Quantification of magneto-optically active nanorods and inactive aggregates in nickel nanorod colloids

Tschöpe, Andreas; Krämer, Florian; Birster, Kerstin; Gratz, Micha; Birringer, R.

doi:10.1016/j.colcom.2016.03.001

Cited by 8 publications

(5 citation statements)

References 19 publications

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“…Consequently, many studies in the corresponding literature deal with the different properties of Ni nanorods that are synthesized by electrodeposition into porous templates. Among others, the studied topics account for optical, magnetic, crystallographic and compositional properties [ 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 ]. Within the current review, we focus on Ni nanorod applications that enable to examine phenomena that are additional to the determination of the physical properties of bare Ni nanorods only.…”

Section: Nickel Nanorod Applicationsmentioning

confidence: 99%

Applications, Surface Modification and Functionalization of Nickel Nanorods

2017

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The growing number of nanoparticle applications in science and industry is leading to increasingly complex nanostructures that fulfill certain tasks in a specific environment. Nickel nanorods already possess promising properties due to their magnetic behavior and their elongated shape. The relevance of this kind of nanorod in a complex measurement setting can be further improved by suitable surface modification and functionalization procedures, so that customized nanostructures for a specific application become available. In this review, we focus on nickel nanorods that are synthesized by electrodeposition into porous templates, as this is the most common type of nickel nanorod fabrication method. Moreover, it is a facile synthesis approach that can be easily established in a laboratory environment. Firstly, we will discuss possible applications of nickel nanorods ranging from data storage to catalysis, biosensing and cancer treatment. Secondly, we will focus on nickel nanorod surface modification strategies, which represent a crucial step for the successful application of nanorods in all medical and biological settings. Here, the immobilization of antibodies or peptides onto the nanorod surface adds another functionality in order to yield highly promising nanostructures.

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Section: Nickel Nanorod Applicationsmentioning

confidence: 99%

Applications, Surface Modification and Functionalization of Nickel Nanorods

2017

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“…In such configurations, their magnetization behavior is strongly influenced by dipolar interactions [25,26]. Yet, despite their permanent magnetic moment, Ni nanorods can also be processed to stable colloidal dispersions [27] as well as homogeneous isotropic and anisotropic nanorod/hydrogel composites [28,29]. When exposed to a transversal magnetic field, each nanorod is driven by a torque to align with the field direction.…”

Section: Introductionmentioning

confidence: 99%

Magnetic anisotropy of nickel nanorods and the mechanical torque in an elastic environment

Schopphoven

Tschöpe

2018

J. Phys. D: Appl. Phys.

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Nickel nanorods with average length and diameter were prepared by the anodic aluminum oxide (AAO)-template method, processed to a colloidal dispersion and embedded in a gelatine hydrogel matrix at low volume fraction . The large aspect ratio of these single-domain particles gives rise to a high magnetic shape anisotropy in combination with a significant anisotropic optical polarizability. The magnetic anisotropy enables exertion of a torque on nanorods without contact by applying a homogeneous magnetic field. In response, the nanorods rotate by an angle which is determined by the balance between the magnetic torque and the mechanical counter torque, caused by the elastic deformation of the surrounding matrix. This rotation was experimentally detected using optical transmission of linearly polarized light. We used the combination of magnetization and torque-driven rotation measurements to evaluate an adapted Stoner–Wohlfarth model of the orientation- and field-dependent magnetic torque on Ni nanorods in an elastic environment as base for optimization of torque-driven magnetic actuators.

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“…The nanorods were extracted by dissolving the template in a dilute NaOH solution at pH 11.5 to which 10 g/L poly(vinylpyrrolidone) (PVP, Acros GmbH 276142500, M w = 3500 g/mol) was added as steric stabilizer . After repeated washing by centrifugation (20 min @ 11000 rcf) and redispersion in an ultrasonic bath, large aggregated contaminants were separated from the suspension by centrifugation at 200 rcf for 2 h. The last step ensures that the tracer particles do not show any significant sedimentation over several days, unless the colloid stability is impaired by unsuitable pH or high ionic strength …”

Section: Methodsmentioning

confidence: 99%

“…50 After repeated washing by centrifugation (20 min @ 11000 rcf) and redispersion in an ultrasonic bath, large aggregated contaminants were separated from the suspension by centrifugation at 200 rcf for 2 h. The last step ensures that the tracer particles do not show any significant sedimentation over several days, unless the colloid stability is impaired by unsuitable pH or high ionic strength. 75 A preliminary characterization by TEM and static magnetic fielddependent optical transmission (SFOT, see below) provided the average size and concentration of the nanorod colloid. Based on these data, poly(acrylic acid) (PAA, Sigma Aldrich 323667, average M w = 1800 g/mol) was added to the solution at 15 g PAA/m 2 nanorod surface area and stirred for 24 h. The surface-coated nanorods were retrieved by magnetic separation and redispersed in double-distilled water.…”

Section: Macromoleculesmentioning

confidence: 99%

Size Effects in the Oscillatory Rotation Dynamics of Ni Nanorods in Poly(ethylene oxide) Solutions

Gratz

Tschöpe

2019

Macromolecules

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The rotation of Ni nanorods, dispersed in dilute and semidilute poly(ethylene oxide) solutions, is investigated. Ni nanorods with similar diameter but different lengths are synthesized using the anodic aluminum oxide template method and characterized by transmission electron microscopy and static magnetic field-dependent optical transmission (SFOT) of linearly polarized light. The rotational motion of nanorods, determined by oscillating magnetic field-dependent optical transmission (OFOT) measurements, is analyzed to retrieve the local dynamic modulus of the polymer solution. The effect of probe size relative to intrinsic length scales of the polymer solution is systematically investigated by variation of the nanorod size, polymer molar mass, and concentration. A significant decrease in the zero-shear rate viscosity is observed in the semidilute entangled regime, which depends on the hydrodynamic length of the nanorods, L h, and polymer radius of gyration, R g, but not on PEO concentration. The relative viscosity can be approximated by η 0 OFOT/η 0 macro = exp ( – 5.6R g/L h). The macroscopic dynamic modulus of the entangled polymer solutions is measured by small-amplitude oscillatory shear. The local dynamic modulus, obtained from nanorod oscillation measurements, exhibits systematic changes with decreasing size of the probe particles, which indicate entanglement reduction as the physical origin of the size effect in this particular particle/polymer system.

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Quantification of magneto-optically active nanorods and inactive aggregates in nickel nanorod colloids

Cited by 8 publications

References 19 publications

Applications, Surface Modification and Functionalization of Nickel Nanorods

Applications, Surface Modification and Functionalization of Nickel Nanorods

Magnetic anisotropy of nickel nanorods and the mechanical torque in an elastic environment

Size Effects in the Oscillatory Rotation Dynamics of Ni Nanorods in Poly(ethylene oxide) Solutions

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