Atomised spray plasma deposition of hierarchical superhydrophobic nanocomposite surfaces

Low-Temperature Atmospheric Pressure Plasma Processes for the Deposition of Nanocomposite Coatings

Low-temperature atmospheric pressure (AP) plasma technologies have recently proven to offer a range of interesting opportunities for the preparation of a variety of nanocomposite (NC) coatings with different chemical compositions, structures, and morphologies. Since the late 2000s, numerous strategies have been implemented for the deposition of this intriguing class of coatings by using both direct and remote AP plasma sources. Interestingly, considerable progress has been made in the development of aerosol-assisted deposition processes in which the use of either precursor solutions or nanoparticle dispersions in aerosol form allows greatly widening the range of constituents that can be combined in the plasma-deposited NC films. This review summarizes the research published on this topic so far and, specifically, aims to present a concise survey of the developed plasma processes, with particular focus on their optimization as well as on the structural and functional properties of the NC coatings to which they provide access. Current challenges and opportunities are also briefly discussed to give an outlook on possible future research directions.

Tunable High Refractive Index Polymer Hybrid and Polymer-Inorganic Nanocomposite Coatings

Atomized spray plasma deposition (ASPD) provides a single-step, low-temperature, and dry approach for the preparation of high refractive index hybrid polymer or polymer-inorganic nanocomposite coatings. Refractive indices as high as 1.936 at 635 nm wavelength have been obtained for ASPD 4-bromostyrene/toluene-TiO₂ nanocomposite layers containing low titania loadings. Thin films with any desired refractive index up to 1.936 can be easily deposited onto a variety of substrates by varying the precursor mixture composition. ASPD overcomes disadvantages commonly associated with alternative fabrication methods for depositing high refractive index coatings (elevated temperatures, wet processes, UV curing steps, and much greater inorganic loadings).

Organic carbon dot coating for superhydrophobic aluminum alloy surfaces

A novel fluorine-free and silicon-free superhydrophobic aluminum alloy (treated-Al) is fabricated by chemical etching using hydrochloric acid and hydrogen peroxide and modified with an organic carbon dot (OCD) coating. The water contact angle (CA) of the treated-Al surface increases with the OCD concentration. When etched aluminum (etched-Al) is modified with 0.5 mg/ml OCDs, a CA of 161.4° is achieved, which indicates good nonwettability. SEM results verify that porous microstructures with cavities are uniformly distributed on the surface of etched-Al, in contrast to the bare aluminum alloy, which forms a primary rough structure. After treatment with 0.5 mg/ml OCDs, a nanoparticle coating is dispersed on the rough structures of treated-Al-0.5, which can trap air and make a water droplet essentially rest on a layer of air. The treated-Al-0.5 material has good self-cleaning properties and can sweep away contaminants at both 20 and 0°C. The Ecorr and Icorr of treated-Al-0.5 are - 0.56 V and 2.82 × 10-6 A/cm2, respectively, which shows good anticorrosion performance.

Cu–MoS2 Superhydrophobic Coating by Composite Electrodeposition

In this work, a superhydrophobic coating was developed by composite electrodeposition of MoS2 particles in a copper matrix. AISI 316L stainless steel and N80 carbon steel, with a thin electrodeposited Ni layer to improve adherence of the coating, were used as substrates. Different operational parameters of electrodeposition were studied in order to produce the highest possible contact angle. We demonstrate that, using this method, a coating with a hierarchical structure with feature dimensions in the range of µm to nm is obtained, with advancing contact angle values up to 158.2° and a contact angle hysteresis equal to 1.8°. To study the coating composition energy dispersive X-ray, X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry were performed. Moreover, potentiodynamic polarizations were performed in H2SO4, NaCl and NaOH solutions to study the corrosion behavior of the coating. As a control, a sample coated only with MoS2 particles by means of electrophoretic deposition was produced. The results show that the composite coating can be used in applications where copper is used for corrosion protection, with the addition of the desirable effects of its superhydrophobicity.