Reorientation kinetics of superparamagnetic nanostructured rods

TL;DR

This study investigates the reorientation kinetics of superparamagnetic nanostructured rods under magnetic fields, revealing their superparamagnetic behavior and providing insights into their dynamic response for potential applications.

Contribution

It introduces a method to synthesize nanostructured rods and characterizes their reorientation kinetics, demonstrating superparamagnetic properties in these elongated nanostructures.

Findings

Rods reorient along magnetic field lines upon application.

Reorientation follows an exponential decay of tangent of the angle.

Rods exhibit superparamagnetic behavior.

Abstract

The attractive interactions between oppositely charged species (colloids, macromolecules etc) dispersed in water are strong, and the direct mixing of solutions containing such species generally yields to a precipitation, or to a phase separation. We have recently developed means to control the electrostatically-driven attractions between nanoparticles and polymers in water, and at the same time to preserve the stability of the dispersions. We give here an account of the formation of supracolloidal aggregates obtained by co-assembly of 7 nm particles with copolymers. Nanostructured rods of length comprised between 5 and 50 microns and diameter 500 nm were investigated. By application of a magnetic field, the rods were found to reorient along with the magnetic field lines. The kinetics of reorientation was investigated using step changes of the magnetic field of amplitude 90 degrees. From the various results obtained, among which an exponential decay of the tangent of the angle made between the rod and the field, we concluded that the rods are superparamagnetic.