http://scholar.google.com/citations?hl=en&user=95SvbM8AAAAJ
101.
Nadia F. Andradea Gustavo Brunettoa, Douglas S. Galvao
High Pressure Induced Binding Between Linear Carbon Chains and Nanotubes Proceedings
vol. 1752, não 53-58, 2015, (MRS Proceedings, 1752, pp 53-58).
@proceedings{Brunettoa2015,
title = {High Pressure Induced Binding Between Linear Carbon Chains and Nanotubes},
author = {Gustavo Brunettoa, Nadia F. Andradea, Douglas S. Galvao, Antonio G. Souza Filho},
url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9553206&fileId=S1946427415000913},
doi = {10.1557/opl.2015.91},
year = {2015},
date = {2015-01-01},
volume = {1752},
number = {53-58},
abstract = {Recent studies of single-walled carbon nanotubes (CNTs) in aqueous media have showed that water can significantly affect the tube mechanical properties. CNTs under hydrostatic compression can preserve their elastic properties up to large pressure values, while exhibiting exceptional resistance to mechanical loadings. It was experimentally observed that CNTs with encapsulated linear carbon chains (LCCs), when subjected to high hydrostatic pressure values, present irreversible red shifts in some of their vibrational frequencies. In order to address the cause of this phenomenon, we have carried out fully atomistic reactive (ReaxFF) molecular dynamics (MD) simulations for model structures mimicking the experimental conditions. We have considered the cases of finite and infinite (cyclic boundary conditions) CNTs filled with LCCs (LCC@CNTs) of different lengths (from 9 up to 40 atoms). Our results show that increasing the hydrostatic pressure causes the CNT to be deformed in an inhomogeneous way due to the LCC presence. The LCC/CNT interface regions exhibit convex curvatures, which results in more reactive sites, thus favoring the formation of covalent chemical bonds between the chain and the nanotube. This process is irreversible with the newly formed bonds continuing to exist even after releasing the external pressure and causing an irreversibly red shift in the chain vibrational modes from 1850 to 1500 cm−1.},
note = {MRS Proceedings, 1752, pp 53-58},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Recent studies of single-walled carbon nanotubes (CNTs) in aqueous media have showed that water can significantly affect the tube mechanical properties. CNTs under hydrostatic compression can preserve their elastic properties up to large pressure values, while exhibiting exceptional resistance to mechanical loadings. It was experimentally observed that CNTs with encapsulated linear carbon chains (LCCs), when subjected to high hydrostatic pressure values, present irreversible red shifts in some of their vibrational frequencies. In order to address the cause of this phenomenon, we have carried out fully atomistic reactive (ReaxFF) molecular dynamics (MD) simulations for model structures mimicking the experimental conditions. We have considered the cases of finite and infinite (cyclic boundary conditions) CNTs filled with LCCs (LCC@CNTs) of different lengths (from 9 up to 40 atoms). Our results show that increasing the hydrostatic pressure causes the CNT to be deformed in an inhomogeneous way due to the LCC presence. The LCC/CNT interface regions exhibit convex curvatures, which results in more reactive sites, thus favoring the formation of covalent chemical bonds between the chain and the nanotube. This process is irreversible with the newly formed bonds continuing to exist even after releasing the external pressure and causing an irreversibly red shift in the chain vibrational modes from 1850 to 1500 cm−1.
102.
Perim, Eric; Machado, Leonardo Dantas; Galvao, Douglas Soares
A Brief Review on Syntheses, Structures, and Applications of Nanoscrolls Journal Article
Em: Frontiers in Materials, vol. 1, pp. 31, 2014, (Invited Review Paper).
@article{perim2014brief,
title = {A Brief Review on Syntheses, Structures, and Applications of Nanoscrolls},
author = {Perim, Eric and Machado, Leonardo Dantas and Galvao, Douglas Soares},
url = {http://journal.frontiersin.org/Journal/10.3389/fmats.2014.00031/abstract},
year = {2014},
date = {2014-12-01},
journal = {Frontiers in Materials},
volume = {1},
pages = {31},
publisher = {Frontiers},
abstract = {Nanoscrolls are papyrus-like nanostructures, which present unique properties due to their open ended morphology. These properties can be exploited in a plethora of technological applications, leading to the design of novel and interesting devices. During the past decade, significant advances in the synthesis and characterization of these structures have been made, but many challenges still remain. In this mini review, we provide an overview on their history, experimental synthesis methods, basic properties, and application perspectives.},
note = {Invited Review Paper},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Nanoscrolls are papyrus-like nanostructures, which present unique properties due to their open ended morphology. These properties can be exploited in a plethora of technological applications, leading to the design of novel and interesting devices. During the past decade, significant advances in the synthesis and characterization of these structures have been made, but many challenges still remain. In this mini review, we provide an overview on their history, experimental synthesis methods, basic properties, and application perspectives.
103.
Brunetto, Gustavo; Andrade, Nadia F.; Galvao, Douglas S; Antonio Filho, G Souza
High Pressure Induced Binding Between Linear Carbon Chains and Nanotubes Proceedings
2014.
@proceedings{brunetto2014high,
title = {High Pressure Induced Binding Between Linear Carbon Chains and Nanotubes},
author = {Brunetto, Gustavo and Andrade, Nadia F. and Galvao, Douglas S and Antonio Filho, G Souza},
url = {http://arxiv.org/abs/1412.7966},
year = {2014},
date = {2014-01-01},
journal = {arXiv preprint arXiv:1412.7966},
abstract = {Recent studies of single-walled carbon nanotubes (CNTs) in aqueous media have showed that water can significantly affect the tube mechanical properties. CNTs under hydrostatic compression can preserve their elastic properties up to large pressure values, while exhibiting exceptional resistance to mechanical loadings. It was experimentally observed that CNTs with encapsulated linear carbon chains (LCCs), when subjected to high hydrostatic pressure values, present irreversible red shifts in some of their vibrational frequencies. In order to address the cause of this phenomenon, we have carried out fully atomistic reactive (ReaxFF) molecular dynamics (MD) simulations for model structures mimicking the experimental conditions. We have considered the cases of finite and infinite (cyclic boundary conditions) CNTs filled with LCCs (LCC inside CNTs) of different lengths (from 9 up to 40 atoms). Our results show that increasing the hydrostatic pressure causes the CNT to be deformed in an inhomogeneous way due to the LCC presence. The LCC-CNT interface regions exhibit convex curvatures, which results in more reactive sites, thus favoring the formation of covalent chemical bonds between the chain and the nanotube. This process is irreversible with the newly formed bonds continuing to exist even after releasing the external pressure and causing an irreversibly red shift in the chain vibrational modes from 1850 to 1500 cm−1.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Recent studies of single-walled carbon nanotubes (CNTs) in aqueous media have showed that water can significantly affect the tube mechanical properties. CNTs under hydrostatic compression can preserve their elastic properties up to large pressure values, while exhibiting exceptional resistance to mechanical loadings. It was experimentally observed that CNTs with encapsulated linear carbon chains (LCCs), when subjected to high hydrostatic pressure values, present irreversible red shifts in some of their vibrational frequencies. In order to address the cause of this phenomenon, we have carried out fully atomistic reactive (ReaxFF) molecular dynamics (MD) simulations for model structures mimicking the experimental conditions. We have considered the cases of finite and infinite (cyclic boundary conditions) CNTs filled with LCCs (LCC inside CNTs) of different lengths (from 9 up to 40 atoms). Our results show that increasing the hydrostatic pressure causes the CNT to be deformed in an inhomogeneous way due to the LCC presence. The LCC-CNT interface regions exhibit convex curvatures, which results in more reactive sites, thus favoring the formation of covalent chemical bonds between the chain and the nanotube. This process is irreversible with the newly formed bonds continuing to exist even after releasing the external pressure and causing an irreversibly red shift in the chain vibrational modes from 1850 to 1500 cm−1.
104.
Perim, Eric; Galvao, Douglas S
Novel Nanoscroll Structures from Carbon Nitride Layers Journal Article
Em: ChemPhysChem, vol. 15, não 11, pp. 2367–2371, 2014.
@article{perim2014novelb,
title = {Novel Nanoscroll Structures from Carbon Nitride Layers},
author = {Perim, Eric and Galvao, Douglas S},
url = {http://onlinelibrary.wiley.com/doi/10.1002/cphc.201402059/full},
year = {2014},
date = {2014-01-01},
journal = {ChemPhysChem},
volume = {15},
number = {11},
pages = {2367--2371},
publisher = {WILEY-VCH Verlag},
abstract = {Nanoscrolls (papyrus-like nanostructures) are very attractive structures for a variety of applications, owing to their tunable diameter and large accessible surface area. They have been successfully synthesized from different materials. In this work, we investigate, through fully atomistic molecular dynamics simulations, the dynamics of scroll formation for a series of graphene-like carbon nitride (CN) two-dimensional systems: g-CN, triazine-based g-C3N4, and heptazine-based g-C3N4. Our results show that stable nanoscrolls can be formed for each of these structures. Possible synthetic routes to produce these nanostructures are also addressed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Nanoscrolls (papyrus-like nanostructures) are very attractive structures for a variety of applications, owing to their tunable diameter and large accessible surface area. They have been successfully synthesized from different materials. In this work, we investigate, through fully atomistic molecular dynamics simulations, the dynamics of scroll formation for a series of graphene-like carbon nitride (CN) two-dimensional systems: g-CN, triazine-based g-C3N4, and heptazine-based g-C3N4. Our results show that stable nanoscrolls can be formed for each of these structures. Possible synthetic routes to produce these nanostructures are also addressed.
105.
Bizao, RA; Botari, T; Galvao, DS
Mechanical Properties of Graphene Nanowiggles Proceedings
Cambridge University Press, vol. 1658, 2014.
@proceedings{bizao2014mechanical,
title = {Mechanical Properties of Graphene Nanowiggles},
author = {Bizao, RA and Botari, T and Galvao, DS},
url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9248042&fileId=S1946427414004023},
year = {2014},
date = {2014-01-01},
journal = {MRS Proceedings},
volume = {1658},
pages = {mrsf13--1658},
publisher = {Cambridge University Press},
abstract = {In this work we have investigated the mechanical properties and fracture patterns of some graphene nanowiggles (GNWs). Graphene nanoribbons are finite graphene segments with a large aspect ratio, while GNWs are nonaligned periodic repetitions of graphene nanoribbons. We have carried out fully atomistic molecular dynamics simulations using a reactive force field (ReaxFF), as implemented in the LAMPPS (Large-scale Atomic/Molecular Massively Parallel Simulator) code. Our results showed that the GNW fracture patterns are strongly dependent on the nanoribbon topology and present an interesting behavior, since some narrow sheets have larger ultimate failure strain values. This can be explained by the fact that narrow nanoribbons have more angular freedom when compared to wider ones, which can create a more efficient way to accumulate and to dissipate strain/stress. We have also observed the formation of linear atomic chains (LACs) and some structural defect reconstructions during the material rupture. The reported graphene failure patterns, where zigzag/armchair edge terminated graphene structures are fractured along armchair/zigzag lines, were not observed in the GNW analyzed cases.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
In this work we have investigated the mechanical properties and fracture patterns of some graphene nanowiggles (GNWs). Graphene nanoribbons are finite graphene segments with a large aspect ratio, while GNWs are nonaligned periodic repetitions of graphene nanoribbons. We have carried out fully atomistic molecular dynamics simulations using a reactive force field (ReaxFF), as implemented in the LAMPPS (Large-scale Atomic/Molecular Massively Parallel Simulator) code. Our results showed that the GNW fracture patterns are strongly dependent on the nanoribbon topology and present an interesting behavior, since some narrow sheets have larger ultimate failure strain values. This can be explained by the fact that narrow nanoribbons have more angular freedom when compared to wider ones, which can create a more efficient way to accumulate and to dissipate strain/stress. We have also observed the formation of linear atomic chains (LACs) and some structural defect reconstructions during the material rupture. The reported graphene failure patterns, where zigzag/armchair edge terminated graphene structures are fractured along armchair/zigzag lines, were not observed in the GNW analyzed cases.
106.
SB Legoas LD Machado, JS Soares
Dynamics of the formation of carbon nanotube serpentines Journal Article
Em: Physical Review Letters, vol. 110, não 10, pp. 105502, 2013.
@article{machado2013dynamics,
title = {Dynamics of the formation of carbon nanotube serpentines},
author = {LD Machado, SB Legoas, JS Soares, N Shadmi, A Jorio, E Joselevich, DS Galvão},
url = {http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.110.105502},
year = {2013},
date = {2013-01-01},
journal = {Physical Review Letters},
volume = {110},
number = {10},
pages = {105502},
publisher = {American Physical Society},
abstract = {Recently, Geblinger et al. [Nat. Nanotechnol. 3, 195 (2008)] reported the experimental realization of carbon nanotube S-like shaped nanostructures, the so-called carbon nanotube serpentines. We report here results from multimillion fully atomistic molecular dynamics simulations of their formation. We consider one-μm-long carbon nanotubes placed on stepped substrates with and without a catalyst nanoparticle on the top free end of the tube. A force is applied to the upper part of the tube during a short period of time and turned off; then the system is set free to evolve in time. Our results show that these conditions are sufficient to form robust serpentines and validates the general features of the “falling spaghetti model” proposed to explain their formation.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Recently, Geblinger et al. [Nat. Nanotechnol. 3, 195 (2008)] reported the experimental realization of carbon nanotube S-like shaped nanostructures, the so-called carbon nanotube serpentines. We report here results from multimillion fully atomistic molecular dynamics simulations of their formation. We consider one-μm-long carbon nanotubes placed on stepped substrates with and without a catalyst nanoparticle on the top free end of the tube. A force is applied to the upper part of the tube during a short period of time and turned off; then the system is set free to evolve in time. Our results show that these conditions are sufficient to form robust serpentines and validates the general features of the “falling spaghetti model” proposed to explain their formation.
107.
Perim, Eric; Paupitz, Ricardo; Galvao, Douglas S
Controlled route to the fabrication of carbon and boron nitride nanoscrolls: A molecular dynamics investigation Journal Article
Em: Journal of Applied Physics, vol. 113, não 5, pp. 054306, 2013.
@article{perim2013controlled,
title = {Controlled route to the fabrication of carbon and boron nitride nanoscrolls: A molecular dynamics investigation},
author = {Perim, Eric and Paupitz, Ricardo and Galvao, Douglas S},
url = {http://scitation.aip.org/content/aip/journal/jap/113/5/10.1063/1.4790304},
year = {2013},
date = {2013-01-01},
journal = {Journal of Applied Physics},
volume = {113},
number = {5},
pages = {054306},
publisher = {AIP Publishing},
abstract = {Carbon nanoscrolls (graphene layers rolled up into papyrus-like tubular structures) are nanostructures with unique and interesting characteristics that could be exploited to build several new nanodevices. However, an efficient and controlled synthesis of these structures was not achieved yet, making its large scale production a challenge to materials scientists. Also, the formation process and detailed mechanisms that occur during its synthesis are not completely known. In this work, using fully atomistic molecular dynamics simulations, we discuss a possible route to nanoscrolls made from graphene layers deposited over silicon oxide substrates containing chambers/pits. The scrolling mechanism is triggered by carbon nanotubes deposited on the layers. The process is completely general and can be used to produce scrolls from other lamellar materials, like boron nitride, for instance.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Carbon nanoscrolls (graphene layers rolled up into papyrus-like tubular structures) are nanostructures with unique and interesting characteristics that could be exploited to build several new nanodevices. However, an efficient and controlled synthesis of these structures was not achieved yet, making its large scale production a challenge to materials scientists. Also, the formation process and detailed mechanisms that occur during its synthesis are not completely known. In this work, using fully atomistic molecular dynamics simulations, we discuss a possible route to nanoscrolls made from graphene layers deposited over silicon oxide substrates containing chambers/pits. The scrolling mechanism is triggered by carbon nanotubes deposited on the layers. The process is completely general and can be used to produce scrolls from other lamellar materials, like boron nitride, for instance.
108.
Perim, E; Autreto, PAS; Paupitz, R; Galvao, DS
Dynamical aspects of the unzipping of multiwalled boron nitride nanotubes Journal Article
Em: Physical Chemistry Chemical Physics, vol. 15, não 44, pp. 19147–19150, 2013.
@article{perim2013dynamical,
title = {Dynamical aspects of the unzipping of multiwalled boron nitride nanotubes},
author = {Perim, E and Autreto, PAS and Paupitz, R and Galvao, DS},
url = {http://pubs.rsc.org/EN/content/articlehtml/2013/cp/c3cp52701h},
year = {2013},
date = {2013-01-01},
journal = {Physical Chemistry Chemical Physics},
volume = {15},
number = {44},
pages = {19147--19150},
publisher = {Royal Society of Chemistry},
abstract = {Boron nitride nanoribbons (BNNRs) exhibit very interesting magnetic properties, which could be very useful in the development of spintronic based devices. One possible route to obtain BNNRs is through the unzipping of boron nitride nanotubes (BNNTs), which have been already experimentally realized. In this work, different aspects of the unzipping process of BNNTs were investigated through fully atomistic molecular dynamics simulations using a classical reactive force field (ReaxFF). We investigated multiwalled BNNTs of different diameters and chiralities. Our results show that chirality plays a very important role in the unzipping process, as well as the interlayer coupling. These combined aspects significantly change the fracturing patterns and several other features of the unzipping processes in comparison to the ones observed for carbon nanotubes. Also, similar to carbon nanotubes, defective BNNTs can create regions of very high curvature which can act as a path to the unzipping process.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Boron nitride nanoribbons (BNNRs) exhibit very interesting magnetic properties, which could be very useful in the development of spintronic based devices. One possible route to obtain BNNRs is through the unzipping of boron nitride nanotubes (BNNTs), which have been already experimentally realized. In this work, different aspects of the unzipping process of BNNTs were investigated through fully atomistic molecular dynamics simulations using a classical reactive force field (ReaxFF). We investigated multiwalled BNNTs of different diameters and chiralities. Our results show that chirality plays a very important role in the unzipping process, as well as the interlayer coupling. These combined aspects significantly change the fracturing patterns and several other features of the unzipping processes in comparison to the ones observed for carbon nanotubes. Also, similar to carbon nanotubes, defective BNNTs can create regions of very high curvature which can act as a path to the unzipping process.
109.
Autreto, PA; de Sousa, JM; Galvao, DS
On the Dynamics of Graphdiyne Hydrogenation Proceedings
Cambridge University Press, vol. 1549, 2013.
@proceedings{autreto2013dynamics,
title = {On the Dynamics of Graphdiyne Hydrogenation},
author = {Autreto, PA and de Sousa, JM and Galvao, DS},
url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8915680&fileId=S1946427413006088},
year = {2013},
date = {2013-01-01},
journal = {MRS Proceedings},
volume = {1549},
pages = {59--64},
publisher = {Cambridge University Press},
abstract = {Graphene is a two-dimensional (2D) hexagonal array of carbon atoms in sp2-hybridized states. Graphene presents unique and exceptional electronic, thermal and mechanical properties. However, in its pristine state graphene is a gapless semiconductor, which poses some limitations to its use in some transistor electronics. Because of this there is a renewed interest in other possible two-dimensional carbon-based structures similar to graphene. Examples of this are graphynes and graphdiynes, which are two-dimensional structures, composed of carbon atoms in sp2 and sp-hybridized states. Graphdiynes (benzenoid rings connecting two acetylenic groups) were recently synthesized and they can be intrinsically nonzero gap systems. These systems can be easily hydrogenated and the amount of hydrogenation can be used to tune the band gap value. In this work we have investigated, through fully atomistic molecular dynamics simulations with reactive force field (ReaxFF), the structural and dynamics aspects of the hydrogenation mechanisms of graphdiyne membranes. Our results showed that depending on whether the atoms are in the benzenoid rings or as part of the acetylenic groups, the rates of hydrogenation are quite distinct and change in time in a very complex pattern. Initially, the most probable sites to be hydrogenated are the carbon atoms forming the triple bonds, as expected. But as the amount of hydrogenation increases in time this changes and then the carbon atoms forming single bonds become the preferential sites. The formation of correlated domains observed in hydrogenated graphene is no longer observed in the case of graphdiynes. We have also carried out ab initio DFT calculations for model structures in order to test the reliability of ReaxFF calculations.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Graphene is a two-dimensional (2D) hexagonal array of carbon atoms in sp2-hybridized states. Graphene presents unique and exceptional electronic, thermal and mechanical properties. However, in its pristine state graphene is a gapless semiconductor, which poses some limitations to its use in some transistor electronics. Because of this there is a renewed interest in other possible two-dimensional carbon-based structures similar to graphene. Examples of this are graphynes and graphdiynes, which are two-dimensional structures, composed of carbon atoms in sp2 and sp-hybridized states. Graphdiynes (benzenoid rings connecting two acetylenic groups) were recently synthesized and they can be intrinsically nonzero gap systems. These systems can be easily hydrogenated and the amount of hydrogenation can be used to tune the band gap value. In this work we have investigated, through fully atomistic molecular dynamics simulations with reactive force field (ReaxFF), the structural and dynamics aspects of the hydrogenation mechanisms of graphdiyne membranes. Our results showed that depending on whether the atoms are in the benzenoid rings or as part of the acetylenic groups, the rates of hydrogenation are quite distinct and change in time in a very complex pattern. Initially, the most probable sites to be hydrogenated are the carbon atoms forming the triple bonds, as expected. But as the amount of hydrogenation increases in time this changes and then the carbon atoms forming single bonds become the preferential sites. The formation of correlated domains observed in hydrogenated graphene is no longer observed in the case of graphdiynes. We have also carried out ab initio DFT calculations for model structures in order to test the reliability of ReaxFF calculations.
110.
Perim, Eric; Paupitz, Ricardo; Autreto, PAS; Galvao, DS
The Hydrogenation Dynamics of h-BN Sheets Proceedings
Cambridge University Press, vol. 1549, 2013.
@proceedings{perim2013hydrogenation,
title = {The Hydrogenation Dynamics of h-BN Sheets},
author = {Perim, Eric and Paupitz, Ricardo and Autreto, PAS and Galvao, DS},
url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8943477&fileId=S1946427413007938},
year = {2013},
date = {2013-01-01},
journal = {MRS Proceedings},
volume = {1549},
pages = {91--98},
publisher = {Cambridge University Press},
abstract = {Hexagonal boron nitride (h-BN), also known as white graphite, is the inorganic analogue of graphite. Single layers of both structures have been already experimentally realized.
In this work we have investigated, through fully atomistic reactive molecular dynamics simulations, the dynamics of hydrogenation of h-BN single-layers membranes.
Our results show that the rate of hydrogenation atoms bonded to the membrane is highly dependent on the temperature and that only at low temperatures there is a preferential bond to boron atoms. Unlike graphanes (hydrogenated graphene), hydrogenated h-BN membranes do not exhibit the formation of correlated domains. Also, the out-of-plane deformations are more pronounced in comparison with the graphene case. After a critical number of incorporated hydrogen atoms the membrane become increasingly defective, lost its two-dimensional character and collapses. The hydrogen radial pair distribution and second-nearest neighbor correlations were also analyzed.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Hexagonal boron nitride (h-BN), also known as white graphite, is the inorganic analogue of graphite. Single layers of both structures have been already experimentally realized.
In this work we have investigated, through fully atomistic reactive molecular dynamics simulations, the dynamics of hydrogenation of h-BN single-layers membranes.
Our results show that the rate of hydrogenation atoms bonded to the membrane is highly dependent on the temperature and that only at low temperatures there is a preferential bond to boron atoms. Unlike graphanes (hydrogenated graphene), hydrogenated h-BN membranes do not exhibit the formation of correlated domains. Also, the out-of-plane deformations are more pronounced in comparison with the graphene case. After a critical number of incorporated hydrogen atoms the membrane become increasingly defective, lost its two-dimensional character and collapses. The hydrogen radial pair distribution and second-nearest neighbor correlations were also analyzed.
In this work we have investigated, through fully atomistic reactive molecular dynamics simulations, the dynamics of hydrogenation of h-BN single-layers membranes.
Our results show that the rate of hydrogenation atoms bonded to the membrane is highly dependent on the temperature and that only at low temperatures there is a preferential bond to boron atoms. Unlike graphanes (hydrogenated graphene), hydrogenated h-BN membranes do not exhibit the formation of correlated domains. Also, the out-of-plane deformations are more pronounced in comparison with the graphene case. After a critical number of incorporated hydrogen atoms the membrane become increasingly defective, lost its two-dimensional character and collapses. The hydrogen radial pair distribution and second-nearest neighbor correlations were also analyzed.
111.
Machado, LD; Autreto, PAS; Galvao, DS
Graphyne Oxidation: Insights From a Reactive Molecular Dynamics Investigation Proceedings
Cambridge University Press, vol. 1549, 2013.
@proceedings{machado2013graphyne,
title = {Graphyne Oxidation: Insights From a Reactive Molecular Dynamics Investigation},
author = {Machado, LD and Autreto, PAS and Galvao, DS},
url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8963025&fileId=S194642741300941X},
year = {2013},
date = {2013-01-01},
journal = {MRS Proceedings},
volume = {1549},
pages = {53--58},
publisher = {Cambridge University Press},
abstract = {Graphyne is a generic name for a family of carbon allotrope two-dimensional structures where sp2 (single and double bonds) and sp (triple bonds) hybridized states coexists. They exhibit very interesting electronic and mechanical properties sharing some of the unique graphene characteristics. Similarly to graphene, the graphyne electronic properties can be modified by chemical functionalization, such as; hydrogenation, fluorination and oxidation. Oxidation is of particular interest since it can produce significant structural damages.
In this work we have investigated, through fully atomistic reactive molecular dynamics simulations, the dynamics and structural changes of the oxidation of single-layer graphyne membranes at room temperature. We have considered α, β, and γ-graphyne structures. Our results showed that the oxidation reactions are strongly site dependent and that the sp-hybridized carbon atoms are the preferential sites to chemical attacks. Our results also showed that the effectiveness of the oxidation (estimated from the number of oxygen atoms covalently bonded to carbon atoms) follows the α, β, γ-graphyne structure ordering. These differences can be explained by the fact that for α-graphyne structures the oxidation reactions occur in two steps: first, the oxygen atoms are trapped at the center of the large polygonal rings and then they react with the carbon atoms composing of the triple bonds. The small rings of γ-graphyne structures prevent these reactions to occur. The effectiveness of β-graphyne oxidation is between the α- and γ-graphynes.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Graphyne is a generic name for a family of carbon allotrope two-dimensional structures where sp2 (single and double bonds) and sp (triple bonds) hybridized states coexists. They exhibit very interesting electronic and mechanical properties sharing some of the unique graphene characteristics. Similarly to graphene, the graphyne electronic properties can be modified by chemical functionalization, such as; hydrogenation, fluorination and oxidation. Oxidation is of particular interest since it can produce significant structural damages.
In this work we have investigated, through fully atomistic reactive molecular dynamics simulations, the dynamics and structural changes of the oxidation of single-layer graphyne membranes at room temperature. We have considered α, β, and γ-graphyne structures. Our results showed that the oxidation reactions are strongly site dependent and that the sp-hybridized carbon atoms are the preferential sites to chemical attacks. Our results also showed that the effectiveness of the oxidation (estimated from the number of oxygen atoms covalently bonded to carbon atoms) follows the α, β, γ-graphyne structure ordering. These differences can be explained by the fact that for α-graphyne structures the oxidation reactions occur in two steps: first, the oxygen atoms are trapped at the center of the large polygonal rings and then they react with the carbon atoms composing of the triple bonds. The small rings of γ-graphyne structures prevent these reactions to occur. The effectiveness of β-graphyne oxidation is between the α- and γ-graphynes.
In this work we have investigated, through fully atomistic reactive molecular dynamics simulations, the dynamics and structural changes of the oxidation of single-layer graphyne membranes at room temperature. We have considered α, β, and γ-graphyne structures. Our results showed that the oxidation reactions are strongly site dependent and that the sp-hybridized carbon atoms are the preferential sites to chemical attacks. Our results also showed that the effectiveness of the oxidation (estimated from the number of oxygen atoms covalently bonded to carbon atoms) follows the α, β, γ-graphyne structure ordering. These differences can be explained by the fact that for α-graphyne structures the oxidation reactions occur in two steps: first, the oxygen atoms are trapped at the center of the large polygonal rings and then they react with the carbon atoms composing of the triple bonds. The small rings of γ-graphyne structures prevent these reactions to occur. The effectiveness of β-graphyne oxidation is between the α- and γ-graphynes.
112.
Perim, E; Galvao, DS
Boron Nitride Nanoscrolls Journal Article
Em: Physicæ Proceedings, vol. 1, não 1, pp. 2, 2012.
@article{perim2012boron,
title = {Boron Nitride Nanoscrolls},
author = {Perim, E and Galvao, DS},
url = {http://physicae.ifi.unicamp.br/phyproceedings/article/view/269},
year = {2012},
date = {2012-01-01},
journal = {Physicæ Proceedings},
volume = {1},
number = {1},
pages = {2},
abstract = {Recently, based on computer simulations, it has been proposed that stable boron nitride nanoscrolls (BNNSs) can exist. In this work we show that the BNNSs stability mechanisms follow the same simple physical principles proposed for carbon nanoscrolls (CNSs). For both classes of scrolls, the mechanical stability arises as the result of the interplay between attractive van der Waals forces and the elastic (bending) deformations. The topology (chirality) of the scrolled single-layer membranes plays an important role defining BNNS stability. A controled way to produce BNNSs is also addressed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Recently, based on computer simulations, it has been proposed that stable boron nitride nanoscrolls (BNNSs) can exist. In this work we show that the BNNSs stability mechanisms follow the same simple physical principles proposed for carbon nanoscrolls (CNSs). For both classes of scrolls, the mechanical stability arises as the result of the interplay between attractive van der Waals forces and the elastic (bending) deformations. The topology (chirality) of the scrolled single-layer membranes plays an important role defining BNNS stability. A controled way to produce BNNSs is also addressed.
113.
Autreto, PAS; Galvao, Douglas S; Santos, Ricardo PB; Legoas, SB
Graphene to Fluorographene: A Reactive Molecular Dynamics Study Journal Article
Em: Physicæ Proceedings, vol. 1, não 1, pp. 3, 2012.
@article{autreto2012graphene,
title = {Graphene to Fluorographene: A Reactive Molecular Dynamics Study},
author = {Autreto, PAS and Galvao, Douglas S and Santos, Ricardo PB and Legoas, SB},
url = {http://physicae.ifi.unicamp.br/phyproceedings/article/view/physicae.proceedings.XIYRM.11},
year = {2012},
date = {2012-01-01},
journal = {Physicæ Proceedings},
volume = {1},
number = {1},
pages = {3},
abstract = {We have investigated, using fully reactive molecular dynamics methodology, the structural and dynamical aspects of the fluorination of graphene membranes leading to fluographene formation. The strong and fast chemical reactivity processes involving fluorine produce distinct aspects of the observed in the case of the hydrogenation of graphene (the so called graphane formation). Fluorination tends to produce significant defective areas on the graphene membrane with alteration on the typical carbon-carbon distances, sometimes with the presence of large holes due to carbon losses. This may explain the broad distribution of values of lattice parameter experimentally observed.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We have investigated, using fully reactive molecular dynamics methodology, the structural and dynamical aspects of the fluorination of graphene membranes leading to fluographene formation. The strong and fast chemical reactivity processes involving fluorine produce distinct aspects of the observed in the case of the hydrogenation of graphene (the so called graphane formation). Fluorination tends to produce significant defective areas on the graphene membrane with alteration on the typical carbon-carbon distances, sometimes with the presence of large holes due to carbon losses. This may explain the broad distribution of values of lattice parameter experimentally observed.
114.
Machado, Leonardo D; Legoas, Sergio B; Galvao, Douglas S
Multi-Million Fully Atomistic Molecular Dynamics Simulations of Yarn Formation from Carbon Nanotube Forests Proceedings
Cambridge University Press, vol. 1407, 2012.
@proceedings{machado2012multi,
title = {Multi-Million Fully Atomistic Molecular Dynamics Simulations of Yarn Formation from Carbon Nanotube Forests},
author = {Machado, Leonardo D and Legoas, Sergio B and Galvao, Douglas S},
url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8537115&fulltextType=RA&fileId=S1946427412007105},
year = {2012},
date = {2012-01-01},
journal = {MRS Proceedings},
volume = {1407},
pages = {mrsf11--1407},
publisher = {Cambridge University Press},
abstract = {In this work we present preliminary results from multi-million fully atomistic classical molecular dynamics simulations carried out to test different existing mechanisms that have been proposed in the literature to explain the drawing of yarns from carbon nanotube forests. Despite the fact that it has been almost ten years since yarns were first drawn, there are still controversies on the mechanisms and necessary conditions that can produce yarns and sheets drawn from carbon nanotube forests. Moreover, few works have tried to understand at atomistic level the details of yarn drawing mechanisms, and no fully atomistic simulations have been carried out so far on this particular subject. Our preliminary results suggest that only direct van der Waals interactions among large bundles seem not to be enough to explain the yarn drawing process. Bundle interconnectors (such as small bundles connecting large bundles) were observed to play a critical role in our simulations. Depending on the topology of these interconnectors it was possible to observe from the simulations fibers/yarn formation from proposed structural models. These models were built based on structural information inferred from scanning electron microscopy data.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
In this work we present preliminary results from multi-million fully atomistic classical molecular dynamics simulations carried out to test different existing mechanisms that have been proposed in the literature to explain the drawing of yarns from carbon nanotube forests. Despite the fact that it has been almost ten years since yarns were first drawn, there are still controversies on the mechanisms and necessary conditions that can produce yarns and sheets drawn from carbon nanotube forests. Moreover, few works have tried to understand at atomistic level the details of yarn drawing mechanisms, and no fully atomistic simulations have been carried out so far on this particular subject. Our preliminary results suggest that only direct van der Waals interactions among large bundles seem not to be enough to explain the yarn drawing process. Bundle interconnectors (such as small bundles connecting large bundles) were observed to play a critical role in our simulations. Depending on the topology of these interconnectors it was possible to observe from the simulations fibers/yarn formation from proposed structural models. These models were built based on structural information inferred from scanning electron microscopy data.
115.
dos Santos, Ricardo P; Autreto, Pedro A; Perim, Eric; Brunetto, Gustavo; Galvao, Douglas S
On the Unzipping Mechanisms of Carbon Nanotubes: Insights from Reactive Molecular Dynamics Simulations Proceedings
Cambridge University Press, vol. 1451, 2012.
@proceedings{dos2012unzipping,
title = {On the Unzipping Mechanisms of Carbon Nanotubes: Insights from Reactive Molecular Dynamics Simulations},
author = {dos Santos, Ricardo P and Autreto, Pedro A and Perim, Eric and Brunetto, Gustavo and Galvao, Douglas S},
url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8652294&fileId=S1946427412013292},
year = {2012},
date = {2012-01-01},
journal = {MRS Proceedings},
volume = {1451},
pages = {3--8},
publisher = {Cambridge University Press},
abstract = {Unzipping carbon nanotubes (CNTs) is considered one of the most promising approaches for the controlled and large-scale production of graphene nanoribbons (GNR). These structures are considered of great importance for the development of nanoelectronics because of its dimensions and intrinsic nonzero band gap value. Despite many years of investigations some details on the dynamics of the CNT fracture/unzipping processes remain unclear. In this work we have investigated some of these process through molecular dynamics simulations using reactive force fields (ReaxFF), as implemented in the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code. We considered multi-walled CNTs of different dimensions and chiralities and under induced mechanical stretching. Our preliminary results show that the unzipping mechanisms are highly dependent on CNT chirality. Well-defined and distinct fracture patterns were observed for the different chiralities. Armchair CNTs favor the creation of GNRs with well-defined armchair edges, while zigzag and chiral ones produce GNRs with less defined and defective edges.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Unzipping carbon nanotubes (CNTs) is considered one of the most promising approaches for the controlled and large-scale production of graphene nanoribbons (GNR). These structures are considered of great importance for the development of nanoelectronics because of its dimensions and intrinsic nonzero band gap value. Despite many years of investigations some details on the dynamics of the CNT fracture/unzipping processes remain unclear. In this work we have investigated some of these process through molecular dynamics simulations using reactive force fields (ReaxFF), as implemented in the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code. We considered multi-walled CNTs of different dimensions and chiralities and under induced mechanical stretching. Our preliminary results show that the unzipping mechanisms are highly dependent on CNT chirality. Well-defined and distinct fracture patterns were observed for the different chiralities. Armchair CNTs favor the creation of GNRs with well-defined armchair edges, while zigzag and chiral ones produce GNRs with less defined and defective edges.
116.
Dos Santos, RPB; Perim, E; Autreto, PAS; Brunetto, Gustavo; Galvao, DS
On the unzipping of multiwalled carbon nanotubes Journal Article
Em: Nanotechnology, vol. 23, não 46, pp. 465702, 2012.
@article{dos2012unzippingb,
title = {On the unzipping of multiwalled carbon nanotubes},
author = {Dos Santos, RPB and Perim, E and Autreto, PAS and Brunetto, Gustavo and Galvao, DS},
url = {http://iopscience.iop.org/0957-4484/23/46/465702},
year = {2012},
date = {2012-01-01},
journal = {Nanotechnology},
volume = {23},
number = {46},
pages = {465702},
publisher = {IOP Publishing},
abstract = {Graphene nanoribbons (GNRs) are very interesting structures which can retain graphene's high carrier mobility while presenting a finite bandgap. These properties make GNRs very valuable materials for the building of nanodevices. Unzipping carbon nanotubes (CNTs) is considered one of the most promising approaches for GNR controlled and large-scale production, although some of the details of the CNT unzipping processes are not completely known. In this work we have investigated CNT unzipping processes through fully atomistic molecular dynamics simulations using reactive force fields (ReaxFF). Multiwalled CNTs of different dimensions and chiralities under induced mechanical stretching were considered. Our results show that fracture patterns and stress profiles are highly CNT chirality dependent. Our results also show that the 'crests' (partially unzipped CNT regions presenting high curvature), originating from defective CNT areas, can act as a guide for the unzipping processes, which can explain the almost perfectly linear cuts frequently observed in unzipped CNTs.
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Graphene nanoribbons (GNRs) are very interesting structures which can retain graphene's high carrier mobility while presenting a finite bandgap. These properties make GNRs very valuable materials for the building of nanodevices. Unzipping carbon nanotubes (CNTs) is considered one of the most promising approaches for GNR controlled and large-scale production, although some of the details of the CNT unzipping processes are not completely known. In this work we have investigated CNT unzipping processes through fully atomistic molecular dynamics simulations using reactive force fields (ReaxFF). Multiwalled CNTs of different dimensions and chiralities under induced mechanical stretching were considered. Our results show that fracture patterns and stress profiles are highly CNT chirality dependent. Our results also show that the 'crests' (partially unzipped CNT regions presenting high curvature), originating from defective CNT areas, can act as a guide for the unzipping processes, which can explain the almost perfectly linear cuts frequently observed in unzipped CNTs.
117.
dos Santos, Ricardo P; Machado, Leonardo D; Legoas, Sergio B; Galvao, Douglas S
Tribological Properties of Graphene and Boron-Nitride Layers: A Fully Atomistic Molecular Dynamics Study Proceedings
Cambridge University Press, vol. 1407, 2012.
@proceedings{dos2012tribological,
title = {Tribological Properties of Graphene and Boron-Nitride Layers: A Fully Atomistic Molecular Dynamics Study},
author = {dos Santos, Ricardo P and Machado, Leonardo D and Legoas, Sergio B and Galvao, Douglas S},
url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8537106&fileId=S1946427412007063},
year = {2012},
date = {2012-01-01},
journal = {MRS Proceedings},
volume = {1407},
pages = {mrsf11--1407},
publisher = {Cambridge University Press},
abstract = {Graphene has been one of the most important subjects in materials science in the last years. Recently, the frictional characteristics of atomically thin sheets were experimentally investigated using atomic force microscopy (AFM). A new mechanism to explain the enhanced friction for these materials, based on elastic compliance has been proposed. Here, we have investigated the tribological properties of graphene and boron-nitride (single and multi-layers) membranes using fully atomistic molecular dynamics simulations. These simulations were carried out using classical force fields, as implemented in the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code. The used structural models contain typically hundreds of thousands of atoms. In order to mimic the experimental conditions, an artificial AFM tip was moved over the membranes and the tribological characteristics determined in terms of forces and energies. Our results are in good agreement with the available experimental data. They show that the observed enhanced tribological properties can be explained in terms of out-of-plane geometrical distortions and elastic waves propagation. They validate the general features of the model proposed by Lee et al. (Science 328, 76 (2010).},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Graphene has been one of the most important subjects in materials science in the last years. Recently, the frictional characteristics of atomically thin sheets were experimentally investigated using atomic force microscopy (AFM). A new mechanism to explain the enhanced friction for these materials, based on elastic compliance has been proposed. Here, we have investigated the tribological properties of graphene and boron-nitride (single and multi-layers) membranes using fully atomistic molecular dynamics simulations. These simulations were carried out using classical force fields, as implemented in the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code. The used structural models contain typically hundreds of thousands of atoms. In order to mimic the experimental conditions, an artificial AFM tip was moved over the membranes and the tribological characteristics determined in terms of forces and energies. Our results are in good agreement with the available experimental data. They show that the observed enhanced tribological properties can be explained in terms of out-of-plane geometrical distortions and elastic waves propagation. They validate the general features of the model proposed by Lee et al. (Science 328, 76 (2010).
118.
Autreto, Pedro AS; Flores, Marcelo Z; Legoas, Sergio B; Santos, Ricardo PB; Galvao, Douglas S
Cambridge University Press, vol. 1284, 2011.
@proceedings{autreto2011fully,
title = {A Fully Atomistic Reactive Molecular Dynamics Study on the Formation of Graphane from Graphene Hydrogenated Membranes.},
author = {Autreto, Pedro AS and Flores, Marcelo Z and Legoas, Sergio B and Santos, Ricardo PB and Galvao, Douglas S},
url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8364784&fileId=S1946427411013583},
year = {2011},
date = {2011-01-01},
journal = {MRS Proceedings},
volume = {1284},
pages = {mrsf10--1284},
publisher = {Cambridge University Press},
abstract = {Using fully reactive molecular dynamics methodologies we investigated the structural and dynamical aspects of the fluorination mechanism leading to fluorographene formation from graphene membranes. Fluorination tends to produce significant defective areas on the membranes with variation on the typical carbon-carbon distances, sometimes with the presence of large holes due to carbon losses. The results obtained in our simulations are in good agreement with the broad distribution of values for the lattice parameter experimentally observed. We have also investigated mixed atmospheres composed by H and F atoms. When H is present in small quantities an expressive reduction on the rate of incorporation of fluorine was observed. On the other hand when fluorine atoms are present in small quantities in a hydrogen atmosphere, they induce an increasing on the hydrogen incorporation and the formation of locally self-organized structure of adsorbed H and F atoms.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Using fully reactive molecular dynamics methodologies we investigated the structural and dynamical aspects of the fluorination mechanism leading to fluorographene formation from graphene membranes. Fluorination tends to produce significant defective areas on the membranes with variation on the typical carbon-carbon distances, sometimes with the presence of large holes due to carbon losses. The results obtained in our simulations are in good agreement with the broad distribution of values for the lattice parameter experimentally observed. We have also investigated mixed atmospheres composed by H and F atoms. When H is present in small quantities an expressive reduction on the rate of incorporation of fluorine was observed. On the other hand when fluorine atoms are present in small quantities in a hydrogen atmosphere, they induce an increasing on the hydrogen incorporation and the formation of locally self-organized structure of adsorbed H and F atoms.
119.
Machado, Leonardo D; Legoas, Sergio B; Soares, Jaqueline S; Shadmi, Nitzan; Jorio, Ado; Joselevich, Ernesto; Galvao, Douglas S
Cambridge University Press, vol. 1284, 2011.
@proceedings{machado2011formation,
title = {On the formation of carbon nanotube serpentines: insights from multi-million atom molecular dynamics simulation},
author = {Machado, Leonardo D and Legoas, Sergio B and Soares, Jaqueline S and Shadmi, Nitzan and Jorio, Ado and Joselevich, Ernesto and Galvao, Douglas S},
url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8194288&fileId=S194642741100220X},
year = {2011},
date = {2011-01-01},
journal = {MRS Proceedings},
volume = {1284},
pages = {mrsf10--1284},
publisher = {Cambridge University Press},
abstract = {In this work we present preliminary results from molecular dynamics simulations for carbon nanotubes serpentine dynamics formation. These S-like nanostructures consist of a series of parallel and straight nanotube segments connected by alternating U-turn shaped curves. Nanotube serpentines were experimentally synthesized and reported in recent years, but up to now no atomistic simulations have been carried out to address the dynamics of formation of these structures. We have carried out fully atomistic molecular dynamics simulations in the framework of classical mechanics with a standard molecular force field. Multi-million atoms structures formed by stepped substrates with a carbon nanotube (about 1 micron in length) placed on top of them have been considered in our simulations. A force is applied to the upper part of the tube during a short period of time and then turned off and the system set free to evolve in time. Our results showed that these conditions are sufficient to form robust serpentines and validate the general features of the ‘falling spaghetti mechanism’ previously proposed to explain their formation.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
In this work we present preliminary results from molecular dynamics simulations for carbon nanotubes serpentine dynamics formation. These S-like nanostructures consist of a series of parallel and straight nanotube segments connected by alternating U-turn shaped curves. Nanotube serpentines were experimentally synthesized and reported in recent years, but up to now no atomistic simulations have been carried out to address the dynamics of formation of these structures. We have carried out fully atomistic molecular dynamics simulations in the framework of classical mechanics with a standard molecular force field. Multi-million atoms structures formed by stepped substrates with a carbon nanotube (about 1 micron in length) placed on top of them have been considered in our simulations. A force is applied to the upper part of the tube during a short period of time and then turned off and the system set free to evolve in time. Our results showed that these conditions are sufficient to form robust serpentines and validate the general features of the ‘falling spaghetti mechanism’ previously proposed to explain their formation.
120.
Legoas, SB; Dos Santos, RPB; Troche, KS; Coluci, VR; Galvao, DS
Ordered phases of encapsulated diamondoids into carbon nanotubes Journal Article
Em: Nanotechnology, vol. 22, não 31, pp. 315708, 2011.
@article{legoas2011ordered,
title = {Ordered phases of encapsulated diamondoids into carbon nanotubes},
author = {Legoas, SB and Dos Santos, RPB and Troche, KS and Coluci, VR and Galvao, DS},
url = {http://iopscience.iop.org/0957-4484/22/31/315708},
year = {2011},
date = {2011-01-01},
journal = {Nanotechnology},
volume = {22},
number = {31},
pages = {315708},
publisher = {IOP Publishing},
abstract = {Diamondoids are hydrogen-terminated nanosized diamond fragments that are present in petroleum crude oil at low concentrations. These fragments are found as oligomers of the smallest diamondoid, adamantane (C10H16). Due to their small size, diamondoids can be encapsulated into carbon nanotubes to form linear arrangements. We have investigated the encapsulation of diamondoids into single walled carbon nanotubes with diameters between 1.0 and 2.2 nm using fully atomistic simulations. We performed classical molecular dynamics and energy minimizations calculations to determine the most stable configurations. We observed molecular ordered phases (e.g. double, triple, 4- and 5-stranded helices) for the encapsulation of adamantane, diamantane, and dihydroxy diamantane. Our results also indicate that the functionalization of diamantane with hydroxyl groups can lead to an improvement on the molecular packing factor when compared to non-functionalized compounds. Comparisons to hard-sphere models revealed differences, especially when more asymmetrical diamondoids were considered. For larger diamondoids (i.e., adamantane tetramers), we have not observed long-range ordering but only a tendency to form incomplete helical structures. Our calculations predict that thermally stable (at least up to room temperature) complex ordered phases of diamondoids can be formed through encapsulation into carbon nanotubes.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Diamondoids are hydrogen-terminated nanosized diamond fragments that are present in petroleum crude oil at low concentrations. These fragments are found as oligomers of the smallest diamondoid, adamantane (C10H16). Due to their small size, diamondoids can be encapsulated into carbon nanotubes to form linear arrangements. We have investigated the encapsulation of diamondoids into single walled carbon nanotubes with diameters between 1.0 and 2.2 nm using fully atomistic simulations. We performed classical molecular dynamics and energy minimizations calculations to determine the most stable configurations. We observed molecular ordered phases (e.g. double, triple, 4- and 5-stranded helices) for the encapsulation of adamantane, diamantane, and dihydroxy diamantane. Our results also indicate that the functionalization of diamantane with hydroxyl groups can lead to an improvement on the molecular packing factor when compared to non-functionalized compounds. Comparisons to hard-sphere models revealed differences, especially when more asymmetrical diamondoids were considered. For larger diamondoids (i.e., adamantane tetramers), we have not observed long-range ordering but only a tendency to form incomplete helical structures. Our calculations predict that thermally stable (at least up to room temperature) complex ordered phases of diamondoids can be formed through encapsulation into carbon nanotubes.
Desculpe, nenhuma publicação.
