Solvent-Free Silsesquioxane Self-Welding for 3D Printing Multi-Refractive Index Glass Objects

The growing interest in 3D printing of silica glass has spurred substantial research efforts. The prior work utilizing a liquid silica resin (LSR) demonstrated high printing accuracy and resolution. However, the resin's sensitivity to moisture posed limitations, restricting the printing environment. On the other hand, polyhedral oligomeric silsesquioxane (POSS)-based materials offer excellent water stability and sinterless features. Yet, they suffer from relatively high shrinkage due to the presence of additional organic monomers. In this study, a polymeric silsesquioxane (PSQ) resin is presented with reduced shrinkage, enhanced moisture stability, and the retention of sinterless features, providing a promising solution for achieving high-resolution 3D printing of glass objects. Leveraging the two-photon polymerization (2PP) method, nanostructures are realized with feature sizes below 80 nm. Moreover, the tunability of the refractive index is demonstrated by incorporating zirconium moieties into the resin, facilitating the fabrication of glass micro-optics with varying refractive indices. Importantly, the self-welding capability observed between two individual components provides a flexible approach for producing micro-optics with multiple components, each possessing distinct refractive indices. This research represents a significant advancement in the field of advanced glass manufacturing, paving the way for future applications in micro- and nano-scale glass objects.