Stereolithography-based 3D printing of silica with solutions without organic binders

• Binder-free SLA 3D printing of silica without organic monomers. • Photo-induced inorganic sol-gel reaction used as an alternative to traditional radical photopolymerization. • Compatible with commercial DLP printers for centimeter-scale objects. • Porous silica with moderate transparency produced via 250 °C heat treatment. Herein, we present a novel, binder-free, stereolithography-based 3D printing approach for fabricating complex sol-gel silica glassy structures at the centimeter scale using only sol-gel chemistry. Unlike conventional methods that rely on organic photopolymerizable resins or hybrid monomers, our process eliminates the need for sacrificial organic binders and the associated high temperature debinding steps. The proposed method utilizes a photo-base generator to induce a localized pH change upon irradiation, triggering spatially controlled sol-gel polymerization. After printing and rinsing, the resulting gel structures are transformed into mesoporous silica through low-temperature heat treatment at 250 ℃. The printed silica objects exhibit moderate transparency, minimal shrinkage (∼25 %), and a well-defined mesoporous structure with pore sizes predominantly in the 4-8 nm range. Solid-state 29 Si NMR spectroscopy and energy-dispersive X-ray spectroscopy confirm enhanced silica condensation under vacuum, achieving a near-theoretical Si:O atomic ratio. This approach enables the scalable production of binder-free, high-resolution silica objects with potential applications in optics, biomedical engineering, and microfluidics.