title: Nitroxide-Functionalized Graphene Oxide from Graphite Oxide.
abstract: A facile method for preparing functionalized graphene oxide single layers with nitroxide groups is reported herein. Highly oxidized graphite oxide (GO=90.6%) was obtained, slightly modifying an improved Hummer's method. Oxoammonium salts (OS) were investigated to introduce nitroxide groups to GO, resulting in a one-step functionalization and exfoliation. The mechanisms of functionalization/exfoliation are proposed, where the oxidation of aromatic alcohols to ketone groups, and the formation of alkoxyamine species are suggested. Two kinds of functionalized graphene oxide layers (GOFT1 and GOFT2) were obtained by controlling the amount of OS added. GOFT1 and GOFT2 exhibited a high interlayer spacing (d0001= 1.12nm), which was determined by X-ray diffraction. The presence of new chemical bonds C-N (~9.5 %) and O-O (~4.3 %) from nitroxide attached onto graphene layers were observed by X-ray photoelectron spectroscopy. Single-layers of GOFT1 were observed by HRTEM, exhibiting amorphous and crystalline zones at a 50:50 ratio; in contrast, layers of GOFT2 exhibited a fully amorphous surface. Fingerprint of GOFT1 single layers was obtained by electron diffraction at several tilts. Finally, the potential use of these materials within Nylon 6 matrices was investigated, where an unusual simultaneous increase in tensile stress, tensile strain and Young's modulus was observed.
authors.affiliation: Centro de Investigación en Materiales Avanzados S. C. (CIMAV-Unidad Monterrey), Av. Alianza Norte 202, Autopista Monterrey-Aeropuerto Km 10, PIIT, Apodaca-Nuevo León, México, C.P. 66600. Tel/
authors.forename: Yazmin I
authors.initials: YI
authors.lastname: Avila-Vega
authors.affiliation: Centro de Investigación en Materiales Avanzados S. C. (CIMAV-Unidad Monterrey), Av. Alianza Norte 202, Autopista Monterrey-Aeropuerto Km 10, PIIT, Apodaca-Nuevo León, México, C.P. 66600. Tel/
authors.forename: Cesar C
authors.initials: CC
authors.lastname: Leyva-Porras
authors.affiliation: Department of Material Science and Engineering, The University of Texas-Dallas. 800 W. Campbell, Richardson, TX. 75080, USA.
authors.forename: Marcela
authors.initials: M
authors.lastname: Mireles
authors.affiliation: Department of Material Science and Engineering, The University of Texas-Dallas. 800 W. Campbell, Richardson, TX. 75080, USA.
authors.forename: Manuel
authors.initials: M
authors.lastname: Quevedo-López
authors.affiliation: Chemistry Department, The University of Texas-Pan American. 1201 W. University Dr., Edinburg, TX. 78539, USA.
authors.forename: Javier
authors.initials: J
authors.lastname: Macossay
authors.affiliation: Centro de Investigación en Materiales Avanzados S. C. (CIMAV-Unidad Monterrey), Av. Alianza Norte 202, Autopista Monterrey-Aeropuerto Km 10, PIIT, Apodaca-Nuevo León, México, C.P. 66600. Tel/
authors.forename: José
authors.initials: J
authors.lastname: Bonilla-Cruz