Application of new photoinitiating systems based on BODIPY derivatives in long-wavelength photo-induced free radical polymerization

Four kinds of novel BODIPY derivatives were designed to initiate the free radical polymerization of acrylates under typical visible LED irradiation and their application in 3D printing. • New BODIPY dyes were designed to initiate free radical polymerization. • Photopolymerization was conducted under long-wavelength light irradiation. • Corresponding photochemical mechanisms were well discussed in details. • 3D products were printed with yellow fluorescence. Efficient photopolymerization activated by photoinitiators or photoinitiating systems (PISs) under visible light irradiation, especially at long wavelengths, has remained as a challenging research focus. In this work, four novel boron dipyrromethene (BODIPY) derivatives with high fluorescence properties were systematically investigated as light-harvesting organic dyes, which exhibited remarkable photoinitiation capacities under long-wavelength light irradiation. Markedly, these BODIPY derivatives efficiently induced the free radical photopolymerization of acrylates under irradiation from violet-to-green light-emitting diodes (LEDs), benefiting from the construction of three-component PISs comprising an amine and an iodonium salt. The high photoreactivity of these BODIPY dyes was assessed through steady-state photolysis and excited-state fluorescence quenching analyses, while the corresponding photochemical parameters were attained by theoretical calculations under the density functional theory (DFT) method. In order to expand potential application areas, photopolymerized acrylate monomers by direct laser writing experiments using the investigated PIS, resulting in 3D patterns with smooth surfaces. high spatial resolution and significant fluorescence were successfully fabricated, providing a promising opportunity for developing efficient PIs with high fluorescence in photo-curing 3D printing area.