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

Autor(en)

Pedro A. Sánchez, Elena S. Pyanzina, Ekaterina V. Novak, Joan J. Cerdà, Tomas Sintes, Sofia Kantorovich

Abstrakt

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.

Organisation(en)

Computergestützte Physik und Physik der Weichen Materie

Externe Organisation(en)

Ural Federal University, University of the Balearic Islands

Journal

Macromolecules

Band

48

Seiten

7658–7669

Anzahl der Seiten

12

ISSN

0024-9297

DOI

https://doi.org/10.1021/acs.macromol.5b01086

Publikationsdatum

10-2015

Peer-reviewed

Ja

ÖFOS 2012

103015 Kondensierte Materie, 103023 Polymerphysik, 103017 Magnetismus

ASJC Scopus Sachgebiete

Materials Chemistry, Polymers and Plastics, Inorganic Chemistry, Organic Chemistry

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/213e0429-aa05-4f95-ae7b-9e67e92a0b45