Tough, stable spiroacetal thiol‐ene resin for 3D printing

Sycks, Dalton G.; Wu, Tiffany; Park, Hyun-Sang; Gall, Ken

doi:10.1002/app.46259

Cited by 42 publications

(32 citation statements)

References 46 publications

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“…[ 5–9 ] Introducing alternative crosslinking chemistries to the VAM realm, as well as AM more broadly, is highly desirable as an alternative method to gain access to a wider range of mechanical, thermal, and optical performance. [ 10–14 ] Thiol‐ene‐based polymers are one class of materials that have drawn significant attention owing to their controllable, tunable mechanical properties. [ 15–17 ] This is generally attributed to more uniform molecular networks in thiol‐ene materials, resulting from the step‐growth mechanism of the polymerization reaction.…”

Section: Figurementioning

confidence: 99%

Highly Tunable Thiol‐Ene Photoresins for Volumetric Additive Manufacturing

et al. 2020

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Volumetric additive manufacturing (VAM) is an emerging approach to photo polymerbased 3D printing that produces complex 3D structures in a single step, rather than from layer-by-layer assembly. [1] This paradigm holds promise because it overcomes many of the drawbacks of layerbased fabrication, such as long build times and rough surfaces. VAM also augurs a broadening of the materials available for photopolymer 3D printing, having fewer constraints on viscosity and reactivity compared to layerwise printing. Indeed, though VAM has been demonstrated with extremely soft hydrogels, [2,3] it has relied until now almost exclusively on acrylate-based chemistry. [4] This is natural, because the oxygen inhibition of acrylate polymerization provides the threshold behavior required for VAM. However, acrylate chemistry is in general limiting due to the brittle and glassy properties of the resulting materials. Accordingly, extensive efforts have been made to identify and target specific soft, elastic acrylate formulations. [5-9] Introducing alternative crosslinking chemistries to the VAM realm, as well as AM more broadly, is highly desirable as an alternative method to gain access to a wider range of mechanical, thermal, and optical performance. [10-14] Thiol-ene-based polymers are one class of materials that have drawn significant attention owing to their controllable, tunable mechanical properties. [15-17] This is generally attributed to more uniform molecular networks in thiol-ene materials, resulting from the step-growth mechanism of the polymerization reaction. [18,19] Thiol-ene materials have already shown promise for applications including use in adhesives, electronics, and as biomaterials. [20,21] This work expands the versatility of volumetric AM by introducing a new class of VAM-compatible thiol-ene resins. We demonstrate the formulation of thiol-ene resins with the nonlinear threshold-type kinetics required for VAM and show bulk-equivalent performance in the resulting 3D printed parts, confirming the advantage of the layerless whole-part process. In our volumetric AM system, a 3D distribution of light energy is delivered to the resin vat by superimposing exposures from multiple angles, a method termed computed axial litho graphy (CAL) (Figure 1a). [2] The exposures are a sequence of projections calculated from 3D CAD models using algorithms from computed Volumetric additive manufacturing (VAM) forms complete 3D objects in a single photocuring operation without layering defects, enabling 3D printed polymer parts with mechanical properties similar to their bulk material counterparts. This study presents the first report of VAM-printed thiol-ene resins. With well-ordered molecular networks, thiol-ene chemistry accesses polymer materials with a wide range of mechanical properties, moving VAM beyond the limitations of commonly used acrylate formulations. Since free-radical thiol-ene polymerization is not inhibited by oxygen, the nonlinear threshold response required in VAM is introduced by incorporating 2,2,6,6-tetrameth...

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Section: Figurementioning

confidence: 99%

Highly Tunable Thiol‐Ene Photoresins for Volumetric Additive Manufacturing

et al. 2020

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“…65,66 The flexible thioether linkages in these materials allow for a wide range of T g values [67][68][69][70][71][72][73] and can be exploited to fabricate materials with a broad range of mechanical properties. [74][75][76][77] For example, Childress et al used commercially available thiol and alkene monomers with DLP printing to fabricate crosslinked semicrystalline materials with Young's moduli between 40 and 90 MPa while having an elongation at break between 300% and 800%. 78 At the other end of the mechanical properties spectrum, Warner et al demonstrated the use of diallyl diurethane monomers with multifunctional thiols to synthesize materials with Young's moduli between 400 and 2500 MPa, all with elongation at break exceeding 80%.…”

Section: Materials Compatible With Vp Polymersmentioning

confidence: 99%

Three‐dimensional chemical reactors: in situ materials synthesis to advance vat photopolymerization

Yee

Greer

2021

Polymer International

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Vat photopolymerization (VP) is one of the most remarkable additive manufacturing techniques today and has been used for a variety of applications, from materials research to product manufacturing. The main challenge with VP is the limited choice of compatible materials, which motivates significant interest in VP materials development. We provide a brief overview of the materials that are currently accessible via VP and highlight recent advances in the field. We also provide perspective on expanding the library of materials compatible with VP using in situ materials synthesis.

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“…Photo-induced thiol-ene reactions exhibit the characteristics of both photopolymerization and click reactions, such as spatial and temporal control, high selectivity, insensitivity to oxygen or water, and high yield with no formation of by-products [36]. Due to the unique features of thiol-ene photopolymerization, such as low shrinkage stress and the yielding of homogeneous networks, this type of reaction is very promising for 3D-printing [37,38]. Therefore, thiol-ene resin has been applied to the fabrication of devices via 3D printing [39,40].…”

Section: Thiol-ene Photopolymerization (Tep) Of Methacrylate and Thiomentioning

confidence: 99%

Photochemical Study of a New Bimolecular Photoinitiating System for Vat Photopolymerization 3D Printing Techniques under Visible Light

et al. 2020

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In this work, we presented a new bimolecular photoinitiating system based on 2-amino-4,6-diphenylpyridine-3-carbonitrile derivatives as visible photosensitizers of diphenyliodonium salt. Real-time FTIR and photo-DSC photopolymerization experiments with a cycloaliphatic epoxide and vinyl monomers showed surprisingly good reactivity of the bimolecular photoinitiating systems under UV-A, as well as under visible light sources. Steady-state photolysis, fluorescence experiments, theoretical calculations of molecular orbitals, and electrochemical analysis demonstrated photo-redox behavior as well as the ability to form initiating species via photo-reduction or photo-oxidation pathways, respectively. Therefore, the 2-amino-4,6-diphenylpyridine-3-carbonitrile derivatives were also investigated as a type II free-radical photoinitiator with amine. It was confirmed that the 2-amino-4,6-diphenylpyridine-3-carbonitrile derivatives, in combination with different types of additives, e.g., amine as a co-initiator or the presence of onium salt, can act as bimolecular photoinitiating systems for cationic, free-radical, and thiol-ene photopolymerization processes by hydrogen abstraction and/or electron transfer reactions stimulated by either near-UV or visible light irradiation. Finally, the 2-amino-4,6-diphenylpyridine-3-carbonitrile derivatives were selected for 3D printing rapid prototyping experiments. Test objects were successfully printed using purely cationic photosensitive resin, created on a 3D printer with a visible LED light source.

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Tough, stable spiroacetal thiol‐ene resin for 3D printing

Cited by 42 publications

References 46 publications

Highly Tunable Thiol‐Ene Photoresins for Volumetric Additive Manufacturing

Highly Tunable Thiol‐Ene Photoresins for Volumetric Additive Manufacturing

Three‐dimensional chemical reactors: in situ materials synthesis to advance vat photopolymerization

Photochemical Study of a New Bimolecular Photoinitiating System for Vat Photopolymerization 3D Printing Techniques under Visible Light

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