Balancing Self-Healing and Shape Stability in Dynamic Covalent Photoresins for Stereolithography 3D Printing

Dynamic covalent bonds impart new properties to 3D printable materials that help to establish 3D printing as an accessible and efficient manufacturing technique. Here, we studied the effect of a thermally reversible Diels-Alder cross-linker on the shape stability of photoprintable resins and their self-healing properties. Resins containing different concentrations of dynamic covalent cross-links in a polyacrylate network showed that the content of dynamic cross-links plays a key role in balancing shape stability with self-healing ability. The shape stability of the printed objects was evaluated by measuring the dimensional changes after thermal treatment. The self-healing efficiency of the 3D printed resins was characterized with a scratch test and tensile testing. A dynamic covalent cross-link concentration of 1.8 mol % was enough to provide 99% self-healing efficiency without disrupting the shape stability of the printed objects. Our work shows the potential of dynamic covalent bonds in broadening the availability of 3D printable materials that are compatible with vat photopolymerization.