Photopolymerization in 3D Printing
20 Feb 2019-Vol. 1, Iss: 4, pp 593-611
TL;DR: The field of 3D printing is continuing its rapid development in both academic and industrial research environments as mentioned in this paper, which offers flexibility over the final properties of the 3D printed materials (such as optical, chemical and mechanical properties) using versatile polymer chemistry.
Abstract: The field of 3D printing is continuing its rapid development in both academic and industrial research environments. The development of 3D printing technologies has opened new implementations in rapid prototyping, tooling, dentistry, microfluidics, biomedical devices, tissue engineering, drug delivery, etc. Among different 3D printing techniques, photopolymerization-based process (such as stereolithography and digital light processing) offers flexibility over the final properties of the 3D printed materials (such as optical, chemical, and mechanical properties) using versatile polymer chemistry. The strategy behind the 3D photopolymerization is based on using monomers/oligomers in liquid state (in the presence of photoinitiators) that can be photopolymerized (via radical or cationic mechanism) upon exposure to light source of different wavelengths (depending on the photoinitiator system). An overview of recent evolutions in the field of photopolymerization-based 3D printing and highlights of novel 3D print...
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TL;DR: In this article, three photopolymerization technologies, namely, stereolithography (SLA), digital light processing (DLP), and continuous digital light process (CDLP), are reviewed.
Abstract: Additive manufacturing (3D printing) has significantly changed the prototyping process in terms of technology, construction, materials, and their multiphysical properties. Among the most popular 3D printing techniques is vat photopolymerization, in which ultraviolet (UV) light is deployed to form chains between molecules of liquid light-curable resin, crosslink them, and as a result, solidify the resin. In this manuscript, three photopolymerization technologies, namely, stereolithography (SLA), digital light processing (DLP), and continuous digital light processing (CDLP), are reviewed. Additionally, the after-cured mechanical properties of light-curable resin materials are listed, along with a number of case studies showing their applications in practice. The manuscript aims at providing an overview and future trend of the photopolymerization technology to inspire the readers to engage in further research in this field, especially regarding developing new materials and mathematical models for microrods and bionic structures.
191 citations
04 Jun 2020
TL;DR: This review paper summarizes a few typical applications of P μSL including mechanical metamaterials, optical components, 4D printing, bioinspired materials and biomedical applications, and offers perspectives on the directions of the further development of PμSL based 3D printing technology.
Abstract: Projection Micro Stereolithography (PμSL) is a high-resolution (up to 0.6 μm) 3D printing technology based on area projection triggered photopolymerization, and capable of fabricating complex 3D architectures covering multiple scales and with multiple materials. This paper reviews the recent development of the PμSL based 3D printing technologies, together with the related applications. It introduces the working principle, the commercialized products, and the recent multiscale, multimaterial printing capability of PμSL as well as some functional photopolymers that are suitable to PμSL. This review paper also summarizes a few typical applications of PμSL including mechanical metamaterials, optical components, 4D printing, bioinspired materials and biomedical applications, and offers perspectives on the directions of the further development of PμSL based 3D printing technology.
174 citations
Cites background from "Photopolymerization in 3D Printing"
...The photopolymerization is a free radical based polymerization, and includes four main steps: radical generation, initiation, propagation, and termination [62, 63]....
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TL;DR: In this work, crosslinking methods used in 3D bioprinting studies are reviewed, parameters that affect bioink chemistry are discussed, and the potential toward improving crossl linking outcomes and construct performance is highlighted.
Abstract: Three-dimensional (3D) bioprinting has recently advanced as an important tool to produce viable constructs that can be used for regenerative purposes or as tissue models. To develop biomimetic and sustainable 3D constructs, several important processing aspects need to be considered, among which crosslinking is most important for achieving desirable biomechanical stability of printed structures, which is reflected in subsequent behavior and use of these constructs. In this work, crosslinking methods used in 3D bioprinting studies are reviewed, parameters that affect bioink chemistry are discussed, and the potential toward improving crosslinking outcomes and construct performance is highlighted. Furthermore, current challenges and future prospects are discussed. Due to the direct connection between crosslinking methods and properties of 3D bioprinted structures, this Review can provide a basis for developing necessary modifications to the design and manufacturing process of advanced tissue-like constructs in future.
150 citations
TL;DR: Improved tissue adhesion of the bioinspired MN allows for more stable and robust performance for drug delivery, biofluid collection, and biosensing.
143 citations
TL;DR: An overview of the vat polymerization techniques, their unique applications in the fields of drug delivery and medical device fabrication, material examples and the advantages they provide within healthcare, is provided.
136 citations
References
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TL;DR: In this paper, the authors demonstrate that the addition of singlet oxygen quenchers such as 9,10-dimethylanthracene (DMA), ascorbic acid (AscA), and (R)-(+)-limonene (Lim) allows for oxygen tolerant PET-RAFT polymerization to be achieved in a range of other organic solvents and under low energy red light (λmax = 635 nm, 3.0 mW cm−2).
128 citations
TL;DR: A new strategy toward polymer-protein conjugates using a grafting-from method that employs photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization that should expand the capabilities of grafted-from proteins with RAFT polymerization under mild conditions to afford diverse functional materials.
Abstract: We report a new strategy toward polymer–protein conjugates using a grafting-from method that employs photoinduced electron/energy transfer–reversible addition–fragmentation chain transfer (PET–RAFT) polymerization. Initial screening of reaction conditions showed rapid polymerization of acrylamides under high dilution in water using eosin Y as a photocatalyst in the presence of a tertiary amine. A lysozyme-modified chain transfer agent allowed the same conditions to be utilized for grafting-from polymerizations, and we further demonstrated the broad scope of this technique by polymerizing acrylic and styrenic monomers. Finally, retention of the RAFT end group was suggested by successful chain extension with N-isopropylacrylamide from the polymer–protein conjugates to form block copolymer–protein conjugates. This strategy should expand the capabilities of grafting-from proteins with RAFT polymerization under mild conditions to afford diverse functional materials.
127 citations
TL;DR: This work demonstrates a proof-of-concept study of living additive manufacturing using end-linked polymer gels embedded with trithiocarbonate iniferters that can be activated by photoinduced single-electron transfer from an organic photoredox catalyst in solution.
Abstract: Light-initiated additive manufacturing techniques typically rely on layer-by-layer addition or continuous extraction of polymers formed via nonliving, free radical polymerization methods that render the final materials “dead” toward further monomer insertion; the polymer chains within the materials cannot be reactivated to induce chain extension. An alternative “living additive manufacturing” strategy would involve the use of photocontrolled living radical polymerization to spatiotemporally insert monomers into dormant “parent” materials to generate more complex and diversely functionalized “daughter” materials. Here, we demonstrate a proof-of-concept study of living additive manufacturing using end-linked polymer gels embedded with trithiocarbonate iniferters that can be activated by photoinduced single-electron transfer from an organic photoredox catalyst in solution. This system enables the synthesis of a wide range of chemically and mechanically differentiated daughter gels from a single type of paren...
123 citations
TL;DR: The approach proposed in this study can be used to examine interactions between many different cell types and shift the 3D fabrication paradigm to a next level, which is to fabricate tissues that are not only viable but also functional.
Abstract: A spatially organized three-dimensional (3D) co-culture of multiple cell types is required to recapitulate cellular interactions and microenvironments in complex tissues. Although there are limited reports for 3D patterning of cells and materials, approaches to examine functional interactions of 3D spatially patterned multiple cell types are lacking entirely. This is mostly due to difficulties in controlling the physical arrangement of cells in a 3D matrix and the physical properties of the cell-encapsulating matrix, while keeping the cells alive and functional for extended periods of time. In this study, an automated maskless fabrication technique is combined with a tunable polymer blend to spatially organize primary hippocampus neurons (HNs) and skeletal muscle myoblast cells (MCs) in a 3D hydrogel matrix with tunable mechanical and degradation properties. The spatial organization of these multiple cell types revealed that the presence of MCs resulted in increased cholinergic functionality of the HNs, as quantified by their choline acetyltransferase activity. The presence of a factor alone is not sufficient, but its spatiotemporal control is necessary; a condition that is possibly true for many cellular interactions. Therefore, the system described here offers a different approach to examine such previously unknown interactions. The approach proposed in this study can be used to examine interactions between many different cell types and shift the 3D fabrication paradigm to a next level, which is to fabricate tissues that are not only viable but also functional.
123 citations
TL;DR: In this article, the most recent light-induced modular reactions and their use in the formation of precision polymeric networks are collated, including photoinduced thiol-based reactions, Diels-Alder systems, and photogenerated reactive dipoles, as well as photodimerization.
Abstract: Polymeric networks have been intensely investigated and a large number of applications have been found in areas ranging from biomedicine to materials science. Network fabrication via light-induced reactions is a particularly powerful tool, since light provides ready access to temporal and spatial control, opening an array of synthetic access routes for structuring the network geometry as well as functionality. Herein, the most recent light-induced modular reactions and their use in the formation of precision polymeric networks are collated. The synthetic strategies including photoinduced thiol-based reactions, Diels–Alder systems, and photogenerated reactive dipoles, as well as photodimerizations, are discussed in detail. Importantly, applications of the fabricated networks via the aforementioned reactions are highlighted with selected examples. Concomitantly, we provide future directions for the field, emphasizing the most critically required advances.
117 citations