Stereolithography 3D printing upon near-infrared photopolymerization

Abstract

This research proposes a novel stereolithography (SLA) three-dimensional (3D) printing strategy based on near-infrared (NIR) photopolymerization through photoinduced electron transfer (PET) between cyanine and iodonium salt, reported here for the first time. In contrast to traditional ultraviolet (UV) photopolymerization, NIR method has garnered significant attention due to its safety and deep penetration capabilities. The NIR-sensitive 3D printing formulas were successfully designed, and various products were fabricated using a customized 3D printer equipped with an 808 nm laser source. Furthermore, due to the weak absorption of coloured fillers in the NIR region compared to cyanine, this strategy can easily manufacture polychromatic products, particularly black, and stimulus-responsive materials capable of photochromism, which is difficult to achieve through 3D printing with UV photopolymerization. The utilization of carbon black (CB) as a light absorber with NIR absorption properties enabled the fabrication of black products and led to an enhancement in printing fidelity. This research introduces a novel processing technique for NIR 3D printing and promotes advancements in the 3D printing field, with significant practical applications.