Volumetric Additive Manufacturing of Composites Via Hydrogel Infusion

Volumetric additive manufacturing (VAM) is an emerging polymer additive manufacturing (AM) technique that offers significant advantages over traditional layer-by-layer AM methods. VAM boasts faster print speeds, improved surface finishes, and support-free fabrication of complex structures.<br/>However, one of the current limitations of VAM is that it is only compatible with photoresins that are highly transparent. As such, the use of particle-filled photoresins for the VAM of polymer composites is currently impossible due to extensive particle-induced light scattering and absorption.<br/>In this work, we demonstrate that the post-fabrication in-situ synthesis of nanoparticles can circumvent the transparency limitations in VAM and enable the fabrication of polymer composites. VAM-printed hydrogels are first infused with metals precursor solutions, followed by a precipitation step to form inorganic particles in-situ. By applying multiple post-processing steps, the hydrogel composite can be imbued with enhanced and/or multi-functional properties. We anticipate that our polymer composite fabrication approach can be extended to other AM methods that require high-transparency resins, and thus vastly expand the types of functional materials that can be made.