Command-destruct thermosets <i>via</i> photoinduced thiol-catalyzed β-scission of acyclic benzylidene acetals

Walker, W. D.; Sandoz, Michaela J.; Roland, Samuel B.; Buster, Tony M.; Newman, Jennifer F.; Patton, Derek L.

doi:10.1039/d0py01006e

Cited by 8 publications

(13 citation statements)

References 26 publications

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“…b) Efficient cleavage of the thermoset via the co‐monomer approach (cleavage of ten bonds in the case of both cleavable knots or cleavage linkage in the polymer backbone) adapted from ref. [19]. c) Resin formulation, preparation of 3D objects via VAT 3D printing, and cleavage mechanism.…”

Section: Introductionmentioning

confidence: 99%

“…In the context of biomaterials, poly(propylene fumarate) (PPF) was also used to print stents, for example. [13] To increase the degradability, Bowman and Anseth [14][15][16][17] as well as Patton and coworkers [18,19] showed that the use of similar specific thiol-ene monomers containing a degradable core could be used. In this case, the use of thiol-ene chemistry allowed the preparation of more homogeneous networks that impart good degradation profile.…”

Section: Introductionmentioning

confidence: 99%

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Thionolactone as a Resin Additive to Prepare (Bio)degradable 3D Objects via VAT Photopolymerization**

et al. 2022

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Three‐dimensional (3D) printing and especially VAT photopolymerization leads to cross‐linked materials with high thermal, chemical, and mechanical stability. Nevertheless, these properties are incompatible with requirements of degradability and re/upcyclability. We show here that thionolactone and in particular dibenzo[c,e]‐oxepane‐5‐thione (DOT) can be used as an additive (2 wt %) to acrylate‐based resins to introduce weak bonds into the network via a radical ring‐opening polymerization process. The low amount of additive makes it possible to modify the printability of the resin only slightly, keep its resolution intact, and maintain the mechanical properties of the 3D object. The resin with additive was used in UV microfabrication and two‐photon stereolithography setups and commercial 3D printers. The fabricated objects were shown to degrade in basic solvent as well in a homemade compost. The rate of degradation is nonetheless dependent on the size of the object. This feature was used to prepare 3D objects with support structures that could be easily solubilized.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thionolactone as a Resin Additive to Prepare (Bio)degradable 3D Objects via VAT Photopolymerization**

et al. 2022

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“…Photoprocessable moieties that react only under high irradiation intensities, long irradiation times, and non-overlapping excitation wavelengths have been designed for being compatible with photopolymerization. [29][30][31][32][33][34][35][36] However, methods for designing such materials limit the available wavelengths for photoprocessing and exclude photoreactive moieties that react rapidly under weak light irradiation. Directly over- coming this problem would advance the design and utility of photocontrollable materials, including the photo-molding of photodegradable materials and the fabrication of photoadhesives that are detachable via photodegradation.…”

Section: Introductionmentioning

confidence: 99%

“…To overcome this issue, the photoprocessable moieties should remain intact during photopolymerization. Photoprocessable moieties that react only under high irradiation intensities, long irradiation times, and non‐overlapping excitation wavelengths have been designed for being compatible with photopolymerization [29–36] . However, methods for designing such materials limit the available wavelengths for photoprocessing and exclude photoreactive moieties that react rapidly under weak light irradiation.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Photoprocessable Materials via Photopolymerization Using an Acid‐Induced Photocleavable Platinum‐Acetylide Crosslinker

et al. 2023

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Photopolymerization and photoprocessing are core technologies for molding and tuning polymer materials. However, they are incompatible with single materials owing to their contradictory photoreactivity. Herein, an acid-induced photocleavable crosslinker, a platinum-acetylide complex covered by permethylated cyclodextrins, enables the fabrication of photoprocessable materials via photopolymerization with N-(2hydroxyethyl)acrylamide. The polymer networks are molded by 365 nm irradiation as well as softened and degraded by a cooperative reaction with HCl as an acidic additive under 365 nm UV light, or 470 nm visible light in the presence of a photosensitizer. Moreover, the crosslinker is applied to a photoadhesive triggered by 365 nm irradiation. The adhesion is detachable ondemand through acid-induced photodegradation with the same wavelength and intensity of irradiation. Thus, acid-induced photocleavage allows the integration of light-induced molding and processing under various lights of various wavelengths, opening up new strategies for polymer technologies.

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“…[26][27][28] Separation of the polymerization and degradation processes has been established by a number of means, including using different wavelengths to activate radical-mediated polymerization of one group followed by direct photoscission of another, [29,30] using different wavelengths to activate separate polymerization and scission stages within the same functional group, [24] or using competing reactions with vastly different kinetics. [31] These general polymerizationthen-degradation processes have been used to create 3D prints with sacrificial scaffolds, [32] microelectronics arrays with Scheme 1. On-demand polymerizing-then-degrading networks were created by combining the thiol-ene polymerization reaction with radical-mediated thioaminal scission.…”

Section: Introductionmentioning

confidence: 99%

Radical‐Mediated Scission of Thioaminals for On‐Demand Construction‐Then‐Destruction of Cross‐Linked Polymer Networks

Hernandez,

Sama,

et al. 2023

Adv Funct Materials

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Two‐stage polymerizing‐then‐degrading networks are achieved by exposure to a single near UV light source, by sequentially performing thiol–ene photopolymerization and radical‐mediated thioaminal scission. To understand the mechanisms involved, synthesis of model thioaminal small molecules shows photo‐activated thioaminal scission produces thioamide moieties, identifiable by distinct NMR singlets at 3.29 and 3.26 ppm and a Fourier Transform IR (FTIR) peak ≈1530 cm−1. The scission process is proposed to occur via ß‐scission of the carbon next to the sulfur atom and is found to be influenced by thiol substitution on the thioaminal, leading to scission conversion increasing from 5 ± 1 to 39 ± 3% and scission time decreasing from 6 to 2 min as the thiols become progressively more substituted. Thioaminal scission occurs semi‐orthogonally with radical‐mediated thiol–ene reactions; the thiol–ene reaction achieves near quantitative yield within the first 0.5 min while thioaminal scission requires a further 5–15 min. This semi‐orthogonality is exploited to create two‐stage polymerizing‐then‐degrading networks, with both regimes dependent on total light dose from a single light source and the transition occurring ≈2 J cm−2 under these exposure and polymerization conditions. This work establishes thioaminals as a new photo‐mediated scission chemistry and a means to create multi‐stage, light‐activated networks.

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Command-destruct thermosets via photoinduced thiol-catalyzed β-scission of acyclic benzylidene acetals

Abstract: Photoinduced thiol-catalyzed hydrogen abstraction and ß-scission of acyclic benzylidene acetals is demostrated as a new route to “command-destruct” polymer thermosets. Using this approach, we show that poly(thioether acetal) networks synthesized...

Cited by 8 publications

References 26 publications

Thionolactone as a Resin Additive to Prepare (Bio)degradable 3D Objects via VAT Photopolymerization**

Thionolactone as a Resin Additive to Prepare (Bio)degradable 3D Objects via VAT Photopolymerization**

Fabrication of Photoprocessable Materials via Photopolymerization Using an Acid‐Induced Photocleavable Platinum‐Acetylide Crosslinker

Radical‐Mediated Scission of Thioaminals for On‐Demand Construction‐Then‐Destruction of Cross‐Linked Polymer Networks

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