scholarly journals Mechanisms in Carbon Nanotube Growth: Modelling and Molecular Dynamics Simulations

2021 ◽  
Author(s):  
◽  
Dmitri Schebarchov
Keyword(s):  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Supported Catalysts ◽  
Critical Role ◽  
Chemical Vapour ◽  
Catalyst Particle ◽  
Md Simulations ◽  
Capillary Absorption ◽  
Supported Nickel Catalyst ◽  
Lift Off

<p><b>A selection of nanoscale processes is studied theoretically, with the aim of identifying themechanisms that could lead to selective carbon nanotube (CNT) growth. Only mechanisms relevant to catalytic chemical vapour deposition (CVD) are considered. The selected processes are analysed with classical molecular dynamics (MD) simulations and continuum modelling.</b></p> <p>The melting and pre-melting behaviour of supported nickel catalyst particles is investigated. Favourable epitaxy between a nanoparticle and the substrate is shown to significantly raise themelting point of the particle. It is also demonstrated that substrate binding can induce solid-solid transformations, whilst the epitaxy may even determine the orientation of individual crystal planes in supported catalysts. These findings suggest that the substrate crystal structure alone can potentially be used to manipulate the properties of catalyst particles and, hence, influence the structure of CNTs.</p> <p>The first attempt at modelling catalyst dewetting, a process where the catalyst unbinds from the inner walls of a nucleating nanotube, is presented. It is argued that understanding this process and gaining control over itmay lead to better selectivity in CNT growth. Two mutually exclusive dewetting mechanisms, namely cap lift-off and capillary withdrawal, are identified and then modelled as elastocapillary phenomena. The modelling yields an upper bound on the diameter of CNTs that can stem from a catalyst particle of a given size. It is also demonstrated that cap lift-off is sensitive to cap topology, suggesting that it may be possible to link catalyst characteristics to the structural properties of nucleating CNTs. However, a clear link to the chiral vector remains elusive.</p> <p>It is shown that particle size, as well as binding affinity, plays a critical role in capillary absorption and withdrawal of catalyst nanoparticles. This size dependence is explored in detail, revealing interesting ramifications to the statics and dynamics of capillary-driven flows at the nanoscale. The findings bear significant implications for our understanding of CNT growth from catalyst particles, whilst also suggesting new nanofluidic applications and methods for fabricating composite metal-CNT materials.</p>

scholarly journals Mechanisms in Carbon Nanotube Growth: Modelling and Molecular Dynamics Simulations

2021 ◽  
Author(s):  
◽  
Dmitri Schebarchov
Keyword(s):  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Supported Catalysts ◽  
Critical Role ◽  
Chemical Vapour ◽  
Catalyst Particle ◽  
Md Simulations ◽  
Capillary Absorption ◽  
Supported Nickel Catalyst ◽  
Lift Off

<p>A selection of nanoscale processes is studied theoretically, with the aim of identifying themechanisms that could lead to selective carbon nanotube (CNT) growth. Only mechanisms relevant to catalytic chemical vapour deposition (CVD) are considered. The selected processes are analysed with classical molecular dynamics (MD) simulations and continuum modelling. The melting and pre-melting behaviour of supported nickel catalyst particles is investigated. Favourable epitaxy between a nanoparticle and the substrate is shown to significantly raise themelting point of the particle. It is also demonstrated that substrate binding can induce solid-solid transformations, whilst the epitaxy may even determine the orientation of individual crystal planes in supported catalysts. These findings suggest that the substrate crystal structure alone can potentially be used to manipulate the properties of catalyst particles and, hence, influence the structure of CNTs. The first attempt at modelling catalyst dewetting, a process where the catalyst unbinds from the inner walls of a nucleating nanotube, is presented. It is argued that understanding this process and gaining control over itmay lead to better selectivity in CNT growth. Two mutually exclusive dewetting mechanisms, namely cap lift-off and capillary withdrawal, are identified and then modelled as elastocapillary phenomena. The modelling yields an upper bound on the diameter of CNTs that can stem from a catalyst particle of a given size. It is also demonstrated that cap lift-off is sensitive to cap topology, suggesting that it may be possible to link catalyst characteristics to the structural properties of nucleating CNTs. However, a clear link to the chiral vector remains elusive. It is shown that particle size, as well as binding affinity, plays a critical role in capillary absorption and withdrawal of catalyst nanoparticles. This size dependence is explored in detail, revealing interesting ramifications to the statics and dynamics of capillary-driven flows at the nanoscale. The findings bear significant implications for our understanding of CNT growth from catalyst particles, whilst also suggesting new nanofluidic applications and methods for fabricating composite metal-CNT materials.</p>

scholarly journals Mechanisms in Carbon Nanotube Growth: Modelling and Molecular Dynamics Simulations

2021 ◽  
Author(s):  
◽  
Dmitri Schebarchov
Keyword(s):  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Supported Catalysts ◽  
Critical Role ◽  
Chemical Vapour ◽  
Catalyst Particle ◽  
Md Simulations ◽  
Capillary Absorption ◽  
Supported Nickel Catalyst ◽  
Lift Off

<p>A selection of nanoscale processes is studied theoretically, with the aim of identifying themechanisms that could lead to selective carbon nanotube (CNT) growth. Only mechanisms relevant to catalytic chemical vapour deposition (CVD) are considered. The selected processes are analysed with classical molecular dynamics (MD) simulations and continuum modelling. The melting and pre-melting behaviour of supported nickel catalyst particles is investigated. Favourable epitaxy between a nanoparticle and the substrate is shown to significantly raise themelting point of the particle. It is also demonstrated that substrate binding can induce solid-solid transformations, whilst the epitaxy may even determine the orientation of individual crystal planes in supported catalysts. These findings suggest that the substrate crystal structure alone can potentially be used to manipulate the properties of catalyst particles and, hence, influence the structure of CNTs. The first attempt at modelling catalyst dewetting, a process where the catalyst unbinds from the inner walls of a nucleating nanotube, is presented. It is argued that understanding this process and gaining control over itmay lead to better selectivity in CNT growth. Two mutually exclusive dewetting mechanisms, namely cap lift-off and capillary withdrawal, are identified and then modelled as elastocapillary phenomena. The modelling yields an upper bound on the diameter of CNTs that can stem from a catalyst particle of a given size. It is also demonstrated that cap lift-off is sensitive to cap topology, suggesting that it may be possible to link catalyst characteristics to the structural properties of nucleating CNTs. However, a clear link to the chiral vector remains elusive. It is shown that particle size, as well as binding affinity, plays a critical role in capillary absorption and withdrawal of catalyst nanoparticles. This size dependence is explored in detail, revealing interesting ramifications to the statics and dynamics of capillary-driven flows at the nanoscale. The findings bear significant implications for our understanding of CNT growth from catalyst particles, whilst also suggesting new nanofluidic applications and methods for fabricating composite metal-CNT materials.</p>

scholarly journals Mechanisms in Carbon Nanotube Growth: Modelling and Molecular Dynamics Simulations

2021 ◽  
Author(s):  
◽  
Dmitri Schebarchov
Keyword(s):  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Supported Catalysts ◽  
Critical Role ◽  
Chemical Vapour ◽  
Catalyst Particle ◽  
Md Simulations ◽  
Capillary Absorption ◽  
Supported Nickel Catalyst ◽  
Lift Off

<p><b>A selection of nanoscale processes is studied theoretically, with the aim of identifying themechanisms that could lead to selective carbon nanotube (CNT) growth. Only mechanisms relevant to catalytic chemical vapour deposition (CVD) are considered. The selected processes are analysed with classical molecular dynamics (MD) simulations and continuum modelling.</b></p> <p>The melting and pre-melting behaviour of supported nickel catalyst particles is investigated. Favourable epitaxy between a nanoparticle and the substrate is shown to significantly raise themelting point of the particle. It is also demonstrated that substrate binding can induce solid-solid transformations, whilst the epitaxy may even determine the orientation of individual crystal planes in supported catalysts. These findings suggest that the substrate crystal structure alone can potentially be used to manipulate the properties of catalyst particles and, hence, influence the structure of CNTs.</p> <p>The first attempt at modelling catalyst dewetting, a process where the catalyst unbinds from the inner walls of a nucleating nanotube, is presented. It is argued that understanding this process and gaining control over itmay lead to better selectivity in CNT growth. Two mutually exclusive dewetting mechanisms, namely cap lift-off and capillary withdrawal, are identified and then modelled as elastocapillary phenomena. The modelling yields an upper bound on the diameter of CNTs that can stem from a catalyst particle of a given size. It is also demonstrated that cap lift-off is sensitive to cap topology, suggesting that it may be possible to link catalyst characteristics to the structural properties of nucleating CNTs. However, a clear link to the chiral vector remains elusive.</p> <p>It is shown that particle size, as well as binding affinity, plays a critical role in capillary absorption and withdrawal of catalyst nanoparticles. This size dependence is explored in detail, revealing interesting ramifications to the statics and dynamics of capillary-driven flows at the nanoscale. The findings bear significant implications for our understanding of CNT growth from catalyst particles, whilst also suggesting new nanofluidic applications and methods for fabricating composite metal-CNT materials.</p>

Influence of Carbon Nanotube Aspect Ratio on Glass Transition Temperature of Polymers: A Molecular Dynamics Simulation Study

2015 ◽  
Vol 817 ◽  
pp. 797-802 ◽  
Author(s):  
Cai Jiang ◽  
Jian Wei Zhang ◽  
Shao Feng Lin ◽  
Su Ju ◽  
Da Zhi Jiang
Keyword(s):  
Molecular Dynamics ◽  
Glass Transition ◽  
Carbon Nanotube ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Aspect Ratio ◽  
Epoxy Resin ◽  
Md Simulations ◽  
Diglycidyl Ether ◽  
Dynamics Simulation

Molecular dynamics (MD) simulations on three single walled carbon nanotube (SWCNT) reinforced epoxy resin composites were conducted to study the influence of SWCNT type on the glass transition temperature (Tg) of the composites. The composite matrix is cross-linked epoxy resin based on the epoxy monomers bisphenol A diglycidyl ether (DGEBA) cured by diaminodiphenylmethane (DDM). MD simulations of NPT (constant number of particles, constant pressure and constant temperature) dynamics were carried out to obtain density as a function of temperature for each composite system. The Tg was determined as the temperature corresponding to the discontinuity of plot slopes of the densityvsthe temperature. In order to understand the motion of polymer chain segments above and below the Tg, various energy components and the MSD at various temperatures of the composites were investigated and their roles played in the glass transition process were analyzed. The results show that the Tg of the composites increases with increasing aspect ratio of the embedded SWCNT

A Molecular Dynamics Simulation Study of the Mechanical Properties of Carbon-Nanotube Reinforced Polystyrene Composite

2014 ◽  
pp. 466-477
Author(s):  
Nabila Tahreen ◽  
K. M. Masud
Keyword(s):  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Longitudinal Direction ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Minimization Method ◽  
Polymer Properties ◽  
Polystyrene Matrix ◽  
Nanotube Composites ◽  
Strain Energy Minimization

In recent years, polymer/carbon nanotube composites have attracted increased attention because the polymer properties have significantly improved. In this paper, a single walled carbon nanotube (SWCNT) is used to reinforce polystyrene matrix. Molecular dynamics (MD) simulations are used to study two periodic systems - a long CNT-reinforced polystyrene composite and amorphous polystyrene matrix itself. The axial and transverse elastic moduli of the amorphous polystyrene matrix and nanocomposites are evaluated using constant-strain energy minimization method. The results from MD simulations are compared with corresponding rule-of-mixture predictions. The simulation results show that CNTs significantly improve the stiffness of polystyrene/CNT composite, especially in the longitudinal direction of the nanotube. Polystyrene posses a strong attractive interaction with the surface of the SWCNT and therefore play an important role in providing effective adhesion. The conventional rule-of-mixture predicts a smaller value than MD simulation where there are strong interfacial interactions. Here the authors report a study on the interfacial characteristics of a CNT-PS composite system through MD simulations and continuum mechanics.

Structural Tuning Using a Novel Membrane Reactor for Carbon Nanotube Synthesis

2015 ◽  
Vol 1752 ◽  
pp. 39-44
Author(s):  
Dane J. K. Sheppard ◽  
L. P. Felipe Chibante
Keyword(s):  
Particle Size ◽  
Carbon Nanotube ◽  
Membrane Reactor ◽  
Chemical Vapour ◽  
Spray Coating ◽  
Catalyst Particle ◽  
Dip Coating ◽  
Asymmetric Membrane ◽  
Structural Morphology ◽  
Starting Point

ABSTRACTCarbon nanotubes come in many varieties, with chemical, mechanical, and electrical properties depending on carbon nanotube (CNT) structural morphology. In order to provide a platform for CNT structural tuning, a membrane reactor was designed and constructed. This reactor provided more intimate gas-catalyst contact by decoupling the carbon feedstock gas from carrier gas in a chemical vapour deposition (CVD) environment using an asymmetric membrane and a macroporous membrane. Growth using this membrane reactor demonstrated normalized yield improvements of ∼300% and ∼1000% for the asymmetric and macroporous membrane cases, respectively, over standard CVD methods. To illustrate the possibility for control, growth variation with time was successfully demonstrated by growing vertically aligned multi-walled CNTs to heights of 0.71 mm, 1.36 mm, and 1.84 mm after growth for 15, 30, and 60 minutes in a commercial thermal CVD reactor. To demonstrate CNT diameter control via catalyst particle size, dip coating and spray coating methods were explored using ferrofluid and Fe(NO3)3 systems. CNT diameter was demonstrated to increase with increasing particle size, yielding CNT like growth with diameters ranging from 15 -150 nm. Demonstration of these dimensions of control coupled with the dramatic efficiency increases over growth in a commercialized CVD reactor establish this new reactor technology as a starting point for further research into CNT structural tuning.

Cellular Injection Using Carbon Nanotube: A Molecular Dynamics Study

NANO ◽  
2015 ◽  
Vol 10 (02) ◽  
pp. 1550025 ◽  
Author(s):  
Seyed Hanif Mahboobi ◽  
Alireza Taheri ◽  
Hossein Nejat Pishkenari ◽  
Ali Meghdari ◽  
Mahya Hemmat
Keyword(s):  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Cell Membrane ◽  
Minimally Invasive ◽  
Lipid Bilayer ◽  
Membrane Structure ◽  
Md Simulations ◽  
Injection Process ◽  
Drug And Gene Delivery

Determination of an injection condition which is minimally invasive to the cell membrane is of great importance in drug and gene delivery. For this purpose, a series of molecular dynamics (MD) simulations are conducted to study the penetration of a carbon nanotube (CNT) into a pure POPC cell membrane under various injection velocities, CNT tilt angles and chirality parameters. The simulations are nonequilibrium and all-atom. The force and stress exerted on the nanotube, deformation of the lipid bilayer, and strain of the CNT atoms are inspected during the simulations. We found that a lower nanotube velocity results in successfully entering the membrane with minimum disruption in the CNT and the lipid bilayer, and CNT's chirality distinctly affects the results. Moreover, it is shown that the tilt angle of the CNT influences the nanotube's buckling and may result in destroying the membrane structure during the injection process.

Thermal Rectification in Graphene and Carbon Nanotube Systems Using Molecular Dynamics Simulations

2011 ◽  
Author(s):  
Ajit K. Vallabhaneni ◽  
Jiuning Hu ◽  
Yong P. Chen ◽  
Xiulin Ruan
Keyword(s):  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Temperature Difference ◽  
Graphene Nanoribbons ◽  
Md Simulations ◽  
System Size ◽  
Heat Current ◽  
Thermal Rectification ◽  
Mean Temperature ◽  
Rectification Factor

We investigate the thermal rectification phenomena in asymmetric graphene and carbon nanotube systems using molecular dynamics (MD) simulations. The effects of various parameters, including mean temperature, temperature difference, and system size on rectification factor have been studied. In homogenous triangular graphene nanoribbons (T-GNR), the heat current is normally higher from wide to narrow end than that in the opposite direction, resulting in a positive rectification factor. The rectification factor increases further for a double layered T-GNR. It is also found that varying the parameters like mean temperature can result in reverse of the sign of thermal rectification factor. In the case of carbon nanotube (CNT)–silicon system, the heat current is higher when heat flows from CNT to silicon. The thermal rectification factor is almost independent of the diameter of CNT. In both cases, the rectification factor increases with the imposed temperature difference.

Molecular dynamics simulations of single-walled carbon nanotubes and polynylon66

2019 ◽  
Vol 33 (23) ◽  
pp. 1950258 ◽  
Author(s):  
Danhui Zhang ◽  
Houbo Yang ◽  
Zhongkui Liu ◽  
Anmin Liu
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
High Performance ◽  
Single Walled Carbon Nanotubes ◽  
Md Simulations ◽  
Interfacial Interaction ◽  
Radius Of Gyration ◽  
Single Walled Carbon ◽  
Walled Carbon Nanotubes

Polynylon66, as a kind of important engineering plastics, is widely used in various fields. In this work, we studied the interfacial interactions between polynylon66 and single-walled carbon nanotubes (SWCNTs) using molecular dynamics (MD) simulations. The results showed that the polynylon66 could interact with the SWCNTs and the mechanism of interfacial interaction between polynylon66 and SWCNTs was also discussed. Furthermore, the morphology of polynylon66 adsorbed to the surface of SWCNTs was investigated by the radius of gyration. Influence factors such as the initial angle between polynylon66 chain and nanotube axis, SWCNT radius and length of polynylon66 on interfacial adhesion of single-walled carbon nanotube-polymer and the radius of gyration of the polymers were studied. These results will help to better understand the interfacial interaction between polymer and carbon nanotube (CNT) and also guide the fabrication of high performance polymer/carbon nanotube nanocomposites.

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