Rapid three-dimensional structuring of transparent SiO2 glass using interparticle photo-cross-linkable suspensions

Photo-curable suspensions are important materials for shaping complex-structured ceramic and glass components. However, most systems undergo slow debinding and sintering so to avoid structural collapse by rapid gas generation from polymers. Here, we propose a new strategy to fabricate interparticle photo-cross-linkable suspensions for rapid three-dimensional structuring with short debinding and sintering times. SiO2 particles modified with polyethyleneimine complexed with oleic acid (PEI-OA) are dispersed into a refractive-index-tuned solvent, where a photo-radical initiator and a lower-than-typical amount of multifunctional acrylates (MAs) were dissolved. The SiO2 suspension is cured by the photo-radical polymerization of MA and the Michael additive reaction between polymerized MA and amino groups of PEI-OA on SiO2 particles. These photo-curable suspensions can be employed in various shaping processes, from micro-scale stereolithography to centimeter-scale silicone molding. The SiO2 green compacts with complex structures are also debinded and sintered into transparent glass components by rapid heating. Glasses and ceramics offer attractive properties for optical applications, but shaping them into components is challenging. Here, photo-cross-linkable suspensions enable the fabrication of structured, transparent SiO2 glass components quicker than for typical photo-curing processes.