechanism. The optimized dual catalysts EY/fac-Ir(ppy)(3) system not only facilitate the faster thiol-yne reaction but also potentially enables wider visible light wavelength coverage for 3D printing process. This work illustrates the possibility of replacing traditional photoinitiator with photoredox catalysts in the visible light range, thus, enriching the photoresin formulations for polymer-based 3D printing industry.