Omniphobic Etched Aluminum Surfaces with Anti-Icing Ability.

In this work, omniphobic surfaces are developed by combining chemical etching and surface modification of aluminum. In the first step, hierarchical micro/nanostructuring is carried out by chemical etching. Thereafter, a perfluoropolyether is grafted onto the corrugated aluminum substrate, decreasing its surface free energy and turning the system omniphobic. The morphology and chemical composition of the developed surfaces are characterized. We observed a low affinity toward liquids, regardless of their chemical nature and surface tension. The surface shows superhydrophobic properties with a water contact angle of 160° and simultaneously strong oleophobic properties with a hexadecane contact angle of 141°. Furthermore, these omniphobic surfaces significantly delay the freezing time of water droplets to 5100 s, which is about 20-fold of the freezing time on pristine aluminum (260 s), and they even inhibit ice growth by repelling the incoming droplets prior to ice nucleation.

Towards molecular electronic devices based on 'all-carbon' wires.

Nascent molecular electronic devices based on linear 'all-carbon' wires attached to gold electrodes through robust and reliable C-Au contacts are prepared via efficient in situ sequential cleavage of trimethylsilyl end groups from an oligoyne, Me3Si-(C[triple bond, length as m-dash]C)4-SiMe3 (1). In the first stage of the fabrication process, removal of one trimethylsilyl (TMS) group in the presence of a gold substrate, which ultimately serves as the bottom electrode, using a stoichiometric fluoride-driven process gives a highly-ordered monolayer, Au|C[triple bond, length as m-dash]CC[triple bond, length as m-dash]CC[triple bond, length as m-dash]CC[triple bond, length as m-dash]CSiMe3 (Au|C8SiMe3). In the second stage, treatment of Au|C8SiMe3 with excess fluoride results in removal of the remaining TMS protecting group to give a modified monolayer Au|C[triple bond, length as m-dash]CC[triple bond, length as m-dash]CC[triple bond, length as m-dash]CC[triple bond, length as m-dash]CH (Au|C8H). The reactive terminal C[triple bond, length as m-dash]C-H moiety in Au|C8H can be modified by 'click' reactions with (azidomethyl)ferrocene (N3CH2Fc) to introduce a redox probe, to give Au|C6C2N3HCH2Fc. Alternatively, incubation of the modified gold substrate supported monolayer Au|C8H in a solution of gold nanoparticles (GNPs), results in covalent attachment of GNPs on top of the film via a second alkynyl carbon-Au σ-bond, to give structures Au|C8|GNP in which the monolayer of linear, 'all-carbon' C8 chains is sandwiched between two macroscopic gold contacts. The covalent carbon-surface bond as well as the covalent attachment of the metal particles to the monolayer by cleavage of the alkyne C-H bond is confirmed by surface-enhanced Raman scattering (SERS). The integrity of the carbon chain in both Au|C6C2N3HCH2Fc systems and after formation of the gold top-contact electrode in Au|C8|GNP is demonstrated through electrochemical methods. The electrical properties of these nascent metal-monolayer-metal devices Au|C8|GNP featuring 'all-carbon' molecular wires were characterised by sigmoidal I-V curves, indicative of well-behaved junctions free of short circuits.

Laponite-Based Surfaces with Holistic Self-Cleaning Functionality by Combining Antistatics and Omniphobicity.

In the present work, perfluoroalkylated laponite nanoparticles with a high degree of functionalization (60 wt %) have been prepared and a methodology to prepare transparent, antistatic, and omniphobic laponite-based films with holistic self-cleaning properties against liquids, solids and liquid-solid mixtures has been developed. The intrinsic electrical and ionic conductivities observed in unmodified laponite coatings are combined with perfluoroalkyl-modified laponite clays. As a result, films with improved self-cleaning functionality based on dust-repellency and omniphobic liquid-repellence (sheet resistance in the range of 107 Ω/□ and contact angles of 106° (H2O) and 93° (oil)) were obtained. These unique films, being capable to repel dust and liquids, were applied to a variety of substrates (i.e., glass and plastics) and tested against solids and liquids of different nature with excellent performance. Bending tests of these holistic self-cleaning films deposited over flexible substrates showed better mechanical performance than unmodified laponite films.