3D PrintingIn article number 2311917 by Hyun‐Jong Paik, Wonjoo Lee, Min Sang Kwon, Dowon Ahn, and co‐workers, panchromatic photopolymer resins, selectively reacting to two colors of lights, are ...developed and applied to realize photoactive 3D printing. Longer‐wavelength of light (red light, ≈620 nm) irradiation initiates rapid photopolymerization and 3D printing, resulting in remarkable build speed and feature resolution. Incorporating violet/blue‐light‐sensitive moieties (≈405–450 nm), such as hexaarylbiimidazoles, enable independent spatiotemporal degradation/erasing.
Photo‐curing 3D printing technology has promoted the advanced manufacturing in various fields, but has exacerbated the environmental crisis by the demand for the chemically cross‐linked thermosetting ...photopolymers. Here, the authors report a generic strategy to develop catalyst‐free dynamic thermosetting photopolymers, based on photopolymerization and transesterification, that can enable users to realize repeatable 3D printing, providing a practical solution to the environmental challenges. That the β‐carbonyl group adjacent to the ester group greatly accelerates the rate of transesterification is demonstrated. The generated resins from the immobilization of the catalyst‐free reversible bonds into the photopolymers leads to a dynamic covalently crosslinked network structure upon UV based 3D printing, which exhibit controllable mechanical properties with elastomeric behaviors to thermadapt shape memory polymers. Furthermore, the resulting network can be reverted into an acrylate‐functioned photopolymer that is suitable for 3D printing again, presenting an on‐demand, repeatedly recyclable thermosetting photopolymer platform for sustainable 3D printing.
Catalyst‐free dynamic thermosetting photopolymers are developed by immobilized the catalyst‐free reversible bonds into the photopolymers, that can enable users to realize repeatable 3D printing. The generated resins demonstrate controllable mechanical properties with elastomeric behaviors to thermadapt shape memory polymers. Furthermore, the resulting network presents an on‐demand, repeatedly recyclable thermosetting photopolymer platform for sustainable 3D printing.
Chemische Verstärkung ist ein etabliertes Konzept in der Photolack‐Technologie, bei dem ein photochemisches Ereignis zu einer Kaskade von Folgereaktionen führt, die eine kontrollierte Veränderung der ...Löslichkeit eines Polymers ermöglichen. Wir übertragen dieses Konzept auf dynamische Polymernetzwerke, um durch UV‐Bestrahlung sowohl Katalysatoren als auch funktionelle Gruppen freizusetzen, die für Bindungsaustauschreaktionen erforderlich sind. In diesem Zusammenhang wird eine photochemisch erzeugte Säure zur Katalyse der Entschützungsreaktion der säurelabilen tert‐Butoxycarbonylgruppe verwendet, die zur Maskierung der Hydroxygruppen (−OH) eines Vinylmonomers eingesetzt wird. Zusätzlich dient die freigesetzte Säure auch als Katalysator für thermoaktivierte Umesterungen zwischen den entschützten Hydroxyl‐ und Estereinheiten. Eingeführt in ein orthogonal gehärtetes (450 nm) Thiol‐Klick‐Photopolymer, ermöglicht dieser Ansatz eine räumlich‐zeitlich kontrollierte Aktivierung von Bindungsaustauschreaktionen, was angesichts des Kompromisses zwischen Kriechbeständigkeit und Fließfähigkeit dynamischer Polymernetzwerke von entscheidender Bedeutung ist.
In tomographic volumetric additive manufacturing, an entire three-dimensional object is simultaneously solidified by irradiating a liquid photopolymer volume from multiple angles with dynamic light ...patterns. Though tomographic additive manufacturing has the potential to produce complex parts with a higher throughput and a wider range of printable materials than layer-by-layer additive manufacturing, its resolution currently remains limited to 300 µm. Here, we show that a low-étendue illumination system enables the production of high-resolution features. We further demonstrate an integrated feedback system to accurately control the photopolymerization kinetics over the entire build volume and improve the geometric fidelity of the object solidification. Hard and soft centimeter-scale parts are produced in less than 30 seconds with 80 µm positive and 500 µm negative features, thus demonstrating that tomographic additive manufacturing is potentially suitable for the ultrafast fabrication of advanced and functional constructs.
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•Design, modeling, realization, and testing of material jetting (MJ) lattices (single- and multi-material) are quantitatively discussed.•The achieved mechanical performances of the ...main studied MJ lattices are highlighted in Ashby plots.•Printing effects, cost analysis, and fabrication limitations of MJ lattices are thoroughly discussed.•Challenges, potential applications, and envisaged future studies are indicated.•The main fabrication aspects related to the MJ process are analyzed.
High-precision 3D printing technology opens to almost endless opportunities to design complex shapes present in tailored architected materials. The scope of this work is to review the latest studies regarding 3D printed lattice structures that involve the use of photopolymers fabricated by Material Jetting (MJ), with a focus on the widely used Polyjet and MultiJet techniques. The main aspects governing this printing process are introduced to determine their influence during the fabrication of 3D printed lattices. Performed experimental studies, considered assumptions, and constitutive models for the respective numerical simulations are analyzed. Furthermore, an overview of the latest extensively studied 3D printed architected lattice materials is exposed by emphasizing their achieved mechanical performances through the use of Ashby plots. Then, we highlight the advantages, limitations, and challenges of the material jetting technology to manufacture tunable architected materials for innovative devices, oriented to several engineering applications. Finally, possible approaches for future works and gaps to be covered by further research are indicated, including cost and environmental-related issues.
Among all three-dimensional (3D) printing materials, thermosetting photopolymers claim almost half of the market, and have been widely used in various fields owing to their superior mechanical ...stability at high temperatures, excellent chemical resistance as well as good compatibility with high-resolution 3D printing technologies. However, once these thermosetting photopolymers form 3D parts through photopolymerization, the covalent networks are permanent and cannot be reprocessed, i.e., reshaped, repaired, or recycled. Here, we report a two-step polymerization strategy to develop 3D printing reprocessable thermosets (3DPRTs) that allow users to reform a printed 3D structure into a new arbitrary shape, repair a broken part by simply 3D printing new material on the damaged site, and recycle unwanted printed parts so the material can be reused for other applications. These 3DPRTs provide a practical solution to address environmental challenges associated with the rapid increase in consumption of 3D printing materials.
Mechanically robust shape‐morphing materials that can transform from miniaturization into complex structures are highly desirable for real‐world device applications. However, fabricating mechanically ...robust yet geometrically complex 3D shape‐morphing structures with excellent functionality and high load‐bearing capacity remains a challenge. Inspired by drum tower buildings, a simple, rapid, and universal method is presented for fabricating multifunctional shape‐memory smart devices with complex and rigid 3D kirigami geometry in the two‐stage epoxy‐amine‐acrylate photopolymer systems. In the first‐stage reaction, transparent polymer films with a Tg of 29–49 °C are obtained by the epoxy‐amine chemistry. The shape‐memory programming process allows the first‐stage film with a drum tower‐inspired 2D kirigami pattern to be manipulated into an unsupported 3D structure. In the second‐stage reaction, UV‐induced free‐radical polymerization of methacrylate groups in the first‐stage network is employed to rapidly lock the programmed 3D kirigami structure with a Tg of 66–138 °C. The drum tower‐inspired 3D kirigami structure withstands 1000 times its own weight. The shape memory fluorescent 3D device and shape memory electronic 3D device are engineered by combining the two‐stage photopolymer system and a 3D kirigami structure. This work represents a versatile method to create multifunctional shape‐memory devices with rigid 3D geometry for potential applications.
A mechanically robust yet geometrically complex 3D shape‐morphing structure with excellent shape memory effect and high load‐bearing capacity is successfully constructed by combining drum tower‐inspired kirigami structures and two‐stage epoxy‐amine‐acrylate photopolymer systems. This work presents a simple, rapid, and universal method to create multifunctional shape‐memory devices with rigid 3D geometry for potential applications.
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