A Cleavable Crosslinking Strategy for Commodity Polymer Functionalization and Generation of Reprocessable Thermosets

Bi, Liting; Godwin, Benjamin; Baran, Miranda J.; Nazir, Rashid; Wulff, Jeremy E.

doi:10.1002/anie.202304708

Cited by 12 publications

(6 citation statements)

References 62 publications

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“… 21 Most importantly, 13 C NMR spectra confirmed the aryltrifluoromethyldiazirine moiety to be intact through the presence of a quartet at 28 ppm ( Figure S2 ). 22 The crosslinker was then subjected to thermochemical analysis through differential scanning calorimetry (DSC). 23 With a measured enthalpy of decomposition Δ H D of 338 J/g and a T onset of 88 °C, this compound was found unlikely to be explosive ( Figure S6 ).…”

Section: Resultsmentioning

confidence: 99%

Diazirine-Functionalized Polyurethane Crosslinkers for Isocyanate-Free Curing of Polyol-Based Coatings

de Zwart,

Wolzak,

J van den Berg

et al. 2024

ACS Appl. Polym. Mater.

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Polyurethane coatings have strong material properties due to the hydrogen bonding inherent to the urethane groups. However, installing this urethane moiety usually requires curing through difficult-to-handle isocyanates. In this work, we show the development of a polyurethane-based crosslinker that can be used to formulate a one-component polyurethane coating with material properties similar to those of isocyanate-based polyurethane coatings. To achieve this, we used diazirine functionalities that generate carbenes upon heating, which react with alcohol functionalities in a polyol to generate a crosslinked network with a high storage modulus.

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Section: Resultsmentioning

confidence: 99%

Diazirine-Functionalized Polyurethane Crosslinkers for Isocyanate-Free Curing of Polyol-Based Coatings

de Zwart,

Wolzak,

J van den Berg

et al. 2024

ACS Appl. Polym. Mater.

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“…Pioneering work by Wulff and Chen have demonstrated that small-molecule bis(diazirines), featuring two diazirine reactive units and either static or dynamic small molecules, can be used to cross-link polymeric mixtures (Figure B). − In addition, a single tetrasubstituted diazirine derivative has been reported to give higher cross-linking efficiency when compared to disubstituted derivatives, though the synthesis and scalability of the tetra(diazirine) presents challenges . This expanding family of diazirine cross-linkers has found application in a diverse range of fields, including plastic compatibilization, LED processing, , photopatterning, ,− and adhesives, − among others. − …”

Section: Introductionmentioning

confidence: 99%

Synthesis and Reactivity of Diazirine-Containing Polymers via Controlled Radical Polymerization

Huang,

Xu,

Hawker

2024

Macromolecules

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The synthesis and application of multifunctional diazirines as efficient precursors for the on-demand generation of carbenes is demonstrated. While small-molecule multifunctional diazirines have seen significant application in fields such as plastic compatibilization and photopatterning, the synthesis and polymerization of diazirine-based monomers is unexplored. This study focuses on the preparation of diazirine-containing polyacrylates and polymethacrylates through controlled radical polymerization. Both reversible addition–fragmentation chain-transfer (RAFT) polymerization and atom-transfer radical polymerization (ATRP) techniques are shown to be efficient for preparing polymers with targeted diazirine contents and degrees of polymerization. The resulting polymers represent a versatile cross-linking platform through reaction with ubiquitous C–H bonds. This stability and synthetic accessibility underscore the potential of diazirine-containing polymers for efficient cross-linking and functionalization strategies.

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“…The self-sustaining nature of FP processes like FROMP enables the rapid curing of thermoset polymers and composites, offering significant time savings compared to traditional curing methods [ 19 ]. Furthermore, the use of additives and co-monomers in FP can facilitate the deconstruction of thermosets, providing avenues for recyclability and reprocess ability [ 20 , 21 ]. Overall, the advancements in FP techniques hold great promise for the AM of thermoset polymers with tailored properties and improved production efficiency.…”

Section: Introductionmentioning

confidence: 99%

Degree of Cure, Microstructures, and Properties of Carbon/Epoxy Composites Processed via Frontal Polymerization

Shams,

Papon,

Shinde

et al. 2024

Polymers

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The frontal polymerization (FP) of carbon/epoxy (C/Ep) composites is investigated, considering FP as a viable route for the additive manufacturing (AM) of thermoset composites. Neat epoxy (Ep) resin-, short carbon fiber (SCF)-, and continuous carbon fiber (CCF)-reinforced composites are considered in this study. The evolution of the exothermic reaction temperature, polymerization frontal velocity, degree of cure, microstructures, effects of fiber concentration, fracture surface, and thermal and mechanical properties are investigated. The results show that exothermic reaction temperatures range between 110 °C and 153 °C, while the initial excitation temperatures range from 150 °C to 270 °C. It is observed that a higher fiber content increases cure time and decreases average frontal velocity, particularly in low SCF concentrations. This occurs because resin content, which predominantly drives the exothermic reaction, decreases with increased fiber content. The FP velocities of neat Ep resin- and SCF-reinforced composites are seen to be 0.58 and 0.50 mm/s, respectively. The maximum FP velocity (0.64 mm/s) is observed in CCF/Ep composites. The degree of cure (αc) is observed to be in the range of 70% to 85% in FP-processed composites. Such a range of αc is significantly low in comparison to traditional composites processed through a long cure cycle. The glass transition temperature (Tg) of neat epoxy resin is seen to be approximately 154 °C, and it reduces slightly to a lower value (149 °C) for SCF-reinforced composites. The microstructures show significantly high void contents (12%) and large internal cracks. These internal cracks are initiated due to high thermal residual stress developed during curing for non-uniform temperature distribution. The tensile properties of FP-cured samples are seen to be inferior in comparison to autoclave-processed neat epoxy. This occurs mostly due to the presence of large void contents, internal cracks, and a poor degree of cure. Finally, a highly efficient and controlled FP method is desirable to achieve a defect-free microstructure with improved mechanical and thermal properties.

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A Cleavable Crosslinking Strategy for Commodity Polymer Functionalization and Generation of Reprocessable Thermosets

Cited by 12 publications

References 62 publications

Diazirine-Functionalized Polyurethane Crosslinkers for Isocyanate-Free Curing of Polyol-Based Coatings

Diazirine-Functionalized Polyurethane Crosslinkers for Isocyanate-Free Curing of Polyol-Based Coatings

Synthesis and Reactivity of Diazirine-Containing Polymers via Controlled Radical Polymerization

Degree of Cure, Microstructures, and Properties of Carbon/Epoxy Composites Processed via Frontal Polymerization

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