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Hydrodynamic Properties of Magnetic Nanoparticles with Tunable Shape Anisotropy: Prediction and Experimental Verification

Martchenko, Ilya LU ; Dietsch, Herve; Moitzi, Christian and Schurtenberger, Peter LU (2011) In The Journal of Physical Chemistry Part B 115(49). p.14838-14845
Abstract
We describe the characterization of the hydrodynamic properties of anisotropic magnetic nanoparticles using a combination of transmission electron microscopy (TEM) and dynamic as well as depolarized dynamic light scattering (DLS/DDLS). The particles used are nearly monodisperse hematite spindles with an average length of 280 nm and a minor axis of 57 nm, coated with a layer of silica of variable thickness that allows us to tune the particle aspect ratio between 5 and 2. Their geometrical dimensions can thus be determined easily and quantitatively from TEM. Moreover, their size is ideal to employ DLS and DDLS to measure the translational and rotational diffusion coefficients D-T and D-R, while the presence of a magnetic core opens a... (More)
We describe the characterization of the hydrodynamic properties of anisotropic magnetic nanoparticles using a combination of transmission electron microscopy (TEM) and dynamic as well as depolarized dynamic light scattering (DLS/DDLS). The particles used are nearly monodisperse hematite spindles with an average length of 280 nm and a minor axis of 57 nm, coated with a layer of silica of variable thickness that allows us to tune the particle aspect ratio between 5 and 2. Their geometrical dimensions can thus be determined easily and quantitatively from TEM. Moreover, their size is ideal to employ DLS and DDLS to measure the translational and rotational diffusion coefficients D-T and D-R, while the presence of a magnetic core opens a plethora of opportunities for future studies and applications. We demonstrate that we can successfully predict the hydrodynamic properties of the different particles based on a TEM characterization of their size distribution and using established theoretical models for the hydrodynamic properties of anisotropic particles. When compared with the theoretical predictions, our light scattering measurements are in quantitative agreement. This agreement between theory and experiment is achieved without having to invoke any adjustable free parameter, as the TEM results are used to calculate the corresponding diffusion coefficients on an absolute scale We demonstrate that this is achieved due to a new and simple method for the statistical weighting of the TEM information, and the use of the correct hydrodynamic models for the observed particle shape. In addition, we also demonstrate an enhanced sensitivity of the rotational diffusion for the surface properties of ellipsoidal nanoparticles, and point out that this may serve as an ideal tool toward characterizing functionalized surfaces. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Part B
volume
115
issue
49
pages
14838 - 14845
publisher
The American Chemical Society
external identifiers
  • wos:000297608600056
  • scopus:83455225487
ISSN
1520-5207
DOI
10.1021/jp2078264
language
English
LU publication?
yes
id
7b76176f-8709-4bf2-9923-69f227fa57bc (old id 2291765)
date added to LUP
2012-01-11 12:42:42
date last changed
2017-09-03 04:02:28
@article{7b76176f-8709-4bf2-9923-69f227fa57bc,
  abstract     = {We describe the characterization of the hydrodynamic properties of anisotropic magnetic nanoparticles using a combination of transmission electron microscopy (TEM) and dynamic as well as depolarized dynamic light scattering (DLS/DDLS). The particles used are nearly monodisperse hematite spindles with an average length of 280 nm and a minor axis of 57 nm, coated with a layer of silica of variable thickness that allows us to tune the particle aspect ratio between 5 and 2. Their geometrical dimensions can thus be determined easily and quantitatively from TEM. Moreover, their size is ideal to employ DLS and DDLS to measure the translational and rotational diffusion coefficients D-T and D-R, while the presence of a magnetic core opens a plethora of opportunities for future studies and applications. We demonstrate that we can successfully predict the hydrodynamic properties of the different particles based on a TEM characterization of their size distribution and using established theoretical models for the hydrodynamic properties of anisotropic particles. When compared with the theoretical predictions, our light scattering measurements are in quantitative agreement. This agreement between theory and experiment is achieved without having to invoke any adjustable free parameter, as the TEM results are used to calculate the corresponding diffusion coefficients on an absolute scale We demonstrate that this is achieved due to a new and simple method for the statistical weighting of the TEM information, and the use of the correct hydrodynamic models for the observed particle shape. In addition, we also demonstrate an enhanced sensitivity of the rotational diffusion for the surface properties of ellipsoidal nanoparticles, and point out that this may serve as an ideal tool toward characterizing functionalized surfaces.},
  author       = {Martchenko, Ilya and Dietsch, Herve and Moitzi, Christian and Schurtenberger, Peter},
  issn         = {1520-5207},
  language     = {eng},
  number       = {49},
  pages        = {14838--14845},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part B},
  title        = {Hydrodynamic Properties of Magnetic Nanoparticles with Tunable Shape Anisotropy: Prediction and Experimental Verification},
  url          = {http://dx.doi.org/10.1021/jp2078264},
  volume       = {115},
  year         = {2011},
}