Magnetically anisotropic additive for scalable manufacturing of polymer nanocomposite: Iron-Coated carbon nanotubes

Novel nanoparticles additives for polymer nanocomposites were prepared by coating carbon nanotubes (CNTs) with ferromagnetic iron (Fe) layers, so that their micro-structures can be bulkcontrolled by external magnetic field application. Application of magnetic fields is a promising, scalable method to deliver bulk amount of nanocomposites while maintaining organized nanoparticle assembly throughout the uncured polymer matrix. In this work, Fe layers (∼18 nmthick) were deposited on CNTs (∼38 nmdiameter and∼50 μmlength) to form thin films with high aspect ratio, resulting in a dominance of shape anisotropy and thus high coercivity of∼50-100 Oe. The Fe-coated CNTs were suspended in water and applied with a weak magnetic field of∼75 G, and yet preliminary magnetic assembly was confirmed. Our results demonstrate that the fabricated Fe-coated CNTs are magnetically anisotropic and effectively respond to magnetic fields that are∼103 times smaller than other existing work (∼105 G).We anticipate this work will pave the way for effective property enhancement and bulk application of CNT-polymer nanocomposites, through controlled microstructure and scalable manufacturing.