scholarly journals Theoretical and numerical analysis of nano-actuators based on grafted polyelectrolytes in an electric field

2017 ◽  
Vol 199 ◽  
pp. 487-510 ◽  
Author(s):  
N. V. Brilliantov ◽  
Yu. A. Budkov ◽  
C. Seidel
Keyword(s):  
Electric Field ◽  
External Electric Field ◽  
Md Simulations ◽  
Friction Model ◽  
Nano Particle ◽  
Variational Theory ◽  
Vibration Direction ◽  
Theoretical And Numerical Analysis ◽  
The Impact ◽  
Bulk Part

We analyze, theoretically and by means of molecular dynamics (MD) simulations, the generation of mechanical force by a polyelectrolyte (PE) chain grafted to a plane and exposed to an external electric field; the free end of the chain is linked to a deformable target body. Varying the field, one can alter the length of the non-adsorbed (bulk) part of the chain and hence the deformation of the target body and the arising force. We focus on the impact of added salt on the magnitude of the generated force, which is especially important for applications. In particular, we develop a simple variational theory for the double layer formed near electrodes to compute the electric field acting on the bulk part of the chain. Our theoretical predictions agree well with the MD simulations. Next, we study the effectiveness of possible PE-based nano-vices, comprised of two clenching planes connected by PEs exposed to an external electric field. We analyze a novel phenomenon – two-dimensional diffusion of a nano-particle, clenched between two planes, and introduce a quantitative criterion for clenching efficiency, the clenching coefficient. It is defined as a logarithm of the ratio of the diffusion coefficients of a free and clenched particle. Using first a microscopic counterpart of the Coulomb friction model, and then a novel microscopic model based on surface phonons, with the vibration direction normal to the surface, we calculate the clenching coefficient as a function of the external electric field. Our results demonstrate a dramatic decrease of the diffusion coefficient of a clenched nano-particle for the range of parameters relevant for applications; this proves the effectiveness of the PE-based nano-vices.

scholarly journals Generation of mechanical force by grafted polyelectrolytes in an electric field: application to polyelectrolyte-based nano-devices

2016 ◽  
Vol 374 (2080) ◽  
pp. 20160143 ◽  
Author(s):  
N. V. Brilliantov ◽  
Yu. A. Budkov ◽  
C. Seidel
Keyword(s):  
Electric Field ◽  
External Electric Field ◽  
Optical Tweezers ◽  
Md Simulations ◽  
Friction Model ◽  
Field Application ◽  
Mechanical Force ◽  
The Body ◽  
Theoretical Predictions ◽  
Solid Friction

We analyse theoretically and by means of molecular dynamics (MD) simulations the generation of mechanical force by a polyelectrolyte (PE) chain grafted to a plane. The PE is exposed to an external electric field that favours its adsorption on the plane. The free end of the chain is linked to a deformable target body. By varying the field, one can alter the length of the non-adsorbed part of the chain. This entails variation of the deformation of the target body and hence variation of the force arising in the body. Our theoretical predictions for the generated force are in very good agreement with the MD data. Using the theory developed for the generated force, we study the effectiveness of possible PE-based nano-vices, composed of two clenching planes connected by PEs and exposed to an external electric field. We exploit the Cundall–Strack solid friction model to describe the friction between a particle and the clenching planes. We compute the diffusion coefficient of a clenched particle and show that it drastically decreases even in weak applied fields. This demonstrates the efficacy of the PE-based nano-vices, which may be a possible alternative to the existing nanotube nano-tweezers and optical tweezers. This article is part of the themed issue ‘Multiscale modelling at the physics–chemistry–biology interface’.

scholarly journals Heavy Metals Nanofiltration Using Nanotube and Electric Field by Molecular Dynamics

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Tiago da Silva Arouche ◽  
Rosely Maria dos Santos Cavaleiro ◽  
Phelipe Seiichi Martins Tanoue ◽  
Tais Sousa de Sa Pereira ◽  
Tarciso Andrade Filho ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Boron Nitride ◽  
Electric Field ◽  
Metal Ions ◽  
External Electric Field ◽  
Ion Selectivity ◽  
Intermolecular Forces ◽  
Water Molecules ◽  
The Impact

Heavy metal contamination in the world is increasing the impact on the environment and human life. Currently, carbon nanotubes and boron are some possible ideals for the nanofiltration of heavy metals due to the property of ion selectivity, optimized by the applications of the surface and the application of an external electric field. In this work, molecular dynamic was used to transport water with heavy metals under the force exerted by the electric field action inside nanotubes. This external electric field generates a propelling electrical force to expel only water molecules and retain ions. These metal ions were retained to pass through only water molecules, under constant temperature and pressure, for a time of 100 ps under the action of electric fields with values from 10-8 to 10-1 au. Each of the metallic contaminants evaluated (Pb2+, Cd2+, Fe2+, Zn2+, Hg2+) was subjected to molecular test simulations in the water. It was found that the measurement of the intensity of the electric field increased or the percentage of filtered water reduced (in both nanotubes), in which the intramolecular and intermolecular forces intensified by the action of the electric field contribute to retain the heavy metal ions due to the evanescent effect. The best results for nanofiltration in carbon and boron nanotubes occur under the field 10-8 au. Since the filtration in the boron nitride nanotubes, a small difference in the percentage of filtered water for the boron nitride nanotube was the most effective (90 to 98%) in relation to the carbon nanotube (80 to 90%). The greater hydrophobicity and thermal stability of boron nanotubes are some of the factors that contributed to this result.

Influence of an external electric field on the deprotonation reactions of an Fe3+-solvated molecule: a reactive molecular dynamics study

2020 ◽  
Vol 22 (11) ◽  
pp. 6291-6299 ◽  
Author(s):  
Qiaofeng Gao ◽  
Yong Han ◽  
Pengyuan Liang ◽  
Jie Meng
Keyword(s):  
Molecular Dynamics ◽  
Electric Field ◽  
External Electric Field ◽  
Md Simulations ◽  
Reactive Molecular Dynamics

An EEF can promote deprotonation reactions of Fe3+ using associated methods of MD simulations and experiments.

scholarly journals Polyelectrolytes polarization in nonuniform electric fields

2014 ◽  
Vol 25 (12) ◽  
pp. 1441010 ◽  
Author(s):  
Farnoush Farahpour ◽  
Mohammad Reza Ejtehadi ◽  
Fathollah Varnik
Keyword(s):  
Molecular Dynamics ◽  
Electric Field ◽  
External Electric Field ◽  
Electric Fields ◽  
Lattice Boltzmann ◽  
Driving Force ◽  
Equilibrium Configuration ◽  
Md Simulations ◽  
Extended Chain ◽  
Entropic Traps

Stretching dynamics of polymers in microfluidics is of particular interest for polymer scientists. As a charged polymer, a polyelectrolyte (PE) can be deformed from its coiled equilibrium configuration to an extended chain by applying uniform or nonuniform electric fields. By means of hybrid lattice Boltzmann (LB)-molecular dynamics (MD) simulations, we investigate how the condensed counterions (CIs) around the PE contribute to the polymer stretching in inhomogeneous fields. As an application, we discuss the translocation phenomena and entropic traps, when the driving force is an applied external electric field.

scholarly journals The influence of external electrostatic field on the combustion of hexamine

2020 ◽  
pp. 42-49
Author(s):  
Ilya A. Zur ◽  
Alexander S. Fedotov
Keyword(s):  
Electric Field ◽  
External Electric Field ◽  
Electric Fields ◽  
Spatial Configuration ◽  
Scientific Work ◽  
Threshold Value ◽  
Degree Of Ionization ◽  
Fire Extinguishing ◽  
Electrode Space ◽  
The Impact

In scientific work investigates the impact of electric fields on combustion of hexamine. The experimental setup has been developed to study the interaction of an electric field with a low-temperature flame. The optimal spatial configuration of the electrodes for extinguishing the flame was established; the dynamics of airflows caused by the ion wind was studied; the threshold value of the electric field leading to flame extinguishing was determined. An expression is proposed based on the equation of motion that connects the speed of motion of partially ionized gas particles, the viscosity and degree of ionization of the gas, and the intensity of the external electric field. It is shown that the strength of the external electric field, leading to extinguishing of hexamine combustion, increases with decreasing inter-electrode space. The values of corresponding electric field strength lied in range from 80 to 135 kV/m at interelectrode distances of 0.4 and 0.1 m, respectively. The results of the study can be used for effective fire extinguishing in compact devices running on dry fuel.

Interaction of H2O and H2S with Cu(111) and the impact of the electric field: the rotating & translating adsorbate, and the rippled surface

2015 ◽  
Vol 17 (1) ◽  
pp. 588-598 ◽  
Author(s):  
Jin Hyun Chang ◽  
Ahmed Huzayyin ◽  
Keryn Lian ◽  
Francis Dawson
Keyword(s):  
Density Functional Theory ◽  
Electric Field ◽  
External Electric Field ◽  
Density Functional ◽  
Functional Theory ◽  
The Impact

The interactions of H2O and H2S monomers with Cu(111) in the absence and presence of an external electric field are studied using density functional theory.

scholarly journals Modeling of orientational polarization within the framework of extended micropolar theory

2021 ◽  
Author(s):  
Elena N. Vilchevskaya ◽  
Wolfgang H. Müller
Keyword(s):  
Electric Field ◽  
External Electric Field ◽  
Dielectric Material ◽  
Traditional Approach ◽  
Relaxation Times ◽  
Thermal Motion ◽  
Effective Length ◽  
Micropolar Theory ◽  
Production Term ◽  
The Impact

AbstractIn this paper the process of polarization of transversally polarizable matter is investigated based on concepts from micropolar theory. The process is modeled as a structural change of a dielectric material. On the microscale it is assumed that it consists of rigid dipoles subjected to an external electric field, which leads to a certain degree of ordering. The ordering is limited, because it is counteracted by thermal motion, which favors stochastic orientation of the dipoles. An extended balance equation for the microinertia tensor is used to model these effects. This balance contains a production term. The constitutive equations for this term are split into two parts, one , which accounts for the orienting effect of the applied external electric field, and another one, which is used to represent chaotic thermal motion. Two relaxation times are used to characterize the impact of each term on the temporal development. In addition homogenization techniques are applied in order to determine the final state of polarization. The traditional homogenization is based on calculating the average effective length of polarized dipoles. In a non-traditional approach the inertia tensor of the rigid rods is homogenized. Both methods lead to similar results. The final states of polarization are then compared with the transient simulation. By doing so it becomes possible to link the relaxation times to the finally observed state of order, which in terms of the finally obtained polarization is a measurable quantity.

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