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Magnetic anisotropy of functionalized multi-walled carbon nanotube suspensions

Magnetic anisotropy of functionalized multi-walled carbon nanotube suspensions
Magnetic anisotropy of functionalized multi-walled carbon nanotube suspensions

We report on the magnetic properties of stable suspensions from oxidized Multiwalled Carbon Nanotubes (MWCNT) functionalized with aminopyrene (AP). MWCNT form π−π stacking adducts with AP (AP-MWCNT), originating homogenous, stable, suspensions in N,N-dimethylformamide (DMF) or melted agarose. First, we investigated the magneto-optical properties of these adducts. When applying series of pulsed magnetic fields to nanotube suspensions in DMF, the pattern of light dispersed increased during the magnetic pulse and decreased in the intervals, a behavior consistent with magnetic field induced orientation of the adducts. When adducts were suspended in a melted agarose gel under an external magnetic field, the extinction coefficient of polarized light through the gel, was larger when the polarization plane was parallel to the magnetic field direction. Based on the magneto-optical responses observed, we further investigated the magnetic properties of AP-MWCNT implementing measurements with Superconducting Quantum Interference Device, Zero Field Cooling and Field Cooling, Thermogravimetric and Differential Scanning Calorimetry. Pre-oriented AP-MWCNT suspensions depicted a clear superparamagnetic character with hysteresis loops revealing larger magnetic susceptibility values along their longitudinal axis. In summary, magneto-optical and SQUID measurements revealed that nanotube adducts in suspension, behave as nanoscale compass needles aligning their long axis parallel to externally applied magnetic fields.

Aminopyrene, Functionalized multi-walled carbon nanotubes, Magnetic anisotropy, Optical properties, SQUID
0008-6223
229-237
Calle, Daniel
23891e36-be5c-4f35-9817-b255c72c679a
Negri, Viviana
95a1cb11-45d7-4b88-93c0-40770b027460
Munuera, Carmen
708f634f-9044-4f4b-bc50-4d6eaf3addd1
Mateos, Luis
4b1917f7-4dc8-4cf1-b22f-6622a665660a
Touriño, Isabel Lado
7b94d298-2738-433e-a60c-6c28e686d030
Viñegla, Piedad Ros
27d1196d-00e0-4e29-98eb-95c29fa9a3bf
Ramírez, Mariola O.
7ed7b7c7-cd1e-4b50-82f8-14d0fe2b13ea
García-Hernández, Mar
e210c405-ad93-4dac-95bb-f41bf46a1ec8
Cerdán, Sebastián
1a238395-128d-485c-9e67-658d8a3bbb38
Ballesteros, Paloma
79bc6c31-6d3c-4b77-8735-0acbe085fe29
Calle, Daniel
23891e36-be5c-4f35-9817-b255c72c679a
Negri, Viviana
95a1cb11-45d7-4b88-93c0-40770b027460
Munuera, Carmen
708f634f-9044-4f4b-bc50-4d6eaf3addd1
Mateos, Luis
4b1917f7-4dc8-4cf1-b22f-6622a665660a
Touriño, Isabel Lado
7b94d298-2738-433e-a60c-6c28e686d030
Viñegla, Piedad Ros
27d1196d-00e0-4e29-98eb-95c29fa9a3bf
Ramírez, Mariola O.
7ed7b7c7-cd1e-4b50-82f8-14d0fe2b13ea
García-Hernández, Mar
e210c405-ad93-4dac-95bb-f41bf46a1ec8
Cerdán, Sebastián
1a238395-128d-485c-9e67-658d8a3bbb38
Ballesteros, Paloma
79bc6c31-6d3c-4b77-8735-0acbe085fe29

Calle, Daniel, Negri, Viviana, Munuera, Carmen, Mateos, Luis, Touriño, Isabel Lado, Viñegla, Piedad Ros, Ramírez, Mariola O., García-Hernández, Mar, Cerdán, Sebastián and Ballesteros, Paloma (2018) Magnetic anisotropy of functionalized multi-walled carbon nanotube suspensions. Carbon, 131, 229-237. (doi:10.1016/j.carbon.2018.01.104).

Record type: Article

Abstract

We report on the magnetic properties of stable suspensions from oxidized Multiwalled Carbon Nanotubes (MWCNT) functionalized with aminopyrene (AP). MWCNT form π−π stacking adducts with AP (AP-MWCNT), originating homogenous, stable, suspensions in N,N-dimethylformamide (DMF) or melted agarose. First, we investigated the magneto-optical properties of these adducts. When applying series of pulsed magnetic fields to nanotube suspensions in DMF, the pattern of light dispersed increased during the magnetic pulse and decreased in the intervals, a behavior consistent with magnetic field induced orientation of the adducts. When adducts were suspended in a melted agarose gel under an external magnetic field, the extinction coefficient of polarized light through the gel, was larger when the polarization plane was parallel to the magnetic field direction. Based on the magneto-optical responses observed, we further investigated the magnetic properties of AP-MWCNT implementing measurements with Superconducting Quantum Interference Device, Zero Field Cooling and Field Cooling, Thermogravimetric and Differential Scanning Calorimetry. Pre-oriented AP-MWCNT suspensions depicted a clear superparamagnetic character with hysteresis loops revealing larger magnetic susceptibility values along their longitudinal axis. In summary, magneto-optical and SQUID measurements revealed that nanotube adducts in suspension, behave as nanoscale compass needles aligning their long axis parallel to externally applied magnetic fields.

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More information

Accepted/In Press date: 31 January 2018
e-pub ahead of print date: 5 February 2018
Keywords: Aminopyrene, Functionalized multi-walled carbon nanotubes, Magnetic anisotropy, Optical properties, SQUID

Identifiers

Local EPrints ID: 418092
URI: https://eprints.soton.ac.uk/id/eprint/418092
ISSN: 0008-6223
PURE UUID: dfd92d25-5015-48e5-b677-75ba5fdca927

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Date deposited: 22 Feb 2018 17:30
Last modified: 13 Mar 2019 18:50

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Contributors

Author: Daniel Calle
Author: Viviana Negri
Author: Carmen Munuera
Author: Luis Mateos
Author: Isabel Lado Touriño
Author: Piedad Ros Viñegla
Author: Mariola O. Ramírez
Author: Mar García-Hernández
Author: Sebastián Cerdán
Author: Paloma Ballesteros

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