Mesoscopic modeling of structural self-organization of carbon nanotubes into vertically aligned networks of nanotube bundles

Wittmaack, Bernard K.; Banna, Abu Horaira; Volkov, Alexey N.; Zhigilei, Leonid V.

doi:10.1016/j.carbon.2017.12.078

Cited by 16 publications

(7 citation statements)

References 117 publications

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“…For a given N B , an equivalent diameter of a circular bundle can be calculated as D B = (2R T + δh 0 )[6N B /(π√3)] 1/2 . 91 The average ⟨D⟩, most probable D 0 , and maximum D max diameters of equivalent circular bundles are listed in the inset of Figure 4d. All these diameters monotonically increase with increasing diameter of individual nanotubes.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The larger average bundle sizes reported in refs 28 and 48, compared to the bundle sizes in the in-silico-generated films, can be also explained by a few-fold larger density of CNT films used in experiments, compared to the samples considered in the present work, as ⟨D⟩ increases with increasing material density. 91 Computational Setup for In-Plane Tension and Compression of CNT Films and Effect of the Deforma- tion Velocity. The in-silico-generated film samples are subjected to the in-plane tensile or compressive mechanical loading under conditions of a constant mesoscopic temperature of 300 K. For this purpose, the periodic boundary conditions in the direction of applied deformation Ox (the horizontal direction in Figure 4a−c) are released by "cutting" the CNTs that cross the sample boundaries perpendicular to that direction.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Chirality-Dependent Mechanical Properties of Bundles and Thin Films Composed of Covalently Cross-Linked Carbon Nanotubes

2022

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The effect of nanotube chirality on the mechanical properties of materials composed of single-walled carbon nanotubes (CNTs) is poorly understood since the interfacial load transfer in such materials is strongly dependent on the intertube interaction and structure of the nanotube network. Here, a combined atomistic-mesoscopic study is performed to reveal the effect of CNT diameter on the deformation mechanisms and mechanical properties of CNT bundles and low-density CNT films with covalent cross-links (CLs). First, the pullout of the central nanotube from bundles composed of seven (5,5), (10,10), (20,20), (17,0), and (26,0) CNTs is studied in molecular dynamics simulations based on the ReaxFF force field. The simulations show that the shear modulus and strength increase with decreasing CNT diameter. The results of atomistic simulations are used to parametrize a mesoscopic model of CLs and to perform mesoscopic simulations of in-plane tension and compression of thin films composed of thousands of cross-linked CNTs. The mechanical properties of CNT films are found to be strongly dependent on CNT diameter. The film modulus increases as the CNT diameter increases, while the tensile strength decreases. The in-plane compression is characterized by collective bending of whole films and order-of-magnitude smaller compressive strengths. The films composed of (5,5) CNTs exhibit the ability for large-strain compression without irreversible changes in the material structure. The stretching rigidity of individual nanotubes and volumetric CL density are identified as the key factors that dominate the effect of CNT chirality on the mechanical properties of CNT films. The film modulus is affected by both CL density and stretching rigidity of CNTs, while the tensile strength is dominated by CL density. The obtained results suggest that the on-demand optimization of the mechanical properties of CNT films can be performed by tuning the nanotube chirality distribution.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Chirality-Dependent Mechanical Properties of Bundles and Thin Films Composed of Covalently Cross-Linked Carbon Nanotubes

2022

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“…The use of the structure directly duplicated from scanning electron microscopy (SEM) images enabled successful simulation of the role of each structure type in the VA-SWCNT forest. Further research on multiscale modeling that showed good efficiency and precision for the VA-SWCNT forest 28 , 29 proved that even the dynamic replication of VA-SWCNTs in chemical vapor deposition (CVD) and its further processing 32 are feasible.…”

Section: Introductionmentioning

confidence: 99%

“…The CG modeling for saving the computational expenses of atomic simulation directly means that the trial should lose its detailed dynamic characteristics caused by such condition. Most progressed CGMD simulation for morphology, such as VA-SWCNT forest 28,29 or buckypaper 26,27 , has a cylinder shaped CNT to keep realistic dynamic and structural characteristics with taking computational expanse. Some exceptions are dissipative particle dynamics (DPD) modeling with polymers [33][34][35] and the mathematical random network of the sparse entanglement 36 .…”

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confidence: 99%

Heat diffusion-related damping process in a highly precise coarse-grained model for nonlinear motion of SWCNT

Koh

Chiashi

Shiomi

et al. 2021

Sci Rep

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Second sound and heat diffusion in single-walled carbon nanotubes (SWCNT) are well-known phenomena which is related to the high thermal conductivity of this material. In this paper, we have shown that the heat diffusion along the tube axis affects the macroscopic motion of SWCNT and adapting this phenomena to coarse-grained (CG) model can improve the precision of the coarse-grained molecular dynamics (CGMD) exceptionally. The nonlinear macroscopic motion of SWCNT in the free thermal vibration condition in adiabatic environment is demonstrated in the most simplified version of CG modeling as maintaining finite temperature and total energy with suggested dissipation process derived from internal heat diffusion. The internal heat diffusion related to the cross correlated momentum from different potential energy functions is considered, and it can reproduce the nonlinear dynamic nature of SWCNTs without external thermostatting in CG model. Memory effect and thermostat with random noise distribution are not included, and the effect of heat diffusion on memory effect is quantified through Mori–Zwanzig formalism. This diffusion shows perfect syncronization of the motion between that of CGMD and MD simulation, which is started with initial conditions from the molecular dynamics (MD) simulation. The heat diffusion related to this process has shown the same dispersive characteristics to second wave in SWCNT. This replication with good precision indicates that the internal heat diffusion process is the essential cause of the nonlinearity of the tube. The nonlinear dynamic characteristics from the various scale of simple beads systems are examined with expanding its time step and node length.

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“…Among them, vertically aligned (VA) CNT pillars have been recognized as a promising structural material for the fabrication of high aspect ratio (AR) 3D micro- and nano-architectures [ 24 , 25 ]. VACNT pillars represent a promising class of mechanically strong and resilient lightweight materials, capable of supporting large reversible deformation and absorbing mechanical energy [ 26 ]. The mechanical response of VACNTs to uniaxial compression depends on various factors, including the material microstructure, density, height, rate of deformation, and the nature of the interaction between the CNTs and the compressing indenter [ 27 ].…”

Section: Introductionmentioning

confidence: 99%

Vertically-Aligned Multi-Walled Carbon Nano Tube Pillars with Various Diameters under Compression: Pristine and NbTiN Coated

et al. 2020

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In this paper, the compressive stress of pristine and coated vertically-aligned (VA) multi-walled (MW) carbon nanotube (CNT) pillars were investigated using flat-punch nano-indentation. VA-MWCNT pillars of various diameters (30–150 µm) grown by low-pressure chemical vapor deposition on silicon wafer. A conformal brittle coating of niobium-titanium-nitride with high superconductivity temperature was deposited on the VA-MWCNT pillars using atomic layer deposition. The coating together with the pillars could form a superconductive vertical interconnect. The indentation tests showed foam-like behavior of pristine CNTs and ceramic-like fracture of conformal coated CNTs. The compressive strength and the elastic modulus for pristine CNTs could be divided into three regimes of linear elastic, oscillatory plateau, and exponential densification. The elastic modulus of pristine CNTs increased for a smaller pillar diameter. The response of the coated VA-MWCNTs depended on the diffusion depth of the coating in the pillar and their elastic modulus increased with pillar diameter due to the higher sidewall area. Tuning the material properties by conformal coating on various diameter pillars enhanced the mechanical performance and the vertical interconnect access (via) reliability. The results could be useful for quantum computing applications that require high-density superconducting vertical interconnects and reliable operation at reduced temperatures.

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Mesoscopic modeling of structural self-organization of carbon nanotubes into vertically aligned networks of nanotube bundles

Cited by 16 publications

References 117 publications

Chirality-Dependent Mechanical Properties of Bundles and Thin Films Composed of Covalently Cross-Linked Carbon Nanotubes

Chirality-Dependent Mechanical Properties of Bundles and Thin Films Composed of Covalently Cross-Linked Carbon Nanotubes

Heat diffusion-related damping process in a highly precise coarse-grained model for nonlinear motion of SWCNT

Vertically-Aligned Multi-Walled Carbon Nano Tube Pillars with Various Diameters under Compression: Pristine and NbTiN Coated

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