Abstract
Carbon nanostructures are widely used as fillers to tailor the mechanical, thermal, barrier, and electrical properties of polymeric matrices employed for a wide range of applications. Reduced graphene oxide (rGO), a carbon nanostructure from the graphene derivatives family, has been incorporated in composite materials due to its remarkable electrical conductivity, mechanical strength capacity, and low cost. Graphene oxide (GO) is typically synthesized by the improved Hummers’ method and then chemically reduced to obtain rGO. However, the chemical reduction commonly uses toxic reducing agents, such as hydrazine, being environmentally unfriendly and limiting the final application of composites. Therefore, green chemical reducing agents and synthesis methods of carbon nanostructures should be employed. This paper reviews the state of the art regarding the green chemical reduction of graphene oxide reported in the last 3 years. Moreover, alternative graphitic nanostructures, such as carbons derived from biomass and carbon nanostructures supported on clays, are pointed as eco-friendly and sustainable carbonaceous additives to engineering polymer properties in composites. Finally, the application of these carbon nanostructures in polymer composites is briefly overviewed.
Highlights
Method and chemically reduced to obtain reduced graphene oxide (rGO)
This review presents different approaches to prepare sustainable carbon nanostruccarbon nanostructures, graphitic materials derived from biomass, and graphitic materitures suitable for polymer-based composites
Graphite, constituted by graphene rGO is the most used 2D carbon material for the development of electrically conduclayers bonded by strong van der
Summary
Oxide and mechanically reinforced polymer composites [3]. Graphite, constituted by graphene rGO is the most used 2D carbon material for the development of electrically conduclayers bonded by strong van der. The oxygenation the separated graphene layers is accomplished using oxidants, concentrated sulfuric and of phosphoric acids, which promote the graphene layers’ separation Such as hydrogen peroxide and potassium permanganate. The reduction process consists in tiary alcohols and epoxides attached to sp carbons, and hydroxyl and carboxylic groups the partial removal of oxygen functionalities present in the structure, namely, tertiary attached to the sp lattice. The quantification of carbon and oxygen atomic percentages is used to determine the C/O ratio, which is one of the main parameters to evaluate the extent of the GO reduction [18,19]. The high percentage of oxygen functional groups on the GO structure leads to a thermal degradation at lower temperatures than rGO, which allows us to distinguish both materials by TGA [24,25]
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