Low-Temperature Fabrication of Transparent Silica Structures via 3D Printing: A Sustainable Approach for Energy-Efficient Additive Manufacturing

High Resolution Image Download MS PowerPoint Slide The fabrication of transparent silica glass structures via 3D printing is severely constrained by the need for energy-intensive high-temperature sintering (often exceeding 1000 °C) to eliminate voids and achieve material densification. This energy demand directly contributes to CO 2 emissions and limits the application of silica glass in energy and environmental technologies requiring composite functionalization. We report a low-temperature vitrification strategy that successfully addresses this issue, demonstrating a significant contribution to sustainable additive manufacturing. Our approach utilizes ultrasmall, single-nanometer silica nanoparticles (SNPs) (2–5 nm) surface-functionalized with vinyl groups, which minimize chemical and density fluctuation, suppressing light scattering without thermal densification. The photocurable resin employs these functionalized nanoparticles and a multifunctional thiol to establish a dense 3D network via the highly selective thiol–ene reaction at room temperature. A crucial intermediate carbonization step was implemented to effectively suppress the drastic volume change associated with organic decomposition, enabling subsequent siloxane linking and mechanical strengthening. As a result, we successfully fabricated crack-free silica structures with high transparency (>90% transmission) at a remarkably low maximum heat treatment temperature of only 400 °C. This process eliminates the need for silica melting above 1000 °C, achieving a substantial reduction in energy consumption compared to conventional methods. This low-temperature technique, which eliminates the need for conventional high-temperature sintering, significantly advances sustainable material fabrication for energy and environmental applications, facilitating both the direct incorporation of temperature-sensitive functional elements and the fabrication of high-quality silica-based optical elements.