This paper reports on the thermal properties of reduced graphite oxide (RGO) flakes, studied by means of scanning thermal microscopy (SThM). This technique was demonstrated to allow thermal characterization of the flakes with a spatial resolution of the order of a few tens of nanometers, while recording nanoscale topography at the same time. Several individual RGO flakes were analyzed by SThM, both as obtained after conventional thermal reduction and after a subsequent annealing at 1700°C. Significant differences in the thermal maps were observed between pristine and annealed flakes, reflecting higher heat dissipation on annealed RGO flakes compared with pristine ones. This result was correlated with the reduction of RGO structure defectiveness. In particular, a substantial reduction of oxidized groups and sp 3 carbons upon annealing was proven by X-ray photoelectron and Raman spectroscopies, while the increase of crystalline order was demonstrated by X-ray diffraction, in terms of higher correlation lengths both along and perpendicular to the graphene planes. Results presented in this paper provide experimental evidence for the qualitative correlation between the defectiveness of graphene-related materials and their thermal conductivity, which is clearly crucial for the exploitation of these materials into thermally conductive nanocomposites.©2016. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/

The influence of different graphite-based nanofillers on epoxide ring opening reactions, as induced by amines for diglycidyl ether of bisphenol A (DGEBA), is studied. Direct kinetic studies, with full chemical characterization and quantitative evaluation of the low molecular mass products, for reactions of DGEBA with primary and secondary monoamines as well with alcohols, are conducted. Moreover, the kinetic behavior of a commercial epoxy resin based on DGEBA and a diamine, leading to crosslinked insoluble networks, is studied by indirect methods, such as differential scanning calorimetry (DSC) and rheometry. The reported results show a relevant catalytic activity of graphene oxide on epoxy resin crosslinking by amines. For instance, for a graphene oxide content of 3 wt%, the exothermic crosslinking DSC peak is shifted (upon heating at 10 °C min-1) from 113 °C down to 96 °C, while the gel time at 50 °C is reduced by a factor of 2.5. This behavior is due to the ability of graphene oxide to catalyze primary amine-epoxy, secondary amine-epoxy and mainly hydroxyl-epoxy additions

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Highly ordered graphite oxide intercalation compounds (GOIC) and fully disordered graphite oxide exfoliated compounds (GOEC) have been obtained, for two quaternary phosphonium salts. X-ray diffraction patterns of both GOIC and GOEC maintain the 100 and 110 reflections of GO, clearly indicating the maintenance of in-plane GO order. For GOICs, few 00ℓ reflections (with ℓ up to 3) appear, indicating an increase with respect to GO of crystalline order as well as an increase of spacing between GO layers from 0.84 nm up to 1.40 nm. GOIC and GOEC have been compared as for their kinetics of release in aqueous solutions of a phosphonium ion, being a known antibacterial agent. The GOICs exhibit pH sensitive cation release, with zero order kinetics, which could be helpful for applications requiring triggered and constant supply of active ions.