Naturally Derived Donor‐π‐Acceptor Compounds for Efficient Long‐Wavelength LEDs/Sunlight‐Induced Polymerization and High‐Precision Multiple 3D Printing

Abstract Photopolymerization driven by long‐wavelength visible LEDs offers a promising approach for biocompatible, low‐energy 3D printing, minimizing light scattering and photodamage compared to conventional ultraviolet (UV) and near‐UV systems. However, the inherently slow polymerization kinetics of long‐wavelength photoinitiators (PIs) typically necessitate high light intensities, extended curing times, or excessive PI loadings, limiting their practical applications. To address these challenges, the design and synthesis of two novel donor‐π‐acceptor (D‐π‐A) PIs are reported, incorporating 2‐phenylnaphtho[2,3‐ d ]thiazole‐4,9‐dione as an electron acceptor and two naturally derived aldehydes (furfural and butyraldehyde) as electron donors. These compounds enable exceptionally rapid polymerization under blue and green light LEDs, as well as natural sunlight, even at low light intensities and minimal PI concentrations. The unprecedented curing speed and efficiency are further demonstrated through the fabrication of intricate 3D structures using three distinct printing techniques—direct laser writing (DLW), digital light processing (DLP), and liquid crystal display (LCD) printing. This work expands the frontiers of long‐wavelength photopolymerization by combining high efficiency with eco‐friendly, low‐energy activation, paving the way for advanced applications in biocompatible additive manufacturing.