Glassomer (Germany)

ABSTRACT Hydroxyapatite is widely used in tissue engineering due to its similarity to the mineral in bone. Microstructured hydroxyapatite scaffolds are of interest as they provide mechanical support for cells and guide cell behavior through structural cues. However, current structuring methods are limited to either large structures that lack the smallest features of bone or to nanoscale structuring that is not scalable to larger constructs. In this work, we bridge this gap by using two‐photon lithography of a transparent nanocomposite to fabricate dense and mechanically stable hydroxyapatite microscaffolds. Structures ranging from one centimeter in length to structuring submicron features are achieved, enabling multiscale structuring. Mesenchymal stromal/stem cells that are seeded on hydroxyapatite show high viability, and an examination of cell morphology and osteogenic differentiation demonstrates the impact of high‐resolution scaffolds for cell culture over commercial low‐resolution counterparts. This approach enables efficient fabrication of multiscale hydroxyapatite scaffolds, with great potential for bone tissue engineering.

High-Precision 3D Doping of Fused Silica Glass In their Research Article (DOI: 10.1002/adma.202511245), Frederik Kotz-Helmer and co-workers demonstrate a novel strategy to locally tailor the properties of silica glass by incorporating photocurable dopants during fabrication via high resolution 3D printing. This approach enables precise, micron-scale control over color, luminescence and refractive index in all three-dimensions.

Fabricating microstructures on curved surfaces is of great importance in several engineering fields, and it is an ongoing challenge to develop technologies that do not require complicated devices and cumbersome procedures. A novel approach is presented for fabricating microstructures with different topographies on curved surfaces using flexible microstructured hydrogels as molds. The hydrogel film is first microstructured via spatially controlled ultraviolet illumination utilizing its photo-responsive property. The microstructured hydrogel film is then transferred to a desired surface. Due to its low modulus, the hydrogel film can be adapted to the curved surfaces including semi-cylindrical and semi-spherical surfaces as well as freeform surfaces with both convex and concave features. The final freeform surfaces with microstructures are obtained by polydimethylsiloxane (PDMS) casting. The resulting microstructures show high uniformity and high surface smoothness with an average roughness (Ra) ≈2.7 nm and a root mean square roughness (Rq) ≈4.1 nm. The ability to fabricate microstructures on large-area curved surfaces of ≈4.5cm by 6.5cm is demonstrated. Finally, it is shown that the fabricated microstructures allow good imaging performance. This method utilizes the hydrogel's photo-responsive ability to construct flexible molds and flexibility to adapt to freeform surfaces, thereby allowing significantly simplified fabrication processes.

Transparent polycrystalline magnesium aluminate (MAS) spinel ceramics are of great interest for industry and academia due to their excellent optical and mechanical properties. However, shaping of MAS is notoriously challenging especially on the microscale requiring hazardous etching methods. Therefore, a photochemically curable nanocomposite is demonstrated that can be structured using high-resolution two-photon lithography. The printed nanocomposites are converted intro transparent MAS by subsequent debinding, sintering, and hot isostatic pressing. The resulting transparent spinel ceramics exhibit a surface roughness Sq of only 10nm and can be shaped with minimum feature sizes of down to 13µm. This technology will be important for the production of microstructured ceramics used for optics, photonics, or photocatalysis.

Polymers are still gaining a lot of interest in the field of optics and sensor technology. Structuring of these components is usually done using high-throughput manufacturing processes such as injection molding, allowing excellent shaping quality and high degree of automation. However, tool production for these tool-based manufacturing methods tends to be time consuming and expensive, limiting the flexibility of these processes. We developed a novel process enabling the fabrication of metallic insets with optical surfaces and structures at the micrometer scale. This involves utilizing high-temperature-stable fused silica glass bodies as molds for metal casting. The process enables the processing of metal alloys such as bronze, brass, and cobalt-chromium at temperatures reaching up to 1400 °C. The metal replications achieve resolutions in the single-digit micrometer range and exhibit a surface roughness in the order of a few nanometers. The manufactured mold tools were successfully tested in a polymer injection molding process.

Due to high optical transparency combined with high thermal and chemical stability transparent fused silica glass is of high interest for many applications in microsystems engineering, especially in the field of microfluidics and micro optics. However, structuring of fused silica is inherently difficult and usually includes high temperatures, complicated and toxic etching processes or time consuming grinding protocols with severe limitation to freedom of design and manufacturing speed. Thus, complex structured fused silica glass has been limited especially on the industrial scale. We developed highly filled, thermoplastic fused silica nanocomposites (so-called Glassomers), that can be processed using commonly available high-throughput polymer manufacturing technologies such as injection molding or continuous extrusion. After the shaping process the thermoplastic Glassomer is converted to pure, transparent glass by subsequent debinding and sintering yielding high-quality fused silica glass with high optical transparency (transmission >90 %) and optical surface quality (R_q < 5 nm). We show injection molding of high-resolution microstructures as well as complex shaped macroscopic components that are subsequently converted to pure fused silica glass enabling for the first time mass-market manufacturing of fused silica glass components, enabling a plethora of applications in micro optics and lab-on-a-chip devices.

Glass is one of the most relevant high-performance materials that has the benefit of a favorable environmental footprint compared with that of other commodity materials. Despite the advantageous properties of glasses, polymers are often favored because they can be processed using scalable industrial replication techniques like injection molding (IM). Glasses are generally processed through melting, which is both energy intensive and technologically challenging. We present a process for glassworks using high-throughput IM of an amorphous silicon dioxide nanocomposite that combines established process technologies and low-energy sintering. We produce highly transparent glass using classical IM and sintering, allowing for a potentially substantial reduction in energy consumption. Our strategy merges polymer and glass processing, with substantial implications for glass utilization.

Haftklebstoffe Einführung Chemie der Haftklebstoffe Physikalische Eigenschaften der Haftklebstoffe Zeitabhängiges Verhalten von Haftklebstoffen Klebrigkeit (Tack) Schälwiderstand Kriechverhalten (Creep) Kontaktklebstoffe Zusammensetzung der Kontaktklebstoffe Verhalten und Anwendungen der Kontaktklebstoffe Schmelzklebstoffe Thermoplastische Schmelzklebstoffe Heißsiegel-Klebstoffe Plastisole Schmelzkleblacke Reaktive Schmelzklebstoffe auf Polyurethanbasis Reaktive Epoxidharz-Schmelzklebstoffe Trends in der Schmelzklebstoff-Technik Phenolharz-Klebstoffe Chemie der Phenolharz-Klebstoffe Verhalten und Anwendungen der Phenolharz-Klebstoffe Epoxidharz-Klebstoffe Chemie der Epoxidharze Reaktionen von Epoxidharzen Eigenschaften von Epoxidharz-Klebstoffen Polyurethanklebstoffe Chemie der Polyurethane Verwendete Rohstoffe Struktur und Eigenschaften der Polyurethanklebstoffe Füllstoffe und Additive bei Polyurethanklebstoffen Acrylatklebstoffe Physikalisch härtende Acrylate Chemisch härtende Acrylate Silicone Einkomponenten-Systeme Zweikomponenten-Systeme Kondensationsvernetzung Additionsvernetzung Klebstoffe auf Naturstoffbasis Einführung Klebrohstoffe aus der Natur Moderne Klebstoffe auf Naturstoffbasis Zukünftige Entwicklungen Aufbau der Primer und Haftvermittler Primer Haftvermittler Füllstoffe