Polymerization of acetylene: polyynes, but not carbyne

Prenzel, Dominik; Kirschbaum, Rolf W.; Chalifoux, Wesley A.; McDonald, Robert; Ferguson, Michael J.; Drewello, Thomas; Tykwinski, Rik R.

doi:10.1039/c6qo00648e

Cited by 14 publications

(10 citation statements)

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“…The stability of NTWCs with respect to inter-carbyne-chain reactions is of special interest, since such reactions can make polyynes explosive. , Depending on the packing of diacetylene groups, triacetylene groups, or longer polyyne groups in neighboring carbyne chains, 1,4-addition, 1,6-addition, or higher-addition polymerization (Figure a and b) potentially occur . In fact, 1,4-addition polymerization commonly occurs for conjugated diynes, triynes, and tetraynes, and 1,6-addition polymerization has been observed for a specially engineered triyne crystal. , These polymerizations can occur rapidly, and the corresponding heat release can be sufficient to cause an explosion .…”

Section: Results and Discussionmentioning

confidence: 99%

“…However, because of sp 1 hybridization, carbyne has a much higher energy than graphitic carbons, and some materials containing carbyne chains even explode. 3,27,28 The high reactivity makes carbyne chains prefer to crosslink and degrade into more stable forms. 29−32 Hence, the existence of carbyne and bulk carbyne has long been questioned.…”

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confidence: 99%

“…Carbyne’s predicted modulus and strength are greater than any known material, including diamond, CNTs, and graphene, , and this encourages considering assemblies containing carbyne chains. However, because of sp 1 hybridization, carbyne has a much higher energy than graphitic carbons, and some materials containing carbyne chains even explode. ,, The high reactivity makes carbyne chains prefer to crosslink and degrade into more stable forms. − Hence, the existence of carbyne and bulk carbyne has long been questioned. Fortunately, a few methods for the synthesis of carbyne chains have been developed, including using end-capping groups for stabilization − and using CNTs as confining hosts. − By capping the carbyne chains with end-groups that separate different molecules to reduce the possibility of crosslinking, Tykwinski and Chalifoux have synthesized carbyne segments containing 44 carbon atoms .…”

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confidence: 99%

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Predicted Confinement-Enhanced Stability and Extraordinary Mechanical Properties for Carbon Nanotube Wrapped Chains of Linear Carbon

Gao

Baughman

2020

ACS Nano

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The demand for high-modulus, high-strength, lightweight materials has continuously driven the bottom-up assembly of carbon nanostructures into high-performance bulk carbon materials, such as graphene sheets and carbon nanotube yarns. Carbyne, often called linear carbon, has a higher predicted gravimetric modulus and gravimetric strength than any other form of carbon, but possibly reacts under near-ambient conditions because of the extended sp 1 hybridization. The successful fabrication of carbon nanotube wrapped single carbyne chain (Shi et al. Nat. Mater. 2016, 15, 634) suggests the possibility of carbyne’s bulk production. Herein, we designed a type of carbon assembly that includes a possibly large array of carbyne chains confined within a single-walled nanotube sheath (nanotube wrapped carbynes, NTWCs), in which carbyne chains act as reinforcing building blocks, and the carbon nanotube sheath protects the multiple carbyne chains against chemical or topochemical reaction. We showed that NTWCs exhibit confinement-enhanced stabilities, even when they contain multiple neighboring carbyne chains. We developed a mechanics model for exploring the mechanical properties of NTWCs. On the basis of this model, the gravimetric modulus (and strength) of NTWCs was predicted to increase from 356.4 (50.25) to 977.2 GPa·g–1·cm3 (71.20 GPa·g–1·cm3) as the mass ratio of carbyne carbons to sheath carbons increases, which is supported by atomistic simulations. The highest calculated gravimetric modulus and strength of NTWCs are 174.2% and 41.7%, respectively, higher than those of either graphene or carbon nanotubes. The corresponding highest values of engineering modulus and strength of NTWCs with a density of 1.54 g·cm–3 are 1505 and 109.6 GPa, respectively. Hence, NTWCs are promising for uses in high-modulus, high-strength, lightweight composites.

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Section: Results and Discussionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Predicted Confinement-Enhanced Stability and Extraordinary Mechanical Properties for Carbon Nanotube Wrapped Chains of Linear Carbon

Gao

Baughman

2020

ACS Nano

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“…In this work, uncapped cumulenic C n chains (also experimentally observed in inert gas atmosphere [10,11] ) and vinylidene-capped chains have been modelled by DFT computations, showing indeed an almost equalized (cumulenic) geometry (BLA < 0.05 A) together with a non-negligible Raman activity. This paper clearly demonstrated that the structural trend in CC bond lengths is a consequence of the termination in short chains: considering as an example vinylidene groups >CH 2 , the existence of two single CH bonds on the last sp 2 carbons of the chain, implies that this carbon will form a double bond with the next sp carbon and the latter one is forced to form again a double bond with the next atom in the chain and so on, thus obtaining a =C=C=C= cumulenic structure on the sp-carbon chain (see Figure 5) [44,45] . paving the way to a true molecular engineering of CAWs, as discussed in the next section.…”

Section: Carbon Atom Wires As Finite Carbyne-like Systemsmentioning

confidence: 99%

Carbyne: from the elusive allotrope to stable carbon atom wires

Casari¹,

Milani²

2018

MRS Communications

113

103

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Besides graphite and diamond, the solid allotropes of carbon in sp 2 and sp 3 hybridization, the possible existence of a third allotrope based on the sp-carbon linear chain, the Carbyne, has stimulated researchers for a long time. The advent of fullerenes, nanotubes and graphene has opened new opportunities and nurtured the interest in novel carbon allotropes including linear structures. The efforts made in this direction produced a number of interesting sp-hybridized carbon molecules and nanostructures in the form of carbon-atom wires. We here discuss some of the new perspectives opened by the recent advancements in the research on sp-carbon systems.

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“…[12,13]. Other forms of hybridization have also been observed, such as altering single and triple bonds (polyyne) or altering single and double bonds (polycumulene) with stabilizing molecular complexes at the end of the chains [14,15].…”

Section: Introductionmentioning

confidence: 99%

Carbon-based nanomaterial synthesis using nanosecond electrical discharges in immiscible layered liquids: n-heptane and water

Hamdan¹,

Suk²

2018

J. Phys. D: Appl. Phys.

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Plasmas in-or in-contact with liquids have been extensively investigated due to their high potential for a wide range of applications including but not limited to, water treatment, material synthesis and functionalization, bio-medical applications, and liquid fuel reformation. Recently, we successfully developed a discharge using two immiscible liquids, having very different electrical permittivities, which could significantly intensify the electric field intensity. Here, we establish nanosecond discharges at the interface n-heptane-water (with respective relative dielectric permittivities of 2 and 80) to enable the synthesis of carbon-based nanomaterials. A characterization of the as-synthesized material and the annealed (500 °C) material, using various techniques (Fourier-Transform, Infra-Red, Scanning and Transmission electron microscopes, etc.), shows that the as-synthesized material is a mixture of two carbonbased phases: a crystalline phase (graphite like) embedded into a phase of hydrogenated amorphous carbon. The existence of two-phases may be explained by the non-homogeneity of the discharge that induces various chemical reactions in the plasma channel.

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Polymerization of acetylene: polyynes, but not carbyne

Abstract: Polymerization of acetylene in the presence of sterically-hindered endgroups leads to polyynes, but with lengths shorter than by stepwise syntheses.

Cited by 14 publications

References 48 publications

Predicted Confinement-Enhanced Stability and Extraordinary Mechanical Properties for Carbon Nanotube Wrapped Chains of Linear Carbon

Predicted Confinement-Enhanced Stability and Extraordinary Mechanical Properties for Carbon Nanotube Wrapped Chains of Linear Carbon

Carbyne: from the elusive allotrope to stable carbon atom wires

Carbon-based nanomaterial synthesis using nanosecond electrical discharges in immiscible layered liquids: n-heptane and water

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