http://scholar.google.com/citations?hl=en&user=95SvbM8AAAAJ
21.
Nakar, Dekel; Gordeev, Georgy; Machado, Leonardo D.; Popovitz-Biro, Ronit; Rechav, Katya; Oliveira, Eliezer F.; Kusch, Patryk; Jorio, Ado; Galvao, Douglas S.; Reich, Stephanie; Joselevich, Ernesto
Few-Wall Carbon Nanotube Coils (under review) Journal Article
Em: 2019.
@article{Nakar2019,
title = {Few-Wall Carbon Nanotube Coils (under review)},
author = {Dekel Nakar and Georgy Gordeev and Leonardo D. Machado and Ronit Popovitz-Biro and Katya Rechav and Eliezer F. Oliveira and Patryk Kusch and Ado Jorio and Douglas S. Galvao and Stephanie Reich and Ernesto Joselevich},
year = {2019},
date = {2019-01-01},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
22.
Pedro AS Autreto Eliezer F Oliveira, Cristiano F Woellner
Mechanical Properties of Protomene: A Molecular Dynamics Investigation Online
2018, (preprint arXiv:1810.09924v1 ).
@online{Oliveira2018g,
title = {Mechanical Properties of Protomene: A Molecular Dynamics Investigation},
author = {Eliezer F Oliveira, Pedro AS Autreto, Cristiano F Woellner, Douglas S Galvao},
url = {https://arxiv.org/abs/1810.09924},
year = {2018},
date = {2018-10-23},
abstract = {Recently, a new class of carbon allotrope called protomene was proposed. This new structure is
composed of sp2 and sp3 carbon-bonds. Topologically, protomene can be considered as an sp3
carbon structure (~80% of this bond type) doped by sp2 carbons. First-principles simulations
have shown that protomene presents an electronic bandgap of ~3.4 eV. However, up to now,
its mechanical properties have not been investigated. In this work, we have investigated
protomene mechanical behavior under tensile strain through fully atomistic reactive
molecular dynamics simulations using the ReaxFF force field, as available in the LAMMPS
code. At room temperature, our results show that the protomene is very stable and the
obtained ultimate strength and ultimate stress indicates an anisotropic behavior. The highest
ultimate strength was obtained for the x-direction, with a value of ~110 GPa. As for the ultimate
strain, the highest one was for the z-direction (~25% of strain) before protomene mechanical
fracture.},
note = {preprint arXiv:1810.09924v1 },
keywords = {},
pubstate = {published},
tppubtype = {online}
}
Recently, a new class of carbon allotrope called protomene was proposed. This new structure is
composed of sp2 and sp3 carbon-bonds. Topologically, protomene can be considered as an sp3
carbon structure (~80% of this bond type) doped by sp2 carbons. First-principles simulations
have shown that protomene presents an electronic bandgap of ~3.4 eV. However, up to now,
its mechanical properties have not been investigated. In this work, we have investigated
protomene mechanical behavior under tensile strain through fully atomistic reactive
molecular dynamics simulations using the ReaxFF force field, as available in the LAMMPS
code. At room temperature, our results show that the protomene is very stable and the
obtained ultimate strength and ultimate stress indicates an anisotropic behavior. The highest
ultimate strength was obtained for the x-direction, with a value of ~110 GPa. As for the ultimate
strain, the highest one was for the z-direction (~25% of strain) before protomene mechanical
fracture.
composed of sp2 and sp3 carbon-bonds. Topologically, protomene can be considered as an sp3
carbon structure (~80% of this bond type) doped by sp2 carbons. First-principles simulations
have shown that protomene presents an electronic bandgap of ~3.4 eV. However, up to now,
its mechanical properties have not been investigated. In this work, we have investigated
protomene mechanical behavior under tensile strain through fully atomistic reactive
molecular dynamics simulations using the ReaxFF force field, as available in the LAMMPS
code. At room temperature, our results show that the protomene is very stable and the
obtained ultimate strength and ultimate stress indicates an anisotropic behavior. The highest
ultimate strength was obtained for the x-direction, with a value of ~110 GPa. As for the ultimate
strain, the highest one was for the z-direction (~25% of strain) before protomene mechanical
fracture.
23.
Alexandre F. Fonseca, Douglas S. Galvao
Self-tearing and self-peeling of folded graphene nanoribbons Online
2018, (preprint arXiv:1808.08872).
@online{Fonseca2018d,
title = { Self-tearing and self-peeling of folded graphene nanoribbons},
author = {Alexandre F. Fonseca, Douglas S. Galvao
},
url = {https://arxiv.org/abs/1808.08872},
year = {2018},
date = {2018-08-27},
abstract = {A recent experimental study showed that an induced folded flap of graphene can spontaneously drive itself its tearing and peeling off a substrate, thus producing long, micrometer sized, regular trapezoidal-shaped folded graphene nanoribbons. As long as the size of the graphene flaps is above a threshold value, the 'tug of war' between the forces of adhesion of graphene-graphene and graphene-substrate, flexural strain of folded region and carbon-carbon (C-C) covalent bonds favor the self-tearing and self-peeling off process. As the detailed information regarding the atomic scale mechanism involved in the process remains not fully understood, we carried out atomistic reactive molecular dynamics simulations to address some features of the process. We show that large thermal fluctuations can prevent the process by increasing the probability of chemical reactions between carbon dangling bonds of adjacent graphene layers. The effects of the strength of attraction between graphene and the substrate on the ribbon growth velocities at the early stages of the phenomenon were also investigated. Structures with initial armchair crack-edges were observed to form more uniform cuts than those having initial zigzag ones. Our results are of importance to help set up new experiments on this phenomenon, especially with samples with nanoscale sized cuts.},
note = {preprint arXiv:1808.08872},
keywords = {},
pubstate = {published},
tppubtype = {online}
}
A recent experimental study showed that an induced folded flap of graphene can spontaneously drive itself its tearing and peeling off a substrate, thus producing long, micrometer sized, regular trapezoidal-shaped folded graphene nanoribbons. As long as the size of the graphene flaps is above a threshold value, the 'tug of war' between the forces of adhesion of graphene-graphene and graphene-substrate, flexural strain of folded region and carbon-carbon (C-C) covalent bonds favor the self-tearing and self-peeling off process. As the detailed information regarding the atomic scale mechanism involved in the process remains not fully understood, we carried out atomistic reactive molecular dynamics simulations to address some features of the process. We show that large thermal fluctuations can prevent the process by increasing the probability of chemical reactions between carbon dangling bonds of adjacent graphene layers. The effects of the strength of attraction between graphene and the substrate on the ribbon growth velocities at the early stages of the phenomenon were also investigated. Structures with initial armchair crack-edges were observed to form more uniform cuts than those having initial zigzag ones. Our results are of importance to help set up new experiments on this phenomenon, especially with samples with nanoscale sized cuts.
24.
Chipara, A. C.; Tsafack, T.; Owuor, P. S.; Yeon, J.; Junkermeier, C. E.; van Duin, A. C. T.; Bhowmick, S.; Asif, S. A. S.; Radhakrishnan, S.; Park, J. H.; Brunetto, G.; Kaipparettu, B. A.; Galvão, D. S.; Chipara, M.; Lou, J.; Tsang, H. H.; Dubey, M.; Vajtai, R.; Tiwary, C. S.; Ajayan, P. M.
Underwater Adhesive using Solid–liquid Polymer Mixes Journal Article
Em: Materials Today Chemistry, vol. 9, pp. 149-157, 2018.
@article{Chipara2018,
title = {Underwater Adhesive using Solid–liquid Polymer Mixes},
author = {A.C. Chipara and T. Tsafack and P.S. Owuor and J. Yeon and C.E. Junkermeier and A.C.T. van Duin and S. Bhowmick and S.A.S. Asif and S. Radhakrishnan and J.H. Park and G. Brunetto and B.A. Kaipparettu and D.S. Galvão and M. Chipara and J. Lou and H.H. Tsang and M. Dubey and R. Vajtai and C.S. Tiwary and P.M. Ajayan},
url = {https://www.sciencedirect.com/science/article/pii/S2468519418301423#appsec1},
doi = {10.1016/j.mtchem.2018.07.002},
year = {2018},
date = {2018-08-08},
journal = {Materials Today Chemistry},
volume = {9},
pages = {149-157},
abstract = {Instantaneous adhesion between different materials is a requirement for several applications ranging from electronics to biomedicine. Approaches such as surface patterning, chemical cross-linking, surface modification, and chemical synthesis have been adopted to generate temporary adhesion between various materials and surfaces. Because of the lack of curing times, temporary adhesives are instantaneous, a useful property for specific applications that need quick bonding. However, to this day, temporary adhesives have been mainly demonstrated under dry conditions and do not work well in submerged or humid environments. Furthermore, most rely on chemical bonds resulting from strong interactions with the substrate such as acrylate based. This work demonstrates the synthesis of a universal amphibious adhesive solely by combining solid polytetrafluoroethylene (PTFE) and liquid polydimethylsiloxane (PDMS) polymers. While the dipole-dipole interactions are induced by a large electronegativity difference between fluorine atoms in PTFE and hydrogen atoms in PDMS, strong surface wetting allows the proposed adhesive to fully coat both substrates and PTFE particles, thereby maximizing the interfacial chemistry. The two-phase solid–liquid polymer system displays adhesive characteristics applicable both in air and water, and enables joining of a wide range of similar and dissimilar materials (glasses, metals, ceramics, papers, and biomaterials). The adhesive exhibits excellent mechanical properties for the joints between various surfaces as observed in lap shear testing, T-peel testing, and tensile testing. The proposed biocompatible adhesive can also be reused multiple times in different dry and wet environments. Additionally, we have developed a new reactive force field parameterization and used it in our molecular dynamics simulations to validate the adhesive nature of the mixed polymer system with different surfaces. This simple amphibious adhesive could meet the need for a universal glue that performs well with a number of materials for a wide range of conditions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Instantaneous adhesion between different materials is a requirement for several applications ranging from electronics to biomedicine. Approaches such as surface patterning, chemical cross-linking, surface modification, and chemical synthesis have been adopted to generate temporary adhesion between various materials and surfaces. Because of the lack of curing times, temporary adhesives are instantaneous, a useful property for specific applications that need quick bonding. However, to this day, temporary adhesives have been mainly demonstrated under dry conditions and do not work well in submerged or humid environments. Furthermore, most rely on chemical bonds resulting from strong interactions with the substrate such as acrylate based. This work demonstrates the synthesis of a universal amphibious adhesive solely by combining solid polytetrafluoroethylene (PTFE) and liquid polydimethylsiloxane (PDMS) polymers. While the dipole-dipole interactions are induced by a large electronegativity difference between fluorine atoms in PTFE and hydrogen atoms in PDMS, strong surface wetting allows the proposed adhesive to fully coat both substrates and PTFE particles, thereby maximizing the interfacial chemistry. The two-phase solid–liquid polymer system displays adhesive characteristics applicable both in air and water, and enables joining of a wide range of similar and dissimilar materials (glasses, metals, ceramics, papers, and biomaterials). The adhesive exhibits excellent mechanical properties for the joints between various surfaces as observed in lap shear testing, T-peel testing, and tensile testing. The proposed biocompatible adhesive can also be reused multiple times in different dry and wet environments. Additionally, we have developed a new reactive force field parameterization and used it in our molecular dynamics simulations to validate the adhesive nature of the mixed polymer system with different surfaces. This simple amphibious adhesive could meet the need for a universal glue that performs well with a number of materials for a wide range of conditions.
25.
Oliveira, Eliezer F.; Autreto, Pedro A. S.; Woellner, Cristiano F.; Galvao, Douglas S.
On the mechanical properties of novamene: a fully atomistic molecular dynamics and DFT investigation Journal Article
Em: Carbon, vol. 139, pp. 782-788, 2018.
@article{Oliveira2018e,
title = {On the mechanical properties of novamene: a fully atomistic molecular dynamics and DFT investigation},
author = {Eliezer F. Oliveira and Pedro A. S. Autreto and Cristiano F. Woellner and Douglas S. Galvao},
url = {https://www.sciencedirect.com/science/article/pii/S0008622318306882?via%3Dihub#appsec1},
doi = {10.1016/j.carbon.2018.07.038},
year = {2018},
date = {2018-07-19},
journal = {Carbon},
volume = {139},
pages = {782-788},
abstract = {We have investigated through fully atomistic reactive molecular dynamics and density functional theory simulations, the mechanical properties and fracture dynamics of single-ringed novamene (1R-novamene), a new 3D carbon allotrope structure recently proposed. Our results showed that 1R-novamene is an anisotropic structure with relation to tensile deformation. Although 1R-novamente shares some mechanical features with other carbon allotropes, it also exhibits distinct ones, such as, extensive structural reconstructions. 1R-novamene presents ultimate strength (∼100 GPa) values lower than other carbon allotropes, but it has the highest ultimate strain along the z-direction (∼22.5%). Although the Young's modulus (∼600 GPa) and ultimate strength values are smaller than for other carbon allotropes, they still outperform other materials, such as for example silicon, steel or titanium alloys. With relation to the fracture dynamics, 1R-novamene is again anisotropic with the fracture/crack propagation originating from deformed heptagons and pentagons for x and y directions and broken sp3 bonds connecting structural planes. Another interesting feature is the formation of multiple and long carbon linear chains in the final fracture stages.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We have investigated through fully atomistic reactive molecular dynamics and density functional theory simulations, the mechanical properties and fracture dynamics of single-ringed novamene (1R-novamene), a new 3D carbon allotrope structure recently proposed. Our results showed that 1R-novamene is an anisotropic structure with relation to tensile deformation. Although 1R-novamente shares some mechanical features with other carbon allotropes, it also exhibits distinct ones, such as, extensive structural reconstructions. 1R-novamene presents ultimate strength (∼100 GPa) values lower than other carbon allotropes, but it has the highest ultimate strain along the z-direction (∼22.5%). Although the Young's modulus (∼600 GPa) and ultimate strength values are smaller than for other carbon allotropes, they still outperform other materials, such as for example silicon, steel or titanium alloys. With relation to the fracture dynamics, 1R-novamene is again anisotropic with the fracture/crack propagation originating from deformed heptagons and pentagons for x and y directions and broken sp3 bonds connecting structural planes. Another interesting feature is the formation of multiple and long carbon linear chains in the final fracture stages.
26.
Gautam, Chandkiram; Chakravarty, Dibyendu; Woellner, Cristiano F.; Mishra, Vijay Kumar; Ahamad, Naseer; Gautam, Amarendra; Ozden, Sehmus; Jose, Sujin; Biradar, Santosh Kumar; Vajtai, Robert; Trivedi, Ritu; Tiwary, Chandra Sekhar; Galvao, Douglas S.; Ajayan, P. M.
Synthesis and 3D Interconnected Nanostructured h-BN-Based Biocomposites by Low-Temperature Plasma Sintering: Bone Regeneration Applications Journal Article
Em: ACS Omega, vol. 3, no. 6, pp. 6013–6021, 2018.
@article{Gautam2018,
title = {Synthesis and 3D Interconnected Nanostructured h-BN-Based Biocomposites by Low-Temperature Plasma Sintering: Bone Regeneration Applications},
author = {Chandkiram Gautam and Dibyendu Chakravarty and Cristiano F. Woellner and Vijay Kumar Mishra and Naseer Ahamad and Amarendra Gautam and Sehmus Ozden and Sujin Jose and Santosh Kumar Biradar and Robert Vajtai and Ritu Trivedi and Chandra Sekhar Tiwary and Douglas S. Galvao and P.M. Ajayan},
url = {https://pubs.acs.org/doi/abs/10.1021/acsomega.8b00707},
doi = {10.1021/acsomega.8b00707},
year = {2018},
date = {2018-06-05},
journal = {ACS Omega},
volume = {3},
number = {6},
pages = {6013–6021},
abstract = {Recent advances and demands in biomedical applications drive a large amount of research to synthesize easily scalable low-density, high-strength, and wear-resistant biomaterials. The chemical inertness with low density combined with high strength makes h-BN one of the promising materials for such application. In this work, three-dimensional hexagonal boron nitride (h-BN) interconnected with boron trioxide (B2O3) was prepared by easily scalable and energy efficient spark plasma sintering (SPS) process. The composite structure shows significant densification (1.6–1.9 g/cm3) and high surface area (0.97–14.5 m2/g) at an extremely low SPS temperature of 250 °C. A high compressive strength of 291 MPa with a reasonably good wear resistance was obtained for the composite structure. The formation of strong covalent bonds between h-BN and B2O3 was formulated and established by molecular dynamics simulation. The composite showed significant effect on cell viability/proliferation. It shows a high mineralized nodule formation over the control, which suggests its use as a possible osteogenic agent in bone formation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Recent advances and demands in biomedical applications drive a large amount of research to synthesize easily scalable low-density, high-strength, and wear-resistant biomaterials. The chemical inertness with low density combined with high strength makes h-BN one of the promising materials for such application. In this work, three-dimensional hexagonal boron nitride (h-BN) interconnected with boron trioxide (B2O3) was prepared by easily scalable and energy efficient spark plasma sintering (SPS) process. The composite structure shows significant densification (1.6–1.9 g/cm3) and high surface area (0.97–14.5 m2/g) at an extremely low SPS temperature of 250 °C. A high compressive strength of 291 MPa with a reasonably good wear resistance was obtained for the composite structure. The formation of strong covalent bonds between h-BN and B2O3 was formulated and established by molecular dynamics simulation. The composite showed significant effect on cell viability/proliferation. It shows a high mineralized nodule formation over the control, which suggests its use as a possible osteogenic agent in bone formation.
27.
Balan, Aravind Puthirath; Radhakrishnan, Sruthi; Woellner, Cristiano F.; Sinha, Shyam K.; Deng, Liangzi; de los Reyes, Carlos; Rao, Manmadha; Paulose, Maggie; Neupane, Ram; Vajtai, Robert; Chu, Ching-Wu; Costin, Gelu; Galvao, Douglas S.; Marti, Angel A.; van Aken, Peter; Varghese, Oomman K; Tiwary, Chandra Sekhar; Anantharaman, M R; Ajayan, Pulickel M
Exfoliation of a non-van der Waals material from iron ore hematite Journal Article
Em: Nature Nanotechnology, vol. 13, pp. 602–610, 2018.
@article{Balan2018,
title = {Exfoliation of a non-van der Waals material from iron ore hematite},
author = {Aravind Puthirath Balan and Sruthi Radhakrishnan and Cristiano F. Woellner and Shyam K. Sinha and Liangzi Deng and Carlos de los Reyes and Manmadha Rao and Maggie Paulose and Ram Neupane and Robert Vajtai and Ching-Wu Chu and Gelu Costin and Douglas S. Galvao and Angel A. Marti and Peter van Aken and Oomman K Varghese and Chandra Sekhar Tiwary and M R Anantharaman and Pulickel M Ajayan
},
url = {https://www.nature.com/articles/s41565-018-0134-y},
year = {2018},
date = {2018-05-07},
journal = {Nature Nanotechnology},
volume = {13},
pages = {602--610},
abstract = {With the advent of graphene, the most studied of all two-dimensional materials, many inorganic analogues have been synthesized and are being exploited for novel applications. Several approaches have been used to obtain large-grain, high-quality materials. Naturally occurring ores, for example, are the best precursors for obtaining highly ordered and large-grain atomic layers by exfoliation. Here, we demonstrate a new two-dimensional material ‘hematene’ obtained from natural iron ore hematite (α-Fe2O3), which is isolated by means of liquid exfoliation. The two-dimensional morphology of hematene is confirmed by transmission electron microscopy. Magnetic measurements together with density functional theory calculations confirm the ferromagnetic order in hematene while its parent form exhibits antiferromagnetic order. When loaded on titania nanotube arrays, hematene exhibits enhanced visible light photocatalytic activity. Our study indicates that photogenerated electrons can be transferred from hematene to titania despite a band alignment unfavourable for charge transfer.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
With the advent of graphene, the most studied of all two-dimensional materials, many inorganic analogues have been synthesized and are being exploited for novel applications. Several approaches have been used to obtain large-grain, high-quality materials. Naturally occurring ores, for example, are the best precursors for obtaining highly ordered and large-grain atomic layers by exfoliation. Here, we demonstrate a new two-dimensional material ‘hematene’ obtained from natural iron ore hematite (α-Fe2O3), which is isolated by means of liquid exfoliation. The two-dimensional morphology of hematene is confirmed by transmission electron microscopy. Magnetic measurements together with density functional theory calculations confirm the ferromagnetic order in hematene while its parent form exhibits antiferromagnetic order. When loaded on titania nanotube arrays, hematene exhibits enhanced visible light photocatalytic activity. Our study indicates that photogenerated electrons can be transferred from hematene to titania despite a band alignment unfavourable for charge transfer.
28.
Bizao, Rafael A; Machado, Leonardo D; de Sousa, Jose M; Pugno, Nicola M; Galvao, Douglas S
Scale Effects on the Ballistic Penetration of Graphene Sheets Journal Article
Em: Nature Scientific Reports, vol. 8, pp. 6750, 2018.
@article{Bizao2018,
title = {Scale Effects on the Ballistic Penetration of Graphene Sheets},
author = {Bizao, Rafael A and Machado, Leonardo D and de Sousa, Jose M and Pugno, Nicola M and Galvao, Douglas S},
url = {https://www.nature.com/articles/s41598-018-25050-2},
doi = {doi:10.1038/s41598-018-25050-2},
year = {2018},
date = {2018-04-30},
journal = {Nature Scientific Reports},
volume = {8},
pages = {6750},
abstract = {Carbon nanostructures are promising ballistic protection materials, due to their low density and excellent mechanical properties. Recent experimental and computational investigations on the behavior of graphene under impact conditions revealed exceptional energy absorption properties as well. However, the reported numerical and experimental values differ by an order of magnitude. In this work, we combined numerical and analytical modeling to address this issue. In the numerical part, we employed reactive molecular dynamics to carry out ballistic tests on single, double, and triple-layered graphene sheets. We used velocity values within the range tested in experiments. Our numerical and the experimental results were used to determine parameters for a scaling law. We find that the specific penetration energy decreases as the number of layers (N) increases, from ∼15 MJ/kg for N = 1 to ∼0.9 MJ/kg for N = 350, for an impact velocity of 900 m/s. These values are in good agreement with simulations and experiments, within the entire range of N values for which data is presently available. Scale effects explain the apparent discrepancy between simulations and experiments.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Carbon nanostructures are promising ballistic protection materials, due to their low density and excellent mechanical properties. Recent experimental and computational investigations on the behavior of graphene under impact conditions revealed exceptional energy absorption properties as well. However, the reported numerical and experimental values differ by an order of magnitude. In this work, we combined numerical and analytical modeling to address this issue. In the numerical part, we employed reactive molecular dynamics to carry out ballistic tests on single, double, and triple-layered graphene sheets. We used velocity values within the range tested in experiments. Our numerical and the experimental results were used to determine parameters for a scaling law. We find that the specific penetration energy decreases as the number of layers (N) increases, from ∼15 MJ/kg for N = 1 to ∼0.9 MJ/kg for N = 350, for an impact velocity of 900 m/s. These values are in good agreement with simulations and experiments, within the entire range of N values for which data is presently available. Scale effects explain the apparent discrepancy between simulations and experiments.
29.
Ygor M.; Galvao Jaques, Douglas S.
Structural Properties of Nanodroplets Impacting Graphene at High Velocities Online
2018, (Preprint ArXiv:1804.07784).
@online{Jaques2018d,
title = {Structural Properties of Nanodroplets Impacting Graphene at High Velocities},
author = {Jaques, Ygor M.; Galvao, Douglas S.},
url = {https://arxiv.org/abs/1804.07784},
year = {2018},
date = {2018-04-24},
abstract = {We report here a fully atomistic molecular dynamics study on the dynamics of impact of water
nanodroplets (50, 100 and 120 Å of diameter) at high velocity (from 100 up to 1000 m/s) against
graphene targets. Our results show that tuning graphene wettability (through parameter changes)
significantly affects the structural and dynamical aspects of the nanodroplets. We identified three
ranges of velocities with distinct characteristics, from simple deposition of the droplet to
spreading with rebound and finally fragmentation. At Weber numbers lower than 10, the droplets
maintain a steady spreading factor independent of size. After this threshold value, the spread
rapidly grows with increasing Weber numbers. A more hydrophilic graphene surface increases
the spreading values, due to stronger solid-liquid interactions. Nevertheless, droplet size also
influences the fragmentation threshold, as an increased number of molecules make it easier for
the whole droplet overcomes the surface repulsion. },
note = {Preprint ArXiv:1804.07784},
keywords = {},
pubstate = {published},
tppubtype = {online}
}
We report here a fully atomistic molecular dynamics study on the dynamics of impact of water
nanodroplets (50, 100 and 120 Å of diameter) at high velocity (from 100 up to 1000 m/s) against
graphene targets. Our results show that tuning graphene wettability (through parameter changes)
significantly affects the structural and dynamical aspects of the nanodroplets. We identified three
ranges of velocities with distinct characteristics, from simple deposition of the droplet to
spreading with rebound and finally fragmentation. At Weber numbers lower than 10, the droplets
maintain a steady spreading factor independent of size. After this threshold value, the spread
rapidly grows with increasing Weber numbers. A more hydrophilic graphene surface increases
the spreading values, due to stronger solid-liquid interactions. Nevertheless, droplet size also
influences the fragmentation threshold, as an increased number of molecules make it easier for
the whole droplet overcomes the surface repulsion.
nanodroplets (50, 100 and 120 Å of diameter) at high velocity (from 100 up to 1000 m/s) against
graphene targets. Our results show that tuning graphene wettability (through parameter changes)
significantly affects the structural and dynamical aspects of the nanodroplets. We identified three
ranges of velocities with distinct characteristics, from simple deposition of the droplet to
spreading with rebound and finally fragmentation. At Weber numbers lower than 10, the droplets
maintain a steady spreading factor independent of size. After this threshold value, the spread
rapidly grows with increasing Weber numbers. A more hydrophilic graphene surface increases
the spreading values, due to stronger solid-liquid interactions. Nevertheless, droplet size also
influences the fragmentation threshold, as an increased number of molecules make it easier for
the whole droplet overcomes the surface repulsion.
30.
Thakur P.; Woellner Yadav, Cristiano F. ; Sinha
Liquid Exfoliation of Icosahedral Quasicrystals Journal Article
Em: Advanced Functional Materials, vol. 2018, pp. 1801181, 2018.
@article{Yadav2018b,
title = {Liquid Exfoliation of Icosahedral Quasicrystals},
author = {Yadav, Thakur P.; Woellner, Cristiano F.; Sinha, Shyam K.; Sharifi, Tiva; Apte, Amey; Mukhopadhyay, Nilay K.; Srivastava, Onkar N.; Vajtai, Robert; Galvao, Douglas S.; Tiwary, Chandra S.; Ajayan, Pulickel M.},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.201801181?campaign=wolearlyview},
doi = {DOI: 10.1002/adfm.201801181},
year = {2018},
date = {2018-04-24},
journal = {Advanced Functional Materials},
volume = {2018},
pages = {1801181},
abstract = {The realization of quasicrystals has attracted a considerable attention due to their unusual structures and properties. The concept of quasicrystals in the atomically thin materials is even more appealing due to the in-plane cova-lent bonds and weak interlayer interactions. Here, it is demonstrated that 2D quasicrystals can be created/isolated from bulk phases because of long-range interlayer ordered aperiodic arrangements. An ultrasonication-assisted exfolia-tion of polygrained icosahedral Al–Pd–Mn quasicrystals at room temperature shows the formation of a large area of mono- and few layers in threefold qua-sicrystalline plane. The formation of these layers from random grain orientation consistently indicates that the threefold plane is most stable in comparison to the twofold and fivefold planes in icosahedral clusters. The above experimental observations are further supported with help of theoretical simulations. The mono- and few-layered aperiodic planes render plentiful active sites for the catalysis of hydrogen evolution reaction. The threefold 2D quasicrystalline plane exhibits a hydrogen evolution reaction overpotential of ≈100 mV (160 times less than bulk counterpart) and long-term durability. These systems constitute the first demonstration of quasicrystalline monolayer ordering in a free-standing thin layer without requiring the support of periodic or aperiodic substrate.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The realization of quasicrystals has attracted a considerable attention due to their unusual structures and properties. The concept of quasicrystals in the atomically thin materials is even more appealing due to the in-plane cova-lent bonds and weak interlayer interactions. Here, it is demonstrated that 2D quasicrystals can be created/isolated from bulk phases because of long-range interlayer ordered aperiodic arrangements. An ultrasonication-assisted exfolia-tion of polygrained icosahedral Al–Pd–Mn quasicrystals at room temperature shows the formation of a large area of mono- and few layers in threefold qua-sicrystalline plane. The formation of these layers from random grain orientation consistently indicates that the threefold plane is most stable in comparison to the twofold and fivefold planes in icosahedral clusters. The above experimental observations are further supported with help of theoretical simulations. The mono- and few-layered aperiodic planes render plentiful active sites for the catalysis of hydrogen evolution reaction. The threefold 2D quasicrystalline plane exhibits a hydrogen evolution reaction overpotential of ≈100 mV (160 times less than bulk counterpart) and long-term durability. These systems constitute the first demonstration of quasicrystalline monolayer ordering in a free-standing thin layer without requiring the support of periodic or aperiodic substrate.
31.
Marco AE Maria Celina M Miyazaki, Daiane Damasceno Borges
Experimental and computational investigation of reduced graphene oxide nanoplatelets stabilized in poly(styrene sulfonate) sodium salt Journal Article
Em: Journal of Materials Science, vol. 53, no. 14, pp. 10049-10056, 2018.
@article{Miyazaki2018,
title = {Experimental and computational investigation of reduced graphene oxide nanoplatelets stabilized in poly(styrene sulfonate) sodium salt},
author = {Celina M Miyazaki, Marco AE Maria, Daiane Damasceno Borges, Cristiano F Woellner, Gustavo Brunetto, Alexandre F Fonseca, Carlos JL Constantino, Marcelo A Pereira-da-Silva, Abner de Siervo, Douglas S Galvao, Antonio Riul Jr},
url = {https://link.springer.com/article/10.1007/s10853-018-2325-1},
doi = {https://link.springer.com/article/10.1007/s10853-018-2325-1},
year = {2018},
date = {2018-04-19},
journal = {Journal of Materials Science},
volume = {53},
number = {14},
pages = {10049-10056},
abstract = {The production of large-area interfaces and the use of scalable methods to build up
designed nanostructures generating advanced functional properties are of high
interest for many materials science applications. Nevertheless, large-area coverage
remains a major problem even for pristine graphene, and here we present a hybrid,
composite graphene-like material soluble in water that can be exploited in many
areas such as energy storage, electrodes fabrication, selective membranes and
biosensing. Graphene oxide (GO) was produced by the traditional Hummers’
method being further reduced in the presence of poly(styrene sulfonate) sodium salt
(PSS), thus creating stable reduced graphene oxide (rGO) nanoplatelets wrapped by
PSS (GPSS). Molecular dynamics simulations were carried out to further clarify the
interactions between PSS molecules and rGO nanoplatelets, with calculations
supported by Fourier transform infrared spectroscopy analysis. The intermolecular
forces between rGO nanoplatelets and PSS lead to the formation of a hybrid material
(GPSS) stabilized by van der Waals forces, allowing the fabrication of high-quality
layer-by-layer (LbL) films with poly(allylamine hydrochloride) (PAH). Raman and
electrical characterizations corroborated the successful modifications in the electronic
structures from GO to GPSS after the chemical treatment, resulting in (PAH/
GPSS) LbL films four orders of magnitude more conductive than (PAH/GO).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The production of large-area interfaces and the use of scalable methods to build up
designed nanostructures generating advanced functional properties are of high
interest for many materials science applications. Nevertheless, large-area coverage
remains a major problem even for pristine graphene, and here we present a hybrid,
composite graphene-like material soluble in water that can be exploited in many
areas such as energy storage, electrodes fabrication, selective membranes and
biosensing. Graphene oxide (GO) was produced by the traditional Hummers’
method being further reduced in the presence of poly(styrene sulfonate) sodium salt
(PSS), thus creating stable reduced graphene oxide (rGO) nanoplatelets wrapped by
PSS (GPSS). Molecular dynamics simulations were carried out to further clarify the
interactions between PSS molecules and rGO nanoplatelets, with calculations
supported by Fourier transform infrared spectroscopy analysis. The intermolecular
forces between rGO nanoplatelets and PSS lead to the formation of a hybrid material
(GPSS) stabilized by van der Waals forces, allowing the fabrication of high-quality
layer-by-layer (LbL) films with poly(allylamine hydrochloride) (PAH). Raman and
electrical characterizations corroborated the successful modifications in the electronic
structures from GO to GPSS after the chemical treatment, resulting in (PAH/
GPSS) LbL films four orders of magnitude more conductive than (PAH/GO).
designed nanostructures generating advanced functional properties are of high
interest for many materials science applications. Nevertheless, large-area coverage
remains a major problem even for pristine graphene, and here we present a hybrid,
composite graphene-like material soluble in water that can be exploited in many
areas such as energy storage, electrodes fabrication, selective membranes and
biosensing. Graphene oxide (GO) was produced by the traditional Hummers’
method being further reduced in the presence of poly(styrene sulfonate) sodium salt
(PSS), thus creating stable reduced graphene oxide (rGO) nanoplatelets wrapped by
PSS (GPSS). Molecular dynamics simulations were carried out to further clarify the
interactions between PSS molecules and rGO nanoplatelets, with calculations
supported by Fourier transform infrared spectroscopy analysis. The intermolecular
forces between rGO nanoplatelets and PSS lead to the formation of a hybrid material
(GPSS) stabilized by van der Waals forces, allowing the fabrication of high-quality
layer-by-layer (LbL) films with poly(allylamine hydrochloride) (PAH). Raman and
electrical characterizations corroborated the successful modifications in the electronic
structures from GO to GPSS after the chemical treatment, resulting in (PAH/
GPSS) LbL films four orders of magnitude more conductive than (PAH/GO).
32.
Eliezer F.; Autreto Oliveira, Pedro A. S. ; Woellner
On the mechanical properties of novamene: a fully atomistic molecular dynamics and DFT investigation Online
2018, (preprint ArXiv:1804.07215).
@online{Oliveira2018f,
title = {On the mechanical properties of novamene: a fully atomistic molecular dynamics and DFT investigation},
author = {Oliveira, Eliezer F.; Autreto, Pedro A. S.; Woellner, Cristiano F.; Galvao, Douglas S.},
url = {https://arxiv.org/abs/1804.07215},
year = {2018},
date = {2018-04-19},
abstract = {We have investigated through fully atomistic reactive molecular dynamics and DFT simulations, the mechanical properties and fracture dynamics of novamene, a new 3D carbon allotrope structure recently proposed. Our results showed that novamene is an anisotropic structure with relation to tensile deformation. Although novamente shares some mechanical features with other carbon allotropes, it also exhibits distinct ones, such as, extensive structural reconstructions (self-healing effect). Novamene presents ultimate strength (~ 100 GPa) values lower than other carbon allotropes, but it has the highest ultimate strain along the z-direction (~ 22.5%). Although the Young's modulus (~ 600 GPa) and ultimate strength values are smaller than for other carbon allotropes, they still outperform other materials, such as for example silicon, steel or titanium alloys. With relation to the fracture dynamics, novamene is again anisotropic with the fracture/crack propagation originating from deformed heptagons and pentagons for x and y directions and broken sp3 bonds connecting structural planes. Another interesting feature is the formation of multiple and long carbon linear chains in the final fracture stages.},
note = {preprint ArXiv:1804.07215},
keywords = {},
pubstate = {published},
tppubtype = {online}
}
We have investigated through fully atomistic reactive molecular dynamics and DFT simulations, the mechanical properties and fracture dynamics of novamene, a new 3D carbon allotrope structure recently proposed. Our results showed that novamene is an anisotropic structure with relation to tensile deformation. Although novamente shares some mechanical features with other carbon allotropes, it also exhibits distinct ones, such as, extensive structural reconstructions (self-healing effect). Novamene presents ultimate strength (~ 100 GPa) values lower than other carbon allotropes, but it has the highest ultimate strain along the z-direction (~ 22.5%). Although the Young's modulus (~ 600 GPa) and ultimate strength values are smaller than for other carbon allotropes, they still outperform other materials, such as for example silicon, steel or titanium alloys. With relation to the fracture dynamics, novamene is again anisotropic with the fracture/crack propagation originating from deformed heptagons and pentagons for x and y directions and broken sp3 bonds connecting structural planes. Another interesting feature is the formation of multiple and long carbon linear chains in the final fracture stages.
33.
Devi, M. Manolata; Dolai, N.; S, S. Sreehala; Jaques, Y. M.; Galvao, Douglas S.; C.S.Tiwary,; Sharma, Sudhanshu; Biswas, Krishanu
Morphology Controlled Graphene-Alloy Nanoparticles Hybrids with Tunable Catalytic Activity Journal Article
Em: Nanoscale, vol. 10, pp. 8840-8850, 2018.
@article{Devi2018b,
title = {Morphology Controlled Graphene-Alloy Nanoparticles Hybrids with Tunable Catalytic Activity},
author = {M. Manolata Devi and N. Dolai and S. Sreehala S and Y. M. Jaques and Douglas S. Galvao and C.S.Tiwary and Sudhanshu Sharma and Krishanu Biswas},
url = {pubs.rsc.org/en/content/articlehtml/2018/nr/c7nr09688g},
doi = {10.1039/C7NR09688G},
year = {2018},
date = {2018-04-07},
journal = {Nanoscale},
volume = {10},
pages = {8840-8850},
abstract = {Selective oxidation of CO to CO2 using metallic or alloy nanoparticles as catalysts can solve two major problems of energy requirements and environmental pollution. Achieving 100% conversion efficiency at a lower temperature is a very important goal. This requires sustained efforts to design and develop novel supported catalysts containing alloy nanoparticles. In this regard, the decoration of nanoalloys with graphene, as a support for the catalyst, can provide a novel structure due to the synergic effect of the nanoalloys and graphene. Here, we demonstrate the effect of nano-PdPt (Palladium–Platinum) alloys having different morphologies on the catalytic efficiency for the selective oxidation of CO. Efforts were made to prepare different morphologies of PdPt alloy nanoparticles with the advantage of tuning the capping agent (PVP – polyvinyl pyrollidone) and decorating them on graphene sheets via the wet-chemical route. The catalytic activity of the G-PdPt hybrids with an urchin-like morphology has been found to be superior (higher % conversion at 135 °C lower) to that with a nanoflower morphology. The above experimental observations are further supported by molecular dynamics (MD) simulations.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Selective oxidation of CO to CO2 using metallic or alloy nanoparticles as catalysts can solve two major problems of energy requirements and environmental pollution. Achieving 100% conversion efficiency at a lower temperature is a very important goal. This requires sustained efforts to design and develop novel supported catalysts containing alloy nanoparticles. In this regard, the decoration of nanoalloys with graphene, as a support for the catalyst, can provide a novel structure due to the synergic effect of the nanoalloys and graphene. Here, we demonstrate the effect of nano-PdPt (Palladium–Platinum) alloys having different morphologies on the catalytic efficiency for the selective oxidation of CO. Efforts were made to prepare different morphologies of PdPt alloy nanoparticles with the advantage of tuning the capping agent (PVP – polyvinyl pyrollidone) and decorating them on graphene sheets via the wet-chemical route. The catalytic activity of the G-PdPt hybrids with an urchin-like morphology has been found to be superior (higher % conversion at 135 °C lower) to that with a nanoflower morphology. The above experimental observations are further supported by molecular dynamics (MD) simulations.
34.
Sandhya; Manimunda Susarla, Praveena; Morais Jaques
Deformation Mechanisms of Vertically Stacked WS2 /MoS2 Heterostructures: The Role of Interfaces Journal Article
Em: ACS Nano, vol. 12, no. 4, pp. 4036−4044, 2018.
@article{Susarla2018,
title = {Deformation Mechanisms of Vertically Stacked WS2 /MoS2 Heterostructures: The Role of Interfaces},
author = {Susarla, Sandhya; Manimunda, Praveena; Morais Jaques, Ygor; Hachtel, Jordan; Idrobo, Juan Carlos; Syed Amanulla, Syed Asif; Galvao, Douglas; Tiwary, Chandra; Ajayan, Pulickel},
url = {https://pubs.acs.org/doi/10.1021/acsnano.8b01786},
doi = {DOI: 10.1021/acsnano.8b01786},
year = {2018},
date = {2018-04-05},
journal = {ACS Nano},
volume = {12},
number = {4},
pages = {4036−4044},
abstract = {The mechanical and optical properties generated due to the stacking of different atomically thin materials
have made it possible to tune and engineer these materials for next-generation electronics. The understanding of the
interlayer interactions in such stacked structures is of fundamental interest for structure and property correlation. Here, a
combined approach of in situ Raman spectroscopy and mechanical straining along with molecular dynamics (MD)
simulations has been used to probe one such interface, namely, the WS2/MoS2 heterostructure. Vertical heterostructures on
poly(methyl methacrylate), when flexed, showed signs of decoupling at 1.2% strain. Theoretical calculations showed straininduced
stacking changes at 1.75% strain. The sliding characteristics of layers were also investigated using scanning probe
microscopy based nanoscratch testing, and the results are further supported by MD simulations. The present study could
be used to design future optoelectronic devices based on WS2/MoS2 heterostructures.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The mechanical and optical properties generated due to the stacking of different atomically thin materials
have made it possible to tune and engineer these materials for next-generation electronics. The understanding of the
interlayer interactions in such stacked structures is of fundamental interest for structure and property correlation. Here, a
combined approach of in situ Raman spectroscopy and mechanical straining along with molecular dynamics (MD)
simulations has been used to probe one such interface, namely, the WS2/MoS2 heterostructure. Vertical heterostructures on
poly(methyl methacrylate), when flexed, showed signs of decoupling at 1.2% strain. Theoretical calculations showed straininduced
stacking changes at 1.75% strain. The sliding characteristics of layers were also investigated using scanning probe
microscopy based nanoscratch testing, and the results are further supported by MD simulations. The present study could
be used to design future optoelectronic devices based on WS2/MoS2 heterostructures.
have made it possible to tune and engineer these materials for next-generation electronics. The understanding of the
interlayer interactions in such stacked structures is of fundamental interest for structure and property correlation. Here, a
combined approach of in situ Raman spectroscopy and mechanical straining along with molecular dynamics (MD)
simulations has been used to probe one such interface, namely, the WS2/MoS2 heterostructure. Vertical heterostructures on
poly(methyl methacrylate), when flexed, showed signs of decoupling at 1.2% strain. Theoretical calculations showed straininduced
stacking changes at 1.75% strain. The sliding characteristics of layers were also investigated using scanning probe
microscopy based nanoscratch testing, and the results are further supported by MD simulations. The present study could
be used to design future optoelectronic devices based on WS2/MoS2 heterostructures.
35.
Kabbani, Mohamad A.; Kochat, Vidya; Bhowmick, Sanjit; Soto, Matias; Som, Anirban; Krishnadas, K. R.; Woellner, Cristiano F.; Jaques, Ygor M.; Barrera, Enrique V.; Asif, Syed; Vajtai, Robert; Pradeep, Thalappil; Galvão, Douglas S.; Kabbani, Ahmad T.; Tiwary, Chandra Sekhar; Ajayan, Pulickel M.
Consolidation of Functionalized Graphene at Ambient Temperature via Mechano-chemistry Journal Article
Em: Carbon, vol. 134, no. 8, pp. 491-499, 2018.
@article{Kabbani2018,
title = {Consolidation of Functionalized Graphene at Ambient Temperature via Mechano-chemistry},
author = {Mohamad A. Kabbani and Vidya Kochat and Sanjit Bhowmick and Matias Soto and Anirban Som and K.R. Krishnadas and Cristiano F. Woellner and Ygor M. Jaques and Enrique V. Barrera and Syed Asif and Robert Vajtai and Thalappil Pradeep and Douglas S. Galvão and Ahmad T. Kabbani and Chandra Sekhar Tiwary and Pulickel M. Ajayan},
url = {https://www.sciencedirect.com/science/article/pii/S0008622318302987?dgcid=raven_sd_aip_email},
doi = {DOI:10.1016/j.carbon.2018.03.049},
year = {2018},
date = {2018-03-22},
journal = {Carbon},
volume = {134},
number = {8},
pages = {491-499},
abstract = {Graphitic solids are typically produced via high temperature and energy consuming
processing (e.g. sintering) of carbon particles. Here, we demonstrate the mechano-chemical
assembly of functionalized graphene layers into 3D graphitic solids via room temperature and
low energy consuming processing. The chemical functional groups on graphene layers are
interconnected at room temperature under pressure leading to porous three-dimensional
structures with tunable mechanical and electrical properties. The formation of mechanochemistry
induced atomic scale junctions and their impact on mechanical properties of
graphene assembled carbon materials are demonstrated through nano-indentation experiments
and confirmed using DFT and molecular dynamics simulations. The results show room
temperature consolidation routes of graphene layers into bulk carbon solids.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Graphitic solids are typically produced via high temperature and energy consuming
processing (e.g. sintering) of carbon particles. Here, we demonstrate the mechano-chemical
assembly of functionalized graphene layers into 3D graphitic solids via room temperature and
low energy consuming processing. The chemical functional groups on graphene layers are
interconnected at room temperature under pressure leading to porous three-dimensional
structures with tunable mechanical and electrical properties. The formation of mechanochemistry
induced atomic scale junctions and their impact on mechanical properties of
graphene assembled carbon materials are demonstrated through nano-indentation experiments
and confirmed using DFT and molecular dynamics simulations. The results show room
temperature consolidation routes of graphene layers into bulk carbon solids.
processing (e.g. sintering) of carbon particles. Here, we demonstrate the mechano-chemical
assembly of functionalized graphene layers into 3D graphitic solids via room temperature and
low energy consuming processing. The chemical functional groups on graphene layers are
interconnected at room temperature under pressure leading to porous three-dimensional
structures with tunable mechanical and electrical properties. The formation of mechanochemistry
induced atomic scale junctions and their impact on mechanical properties of
graphene assembled carbon materials are demonstrated through nano-indentation experiments
and confirmed using DFT and molecular dynamics simulations. The results show room
temperature consolidation routes of graphene layers into bulk carbon solids.
36.
Solis, Daniel; Borges, Daiane D.; Woellner, Cristiano F.; Galvao, Douglas S.
Structural and Thermal Stability of Graphyne and Graphdiyne Nanoscroll Structures Online
2018, visited: 02.03.2018, (preprint ArXiv: 1803.00154).
@online{Solis2018b,
title = {Structural and Thermal Stability of Graphyne and Graphdiyne Nanoscroll Structures},
author = {Daniel Solis and Daiane D. Borges and Cristiano F. Woellner and Douglas S. Galvao},
url = {https://arxiv.org/abs/1803.00154},
year = {2018},
date = {2018-03-02},
urldate = {2018-03-02},
abstract = {Graphynes and graphdiynes are generic names for families of two-dimensional carbon allotropes,
where acetylenic groups connect benzenoid-like hexagonal rings, with the co-existence of sp and
sp
2 hybridized carbon atoms. The main differences between graphynes and graphdiynes are the
number of acetylenic groups (one and two for graphynes and graphdiynes, respectively).
Similarly to graphene nanoscrolls, graphyne and graphdiynes nanoscrolls are nanosized
membranes rolled up into papyrus-like structures. In this work we investigated through fully
atomistic reactive molecular dynamics simulations the structural and thermal (up to 1000K)
stability of α,β,γ-graphyne and α,β,γ-graphdiyne scrolls. Our results show that stable nanoscrolls
can be formed for all the structures investigated here, although they are less stable than
corresponding graphene scrolls. This can be explained as a consequence of the higher
graphyne/graphdiyne structural porosity in relation to graphene, which results in decreased π-π
stacking interactions. },
note = {preprint ArXiv: 1803.00154},
keywords = {},
pubstate = {published},
tppubtype = {online}
}
Graphynes and graphdiynes are generic names for families of two-dimensional carbon allotropes,
where acetylenic groups connect benzenoid-like hexagonal rings, with the co-existence of sp and
sp
2 hybridized carbon atoms. The main differences between graphynes and graphdiynes are the
number of acetylenic groups (one and two for graphynes and graphdiynes, respectively).
Similarly to graphene nanoscrolls, graphyne and graphdiynes nanoscrolls are nanosized
membranes rolled up into papyrus-like structures. In this work we investigated through fully
atomistic reactive molecular dynamics simulations the structural and thermal (up to 1000K)
stability of α,β,γ-graphyne and α,β,γ-graphdiyne scrolls. Our results show that stable nanoscrolls
can be formed for all the structures investigated here, although they are less stable than
corresponding graphene scrolls. This can be explained as a consequence of the higher
graphyne/graphdiyne structural porosity in relation to graphene, which results in decreased π-π
stacking interactions.
where acetylenic groups connect benzenoid-like hexagonal rings, with the co-existence of sp and
sp
2 hybridized carbon atoms. The main differences between graphynes and graphdiynes are the
number of acetylenic groups (one and two for graphynes and graphdiynes, respectively).
Similarly to graphene nanoscrolls, graphyne and graphdiynes nanoscrolls are nanosized
membranes rolled up into papyrus-like structures. In this work we investigated through fully
atomistic reactive molecular dynamics simulations the structural and thermal (up to 1000K)
stability of α,β,γ-graphyne and α,β,γ-graphdiyne scrolls. Our results show that stable nanoscrolls
can be formed for all the structures investigated here, although they are less stable than
corresponding graphene scrolls. This can be explained as a consequence of the higher
graphyne/graphdiyne structural porosity in relation to graphene, which results in decreased π-π
stacking interactions.
37.
Jaques, Y. M.; Manimunda, P.; Nakanishi, Y.; Susarla, S.; Woellner, C. F.; Bhowmick, S.; Asif, S. A. S.; Galvao, D. S.; Tiwary, C. S.; Ajayan, P. M.
Differences in the Mechanical Properties of Monolayer and Multilayer WSe2/MoSe2 Journal Article
Em: MRS Advances, vol. 3, no. 6-7, pp. 373-378, 2018.
@article{Jaques2018,
title = {Differences in the Mechanical Properties of Monolayer and Multilayer WSe2/MoSe2},
author = {Y. M. Jaques and P. Manimunda and Y. Nakanishi and S. Susarla and C. F. Woellner and S. Bhowmick and S. A. S. Asif and D. S. Galvao and C. S. Tiwary and P. M. Ajayan},
url = {https://www.cambridge.org/core/journals/mrs-advances/article/differences-in-the-mechanical-properties-of-monolayer-and-multilayer-wse2mose2/4F6AFF52BCE7DFFF87E35AC424A8F0BE},
doi = { https://doi.org/10.1557/adv.2018.246},
year = {2018},
date = {2018-03-01},
journal = {MRS Advances},
volume = {3},
number = {6-7},
pages = {373-378},
abstract = {Transition metal dichalcogenides are 2D structures with remarkable electronic, chemical, optical and mechanical properties. Monolayer and crystal properties of these structures have been extensively investigated, but a detailed understanding of the properties of their few-layer structures are still missing. In this work we investigated the mechanical differences between monolayer and multilayer WSe2 and MoSe2, through fully atomistic molecular dynamics simulations (MD). It was observed that single layer WSe2/MoSe2 deposited on silicon substrates have larger friction coefficients than 2, 3 and 4 layered structures. For all considered cases it is always easier to peel off and/or to fracture MoSe2 structures. These results suggest that the interactions between first layer and substrate are stronger than interlayer interactions themselves. Similar findings have been reported for other nanomaterials and it has been speculated whether this is a universal-like behavior for 2D layered materials. We have also analyzed fracture patterns. Our results show that fracture is chirality dependent with crack propagation preferentially perpendicular to W(Mo)-Se bonds and faster for zig-zag-like defects.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Transition metal dichalcogenides are 2D structures with remarkable electronic, chemical, optical and mechanical properties. Monolayer and crystal properties of these structures have been extensively investigated, but a detailed understanding of the properties of their few-layer structures are still missing. In this work we investigated the mechanical differences between monolayer and multilayer WSe2 and MoSe2, through fully atomistic molecular dynamics simulations (MD). It was observed that single layer WSe2/MoSe2 deposited on silicon substrates have larger friction coefficients than 2, 3 and 4 layered structures. For all considered cases it is always easier to peel off and/or to fracture MoSe2 structures. These results suggest that the interactions between first layer and substrate are stronger than interlayer interactions themselves. Similar findings have been reported for other nanomaterials and it has been speculated whether this is a universal-like behavior for 2D layered materials. We have also analyzed fracture patterns. Our results show that fracture is chirality dependent with crack propagation preferentially perpendicular to W(Mo)-Se bonds and faster for zig-zag-like defects.
38.
Zink, Stefan; Moura, Francisco Alirio; da Silva Autreto, Pedro Alves; Galvão, Douglas Soares; Mizaikoff, Boris
Efficient prediction of suitable functional monomers for molecular imprinting via local density of states calculations Journal Article
Em: Physical Chemistry Chemical Physics, vol. 20, pp. 13153–13158, 2018.
@article{Zink2018,
title = {Efficient prediction of suitable functional monomers for molecular imprinting via local density of states calculations},
author = {Stefan Zink and Francisco Alirio Moura and Pedro Alves da Silva Autreto and Douglas Soares Galvão and Boris Mizaikoff},
url = {http://pubs.rsc.org/en/content/articlelanding/2018/cp/c7cp08283e/unauth#!divAbstract},
doi = {10.1039/C7CP08283E},
year = {2018},
date = {2018-02-15},
journal = {Physical Chemistry Chemical Physics},
volume = {20},
pages = {13153--13158},
abstract = {Synthetic molecular recognition materials, such as molecularly imprinted polymers (MIPs) are of increasing importance in biotechnology and analytical chemistry, as they are able to selectively bind their respective template. However, due to their specificity, each MIP has to be individually designed for the desired target leading to a molecularly tailored synthesis strategy. While trial-and-error remains the common approach for selecting suitable functional monomers (FM), the study herein introduces a radical new approach towards rationally designing MIPs by rapidly screening suitable functional monomers based on local density of states (LDOS) calculations in a technique known as Electronic Indices Methodology (EIM). An EIM-based method of classification of FMs according to their suitability for imprinting was developed. Starting from a training set of nine different functional monomers, the prediction of suitability of four functional monomers was possible. These predictions were subsequently experimentally confirmed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Synthetic molecular recognition materials, such as molecularly imprinted polymers (MIPs) are of increasing importance in biotechnology and analytical chemistry, as they are able to selectively bind their respective template. However, due to their specificity, each MIP has to be individually designed for the desired target leading to a molecularly tailored synthesis strategy. While trial-and-error remains the common approach for selecting suitable functional monomers (FM), the study herein introduces a radical new approach towards rationally designing MIPs by rapidly screening suitable functional monomers based on local density of states (LDOS) calculations in a technique known as Electronic Indices Methodology (EIM). An EIM-based method of classification of FMs according to their suitability for imprinting was developed. Starting from a training set of nine different functional monomers, the prediction of suitability of four functional monomers was possible. These predictions were subsequently experimentally confirmed.
39.
Zink, Stefan; Moura, Francisco Alirio; da Silva Autreto, Pedro Alves; Galvao, Douglas Soares; Mizaikoff, Boris
Virtually Imprinted Polymers (VIPs): Understanding Molecularly Templated Materials via Molecular Dynamics Simulations Journal Article
Em: Physical Chemistry Chemical Physics, vol. 20, pp. 13145-13152, 2018.
@article{Zink2018b,
title = {Virtually Imprinted Polymers (VIPs): Understanding Molecularly Templated Materials via Molecular Dynamics Simulations},
author = {Stefan Zink and Francisco Alirio Moura and Pedro Alves da Silva Autreto and Douglas Soares Galvao and Boris Mizaikoff},
url = {http://pubs.rsc.org/en/content/articlelanding/2018/cp/c7cp08284c/unauth#!divAbstract},
doi = {10.1039/C7CP08284C},
year = {2018},
date = {2018-02-15},
journal = {Physical Chemistry Chemical Physics},
volume = {20},
pages = {13145-13152},
abstract = {Molecularly imprinted polymers are advanced recognition materials selectively rebinding a target molecule present during synthesis of the polymer matrix. It is commonly understood that the templating process is based on embedding the complex formed between a template and functional monomers into a co-polymer matrix via polymerization with a cross-linker while maintaining their spatial arrangement forming a molecular imprint. Template removal then leads to synthetic recognition sites ready to selectively rebind their targets, which are complementary in functionality, size and shape to the target. In this study, an innovative theoretical concept using fully atomistic molecular dynamics simulations for modeling molecular templating processes is introduced yielding virtually imprinted polymers (VIPs). VIPs created for the template of 17-beta-estradiol and applied in modeled chromatography experiments demonstrated selectivity for their template evidencing the creation of virtual imprints as a result of a template synthesis protocol, which represents a theoretical confirmation of the governing imprinting theory.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Molecularly imprinted polymers are advanced recognition materials selectively rebinding a target molecule present during synthesis of the polymer matrix. It is commonly understood that the templating process is based on embedding the complex formed between a template and functional monomers into a co-polymer matrix via polymerization with a cross-linker while maintaining their spatial arrangement forming a molecular imprint. Template removal then leads to synthetic recognition sites ready to selectively rebind their targets, which are complementary in functionality, size and shape to the target. In this study, an innovative theoretical concept using fully atomistic molecular dynamics simulations for modeling molecular templating processes is introduced yielding virtually imprinted polymers (VIPs). VIPs created for the template of 17-beta-estradiol and applied in modeled chromatography experiments demonstrated selectivity for their template evidencing the creation of virtual imprints as a result of a template synthesis protocol, which represents a theoretical confirmation of the governing imprinting theory.
40.
Leonardo D Machado Cristiano F Woellner, Pedro AS Autreto; Galvao, Douglas S
Structural Transformations of Carbon and Boron Nitride Nanoscrolls at High Impact Collisions Journal Article
Em: Physical Chemistry Chemical Physics, vol. 20, pp. 4911-4916, 2018.
@article{Woellner2018,
title = {Structural Transformations of Carbon and Boron Nitride Nanoscrolls at High Impact Collisions},
author = {Cristiano F Woellner, Leonardo D Machado, Pedro AS Autreto, Jose M de Sousa, and Douglas S Galvao},
url = {http://pubs.rsc.org/en/content/articlelanding/2018/cp/c7cp07402f#!divAbstract},
doi = {DOI:10.1039/C7CP07402F},
year = {2018},
date = {2018-02-14},
journal = {Physical Chemistry Chemical Physics},
volume = {20},
pages = {4911-4916},
abstract = {The behavior of nanostructures under high strain-rate conditions has been the object of theoretical and
experimental investigations in recent years. For instance, it has been shown that carbon and boron
nitride nanotubes can be unzipped into nanoribbons at high-velocity impacts. However, the response of
many nanostructures to high strain-rate conditions is still unknown. In this work, we have investigated
the mechanical behavior of carbon (CNS) and boron nitride nanoscrolls (BNS) colliding against solid
targets at high velocities, using fully atomistic reactive (ReaxFF) molecular dynamics (MD) simulations.
CNS (BNS) are graphene (boron nitride) membranes rolled up into papyrus-like structures. Their openended
topology leads to unique properties not found in their close-ended analogs, such as nanotubes.
Our results show that collision products are mainly determined by impact velocities and by two
orientation angles, which define the position of the scroll (i) axis and (ii) open edge relative to the target.
Our MD results showed that for appropriate velocities and orientations, large-scale deformations and
nanoscroll fractures could occur. We also observed unscrolling (scrolls going back to quasi-planar
membranes), scroll unzipping into nanoribbons, and significant reconstruction due to breaking and/or
formation of new chemical bonds. For particular edge orientations and velocities, conversion from open
to close-ended topology is also possible, due to the fusion of nanoscroll walls.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The behavior of nanostructures under high strain-rate conditions has been the object of theoretical and
experimental investigations in recent years. For instance, it has been shown that carbon and boron
nitride nanotubes can be unzipped into nanoribbons at high-velocity impacts. However, the response of
many nanostructures to high strain-rate conditions is still unknown. In this work, we have investigated
the mechanical behavior of carbon (CNS) and boron nitride nanoscrolls (BNS) colliding against solid
targets at high velocities, using fully atomistic reactive (ReaxFF) molecular dynamics (MD) simulations.
CNS (BNS) are graphene (boron nitride) membranes rolled up into papyrus-like structures. Their openended
topology leads to unique properties not found in their close-ended analogs, such as nanotubes.
Our results show that collision products are mainly determined by impact velocities and by two
orientation angles, which define the position of the scroll (i) axis and (ii) open edge relative to the target.
Our MD results showed that for appropriate velocities and orientations, large-scale deformations and
nanoscroll fractures could occur. We also observed unscrolling (scrolls going back to quasi-planar
membranes), scroll unzipping into nanoribbons, and significant reconstruction due to breaking and/or
formation of new chemical bonds. For particular edge orientations and velocities, conversion from open
to close-ended topology is also possible, due to the fusion of nanoscroll walls.
experimental investigations in recent years. For instance, it has been shown that carbon and boron
nitride nanotubes can be unzipped into nanoribbons at high-velocity impacts. However, the response of
many nanostructures to high strain-rate conditions is still unknown. In this work, we have investigated
the mechanical behavior of carbon (CNS) and boron nitride nanoscrolls (BNS) colliding against solid
targets at high velocities, using fully atomistic reactive (ReaxFF) molecular dynamics (MD) simulations.
CNS (BNS) are graphene (boron nitride) membranes rolled up into papyrus-like structures. Their openended
topology leads to unique properties not found in their close-ended analogs, such as nanotubes.
Our results show that collision products are mainly determined by impact velocities and by two
orientation angles, which define the position of the scroll (i) axis and (ii) open edge relative to the target.
Our MD results showed that for appropriate velocities and orientations, large-scale deformations and
nanoscroll fractures could occur. We also observed unscrolling (scrolls going back to quasi-planar
membranes), scroll unzipping into nanoribbons, and significant reconstruction due to breaking and/or
formation of new chemical bonds. For particular edge orientations and velocities, conversion from open
to close-ended topology is also possible, due to the fusion of nanoscroll walls.
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