Magnetic Anisotropy Effects on the Behavior of a Carbon Nanotube Functionalized by Magnetic Nanoparticles Under External Magnetic Fields

Abstract

The behavior of a multiwalled carbon nanotube functionalized by magnetic nanoparticles through triethylene glycol chains is studied using molecular dynamics simulations. Particular attention is paid to the effect of magnetic anisotropy of nanoparticles which significantly affects the behavior of the system under an external magnetic field. The magnetization reversal process is coupled with the standard atomistic molecular dynamics equations of motion by utilizing the Neel–Brown model and the overdamped Langevin dynamics for description of the inertless magnetization displacements. The key results obtained in this study concern: an energetic profile of the system accompanying transition of a magnetic nanoparticle from the vicinity of the nanotube tip to its sidewall, that is from the capped configuration to the uncapped one; range of the magnetic anisotropy constant in which the system performs structural rearrangements under the external magnetic fields; range of the magnetic field strengths necessary for triggering the structural rearrangements; and other effects like magnetic heating observed during the interaction of the system with the magnetic field. The determined properties of the studied system strongly suggest its application in the area of nanomedicine as a drug targeting and delivery nanovehicle.

Measurement of magnetic anisotropy of multiwalled carbon nanotubes in nematic host

“…21 we obtain the magnetic anisotropy of MWCNT given in Table 1, with an average value of 6.61 × 10 −5 . The results are in good agreement with the ones reported in other papers [22][23][24][25] on SWCNT's. One can notice that the magnetic anisotropy of MWCNT is higher than those of SWCNT.…”

“…15 and Eq. 20 we obtain a simple system where the unknown parameters are the interaction energy and magnetic anisotropy of MWCNT: In this equation we shall only consider the positive value as it has been proven that the carbon nanotubes has positive magnetic anisotropy [23][24][25] …”

“…Previous results [22][23][24][25] showed that carbon nanotubes are diamagnetic both on parallel and perpendicular orientation to their axis but the magnetic susceptibility χ ⊥ is larger than χ resulting a paramagnetic overall behavior and a reorientation of carbon nanotubes parallel to the applied field. This makes them easy to be used in thermotropic liquid crystals as they also to have positive anisotropy.…”

“…Since CNT were discovered, their magnetic properties were studied in many theoretical or experimental ways [22][23][24][25] but they all have to face the inconvenience of clustering and disordered orientation that must be compensated by the magnetic field. Previous results [22][23][24][25] showed that carbon nanotubes are diamagnetic both on parallel and perpendicular orientation to their axis but the magnetic susceptibility χ ⊥ is larger than χ resulting a paramagnetic overall behavior and a reorientation of carbon nanotubes parallel to the applied field.…”

Role of Intermolecular Interactions in Assemblies of Nanocontainers Composed of Carbon Nanotubes and Magnetic Nanoparticles: A Molecular Dynamics Study

“…The presence of silica reduces the range of dispersion forces originating from metallic nanoparticles, provides electrostatic stabilization in solution and provides functional silanol groups for attachment of polyethylene glycol linkers. 9 The force field associated with the NC consists of several types of interactions. The interatomic interactions are set up according to the General Amber Force Field (GAFF).…”