DLP 3D-Printed High-Performance Polymers with Photothermal Dual-Curing Resin Containing Hydrogen Bonds and Reversible Covalent Bonds

Photocuring 3D printing faces challenges in achieving high mechanical strength and thermal stability primarily due to the low conversion degree of photopolymerization. This study presents a molecular design strategy to develop a high-performance, photothermal dual-curing resin for digital light processing (DLP) 3D printing. A polyurethane acrylate containing multiple hydrogen bonds and dynamic hindered urea bonds is synthesized and compounded with an acrylate-modified epoxy monomer, a reactive diluent, and a latent hindered urea curing agent to construct the hybrid system. During the photocuring stage, acrylate groups rapidly polymerize to form precise 3D structures. Subsequently, the latent agent dissociates upon heating and cures the epoxy groups, while the dynamic bonds on polyurethane acrylate dissociate to further increase cross-linking density. The synergy of hydrogen bonding, a rigid–flexible alternating microstructure, and high cross-linking density endows the cured material with superior overall performance. The optimized system achieves a tensile strength of 82.5 ± 3.6 MPa, an elongation at break of 9.5 ± 1.2%, and a glass transition temperature of 174.8 °C. Furthermore, it demonstrates excellent DLP printability for complex structures and outstanding shape memory performance. This work provides a promising pathway for fabricating high-performance structural components via vat photopolymerization 3D printing.