scholarly journals Dynamics of Complexation of a Charged Dendrimer by Linear Polyelectrolyte: Computer Modelling

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Sergey Lyulin ◽  
Anatolij Darinskii ◽  
Alexey Lyulin
Keyword(s):  
Brownian Dynamics ◽  
Computer Modelling ◽  
Rotational Diffusion ◽  
Linear Chain ◽  
Relaxation Times ◽  
Linear Polymer ◽  
Dynamics Simulations ◽  
The Individual ◽  
Brownian Dynamics Simulations ◽  
Oppositely Charged

AbstractBrownian-dynamics simulations have been performed for complexes formed by a charged dendrimer and a long oppositely charged linear polyelectrolyte when overcharging phenomenon is always observed. After complex formation the orientational mobility of the individual dendrimer bonds, the fluctuations of the dendrimer size, and the dendrimer rotational diffusion have been simulated. Corresponding relaxation times do not depend on the linear-chain length in a complex and are close to those for a single neutral dendrimer. At the same time fluctuations of the size of a complex are completely defined by the corresponding fluctuations of a linear polyelectrolyte size. Adsorbed polyelectrolyte practically does not feel the rotation of a dendrimer; simulated complexes may be considered as nuts with light core (dendrimer) and heavy shell (adsorbed linear polymer); the electrostatic contacts between dendrimer and oppositely charged linear polymer are easily broken due to the very fast dendrimer-size fluctuations.

scholarly journals Characterization of structures of particles

2020 ◽  
Vol 126 (7) ◽  
Author(s):  
Konstantinos Manikas ◽  
Georgios G. Vogiatzis ◽  
Patrick D. Anderson ◽  
Markus Hütter
Keyword(s):  
Brownian Dynamics ◽  
Initial Structure ◽  
Branch Points ◽  
The One ◽  
Dynamics Simulations ◽  
The Individual ◽  
Brownian Dynamics Simulations ◽  
Individual Particles ◽  
Image Analysis Techniques

Abstract A methodology for the characterization of particle structures, especially networks, is developed. This scheme combines 3D image analysis techniques with graph theory tools for the simplification of a structure of thick agglomerates to its skeleton. The connectivity graph of the initial structure is compared with the one of the corresponding skeleton, as a measure of simplification. Examples are used to illustrate the effectiveness of our scheme. Particle structures obtained by Brownian Dynamics simulations are characterized qualitatively and quantitatively. Instead of looking at the characteristics of the structure at the level of the individual particles or neighborhoods of particles, our scheme results in quantitative measures of the network, e.g. the number density of branch-points, the degree of branch-points, and the thickness and the orientation of the branches.

scholarly journals Length-scales of dynamic heterogeneity in a driven binary colloid

2020 ◽  
Vol 22 (31) ◽  
pp. 17731-17737
Author(s):  
Suman Dutta ◽  
J. Chakrabarti
Keyword(s):  
Electric Field ◽  
Brownian Dynamics ◽  
Characteristic Length ◽  
Aqueous Suspension ◽  
Uniform Electric Field ◽  
Dynamic Heterogeneity ◽  
Length Scales ◽  
Dynamics Simulations ◽  
Brownian Dynamics Simulations ◽  
Oppositely Charged

Here we study the characteristic length scales in an aqueous suspension of a symmetric oppositely charged colloid subjected to a uniform electric field by Brownian dynamics simulations.

scholarly journals Structure evolution of suspensions under time-dependent electric or magnetic field

2021 ◽  
Author(s):  
Konstantinos Manikas ◽  
Markus Hütter ◽  
Patrick D. Anderson
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Brownian Dynamics ◽  
Thermal Fluctuations ◽  
Time Dependent ◽  
Structure Evolution ◽  
Strength Increase ◽  
Large Rotation ◽  
Dynamics Simulations ◽  
Brownian Dynamics Simulations

AbstractThe effect of time-dependent external fields on the structures formed by particles with induced dipoles dispersed in a viscous fluid is investigated by means of Brownian Dynamics simulations. The physical effects accounted for are thermal fluctuations, dipole-dipole and excluded volume interactions. The emerging structures are characterised in terms of particle clusters (orientation, size, anisotropy and percolation) and network structure. The strength of the external field is increased in one direction and then kept constant for a certain amount of time, with the structure formation being influenced by the slope of the field-strength increase. This effect can be partially rationalized by inhomogeneous time re-scaling with respect to the field strength, however, the presence of thermal fluctuations makes the scaling at low field strength inappropriate. After the re-scaling, one can observe that the lower the slope of the field increase, the more network-like and the thicker the structure is. In the second part of the study the field is also rotated instantaneously by a certain angle, and the effect of this transition on the structure is studied. For small rotation angles ($$\theta \le 20^{{\circ }}$$ θ ≤ 20 ∘ ) the clusters rotate but stay largely intact, while for large rotation angles ($$\theta \ge 80^{{\circ }}$$ θ ≥ 80 ∘ ) the structure disintegrates and then reforms, due to the nature of the interactions (parallel dipoles with perpendicular inter-particle vector repel each other). For intermediate angles ($$20<\theta <80^{{\circ }}$$ 20 < θ < 80 ∘ ), it seems that, during rotation, the structure is altered towards a more network-like state, as a result of cluster fusion (larger clusters). The details provided in this paper concern an electric field, however, all results can be projected into the case of a magnetic field and paramagnetic particles.

scholarly journals Influence of size polydispersity on magnetic field tunable structures in magnetic nanofluids containing superparamagnetic nanoparticles.

2021 ◽  
Author(s):  
Dillip Kumar Mohapatra ◽  
Philip James Camp ◽  
John Philip
Keyword(s):  
Magnetic Field ◽  
Particle Size ◽  
Light Scattering ◽  
Optical Microscopy ◽  
Brownian Dynamics ◽  
Phase Contrast ◽  
Superparamagnetic Nanoparticles ◽  
Magnetic Nanofluids ◽  
Dynamics Simulations ◽  
Brownian Dynamics Simulations

We probe the influence of particle size polydispersity on field-induced structures and structural transitions in magnetic fluids (ferrofluids) using phase contrast optical microscopy, light scattering and Brownian dynamics simulations. Three...

scholarly journals Hard discs under steady shear: comparison of Brownian dynamics simulations and mode coupling theory

2009 ◽  
Vol 367 (1909) ◽  
pp. 5033-5050 ◽  
Author(s):  
Oliver Henrich ◽  
Fabian Weysser ◽  
Michael E. Cates ◽  
Matthias Fuchs
Keyword(s):  
Brownian Dynamics ◽  
Mode Coupling ◽  
Transition Density ◽  
Two Dimensions ◽  
Coupling Theory ◽  
Mode Coupling Theory ◽  
Stationary Structure ◽  
Homogeneous Shear Flow ◽  
Dynamics Simulations ◽  
Brownian Dynamics Simulations

Brownian dynamics simulations of bidisperse hard discs moving in two dimensions in a given steady and homogeneous shear flow are presented close to and above the glass transition density. The stationary structure functions and stresses of shear-melted glass are compared quantitatively to parameter-free numerical calculations of monodisperse hard discs using mode coupling theory within the integration through transients framework. Theory qualitatively explains the properties of the yielding glass but quantitatively overestimates the shear-driven stresses and structural anisotropies.

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