List of Journal Publications
2019
9.
Verners, O., Simone, A.
Characterization of the structural response of a lithiated SiO2 / Si interface: A reactive molecular dynamics study Journal Article
In: MECHANICS OF MATERIALS, vol. 136, 2019.
Abstract | BibTeX | Tags: Composite cathode, Molecular dynamics, Silicon, Silicon oxide, Structural battery | Links:
@article{Verners2019,
title = {Characterization of the structural response of a lithiated SiO2 / Si interface: A reactive molecular dynamics study},
author = {O. Verners and A. Simone},
doi = {10.1016/j.mechmat.2019.04.001},
year = {2019},
date = {2019-01-01},
journal = {MECHANICS OF MATERIALS},
volume = {136},
publisher = {Elsevier B.V.},
abstract = {We report the results of a computational study regarding the mechanical properties of a lithiated Si/SiO2 interface using reactive molecular dynamics. The study is motivated by an intended application of SiO2-coated Si nanotubes as fibers in structural batteries with a fiber-reinforced composite architecture while serving as anodes. According to the results, main failure properties due to partly irreversible bond breakage during mechanical deformation are identified, indicating agreement with bond energy/bond order based estimates. Microscopic failure properties are also identified and interpreted in view of the observed processes of bonding degradation. In particular, the effect of Li distribution on the shear deformation response is evaluated as significant.},
keywords = {Composite cathode, Molecular dynamics, Silicon, Silicon oxide, Structural battery},
pubstate = {published},
tppubtype = {article}
}
We report the results of a computational study regarding the mechanical properties of a lithiated Si/SiO2 interface using reactive molecular dynamics. The study is motivated by an intended application of SiO2-coated Si nanotubes as fibers in structural batteries with a fiber-reinforced composite architecture while serving as anodes. According to the results, main failure properties due to partly irreversible bond breakage during mechanical deformation are identified, indicating agreement with bond energy/bond order based estimates. Microscopic failure properties are also identified and interpreted in view of the observed processes of bonding degradation. In particular, the effect of Li distribution on the shear deformation response is evaluated as significant.
8.
Srinivasan, P., Duff, A. I., Mellan, T. A., Sluiter, M. H. F., Nicola, L., Simone, A.
The effectiveness of reference-free modified embedded atom method potentials demonstrated for NiTi and NbMoTaW Journal Article
In: MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING, vol. 27, no. 6, 2019.
Abstract | BibTeX | Tags: interatomic potential fitting, Molecular dynamics, multi-component alloy, nickel titanium, Phase transformation, reference-free MEAM | Links:
@article{Srinivasan2019,
title = {The effectiveness of reference-free modified embedded atom method potentials demonstrated for NiTi and NbMoTaW},
author = {P. Srinivasan and A. I. Duff and T. A. Mellan and M. H. F. Sluiter and L. Nicola and A. Simone},
doi = {10.1088/1361-651X/ab2604},
year = {2019},
date = {2019-01-01},
journal = {MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING},
volume = {27},
number = {6},
publisher = {Institute of Physics Publishing},
abstract = {One of the effective potentials that has proven to be very versatile and useful for describing metals is the modified embedded atom method (MEAM) potential. The reference-free version of the MEAM (RF-MEAM) potential provides more flexibility for fitting than the 2NN-MEAM because it also describes the pair potential as an explicit function. In this work, we present a methodology to fit RF-MEAM potentials to DFT data. We then evaluate the performance of the fitted potential by comparing MD simulations with experimental and DFT data. As an example, the methodology is applied to a binary and a quaternary alloy, namely NiTi and NbMoTaW. In the case of the equi-atomic NiTi shape memory alloy, our attention focuses on designing a potential that properly captures its mechanical behavior, given that the existing potentials fail to predict elastic constants in agreement with experiments. To reach our aim, we included the stress tensors of different high temperature NiTi configurations in the fitting database. The obtained RF-MEAM potential outperforms existing EAM and MEAM potentials in predicting the lattice and elastic constants of austenitic and martensitic phases as well as the corresponding transformation temperatures. To demonstrate the suitability of this methodology also for more complex systems, a RF-MEAM potential is fitted to model the multi-component NbMoTaW high-entropy alloy. Validation is achieved through comparison between observables obtained through the MD output and ab initio data. The article also reports key improvements to the optimization code MEAMfit v2 and the freely-available LAMMPS implementation of the RF-MEAM formalism. Most notably, resorting to analytic derivatives of the objective function with respect to the potential parameters rather than derivatives through finite differences, the time necessary for fitting has decreased by an order of magnitude.},
keywords = {interatomic potential fitting, Molecular dynamics, multi-component alloy, nickel titanium, Phase transformation, reference-free MEAM},
pubstate = {published},
tppubtype = {article}
}
One of the effective potentials that has proven to be very versatile and useful for describing metals is the modified embedded atom method (MEAM) potential. The reference-free version of the MEAM (RF-MEAM) potential provides more flexibility for fitting than the 2NN-MEAM because it also describes the pair potential as an explicit function. In this work, we present a methodology to fit RF-MEAM potentials to DFT data. We then evaluate the performance of the fitted potential by comparing MD simulations with experimental and DFT data. As an example, the methodology is applied to a binary and a quaternary alloy, namely NiTi and NbMoTaW. In the case of the equi-atomic NiTi shape memory alloy, our attention focuses on designing a potential that properly captures its mechanical behavior, given that the existing potentials fail to predict elastic constants in agreement with experiments. To reach our aim, we included the stress tensors of different high temperature NiTi configurations in the fitting database. The obtained RF-MEAM potential outperforms existing EAM and MEAM potentials in predicting the lattice and elastic constants of austenitic and martensitic phases as well as the corresponding transformation temperatures. To demonstrate the suitability of this methodology also for more complex systems, a RF-MEAM potential is fitted to model the multi-component NbMoTaW high-entropy alloy. Validation is achieved through comparison between observables obtained through the MD output and ab initio data. The article also reports key improvements to the optimization code MEAMfit v2 and the freely-available LAMMPS implementation of the RF-MEAM formalism. Most notably, resorting to analytic derivatives of the objective function with respect to the potential parameters rather than derivatives through finite differences, the time necessary for fitting has decreased by an order of magnitude.
2018
7.
Verners, Osvalds, Lyulin, Alexey V., Simone, A.
Salt concentration dependence of the mechanical properties of LiPF6/poly(propylene glycol) acrylate electrolyte at a graphitic carbon interface: A reactive molecular dynamics study Journal Article
In: JOURNAL OF POLYMER SCIENCE. PART B, POLYMER PHYSICS, vol. 56, no. 9, pp. 718–730, 2018.
Abstract | BibTeX | Tags: Failure properties, Molecular dynamics, Solid polymer electrolyte, Viscoelastic properties | Links:
@article{Verners2018,
title = {Salt concentration dependence of the mechanical properties of LiPF6/poly(propylene glycol) acrylate electrolyte at a graphitic carbon interface: A reactive molecular dynamics study},
author = {Osvalds Verners and Alexey V. Lyulin and A. Simone},
doi = {10.1002/polb.24584},
year = {2018},
date = {2018-01-01},
journal = {JOURNAL OF POLYMER SCIENCE. PART B, POLYMER PHYSICS},
volume = {56},
number = {9},
pages = {718–730},
publisher = {John Wiley and Sons Inc.},
abstract = {This reactive molecular dynamics study explores the salt concentration dependence of the viscoelastic and mechanical failure properties of a poly(propylene glycol)/LiPF6-based solid polymer electrolyte (SPE) at a graphitic carbon electrode interface. To account for the finite-size effect of interface-confined SPE films, the properties of two distinct film thicknesses are compared with the respective bulk properties. Additionally, the effect of uniaxial compression in the interface-normal direction on free energy profiles of Li-ion SPE-desolvation is studied.},
keywords = {Failure properties, Molecular dynamics, Solid polymer electrolyte, Viscoelastic properties},
pubstate = {published},
tppubtype = {article}
}
This reactive molecular dynamics study explores the salt concentration dependence of the viscoelastic and mechanical failure properties of a poly(propylene glycol)/LiPF6-based solid polymer electrolyte (SPE) at a graphitic carbon electrode interface. To account for the finite-size effect of interface-confined SPE films, the properties of two distinct film thicknesses are compared with the respective bulk properties. Additionally, the effect of uniaxial compression in the interface-normal direction on free energy profiles of Li-ion SPE-desolvation is studied.
6.
Srinivasan, Prashanth, Nicola, L., Simone, A.
Atomistic modeling of the orientation-dependent pseudoelasticity in NiTi: Tension, compression, and bending Journal Article
In: COMPUTATIONAL MATERIALS SCIENCE, vol. 154, pp. 25–36, 2018.
Abstract | BibTeX | Tags: Molecular dynamics, Phase transformation, Pseudoelasticity, Shape-memory alloy | Links:
@article{Srinivasan2018,
title = {Atomistic modeling of the orientation-dependent pseudoelasticity in NiTi: Tension, compression, and bending},
author = {Prashanth Srinivasan and L. Nicola and A. Simone},
doi = {10.1016/j.commatsci.2018.07.028},
year = {2018},
date = {2018-01-01},
journal = {COMPUTATIONAL MATERIALS SCIENCE},
volume = {154},
pages = {25–36},
publisher = {Elsevier B.V.},
abstract = {Pseudoelasticity in NiTi shape memory alloy single crystals depends on the loading direction. Here, we present a comprehensive study in which molecular dynamics simulations of austenitic bulk single crystals under strain-controlled tensile and compressive loading along the <110>, <111> and <100> directions are performed, and the mechanical response of the crystals are contrasted. All simulations are performed using the MEAM interatomic potential proposed by Ko et al. (2015). The transformation strains and the Young’s modulus of the initial austenitic and the final martensitic phases are compared with values obtained from the lattice deformation model and experimental results from the literature. Results show that depending on orientation the transformation occurs either through the formation of martensitic Lüders bands or through the transient formation of a multivariant martensite which, upon reorientation, becomes a dominant final single variant.
Simulations are also performed to assess the orientation-dependent behavior of nano-wires subjected to bending, since the flexibility of the wires is orientation dependent.},
keywords = {Molecular dynamics, Phase transformation, Pseudoelasticity, Shape-memory alloy},
pubstate = {published},
tppubtype = {article}
}
Pseudoelasticity in NiTi shape memory alloy single crystals depends on the loading direction. Here, we present a comprehensive study in which molecular dynamics simulations of austenitic bulk single crystals under strain-controlled tensile and compressive loading along the <110>, <111> and <100> directions are performed, and the mechanical response of the crystals are contrasted. All simulations are performed using the MEAM interatomic potential proposed by Ko et al. (2015). The transformation strains and the Young’s modulus of the initial austenitic and the final martensitic phases are compared with values obtained from the lattice deformation model and experimental results from the literature. Results show that depending on orientation the transformation occurs either through the formation of martensitic Lüders bands or through the transient formation of a multivariant martensite which, upon reorientation, becomes a dominant final single variant.
Simulations are also performed to assess the orientation-dependent behavior of nano-wires subjected to bending, since the flexibility of the wires is orientation dependent.
Simulations are also performed to assess the orientation-dependent behavior of nano-wires subjected to bending, since the flexibility of the wires is orientation dependent.
2017
5.
Arash, Behrouz, Thijsse, Barend J., Pecenko, Alessandro, Simone, A.
Effect of water content on the thermal degradation of amorphous polyamide 6,6: A collective variable-driven hyperdynamics study Journal Article
In: POLYMER DEGRADATION AND STABILITY, vol. 146, pp. 260–266, 2017.
Abstract | BibTeX | Tags: 6, Hyperdynamics, Molecular dynamics, Polyamide 6, Reactive molecular simulations, Thermal degradation | Links:
@article{Arash2017,
title = {Effect of water content on the thermal degradation of amorphous polyamide 6,6: A collective variable-driven hyperdynamics study},
author = {Behrouz Arash and Barend J. Thijsse and Alessandro Pecenko and A. Simone},
doi = {10.1016/j.polymdegradstab.2017.10.019},
year = {2017},
date = {2017-01-01},
journal = {POLYMER DEGRADATION AND STABILITY},
volume = {146},
pages = {260–266},
publisher = {Elsevier Ltd},
abstract = {Thermal degradation under wet conditions is considered as an important aging mechanism in polyamide 6,6 (PA 6,6). The effect of water on thermal degradation of amorphous PA 6,6 is investigated at relatively low temperatures, varying from 1000 to 2000 K, using reactive force field molecular dynamics (MD) and collective variable-driven hyperdynamics simulations. The simulation of the related long-term chemical reactions is made possible thanks to the self-learning accelerated MD concept of hyperdynamics in combination with the corresponding accurate reproduction of the correct dynamics, consistent with unbiased MD simulations. The kinetics of cleavage reactions of the amide bonds in the backbone of the polymer chains, responsible for the thermal degradation of the polymer, is studied, and the influence of water content on the activation energy and pre-exponential factor of the cleavage reactions is explored. The results show that activation energy and pre-exponential factor are in agreement with experimental data. The proposed simulation framework not only estimates kinetic properties of thermal degradation that are consistent with experimental observations but also provides a predictive tool for studying long-term thermal degradation of PA 6,6.},
keywords = {6, Hyperdynamics, Molecular dynamics, Polyamide 6, Reactive molecular simulations, Thermal degradation},
pubstate = {published},
tppubtype = {article}
}
Thermal degradation under wet conditions is considered as an important aging mechanism in polyamide 6,6 (PA 6,6). The effect of water on thermal degradation of amorphous PA 6,6 is investigated at relatively low temperatures, varying from 1000 to 2000 K, using reactive force field molecular dynamics (MD) and collective variable-driven hyperdynamics simulations. The simulation of the related long-term chemical reactions is made possible thanks to the self-learning accelerated MD concept of hyperdynamics in combination with the corresponding accurate reproduction of the correct dynamics, consistent with unbiased MD simulations. The kinetics of cleavage reactions of the amide bonds in the backbone of the polymer chains, responsible for the thermal degradation of the polymer, is studied, and the influence of water content on the activation energy and pre-exponential factor of the cleavage reactions is explored. The results show that activation energy and pre-exponential factor are in agreement with experimental data. The proposed simulation framework not only estimates kinetic properties of thermal degradation that are consistent with experimental observations but also provides a predictive tool for studying long-term thermal degradation of PA 6,6.
4.
Dikken, R. J., Thijsse, B. J., Nicola, L.
Impingement of edge dislocations on atomically rough contacts Journal Article
In: COMPUTATIONAL MATERIALS SCIENCE, vol. 128, pp. 310–319, 2017.
Abstract | BibTeX | Tags: Atomic scale roughness, Contact, Dislocation pile-up, Molecular dynamics | Links:
@article{Dikken2017a,
title = {Impingement of edge dislocations on atomically rough contacts},
author = {R. J. Dikken and B. J. Thijsse and L. Nicola},
doi = {10.1016/j.commatsci.2016.11.038},
year = {2017},
date = {2017-01-01},
journal = {COMPUTATIONAL MATERIALS SCIENCE},
volume = {128},
pages = {310–319},
publisher = {Elsevier B.V.},
abstract = {The impingement of edge dislocations on nano-scale interfaces formed when bringing in contact aluminum crystals is investigated using molecular dynamics simulations. Dislocations, inserted in the bottom crystal, glide towards the contact when the two crystals are pressed together. There, dislocations are absorbed and upon further loading new dislocations are nucleated from the impinging site. Absorption and nucleation are events that affect the length of dislocation pile-ups and therefore the plastic behavior of crystals under contact loading. While it is possible to track absorption and nucleation at the nano-scale with molecular dynamics simulations, larger scale models, which are suitable to study plasticity, do not have the right resolution and neglect these events. The goal of this work is to gain a better understanding of dislocation impingement and to assess to which extent absorption and renucleation would play a role at the larger scale. The contacts are here characterized by their initial atomic scale roughness for which a simple, novel definition is introduced. Results show for the first time that roughness controls dislocation nucleation from the contact. This is true for both dislocation-free crystals and for crystals containing one or more dislocations before application of contact loading. In dislocation-free crystals nucleation occurs at decreasing load for increasing roughness. When a dislocation impinges on the contact, it affects its local roughness, by that decreasing the load necessary for dislocation nucleation. Only when the initial roughness of the contact is above a given threshold, dislocation impingement does not affect the load required for nucleation. If instead of a single dislocation, a train of dislocations impinges on the same site, dislocation nucleation is even more facilitated. However, even in this case the contact pressure required to nucleate dislocations is in the order of one GPa, rather high compared with the pressure required to sustain plastic deformation when macro-scale bodies are in contact.},
keywords = {Atomic scale roughness, Contact, Dislocation pile-up, Molecular dynamics},
pubstate = {published},
tppubtype = {article}
}
The impingement of edge dislocations on nano-scale interfaces formed when bringing in contact aluminum crystals is investigated using molecular dynamics simulations. Dislocations, inserted in the bottom crystal, glide towards the contact when the two crystals are pressed together. There, dislocations are absorbed and upon further loading new dislocations are nucleated from the impinging site. Absorption and nucleation are events that affect the length of dislocation pile-ups and therefore the plastic behavior of crystals under contact loading. While it is possible to track absorption and nucleation at the nano-scale with molecular dynamics simulations, larger scale models, which are suitable to study plasticity, do not have the right resolution and neglect these events. The goal of this work is to gain a better understanding of dislocation impingement and to assess to which extent absorption and renucleation would play a role at the larger scale. The contacts are here characterized by their initial atomic scale roughness for which a simple, novel definition is introduced. Results show for the first time that roughness controls dislocation nucleation from the contact. This is true for both dislocation-free crystals and for crystals containing one or more dislocations before application of contact loading. In dislocation-free crystals nucleation occurs at decreasing load for increasing roughness. When a dislocation impinges on the contact, it affects its local roughness, by that decreasing the load necessary for dislocation nucleation. Only when the initial roughness of the contact is above a given threshold, dislocation impingement does not affect the load required for nucleation. If instead of a single dislocation, a train of dislocations impinges on the same site, dislocation nucleation is even more facilitated. However, even in this case the contact pressure required to nucleate dislocations is in the order of one GPa, rather high compared with the pressure required to sustain plastic deformation when macro-scale bodies are in contact.
3.
Srinivasan, Prashanth, Nicola, L., Simone, A.
Modeling pseudo-elasticity in NiTi: Why the MEAM potential outperforms the EAM-FS potential Journal Article
In: COMPUTATIONAL MATERIALS SCIENCE, vol. 134, pp. 145–152, 2017.
Abstract | BibTeX | Tags: Molecular dynamics, Phase transformation, Pseudo-elasticity, Shape memory alloy | Links:
@article{Srinivasan2017,
title = {Modeling pseudo-elasticity in NiTi: Why the MEAM potential outperforms the EAM-FS potential},
author = {Prashanth Srinivasan and L. Nicola and A. Simone},
doi = {10.1016/j.commatsci.2017.03.026},
year = {2017},
date = {2017-01-01},
journal = {COMPUTATIONAL MATERIALS SCIENCE},
volume = {134},
pages = {145–152},
publisher = {Elsevier B.V.},
abstract = {A comparison of the EAM-Finnis-Sinclair and the MEAM potential, two of the recently developed potentials to model NiTi, is carried out. The potentials are compared by studying the pseudo-elastic behavior in bulk NiTi for one specific crystallographic orientation. To this end we perform, for the first time, simulations where the transformation occurs not only under compressive but also under tensile loading along < 100 >(B2) using both potentials. Results indicate that in both cases the MEAM potential captures the pseudo-elastic behavior more accurately. By using a lattice deformation model, it is demonstrated that the inaccurate transformation strains predicted by the EAM-Finnis-Sinclair potential are a direct consequence of its inability to predict experimental values of the lattice constants. Similarly, it is shown that the more precise values of the Young's modulus of the initial austenitic and the final martensitic phase estimated by the MEAM potential are the result of its ability to predict elastic constants more accurately than the EAM-Finnis-Sinclair potential. As a result, it is concluded that the MEAM potential is better suited to study the overall pseudo-elastic behavior in NiTi.},
keywords = {Molecular dynamics, Phase transformation, Pseudo-elasticity, Shape memory alloy},
pubstate = {published},
tppubtype = {article}
}
A comparison of the EAM-Finnis-Sinclair and the MEAM potential, two of the recently developed potentials to model NiTi, is carried out. The potentials are compared by studying the pseudo-elastic behavior in bulk NiTi for one specific crystallographic orientation. To this end we perform, for the first time, simulations where the transformation occurs not only under compressive but also under tensile loading along < 100 >(B2) using both potentials. Results indicate that in both cases the MEAM potential captures the pseudo-elastic behavior more accurately. By using a lattice deformation model, it is demonstrated that the inaccurate transformation strains predicted by the EAM-Finnis-Sinclair potential are a direct consequence of its inability to predict experimental values of the lattice constants. Similarly, it is shown that the more precise values of the Young's modulus of the initial austenitic and the final martensitic phase estimated by the MEAM potential are the result of its ability to predict elastic constants more accurately than the EAM-Finnis-Sinclair potential. As a result, it is concluded that the MEAM potential is better suited to study the overall pseudo-elastic behavior in NiTi.
2016
2.
Verners, Osvalds, Thijsse, Barend J., Duin, Adri C. T., Simone, A.
Salt concentration effects on mechanical properties of LiPF6/poly(propylene glycol) diacrylate solid electrolyte: Insights from reactive molecular dynamics simulations Journal Article
In: ELECTROCHIMICA ACTA, vol. 221, pp. 115–123, 2016.
Abstract | BibTeX | Tags: Failure properties, Molecular dynamics, Solid polymer electrolyte, Viscoelastic properties | Links:
@article{Verners2016,
title = {Salt concentration effects on mechanical properties of LiPF6/poly(propylene glycol) diacrylate solid electrolyte: Insights from reactive molecular dynamics simulations},
author = {Osvalds Verners and Barend J. Thijsse and Adri C. T. Duin and A. Simone},
doi = {10.1016/j.electacta.2016.10.035},
year = {2016},
date = {2016-01-01},
journal = {ELECTROCHIMICA ACTA},
volume = {221},
pages = {115–123},
publisher = {Elsevier Ltd},
abstract = {Multifunctional composites with load carrying and electrical energy storage capability are relevant for diverse applications. Due to often conflicting requirements for improving both functions, extended knowledge of mechanical material properties is crucial. This study analyzes the mechanical properties of a solid polymer electrolyte material for structural battery applications by means of reactive molecular dynamics simulations. Specifically, conditions for improving load carrying capacity are considered. With the aim of determining optimum salt concentration for mechanical performance, we report the findings on the electrolyte salt effects on the polymer's mechanical properties, including hydrostatic failure behavior. The findings indicate a possibility for stiffness improvement above a threshold concentration value, as well as significant differences in isotropic compression and expansion failure behavior. In isotropic expansion and shear, small failure strength and failure strain reduction at increasing salt concentration is observed. In hydrostatic compression no material failure is observed up to 10 GPa. As a part of the molecular dynamics potential validation, the observed differences between references and test simulation results for ion transport related properties of a common solid polymer electrolyte have been assessed and discussed.},
keywords = {Failure properties, Molecular dynamics, Solid polymer electrolyte, Viscoelastic properties},
pubstate = {published},
tppubtype = {article}
}
Multifunctional composites with load carrying and electrical energy storage capability are relevant for diverse applications. Due to often conflicting requirements for improving both functions, extended knowledge of mechanical material properties is crucial. This study analyzes the mechanical properties of a solid polymer electrolyte material for structural battery applications by means of reactive molecular dynamics simulations. Specifically, conditions for improving load carrying capacity are considered. With the aim of determining optimum salt concentration for mechanical performance, we report the findings on the electrolyte salt effects on the polymer's mechanical properties, including hydrostatic failure behavior. The findings indicate a possibility for stiffness improvement above a threshold concentration value, as well as significant differences in isotropic compression and expansion failure behavior. In isotropic expansion and shear, small failure strength and failure strain reduction at increasing salt concentration is observed. In hydrostatic compression no material failure is observed up to 10 GPa. As a part of the molecular dynamics potential validation, the observed differences between references and test simulation results for ion transport related properties of a common solid polymer electrolyte have been assessed and discussed.
1.
Malagù, Marcello, Lyulin, Alexey, Benvenuti, Elena, Simone, A.
A Molecular-Dynamics Study of Size and Chirality Effects on Glass-Transition Temperature and Ordering in Carbon Nanotube-Polymer Composites Journal Article
In: MACROMOLECULAR THEORY AND SIMULATIONS, vol. 25, no. 6, pp. 571–581, 2016.
Abstract | BibTeX | Tags: carbon nanotubes, crystallization, Molecular dynamics, polymer, size effects | Links:
@article{Malagu2016,
title = {A Molecular-Dynamics Study of Size and Chirality Effects on Glass-Transition Temperature and Ordering in Carbon Nanotube-Polymer Composites},
author = {Marcello Malagù and Alexey Lyulin and Elena Benvenuti and A. Simone},
doi = {10.1002/mats.201600041},
year = {2016},
date = {2016-01-01},
journal = {MACROMOLECULAR THEORY AND SIMULATIONS},
volume = {25},
number = {6},
pages = {571–581},
publisher = {Wiley-VCH Verlag},
abstract = {Molecular-dynamics simulations of single-walled carbon nanotubes (CNTs) embedded in a coarse-grained amorphous monodisperse polyethylene-like model system have been carried out. The roles of nanotube diameter and chirality on the physical and structural properties of the composite are thoroughly discussed for several CNTs with different diameter and chirality. It is shown that the glass-transition temperature of the polymer matrix increases with the diameter of the CNT while chirality effects are negligible. A denser and ordered layered region of polymer matrix is found in the vicinity of the nanotube surface. The density and ordering of this layer increases with the CNT diameter. All simulations indicate that chirality does not affect the atomic structure of the highly ordered layer surrounding the CNTs. Despite the simplicity of the polymer model, results of this study are qualitatively comparable with those obtained from experiments and numerical simulations that consider a chemically specific polymer matrix.},
keywords = {carbon nanotubes, crystallization, Molecular dynamics, polymer, size effects},
pubstate = {published},
tppubtype = {article}
}
Molecular-dynamics simulations of single-walled carbon nanotubes (CNTs) embedded in a coarse-grained amorphous monodisperse polyethylene-like model system have been carried out. The roles of nanotube diameter and chirality on the physical and structural properties of the composite are thoroughly discussed for several CNTs with different diameter and chirality. It is shown that the glass-transition temperature of the polymer matrix increases with the diameter of the CNT while chirality effects are negligible. A denser and ordered layered region of polymer matrix is found in the vicinity of the nanotube surface. The density and ordering of this layer increases with the CNT diameter. All simulations indicate that chirality does not affect the atomic structure of the highly ordered layer surrounding the CNTs. Despite the simplicity of the polymer model, results of this study are qualitatively comparable with those obtained from experiments and numerical simulations that consider a chemically specific polymer matrix.
