Nano-Tribology of a Polytetrafluoroethylene Transfer Films Using Molecular Dynamics Simulation and Microtribometry

<div><div>It is very urgent to understand the rheological behavior of polymer nanocomposites (PNCs) on the molecular level, which is very important for their processing and application. Thus, here the reverse nonequilibrium molecular dynamics simulation isemployed to explore it by tuning the nanoparticle (NP) concentration, the polymer-NPinteraction and the NP size. The shear viscosity (η~-m) exhibits a power law with theshear rate where m varies from 0.42 to 0.53 at high shear rates. By adopting the Carreau-Yasuda model, the obtained zero-shear viscosity gradually rises with increasing the NPconcentration, polymer-NP interaction or reducing the NP size. This is attributed to thestrong adsorption of chains by NPs and the formed network, which leads to the retarded dynamics. In addition, both the first and second normal stress differences also show power laws on the shear rates. The chains are gradually extended as the increase of shear rates, which is characterized by the mean-square end-to-end distance and the mean square radius of gyration. Especially, the evolution process of the NP network and the polymer- NP network is analyzed to deeply understand the shear thinning behavior. The number ofthe direct contact structure of NPs increases while the number of polymer-NP bridgedstructure is reduced. This is further proved by the increase of the formation probability of the NP network and the decrease of the polymer-NP interaction energy. Finally, the chain dynamics is found to be enhanced due to the shear flow. In summary, this work provides a further understanding on the mechanism of the shear thinning of PNCs on the molecular level. <br></div></div>

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Rheological Behavior of Polymer Nanocomposites Filled with Spherical Nanoparticles: Insights from Molecular Dynamics Simulation

10.26434/chemrxiv.14084201 ◽

2021 ◽

Author(s):

Haoxiang Li ◽

Haoyu WU ◽

Wenfeng Zhang ◽

Xiuying Zhao ◽

Yangyang Gao ◽

...

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulation ◽

Polymer Nanocomposites ◽

Shear Viscosity ◽

Rheological Behavior ◽

Molecular Level ◽

Dynamics Simulation ◽

Mean Square ◽

Shear Rates ◽

The Mean

<div><div>It is very urgent to understand the rheological behavior of polymer nanocomposites (PNCs) on the molecular level, which is very important for their processing and application. Thus, here the reverse nonequilibrium molecular dynamics simulation isemployed to explore it by tuning the nanoparticle (NP) concentration, the polymer-NPinteraction and the NP size. The shear viscosity (η~-m) exhibits a power law with theshear rate where m varies from 0.42 to 0.53 at high shear rates. By adopting the Carreau-Yasuda model, the obtained zero-shear viscosity gradually rises with increasing the NPconcentration, polymer-NP interaction or reducing the NP size. This is attributed to thestrong adsorption of chains by NPs and the formed network, which leads to the retarded dynamics. In addition, both the first and second normal stress differences also show power laws on the shear rates. The chains are gradually extended as the increase of shear rates, which is characterized by the mean-square end-to-end distance and the mean square radius of gyration. Especially, the evolution process of the NP network and the polymer- NP network is analyzed to deeply understand the shear thinning behavior. The number ofthe direct contact structure of NPs increases while the number of polymer-NP bridgedstructure is reduced. This is further proved by the increase of the formation probability of the NP network and the decrease of the polymer-NP interaction energy. Finally, the chain dynamics is found to be enhanced due to the shear flow. In summary, this work provides a further understanding on the mechanism of the shear thinning of PNCs on the molecular level. <br></div></div>

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A molecular dynamics simulation study of the viscoelastic properties of polymer nanocomposites

The Journal of Chemical Physics ◽

10.1063/1.1516589 ◽

2002 ◽

Vol 117 (20) ◽

pp. 9478-9489 ◽

Cited By ~ 193

Author(s):

Grant D. Smith ◽

Dmitry Bedrov ◽

Liwei Li ◽

Oleksiy Byutner

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulation ◽

Polymer Nanocomposites ◽

Simulation Study ◽

Viscoelastic Properties ◽

Dynamics Simulation

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Molecular dynamics simulation on interfacial mechanical properties of polymer nanocomposites with wrinkled graphene

Computational Materials Science ◽

10.1016/j.commatsci.2015.06.023 ◽

2015 ◽

Vol 108 ◽

pp. 160-167 ◽

Cited By ~ 68

Author(s):

Feng Liu ◽

Ning Hu ◽

Huiming Ning ◽

Yaolu Liu ◽

Yuan Li ◽

...

Keyword(s):

Mechanical Properties ◽

Molecular Dynamics ◽

Molecular Dynamics Simulation ◽

Polymer Nanocomposites ◽

Dynamics Simulation

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An Analysis Based on Molecular Docking and Molecular Dynamics Simulation Study of Bromelain as Anti-SARS-CoV-2 Variants

Frontiers in Pharmacology ◽

10.3389/fphar.2021.717757 ◽

2021 ◽

Vol 12 ◽

Cited By ~ 1

Author(s):

Trina Ekawati Tallei ◽

Fatimawali ◽

Afriza Yelnetty ◽

Rinaldi Idroes ◽

Diah Kusumawaty ◽

...

Keyword(s):

Molecular Dynamics ◽

Molecular Docking ◽

Molecular Dynamics Simulation ◽

Three Dimensional ◽

Md Simulations ◽

Inhibitory Effect ◽

Dynamics Simulation ◽

Novel Coronavirus

The rapid spread of a novel coronavirus known as SARS-CoV-2 has compelled the entire world to seek ways to weaken this virus, prevent its spread and also eliminate it. However, no drug has been approved to treat COVID-19. Furthermore, the receptor-binding domain (RBD) on this viral spike protein, as well as several other important parts of this virus, have recently undergone mutations, resulting in new virus variants. While no treatment is currently available, a naturally derived molecule with known antiviral properties could be used as a potential treatment. Bromelain is an enzyme found in the fruit and stem of pineapples. This substance has been shown to have a broad antiviral activity. In this article, we analyse the ability of bromelain to counteract various variants of the SARS-CoV-2 by targeting bromelain binding on the side of this viral interaction with human angiotensin-converting enzyme 2 (hACE2) using molecular docking and molecular dynamics simulation approaches. We have succeeded in making three-dimensional configurations of various RBD variants using protein modelling. Bromelain exhibited good binding affinity toward various variants of RBDs and binds right at the binding site between RBDs and hACE2. This result is also presented in the modelling between Bromelain, RBD, and hACE2. The molecular dynamics (MD) simulations study revealed significant stability of the bromelain and RBD proteins separately up to 100 ns with an RMSD value of 2 Å. Furthermore, despite increases in RMSD and changes in Rog values of complexes, which are likely due to some destabilized interactions between bromelain and RBD proteins, two proteins in each complex remained bonded, and the site where the two proteins bind remained unchanged. This finding indicated that bromelain could have an inhibitory effect on different SARS-CoV-2 variants, paving the way for a new SARS-CoV-2 inhibitor drug. However, more in vitro and in vivo research on this potential mechanism of action is required.

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Molecular-level insight of hindered phenol AO-70/nitrile-butadiene rubber damping composites through a combination of a molecular dynamics simulation and experimental method

RSC Advances ◽

10.1039/c6ra17283k ◽

2016 ◽

Vol 6 (89) ◽

pp. 85994-86005 ◽

Cited By ~ 20

Author(s):

Xiuying Zhao ◽

Geng Zhang ◽

Feng Lu ◽

Liqun Zhang ◽

Sizhu Wu

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulation ◽

Experimental Method ◽

Molecular Level ◽

Dynamics Simulation ◽

Butadiene Rubber ◽

Damping Properties ◽

Nitrile Butadiene Rubber ◽

Hindered Phenol

The damping properties of AO-70/NBR composites get a noteworthy increase with the introduction of AO-70—max tan δincreased by 66.9%.

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Molecular Dynamics Simulation of Neutron Damage in β-SIC

MRS Proceedings ◽

10.1557/proc-540-171 ◽

1998 ◽

Vol 540 ◽

Cited By ~ 8

Author(s):

J.M. Perlado ◽

L. Malerba ◽

T. Diaz De La Rubia

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulation ◽

Point Defects ◽

Damage Accumulation ◽

Md Simulations ◽

Dynamics Simulation ◽

Temperature Sensitive ◽

Neutron Damage ◽

Preliminary Study ◽

Threshold Displacement

AbstractMolecular Dynamics (MD) simulations of neutron damage in β-SiC have been performed using a modified version of the Tersoff potential. The Threshold Displacement Energy (TDE) for Si and C atoms at 300 K has been determined along directions [001], [110], [111] and [ 1 1 1 ]. The existence of recombination barriers, which allow the formation of metastable, temperature-sensitive defects even below the threshold, has been observed. Displacement cascades produced by both C- and Si-recoils of energies spanning from 0.5 keV up to, respectively, 5 keV and 8 keV have also been simulated at 300 K and 1300 K. Their analysis, together with the analysis of damage accumulation (∼3.4×10-3 DPA) at 1300 K, reveals that the two sub-lattices exhibit opposite responses to irradiation: whereas only a little damage is produced on the “ductile” Si sub-lattice, many point-defects accumulate on the much more “fragile” C sub-lattice. A preliminary study of the nature and clustering tendency of these defects is performed. The possibility of disorder-induced amorphization is considered and the preliminary result is that no amorphization takes place at the dose and temperature simulated.

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Emulsification of Surfactant on Oil Droplets by Molecular Dynamics Simulation

Molecules ◽

10.3390/molecules25133008 ◽

2020 ◽

Vol 25 (13) ◽

pp. 3008

Author(s):

Yaoshuang Cheng ◽

Shiling Yuan

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulation ◽

Heavy Oil ◽

Molecular Level ◽

Sodium Dodecyl ◽

Mean Square Displacement ◽

Dynamics Simulation ◽

Oil Droplets ◽

Hydration Layer ◽

Oil Droplet

Heavy oil in crude oil flooding is extremely difficult to extract due to its high viscosity and poor fluidity. In this paper, molecular dynamics simulation was used to study the emulsification behavior of sodium dodecyl sulfonate (SDSn) micelles on heavy oil droplets composed of asphaltenes (ASP) at the molecular level. Some analyzed techniques were used including root mean square displacement, hydrophile-hydrophobic area of an oil droplet, potential of mean force, and the number of hydrogen bonds between oil droplet and water phase. The simulated results showed that the asphaltene with carboxylate groups significantly enhances the hydration layer on the surface of oil droplets, and SDSn molecules can change the strength of the hydration layer around the surface of the oil droplets. The water bridge structure between both polar heads of the surfactant was commonly formed around the hydration layer of the emulsified oil droplet. During the emulsification of heavy oil, the ratio of hydrophilic hydrophobic surface area around an oil droplet is essential. Molecular dynamics method can be considered as a helpful tool for experimental techniques at the molecular level.

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