Magnetic field-guided orientation of carbon nanotubes through their conjugation with magnetic nanoparticles
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Low intensity magnetic fields (22mT) rendered by a pair of bar magnets have been used to achieve in situ precise orientation of multiwalled carbon nanotubes (MWCNTs) and their directional deposition on solid substrates. The nanotubes were imparted magnetic characteristics through Fe3O4 (magnetite) nanoparticles covalently attached to their surface. The side walls of nanotubes were first acid oxidized with H2SO4/HNO3 (3:1 v/v) mixture and amine-functionalized magnetic nanoparticles were then interfaced to ends and side walls of the nanotubes through covalent linkages in the presence of a zero length cross linker, 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide. Fourier transformed infrared spectroscopic investigations affirmed the functionalization of nanostructures and formation of a magnetic nanohybrid. Transmission electron microscopy results revealed the attachment of nanoparticles along the side walls of MWCNTs. A flow cell was utilized to orient magnetic nanohybrid in the desired direction and also to create thin films of aligned MWCNTs. Further, directional assembly of magnetic MWCNTs at different orientation angles on solid substrates was studied by field emission scanning electron microscopy and optical microscopy. The procedure can be scaled to align CNTs on large surface areas for numerous applications, e.g., nanosensors, field emitters, and composites.
KeywordsExternal Magnetic Field Flow Cell Optical Polarizer Magnetic Orientation Free Amine Group
The authors acknowledge the support from Department of Information Technology (DIT), Ministry of Information technology (MIT), Govt. of India. The authors are thankful to Er. Dinesh Sharma of Sophisticated Analytical Instruments Facility, Panjab University, Chandigarh, India for TEM measurements. The authors are also thankful to Director CSIO, Chandigarh, India for providing necessary facilities. One of the authors, Suresh Kumar thanks University Grant Commission (UGC), Govt. of India for providing Senior Research Fellowship.
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