Degradable Polyphosphoramidate via Ring-Opening Metathesis Polymerization

Liang, Yifei; Sun, Hao; Cao, Wei; Thompson, Matthew P.; Gianneschi, Nathan C.

doi:10.1021/acsmacrolett.0c00401

Cited by 34 publications

(43 citation statements)

References 46 publications

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“…On the other hand, the development of sustainable polymer materials that can be recycled or disposed without putting a burden on earth is highly required, as the environmental impact of the polymer waste has become more and more serious. − For the global issue, a concept of “switching degradation” has attracted attention for the polymer design, because it could allow on-demand degradation after use while the material stability is ensured. Some researchers have recently reported on switching from “stable use” to “degradation” or “depolymerization” under some stimuli, − and the key is an introduction of the “trigger” into the polymer chain.…”

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confidence: 99%

Metal-Catalyzed Switching Degradation of Vinyl Polymers via Introduction of an “In-Chain” Carbon–Halogen Bond as the Trigger

et al. 2021

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In this work, we achieved switching degradation of vinyl polymers made of a carbon–carbon bonded backbone. Crucial in this strategy was a small feed of methyl α-chloroacrylate (MCA) as the comonomer in radical polymerization of methyl methacrylate (MMA) so that the carbon–halogen bonds were introduced as the triggers for degradation. The “in-chain” trigger was activated by a one-electron redox metal catalyst as the chemical stimulus to generate the carbon-centered radical species, and subsequently, the neighboring carbon–carbon bond was cleaved via an electron transfer of the radical species giving the terminal olefin. Particularly, an iron complex (FeCl2) in conjunction with tributylamine (n-Bu3N) was effective as the chemical stimulus to allow the switching degradation, where the molecular weight was gradually decreased over time. The switching feature was confirmed by some control experiments.

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confidence: 99%

Metal-Catalyzed Switching Degradation of Vinyl Polymers via Introduction of an “In-Chain” Carbon–Halogen Bond as the Trigger

et al. 2021

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“…(b) T g (°C) measured with varying DHF concentration (mol %) measured through DSC and DMA via the peak tan (δ). Measurements are compared to Flory–Fox equation calculated using the T g of p(DCPD) ( T g = 165 °C) and p(DHF) ( T g = −50.5 °C) . Error bars are represented as standard deviation ( n = 5) for DSC data and ( n = 3) for DMA data.…”

Section: Resultsmentioning

confidence: 99%

“…An attractive method of addressing sustainability in thermosets is to incorporate cleavable units into the strands of the polymeric network. , Shieh et al recently demonstrated the ring-opening metathesis polymerization (ROMP) of p(DCPD) thermosets having cleavable siloxane repeat units in the strands of the network. , Polymer backbone deconstruction was triggered with a fluoride reagent. Similar strategies have focused on generating thermoplastics utilizing cleavable cyclic olefin comonomers containing acetal, − disulfide, phosphoramidite, carbonate, and enol ether moieties. − Recent work from the Xia group demonstrated the synthesis of cleavable thermoplastics via the copolymerization of 2,3-dihyrdofuran (DHF) with a variety of norbornene derivatives. In addition to functioning as a cleavable unit, DHF suppressed the reactivity of Grubbs catalyst (GC) .…”

Section: Introductionmentioning

confidence: 99%

“…with a fluoride reagent. Similar strategies have focused on generating thermoplastics utilizing cleavable cyclic olefin comonomers containing acetal, 22−24 disulfide, 25 phosphoramidite, 26 carbonate, 27 and enol ether moieties. 28−31 Recent work from the Xia group demonstrated the synthesis of cleavable thermoplastics via the copolymerization of 2,3-dihyrdofuran (DHF) with a variety of norbornene derivatives.…”

Section: ■ Introductionmentioning

confidence: 99%

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Frontal Polymerization of Dihydrofuran Comonomer Facilitates Thermoset Deconstruction

et al. 2022

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Frontal ring-opening metathesis polymerization (FROMP) is a rapid, low-energy manufacturing reaction that is useful for curing thermosetting materials. FROMP of dicyclopentadiene (DCPD) results in poly(dicyclopentadiene) (p(DCPD)), a tough thermoset with excellent mechanical performance and chemical stability. Like most thermosets, p(DCPD) cannot be reprocessed and is therefore difficult to recycle. Previous work demonstrated that the incorporation of a small quantity of cleavable units in the strand segments of p(DCPD) networks enables their deconstruction. Here, we report that a commercially available multifunctional comonomer, 2,3-dihydrofuran (DHF), both acts as a potent Grubbs catalyst inhibitor during FROMP and introduces acid cleavable units. The resulting materials retain high performance characteristics, including glass-transition temperatures ranging from 115 to 165 °C and ultimate strength ranging from 35 to 40 MPa. The addition of DHF above critical loading levels enables deconstructable thermosets. We further demonstrate freeform three-dimensional (3D) printing of deconstructable thermosets via frontal polymerization.

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“…The addition of cleavable units is an attractive strategy for material deconstruction, 31,32 and recent reports of cyclic olefin monomers which install cleavable units into the polymer backbone via ring-opening metathesis polymerization (ROMP) are a promising new approach for component reclamation. [33][34][35][36][37][38][39][40][41][42][43] Moatsou and coworkers utilized seven-membered cyclic acetals as localized spacers in multiblock poly(norbornenes), 34 where hydrolysis of the acid-labile acetals enabled precise scission of the spacer and the release of poly(norbornene) blocks. Shieh and coworkers instead copolymerized norbornene derivatives with a cyclic eight-membered silyl ether to create cleavable linear, bottlebrush and star copolymers.…”

Section: Introductionmentioning

confidence: 99%

Efficient Manufacture, Deconstruction, and Upcycling of High-Performance Thermosets and Composites

Lloyd

Cooper

Shieh

et al. 2022

Preprint

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Thermoset polymers and fiber-reinforced polymer composites possess the chemical, physical, and mechanical properties necessary for energy-efficient vehicles and structures, but their energy-inefficient manufacturing and the lack of end-of-life strategies render these materials unsustainable. Here, we demonstrate end-of-life deconstruction and upcycling of high-performance poly(dicyclopentadiene) (pDCPD) thermosets with a concurrent reduction in the energy demand for curing via frontal copolymerization. Triggered material deconstruction is achieved through cleavage of cyclic silyl ethers and acetals incorporated into pDCPD thermosets. Both solution-state and bulk experiments reveal that seven- and eight-membered cyclic silyl ethers and eight-membered cyclic acetals incorporate efficiently with norbornene-derived monomers, permitting deconstruction at low comonomer loadings. Frontal copolymerization of DCPD with these tailored cleavable comonomers enables energy-efficient manufacturing of sustainable, high-performance thermosets with glass transition temperatures greater than 100 °C and elastic moduli greater than 1 GPa. The polymers are fully deconstructed, yielding hydroxyl-terminated oligomers that are upcycled to polyurethane-containing thermosets with higher glass transition temperatures (ca. 158 °C) than the original polymer upon reaction with diisocyanates. This approach is extended to frontally polymerized fiber-reinforced composites, where high fiber volume fraction composites (Vf = 65%) containing a cleavable comonomer are deconstructed and the reclaimed fibers are used to regenerate composites via frontal polymerization that display near identical properties compared to the original. This work demonstrates that the use of cleavable monomers, in combination with frontal manufacturing, provides a promising strategy to address sustainability challenges for high-performance materials at multiple stages of their lifecycle.

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Degradable Polyphosphoramidate via Ring-Opening Metathesis Polymerization

Cited by 34 publications

References 46 publications

Metal-Catalyzed Switching Degradation of Vinyl Polymers via Introduction of an “In-Chain” Carbon–Halogen Bond as the Trigger

Metal-Catalyzed Switching Degradation of Vinyl Polymers via Introduction of an “In-Chain” Carbon–Halogen Bond as the Trigger

Frontal Polymerization of Dihydrofuran Comonomer Facilitates Thermoset Deconstruction

Efficient Manufacture, Deconstruction, and Upcycling of High-Performance Thermosets and Composites

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