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Albany, NY, United States

Yoonessi M.,Ohio Aerospace Institute | Lebroin-Coloin M.,NASA | Scheiman D.,ASRC | Meador M.A.,NASA
ACS Applied Materials and Interfaces | Year: 2014

Surface functionalization of pretreated carbon nanotubes (CNT) using aromatic, aliphatic, and aliphatic ether diamines was performed. The pretreatment of the CNT consisted of either acid- or photo-oxidation. The acid treated CNT had a higher initial oxygen content compared to the photo-oxidized CNT and this resulted in a higher density of functionalization. X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA) were used to verify the presence of the oxygenated and amine moieties on the CNT surfaces. Epoxy/0.1 wt % CNT nanocomposites were prepared using the functionalized CNT and the bulk properties of the nanocomposites were examined. Macroscale correlations between the interfacial modification and bulk dynamic mechanical and thermal properties were observed. The amine modified epoxy/CNT nanocomposites exhibited up to a 1.9-fold improvement in storage modulus (Ga) below the glass transition (Tg) and up to an almost 4-fold increase above the Tg. They also exhibited a 3-10 °C increase in the glass transition temperature. The aromatic diamine surface modified epoxy/CNT nanocomposites resulted in the largest increase in shear moduli below and above the Tg and the largest increase in the Tg. Surface examination of the nanocomposites with scanning electron microscopy (SEM) revealed indications of a greater adhesion of the epoxy resin matrix to the CNT, most likely due to the covalent bonding. © 2014 American Chemical Society. Source


Yoonessi M.,Ohio Aerospace Institute | Scheiman D.A.,ASRC | Dittler M.,NASA | Peck J.A.,University of Akron | And 3 more authors.
Polymer (United Kingdom) | Year: 2013

Composite Nickel graphene nanoparticles with hybrid magnetic and electrical properties were prepared. Nickel nanoparticles were tethered to the graphene through a carbon layers and were covered with an amorphous carbon layer to protect them from oxidation. Ni-graphene polyimide nanocomposites were prepared and exhibited magnetic characteristics and high electrical conductivity. The saturation magnetization of the polyimide nanocomposites increased with increasing magnetic nanoparticle content. First order reversal curve (FORC) magnetization showed a bimodal size distribution of the magnetic nanoparticles. Ultra-small-angle X-ray scattering (USAXS) of the nickel nanoparticles in Ni-graphene polyimide nanocomposites were estimated by a sphere model with bimodal size distribution. Nickel graphene nanoparticles were examined by high-resolution transmission electron microscopy (HR-TEM) where two size ranges of nickel were observed. Ni-graphene nanoparticles were well dispersed in the polyimide resin when examined by HR-TEM. Ni-graphene polyimide nanocomposites exhibited magnetic actuation when exposed to a static magnetic field. © 2013 Elsevier Ltd. All rights reserved. Source


Yoonessi M.,Ohio Aerospace Institute | Shi Y.,University of Akron | Scheiman D.A.,ASRC | Lebron-Colon M.,NASA | And 3 more authors.
ACS Nano | Year: 2012

Flexible graphene polyimide nanocomposites (0.1-4 wt %) with superior mechanical properties over those of neat polyimide resin have been prepared by solution blending. Imide moieties were grafted to amine-functionalized graphene using a step-by-step condensation and thermal imidization method. The imide-functionalized graphene exhibited excellent compatibility with N-methyl-2-pyrrolidone. The dynamic storage moduli of the graphene polyimide nanocomposites increased linearly with increasing graphene content for both unmodified graphene and imidized graphene. Moduli of the imidized graphene nanocomposites were 25-30% higher than those of unmodified graphene nanocomposites. Both neat polyimide and polyimide nanocomposites exhibited shape memory effects with a triggering temperature of 230 °C. where addition of graphene improved the recovery rate. Addition of graphene improved thermal stability of the polyimide nanocomposites for both graphene and modified graphene. © 2012 American Chemical Society. Source


News Article
Site: http://www.rdmag.com/rss-feeds/all/rss.xml/all

A team of international scientists led by researchers of the CUNY Advanced Science Research Center (ASRC) and the Politecnico of Milan in Italy has demonstrated a novel approach for designing fully reconfigurable magnetic nanopatterns whose properties and functionality can be programmed and reprogrammed on-demand. The method—published in Nature Nanotechnology and led by Elisa Riedo, professor of Physics with the ASRC's Nanoscience Initiative, and Riccardo Bertacco, a professor with the Politecnico of Milan—is based on thermal scanning probe lithography and uses a hot nano-tip to perform a highly localized field heating and cooling in antiferromagnetic and ferromagnetic thin films. The hot tip is then used to align the spins in the material in any desired direction with nanoscale resolution. "The proposed technique is straightforward and combines the full reversibility and stability of exchange bias, as the same pattern can be written and reset many times, with the resolution and versatility of scanning probe lithography," said Riedo. "In particular, this work demonstrates how thermal scanning probe lithography is gaining momentum as a key nanofabrication method for the next generation of nanodevices, from biomedical sensing to sprintronics." This approach offers researchers the opportunity to control magnetism at the nanoscale as never before. The authors used this method to fabricate channels where spin waves can propagate. Spin waves are a propagating re-ordering of the magnetization in a material. A new generation of computing and sensing devices can be fabricated based on the propagation of spin waves instead of the more conventional electric current. ​Bertacco noted these findings will allow for the development of novel metamaterials with finely-tuned magnetic properties, as well as a reconfigurable computing device architectures. "Equally promising is the creation of structures with high response to external magnetic fields, as they can be used as sensors in new architectures of spintronic devices," he said. "The potential target market for these devices is extremely large—especially with the advent of the age of the 'Internet of things'—in which every object has a growing need for integrated sensors and computational capacity." Edoardo Albisetti, postdoctoral research associate at the Politecnico of Milan and the paper's first author, said the new magnetic nanostructure patterning method gives researchers an increased amount of control. "So far, the patterning of magnetic nanostructures has been mainly achieved through irreversible structural or chemical modifications," Albisetti said. "On the contrary, by using this new thermal assisted magnetic scanning probe lithography (tam-SPL) method, the magnetic nanopatterns are fully reconfigurable and obtained without modifying the film chemistry and topography." The ability to draw new meta-magnetic materials opens the way for the development of innovative devices for information processing based on logic cells as well as on the propagation and manipulation of spin waves in magnonic structures.


News Article
Site: http://www.nanotech-now.com/

Abstract: A team of international scientists led by researchers of the CUNY Advanced Science Research Center (ASRC) and the Politecnico of Milan in Italy has demonstrated a novel approach for designing fully reconfigurable magnetic nanopatterns whose properties and functionality can be programmed and reprogrammed on-demand. The method -- published in Nature Nanotechnology and led by Elisa Riedo, Professor of Physics with the ASRC's Nanoscience Initiative, and Riccardo Bertacco, a professor with the Politenico of Milan--is based on thermal scanning probe lithography and uses a hot nano-tip to perform a highly localized field heating and cooling in antiferromagnetic and ferromagnetic thin films. The hot tip is then used to align the spins in the material in any desired direction with nanoscale resolution. "The proposed technique is straightforward and combines the full reversibility and stability of exchange bias, as the same pattern can be written and reset many times, with the resolution and versatility of scanning probe lithography," said Riedo. "In particular, this work demonstrates how thermal scanning probe lithography is gaining momentum as a key nanofabrication method for the next generation of nanodevices, from biomedical sensing to sprintronics." This approach offers researchers the opportunity to control magnetism at the nanoscale as never before. The authors used this method to fabricate channels where spin waves can propagate. Spin waves are a propagating re-ordering of the magnetization in a material. A new generation of computing and sensing devices can be fabricated based on the propagation of spin waves instead of the more conventional electric current. Bertacco noted these findings will allow for the development of novel metamaterials with finely-tuned magnetic properties, as well as a reconfigurable computing device architectures. "Equally promising is the creation of structures with high response to external magnetic fields, as they can be used as sensors in new architectures of spintronic devices," he said. "The potential target market for these devices is extremely large--especially with the advent of the age of the 'Internet of things'--in which every object has a growing need for integrated sensors and computational capacity." Edoardo Albisetti, postdoctoral research associate at the Politecnico of Milan and the paper's first author, said the new magnetic nanostructure patterning method gives researchers an increased amount of control. "So far, the patterning of magnetic nanostructures has been mainly achieved through irreversible structural or chemical modifications," Albisetti said. "On the contrary, by using this new thermal assisted magnetic scanning probe lithography (tam-SPL) method, the magnetic nanopatterns are fully reconfigurable and obtained without modifying the film chemistry and topography." The ability to draw new meta-magnetic materials opens the way for the development of innovative devices for information processing based on logic cells as well as on the propagation and manipulation of spin waves in magnonic structures. ### The work was supported by the U.S. Department of Energy, the US National Science Foundation, and the Fondazione Cariplo. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

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