Tough thiourethane thermoplastics for fused filament fabrication

Ellson, Gregory; Carrier, Xavier; Walton, J. G.; Mahmood, Samsuddin F.; Yang, Kejia; Voit, Walter

doi:10.1002/app.45574

Cited by 15 publications

(8 citation statements)

References 17 publications

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“…Recently, Endo et al used the thiol–isothiocyanate reaction to synthesize aliphatic polydithiourethanes, which have an ability to be reprocessed because of the reversible C–S bond of the dithiocarbamate moiety. Nevertheless, the activation temperature of dithiourethane is 150 °C, which is higher than that of the reversible reaction of the urethane bond. , Besides, the thiol–isocyanate reaction has also been reported to produce polythiourethanes with good mechanical performance. , Indeed, it attracts our attention because the resulting polythiourethane has a structure very similar to that of polyurethane. We expect to develop a dynamic polyurethane network without significantly sacrificing the mechanical properties by incorporating this reversible interaction.…”

Section: Introductionmentioning

confidence: 99%

Adaptable Strategy to Fabricate Self-Healable and Reprocessable Poly(thiourethane-urethane) Elastomers via Reversible Thiol–Isocyanate Click Chemistry

Fan

Wen

et al. 2020

Macromolecules

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Currently, a variety of elastomers with a self-healing capacity and reprocessability have been developed by dynamic chemistry to extend the service life, increase the reliability of polymeric materials, and reduce the waste. However, it is still a large challenge to seek an appropriate dynamic interaction that may perfectly match the general performance of the target polymeric materials such as polyurethane. Herein, we report a poly-(thiourethane-urethane) (PTUU−N x ) elastomer containing dynamic thiourethane bonds prepared via a thiol−isocyanate click reaction, which is stable at room temperature, healable at moderate temperature, and reprocessable at high temperature. Importantly, it exhibits a mechanical strength similar to the polyurethane because of a very similar structure. The dynamic feature of PTUU−N x is demonstrated theoretically and experimentally to originate from the exchange of thiourethane bonds via the reversible generation of isocyanates and thiols. Most importantly, the thiourethane bond possesses a much lower bond dissociation energy than the urethane bond, which not only makes PTUU−N x elastomers easier to be reprocessed but also endows them with a desirable self-healing ability under moderate conditions. In addition, the optimized sample PTUU−N 2 is utilized to fabricate a conductive device by coating Ag glue on the elastomer surface and inserting the coated elastomer into a circuit, which displays a high self-healing efficiency, as the material recovers to its original mechanical property and conductivity. Therefore, these results not only indicate that the PTUU−N x elastomers have considerable potential for applications in intelligent electronic devices but also provide new ideas for developing new self-healing materials by applying the adaptable dynamic bond to the target polymers.

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Section: Introductionmentioning

confidence: 99%

Adaptable Strategy to Fabricate Self-Healable and Reprocessable Poly(thiourethane-urethane) Elastomers via Reversible Thiol–Isocyanate Click Chemistry

Fan

Wen

et al. 2020

Macromolecules

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“…Polymers with divalent counterions provided beneficial melt rheological profiles for FDM due to stronger ionic interactions compared to monovalent counterparts. Printing of these polymers generated an array of complex geometries for controlled release applications. , Recently, Ellson et al reported the synthesis of thiourethane thermoplastics for FDM through step-growth polymerization of 2,20-(ethylenedioxy)diethanethiol (EDDT) and hexamethylene diisocyanate (HDI) . The presence of thermally reversible hydrogen bonds facilitated processing at high temperatures and contributed to excellent mechanical toughness (up to 92 MJ/m 3 ) in molded or printed parts.…”

Section: Introductionmentioning

confidence: 99%

Quadruple Hydrogen Bonding Supramolecular Elastomers for Melt Extrusion Additive Manufacturing

Chen

Zawaski

Spiering

et al. 2020

ACS Appl. Mater. Interfaces

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This manuscript describes the versatility of highly directional, noncovalent interactions, i.e., quadruple hydrogen bonding (QHB), to afford novel polyurea segmented supramolecular polymers for melt extrusion three-dimensional (3D) printing processes. The molecular design of the polyurea elastomers features (1) flexible polyether segments and relatively weak urea hydrogen-bonding sites in the soft segments to provide elasticity and toughness, and (2) strong ureido-cytosine (UCyt) QHB in the hard segments to impart enhanced mechanical integrity. The resulting polyureas were readily compression-molded into mechanically-robust, transparent, and creasable films. Optimization of polyurea composition offered a rare combination of high tensile strength (95 MPa), tensile elongation (788% strain), and toughness (94 MJ/m3), which are superior to a commercially available Ninjaflex elastomer. The incorporation of QHB facilitated melt processability, where hydrogen bonding dissociation provided low viscosities at printing temperatures. During cooling, directional self-assembly of UCyt QHB facilitated the solidification process and contributed to part fidelity with the formation of a robust physical network. The printed objects displayed high layer fidelity, smooth surfaces, minimal warpage, and complex geometries. The presence of highly directional QHB effectively diminished mechanical anisotropy, and the printed samples exhibited comparable Young’s moduli along (x–y direction, 0°) and perpendicular to (z-direction, 90°) the layer direction. Remarkably, the printed samples exhibited ultimate tensile strains approaching 500% in the z-direction prior to failure, which was indicative of improved interlayer adhesion. Thus, this design paradigm, which is demonstrated for novel polyurea copolymers, suggests the potential of supramolecular polymers with enhanced mechanical performance, melt processability, recyclability, and improved interlayer adhesion for melt extrusion additive manufacturing processes.

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“…The respective load‐elongation curves of different fiber samples are shown in Figure . All samples display loading‐strain tensile curves with three stages typical for semicrystalline polymers: At the first stage, the force increases linearly with elongation until it reaches a yield point. Necking (stress‐induced, abrupt decrease in filament cross‐sectional area) appears at the subsequent stage, where the force remains almost constant.…”

Section: Resultsmentioning

confidence: 99%

Flexible phase change filament with ionic liquid core

Lin

Yan

Liu

et al. 2019

J of Applied Polymer Sci

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A flexible phase change filament with core‑sheath structure was successfully prepared by post‐filling of a polypropylene (PP) hollow fiber. The ionic liquid (IL) 1‐butyl‐4‐methylpyridinium hexafluorophosphate was chosen as core component, while copper decorated muscovite (Cu‐MVT) was synthesized via in situ reduction and used as the refining additive for the IL. Results from differential scanning calorimetry demonstrated that the encapsulation ratio of the flexible phase change filament reached 93% with a fusion latent heat of 52.7 J/g at 48.3 °C. Supercooling of the ionic liquid was suppressed effectively as shown by the crystallization in the cooling step due to the addition of Cu‐MVT. The flexible phase change material with core‑sheath structure also showed good thermal stability, durability, and mechanical property under the protection of the sheath polymer material. It is evident that the phase change filament possesses promising characteristics for thermal energy storage and thermoregulation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47830.

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Tough thiourethane thermoplastics for fused filament fabrication

Cited by 15 publications

References 17 publications

Adaptable Strategy to Fabricate Self-Healable and Reprocessable Poly(thiourethane-urethane) Elastomers via Reversible Thiol–Isocyanate Click Chemistry

Adaptable Strategy to Fabricate Self-Healable and Reprocessable Poly(thiourethane-urethane) Elastomers via Reversible Thiol–Isocyanate Click Chemistry

Quadruple Hydrogen Bonding Supramolecular Elastomers for Melt Extrusion Additive Manufacturing

Flexible phase change filament with ionic liquid core

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