Sustainable 3D Printing of Transparent SiO₂ Glass Components by a Photocurable Aqueous Suspension Design

Three-dimensional (3D) printing of transparent SiO2 glass components with on-demand geometries has progressed in recent years. However, most printing systems are unsustainable as they require large amounts of organic solvents and long heat treatments. Here, we propose a new concept of aqueous suspension that can be photocured by the superimposition of a polymer layer grown on the particle surface using limited amounts of monomers. In brief, SiO2 particles were dispersed in aqueous media with an aid of reactive polyethylenimine. Then, a small amount of water-soluble 4-hydroxybutyl acrylate and photoradical initiator were mixed. UV irradiation to the designed suspension resulted in the formation of polymerized acrylate shell layer on SiO2 particles and interparticle cross-linking by superimposition of the generated polymer shell. We demonstrated that the designed suspension can be employed for vat photopolymerization to print 3D structures. Additionally, water-containing printed bodies were further deformable by external forces to generate complex shapes. Owing to the reduced amounts of monomers used in this system, the photocured bodies were debindable and sintered into transparent glass through rapid heating profiles without occurring any cracks. We believe our proposed process provides a new opportunity for sustainable manufacturing of 3D structured glass materials.