Initiator-Free Recyclable Anthracene-Based Photocurable Resin Enabling Sustainable 3D Printing via Single- and Two-Photon Stereolithography

Single- and two-photon stereolithography are high-resolution three-dimensional (3D) printing techniques that are widely used to fabricate complex microstructures. However, the resulting structures have high cross-linking and density, which limits their recyclability. Existing approaches to addressing this issue typically rely on chain-growth polymerization, which requires photoinitiators and additional reagents for recycling. In this study, we present an anthracene-based photocurable resin that undergoes reversible photodimerization, enabling phase transitions between the solid and liquid states without photoinitiators or additives. Using this resin, we fabricated and recycled 3D microstructures via two-photon lithography, demonstrating over ten successful reprocessing cycles with minimal degradation. In addition, the resin is also compatible with single-photon microstereolithography, highlighting its versatility. These findings suggest a promising route for sustainable high-resolution additive manufacturing.