Tough PEG‐only hydrogels with complex 3D structure enabled by digital light processing of “all‐PEG” resins

Abstract Digital light processing (DLP) of structurally complex poly(ethylene glycol) (PEG) hydrogels with high mechanical toughness represents a long‐standing challenge in the field of 3D printing. Here, we report a 3D printing approach for the high‐resolution manufacturing of structurally complex and mechanically strong PEG hydrogels via heat‐assisted DLP. Instead of using aqueous solutions of photo‐crosslinkable monomers, PEG macromonomer melts were first printed in the absence of water, resulting in bulk PEG networks. Then, post‐printing swelling of the printed networks was achieved in water, producing high‐fidelity 3D hydrogels with complex structures. By employing a dual‐macromonomer resin containing a PEG‐based four‐arm macrophotoinitiator, “all‐PEG” hydrogel constructs were produced with compressive toughness up to 1.3 MJ m −3 . By this approach, porous 3D hydrogel scaffolds with trabecular‐like architecture were fabricated, and the scaffold surface supported cell attachment and the formation of a monolayer mimicking bone‐lining cells. This study highlights the promises of heat‐assisted DLP of PEG photopolymers for hydrogel fabrication, which may accelerate the development of 3D tissue‐like constructs for regenerative medicine.