Graphene hydrophobicity

The model of the micelle formation in which some surfactant molecules lie flat on the graphene SWNT surface along the tube axis is preferable than the model with surfactant molecules distributed uniformly around the tube with hydrophobic chains close to the SWNT surface. 

The surface chemistry of activated carbons essentially depends on their heteroatom content, mainly their surface oxygen complex content, which determines the charge of the surface, its hydrophobicity, and the electronic density of the graphene layers. Thus, when a solid such as a carbon material is immersed in an aqueous solution, it develops a surface charge that derives from the... 

Research on the immobilization of metal complexes using carbon materials is scarce compared with inorganic supports, such as zeolites, silicas, and clay-based materials [1-10]. Nevertheless, carbon materials are unique supports, as they can provide a variety of surface groups at the edges and/or defects of graphene sheets that can be tailored by adequate thermal or chemical treatments, besides the inherent chemical-physical reactivity associated with the graphene sheets themselves, which are hydrophobic, have low polarity, and have a rich n-electron density [13-15]. This can lead to a huge diversity of methods for immobilization of molecular species. 

Immobilization on Graphene Sheets The graphene sheets have low polarity, behave as hydrophobic surfaces, and are rich in jt-electron density [13-16,21,24], Consequently, these properties can be used to immobilize molecular species by noncovalent interactions [28,31,32,38] and by covalent bonding. In the latter... 

Noncovalent Interactions on Graphene Sheets The noncovalent interactions inclnde k-k interactions, van der Waals/hydrophobic-hydrophilic, and electrostatic interactions between the carbon snrface and the molecnlar species, and have been nsed in the fnnctionalization of several carbon surfaces, including activated carbons (ACs) several types of graphites, and CNTs [17,18,28,30,31,38,54-57],... 

Surfactant molecules can also be used as anchors for the immobilization of chemical species by noncovalent interactions [38], The hydrophobic part of the molecule interacts with the graphene sheets, whereas the hydrophilic head (charged) can interact with the metal complex by electrostatic interactions or covalent bonding. Polyelectrolytes can also act as spacers for charged chemical species, and in this case, strong electrostatic interactions with carbon materials occur [49,53],... 

Carbon nanotubes (CNTs) are sheets of graphene rolled into cylindrical tubes and exhibit high degree of hydrophobicity, curvature, and surface-area-to-volume ratios, making them as stationary phases for reversed-phase and affinity... 

In the case of a low content of carbon deposits (Cq ==0.5 wt%) formed at a surface of nanosilica, the amount of bound water increases but it decreases at large Q values due to hydrophobic properties of carbon deposits. The properties of carbon deposits on silica are similar to that of carbon black but in the case of cataly tically active substrate or the presence of metals in the precursors (forming a cataly tically active phase) the texture of carbon can be different from carbon black. For water bound to carbon particles, a certain up-held shift can be observed due to the effects of the jt-electrons current at the carbon sheets (small graphene clusters). However, this shift is not larger as in the case of nanoporous AC because carbon deposits do not have nanopores. 

Polymers are usually hydrophobic and mary nucleating agents are either hydrophilic and both hydrophobic and hydrophilic in nature. Dispersion of hydrophilic graphene oxide is difficult in hydrophobic polymers. ... 

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