Superhydrophobic Surfaces Produced by Carbon Nanotube Modified Polystyrene Composite Coating

Wettability and Anti-Corrosion Performances of Carbon Nanotube-Silane Composite Coatings

In this paper, a sol-gel N-propyl-trimethoxy-silane coating filled with different amount of multi-wall carbon nanotubes (MWCNTs) was investigated in order to improve the aluminum corrosion resistance. The nanocomposite coating was applied, by drop casting, on AA6061 aluminum alloy substrate. The morphological analysis highlighted that a uniform sol-gel coating was obtained with 0.4 wt.% CNT. Lower or higher nanotube contents lead to the formation of heterogeneities or agglomeration in the coating, respectively. Furthermore, all nanocomposite coatings exhibited effective adhesion to the substrate. In particular, the pull-off strength ranged in 0.82–1.17 MPa. Corrosion protection of the aluminum alloy in NaCl 3.5 wt.% electrolyte (seawater) was significantly improved after CNT addition to the base coating. The stability in electrochemical impedance was observed during three days of immersion in the sodium chloride solution. AS3-CNT2 and AS3-CNT4 batches showed advanced electrochemical stability during immersion tests. Furthermore, interesting results were evidenced in potentiodynamic polarization curves where a decrease of the corrosion current of at least two order of magnitude was observed. Moreover, the breakdown potential was shifted toward noble values. Best results were observed on AS3-CNT6 specimen which exhibited a passivation current density of approximately 1.0 × 10−5 mA/cm2 and a breaking potential of 0.620 V/AgAgClsat.

Construction of hydrophobic alginate-based foams induced by zirconium ions for oil and organic solvent cleanup

Hydrophobic modification of sodium alginate (SA) foams via a simple freeze-drying and post cross-linking induced by zirconium (Zr) ions was developed. All results demonstrated that Zr ions not only constructed surface microstructure but also lowered surface energy of foams, leading to the hydrophobic character. Hydrophobic and oleophilic foams showed excellent adsorption capacities for different oils and organic solvents (11.2-25.9 g/g). Furthermore, SA solution can be also coated on porous substrates, such as melamine sponges (MS) and Nylon strainers (NS), to give hydrophobic modification by Zr ion crosslinking. These excellent performances made them a promising for oil adsorption and cleanup.

Extremely stretchable and conductive water-repellent coatings for low-cost ultra-flexible electronics

Rapid advances in modern electronics place ever-accelerating demands on innovation towards more robust and versatile functional components. In the flexible electronics domain, novel material solutions often involve creative uses of common materials to reduce cost, while maintaining uncompromised performance. Here we combine a commercially available paraffin wax–polyolefin thermoplastic blend (elastomer matrix binder) with bulk-produced carbon nanofibres (charge percolation network for electron transport, and for imparting nanoscale roughness) to fabricate adherent thin-film composite electrodes. The simple wet-based process produces composite films capable of sustained ultra-high strain (500%) with resilient electrical performance (resistances of the order of 10¹–10² Ω sq⁻¹). The composites are also designed to be superhydrophobic for long-term corrosion protection, even maintaining extreme liquid repellency at severe strain. Comprised of inexpensive common materials applied in a single step, the present scalable approach eliminates manufacturing obstacles for commercially viable wearable electronics, flexible power storage devices and corrosion-resistant circuits.

The development of modern flexible electronics calls for new materials with extreme stretchability and high conductivity. Here, Mates et al. show a printable material made of commercially-available elastomers and carbon nanofibres, which exhibits low resistance and water-repellency at strain up to 500%.

The fluid diode: tunable unidirectional flow through porous substrates

Many important applications in fluid management could benefit from unidirectional transport through porous media via a simple, large-area, low-cost coating treatment; in essence, a fluid diode demonstrated herein for water using common cellulosic paper substrates. In electronics, the diode is an electrical component with asymmetric current transfer characteristics. A light (<2 g/m(2)) superhydrophobic conformal coating applied onto one side of a porous substrate is shown to create a liquid transport function analogous to the electronic diode, facilitating fluid movement in one direction under negligible penetration pressures, but opposing it in reverse up to greater pressures. The phenomenon is driven by capillary action and can be observed using any similarly-thin fluid barrier applied on only one side (i.e., wettability contrast) of an absorbent porous matrix. Diodic action and liquid transport rates are shown to be highly tunable, determined by fiber diameter and spacing, in combination with coating deposition amount. As an example, the device is used to separate an oil/water mixture, relying upon the surface tension differences of the mixture constituents, and may be implemented in multicomponent fluid filtration/separation technologies.