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.

Novel PEPA-functionalized graphene oxide for fire safety enhancement of polypropylene

“…The highly oxidized layers of GO could disperse in DMF with long-term stability (three weeks) [16]. GO was exfoliated into layered structure sp 2 hybridized carbon and dispersed in the DMF solution by ultrasonic treatment to obtain a superior diffusion of reactive species.…”

“…Furthermore, added chemical features are enhancing the possibility of interactions between the graphene and other chemical components. The presence of functional groups on GO surfaces has the additional benefits of easy dispersion in polar solvents or water, and it is the key factor in the physical and chemical properties of modified graphene [16]. More than that, these decorated graphenes provide opportunities for researchers to employ them in designing polymer nanocomposites [17, 18].…”

Toughening of polymers by graphene

“…This is a popular route to fabricate GO sheets for their application to polymer composites. Besides GO and RGO, FG also refers to graphene derivates with other functional groups including small molecules 74,75 or polymer chains. 76,77 Both covalent and noncovalent functionalization methods have been established.…”

EELS analysis of Nylon 6 nanofibers reinforced with nitroxide-functionalized graphene oxide

“…In particular, the functionalization of graphene or GO with chemical organic groups is the best way to achieve an effective dispersion or compatibility with a polymeric matrix, thus avoiding re-agglomeration or re-stacking of the fillers. [9–12] Nonetheless, the choice of functional groups, as well as the control of their concentration onto graphene oxide layers is crucial for the development of advanced materials with remarkable mechanical, physical and chemical properties, among others. [11,12] Therefore, several ingenious methodologies have been developed to modify the surface of graphite oxide flakes or layers of graphene oxide by attaching functional organic groups to increase their dispersability in common organic solvents, and thus achieve relatively good dispersions in a polymer matrix.…”

“…[9–12] Nonetheless, the choice of functional groups, as well as the control of their concentration onto graphene oxide layers is crucial for the development of advanced materials with remarkable mechanical, physical and chemical properties, among others. [11,12] Therefore, several ingenious methodologies have been developed to modify the surface of graphite oxide flakes or layers of graphene oxide by attaching functional organic groups to increase their dispersability in common organic solvents, and thus achieve relatively good dispersions in a polymer matrix. [11] Recently, we have disclosed a simple approach to produce in a one-step synthesis, single layers of graphene oxide decorated with nitroxide moieties (GOFT), using oxoammonium salts (halogen-nitroxide) as intercalating-reaction-compatibilization agents under mild reaction conditions in order to functionalize the groups present on the surface and edges of graphite oxide and promote thus the exfoliation.…”