ABSTRACT:A facile method of simultaneous alignment and micropatterning of multi-wall carbon nanotubes (MWCNTs) is presented. The method uses the combination of the magnetic alignment and patterning techniques. Due to their diamagnetic nature, MWCNTs suspended in a liquid medium are trapped at the minima of the magnetic field created by a field modulator and at the same time they align due to their magnetic anisotropy. The achieved patterning and alignment is fixed by solidification of the matrix. The alignments both parallel and perpendicular to the film surface have been achieved.
We report simultaneous alignment and micropatterning of carbon nanotubes (CNTs) using a high magnetic field. It is important to prepare well-dispersed CNTs for alignment and patterning because CNT aggregation obstructs alignment. In magnetic field, highly anisotropic CNTs rotate in the direction stabilized in energy. Owing to their diamagnetic nature, CNTs suspended in a liquid medium are trapped in a weak magnetic field generated by a field modulator; meanwhile, they align to the applied strong magnetic field. The alignment has been achieved not only in polymers but also in ceramic and silicone composites.
A stable suspension of multi-walled carbon nanofibers (CNFs) in Al 2 O 3 was prepared by adding ammonium polycarboxylate as a dispersant in an aqueous solution. A strong magnetic field of 12 T was applied to the CNFs/Al 2 O 3 suspension to investigate the alignment of the CNFs. The result was that the CNFs in the matrix showed good alignment with the direction of the magnetic field. It was found that 0.5 mass% CNFs showed isolated alignment; in contrast, with 5 mass% CNFs there were mainly aligned bundles. The alignment was only seen with straight CNFs; curved CNFs showed no alignment in a magnetic field.
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