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

Abstract

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 threedimensional structuring with short debinding and sintering times. SiO 2 particles modified with polyethyleneimine complexed with oleic acid (PEI-OA) are dispersed into a refractiveindex-tuned solvent, where a photo-radical initiator and a lower-than-typical amount of multifunctional acrylates (MAs) were dissolved. The SiO 2 suspension is cured by the photoradical polymerization of MA and the Michael additive reaction between polymerized MA and amino groups of PEI-OA on SiO 2 particles. These photo-curable suspensions can be employed in various shaping processes, from micro-scale stereolithography to centimeterscale silicone molding. The SiO 2 green compacts with complex structures are also debinded and sintered into transparent glass components by rapid heating.

Multifunctional 3D Printing of Heterogeneous Polymer Structures by Laser-Scanning Micro-Stereolithography Using Reversible Addition–Fragmentation Chain-Transfer Polymerization

“…First, we confirmed that it was possible to obtain a uniform material without using a sensitizer. We previously developed several types of stereolithography systems, for example, a bottom-up system based on single-photon polymerization using a blue laser, direct writing system using a blue laser and/or a femtosecond laser. , In this study, we used a 375 nm laser instead of a blue laser in a bottom-up stereolithography system (Figure ). In most of their reports on RAFT-based optical fabrication methods, Bagheri et al and Boyer et al used commercially available digital light processing (DLP)-type optical fabrication systems. ,− In contrast, we used a laboratory-constructed laser-scanning stereolithography (SLA) system.…”

Rapid Manufacturing of Complex-Structured Transparent Silica Glass Materials through a Hybridized Approach of Photo-Curing and Machining from Interparticle Photo-Cross-Linkable Suspensions

“…Finally, the photo-responsive suspensions were obtained by degassing the suspension via centrifugation (2200 rpm, 3 min) after removing the balls. Some SiO 2 suspensions were doped with metal ions (0.15 mol % Eu 2+ and Tb 3+ , based on the number of PEI monomer units, respectively) through their complex formation with the amino groups of PEI-OA, similarly to our previous report …”

“…First, the PEI-OA complex (15 mol % OA in PEI monomer units, calculated assuming all amines to be secondary amines) was prepared in a manner similar to that in our previous reports. − Briefly, 0.500 g of PEI and 0.493 g of OA corresponding to 15 mol % OA were mixed with α-terpineol to prepare a 10.0 g solution. The obtained solution was treated in an ultrasonic bath for 5 min and magnetically stirred for 24 h. The PEI-OA was then dissolved in a mixed solution of α-terpineol and THF (45 vol %), and the refractive index was tuned to match with SiO 2 .…”

“…Upon UV light irradiation of this suspension, MA polymerizes via an exothermic reaction, and the generated polymerization heat aids the Michael addition reaction between the polymerized MA and the free amine groups of PEI-OA on the SiO 2 fine particles. Using this mechanism, we designed transparent SiO 2 glass components through a photo-curing process, using stereolithography and silicone molding, followed by high-speed drying and debinding/sintering for the first time . Although the concept of interparticle photo-cross-linkable suspension can open a new window for rapid and energy-effective processing of transparent SiO 2 glass components, some difficulties still exist when applying this suspension to the hybridized shaping process ( i.e.…”

Additive manufacturing of strong silica sand structures enabled by polyethyleneimine binder

“…Binder jet additive manufacturing (BJAM) is well suited for manufacturing these tools and dies due to its high production rates, low operator burden, high resolution, and ability to process low-cost feedstocks, such as sand 6 . BJAM is an AM process that uses a layer-by-layer polymer binding process to rapidly manufacture complex three-dimensional tools and dies at significantly higher throughput when compared with directed-energy binding AM methods 6 , 7 . Selective inkjetting is used to deliver the binding polymer into the layers of powder to bind the powdered materials together (Fig.…”