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Supramolecular Magnetic Brushes: The Impact of Dipolar Interactions on the Equilibrium Structure

[Image: see text] The equilibrium structure of supramolecular magnetic filament brushes is analyzed at two different scales. First, we study the density and height distributions for brushes with various grafting densities and chain lengths. We use Langevin dynamics simulations with a bead–spring mod...

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Autores principales: Sánchez, Pedro A., Pyanzina, Elena S., Novak, Ekaterina V., Cerdà, Joan J., Sintes, Tomas, Kantorovich, Sofia S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2015
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4625168/
https://www.ncbi.nlm.nih.gov/pubmed/26538768
http://dx.doi.org/10.1021/acs.macromol.5b01086
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author Sánchez, Pedro A.
Pyanzina, Elena S.
Novak, Ekaterina V.
Cerdà, Joan J.
Sintes, Tomas
Kantorovich, Sofia S.
author_facet Sánchez, Pedro A.
Pyanzina, Elena S.
Novak, Ekaterina V.
Cerdà, Joan J.
Sintes, Tomas
Kantorovich, Sofia S.
author_sort Sánchez, Pedro A.
collection PubMed
description [Image: see text] The equilibrium structure of supramolecular magnetic filament brushes is analyzed at two different scales. First, we study the density and height distributions for brushes with various grafting densities and chain lengths. We use Langevin dynamics simulations with a bead–spring model that takes into account the cross-links between the surface of the ferromagnetic particles, whose magnetization is characterized by a point dipole. Magnetic filament brushes are shown to be more compact near the substrate than nonmagnetic ones, with a bimodal height distribution for large grafting densities. This latter feature makes them also different from brushes with electric dipoles. Next, in order to explain the observed behavior at the filament scale, we introduce a graph theory analysis to elucidate for the first time the structure of the brush at the scale of individual beads. It turns out that, in contrast to nonmagnetic brushes, in which the internal structure is determined by random density fluctuations, magnetic forces introduce a certain order in the system. Because of their highly directional nature, magnetic dipolar interactions prevent some of the random connections to be formed. On the other hand, they favor a higher connectivity of the chains’ free and grafted ends. We show that this complex dipolar brush microstructure has a strong impact on the magnetic response of the brush, as any weak applied field has to compete with the dipole–dipole interactions within the crowded environment.
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spelling pubmed-46251682015-11-02 Supramolecular Magnetic Brushes: The Impact of Dipolar Interactions on the Equilibrium Structure Sánchez, Pedro A. Pyanzina, Elena S. Novak, Ekaterina V. Cerdà, Joan J. Sintes, Tomas Kantorovich, Sofia S. Macromolecules [Image: see text] The equilibrium structure of supramolecular magnetic filament brushes is analyzed at two different scales. First, we study the density and height distributions for brushes with various grafting densities and chain lengths. We use Langevin dynamics simulations with a bead–spring model that takes into account the cross-links between the surface of the ferromagnetic particles, whose magnetization is characterized by a point dipole. Magnetic filament brushes are shown to be more compact near the substrate than nonmagnetic ones, with a bimodal height distribution for large grafting densities. This latter feature makes them also different from brushes with electric dipoles. Next, in order to explain the observed behavior at the filament scale, we introduce a graph theory analysis to elucidate for the first time the structure of the brush at the scale of individual beads. It turns out that, in contrast to nonmagnetic brushes, in which the internal structure is determined by random density fluctuations, magnetic forces introduce a certain order in the system. Because of their highly directional nature, magnetic dipolar interactions prevent some of the random connections to be formed. On the other hand, they favor a higher connectivity of the chains’ free and grafted ends. We show that this complex dipolar brush microstructure has a strong impact on the magnetic response of the brush, as any weak applied field has to compete with the dipole–dipole interactions within the crowded environment. American Chemical Society 2015-10-12 2015-10-27 /pmc/articles/PMC4625168/ /pubmed/26538768 http://dx.doi.org/10.1021/acs.macromol.5b01086 Text en Copyright © 2015 American Chemical Society This is an open access article published under a Creative Commons Attribution (CC-BY) License (http://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html) , which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.
spellingShingle Sánchez, Pedro A.
Pyanzina, Elena S.
Novak, Ekaterina V.
Cerdà, Joan J.
Sintes, Tomas
Kantorovich, Sofia S.
Supramolecular Magnetic Brushes: The Impact of Dipolar Interactions on the Equilibrium Structure
title Supramolecular Magnetic Brushes: The Impact of Dipolar Interactions on the Equilibrium Structure
title_full Supramolecular Magnetic Brushes: The Impact of Dipolar Interactions on the Equilibrium Structure
title_fullStr Supramolecular Magnetic Brushes: The Impact of Dipolar Interactions on the Equilibrium Structure
title_full_unstemmed Supramolecular Magnetic Brushes: The Impact of Dipolar Interactions on the Equilibrium Structure
title_short Supramolecular Magnetic Brushes: The Impact of Dipolar Interactions on the Equilibrium Structure
title_sort supramolecular magnetic brushes: the impact of dipolar interactions on the equilibrium structure
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4625168/
https://www.ncbi.nlm.nih.gov/pubmed/26538768
http://dx.doi.org/10.1021/acs.macromol.5b01086
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