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The functionalization of multi-walled carbon nanotubes (MW-CNTs) was obtained by generating reactive perfluoropolyether (PFPE) radicals that can covalently bond to MW-CNTs’ surface. Branched and linear PFPE peroxides with equivalent molecular weights of 1275 and 1200 amu, respectively, have been thermally decomposed for the production of PFPE radicals. The functionalization with PFPE chains has changed the wettability of MW-CNTs, which switched their behavior from hydrophilic to super-hydrophobic. The low surface energy properties of PFPEs have been transferred to MW-CNTs surface and branched units with trifluoromethyl groups, CF3, have conferred higher hydrophobicity than linear units. Porosimetry discriminated the effects of PFPE functionalization on meso-porosity and macro-porosity. It has been observed that reactive sites located in MW-CNTs mesopores have been intensively functionalized by branched PFPE peroxide due to its low average molecular weight. Conductivity measurements at different applied pressures have showed that the covalent linkage of PFPE chains, branched as well as linear, weakly modified the electrical conductivity of MW-CNTs. The decomposed portions of PFPE residues, the PFPE chains bonded on carbon nanotubes, and the PFPE fluids obtained by homo-coupling side-reactions were evaluated by mass balances. PFPE-modified MW-CNTs have been characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), static contact angle (SCA), surface area, and porosity measurements.

Herein electrochemical approaches for fabrication of hierarchical nanostructured gold coatings (HNGCs) are presented. Examples of HNGCs obtained by electrodeposition in sulphite based electrolyte on nickel electroplated copper (Ni/Cu) substrates are reported. The morphology and microstructure of the nanostructured surface were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD). The effects of the electrodeposition current density (J) and deposition time on the morphological features of nanostructured gold coating will be discussed. The surface wettability on thiols treated gold surface as a function of the electrodeposition current density is investigated. Thiols treated electrodepsited HNGCs can possess superhydrophobic behavior with water contact angle of 179 °. IntroductionSuperhydrophobic surfaces exhibit a number of exciting properties, which have attracted a lot of interest recently and make them important to a wide range of applications, from microfluidics and lab-on-a-chip devices to biomolecule immobilization and self-cleaning coatings (1,2). Conventionally, super-hydrophobic surfaces have been obtained by enhancing surface roughness or by deposition of low surface energy materials (3). The effect of roughness on hydrophobicity has been described by Wenzel's model and Cassie's model. Based on these models, previous studies suggested that small scale (nanoscale) features with a larger scale spacing (microscale) would yield better hydrophobic property (4). Many methods have been developed to produce rough surfaces for hydrophobicity, including plasma etching, anodic oxidization, chemical vapor deposition, phase separation and molding (5). Hierarchical micro/nanostructures assemblies using micro/nanoparticles, nanorods, nanobelts as building blocks with welldefined shape and inner structure can be obtained through colloidal chemistry strategy. Electrochemical deposition methods are widely used to form rough structures. Although electrodeposition is a general route to fabricate hierarchical micro/nanostructures, most of which are synthesized in the presence of organic additives or surfactants, and others are based on template.