The fifth issue of 2023 offers six original research articles on: graphene coatings and their quality dependence of metal substrate crystal orientation and defects arrangements;1 fabrication of a novel radiative cooling polymeric film;2 patterning of hydrophilic structures for self-propelling liquid droplets;3 spreading and interfacial behavior of intravitreal drugs across animal retinas;4 extraction of natural colorants from flowers for silk dying;5 and ion irradiation of germanium (Ge)–selenium (Se)–bismuth (Bi) semiconducting thin films.6
Graphene and graphene oxide are excellent conductive materials7 that have been recently explored as coatings in fabrication of high-sensitivity transistors and sensors, as well as opto-electronic devices.8 In a unique contribution, Misyura et al.1 analyze the impact of crystal orientation of copper foil on the graphene layer deposition and on the distribution of the oxygen atoms of water in the vicinity of the copper surface. The authors show experimentally and through molecular dynamics simulations that a change in copper crystal orientation affects the structuring of water molecules on the copper surface, and that this effect extends through a thin graphene coating, producing a graphene surface of varying wettability. They also demonstrate that metal substrate defects, in the form of micro-holes and grain boundaries, influence surface roughness characteristics of graphene coatings, important to the fabrication of high-quality, two-dimensional structures.
The second paper of this issue reports on the fabrication of radiative cooling poly(vinylidene fluoride-cohexafluoropropylene) (PVDF-HFP)/poly(vinylidene fluoride) (PVDF) film.2 By embedding PVDF nanoparticles into the PVDF-HFP matrix and manipulating the microscopic and submicroscopic porosity of the film, the authors were able to substantially enhance the scattering of solar light.2 This novel material exhibits superhydrophobicity, self-cleaning capability and enhanced durability, and could serve as a radiative cooling coating material for outdoor product applications, also providing long-term weathering protection. In relation to the interesting application of the superhydrophobic materials described by Zhang et al.,2 we would like to recall that this journal offers many original and review papers on superhydrophobic materials and coatings in its decade-long existence. In this connection it is worth mentioning a couple of quality reviews published in 2022 by Wang et al.9 and Chambers et al.10
A locomotion of liquid droplets using specially designed patterns in the structure of solid surface is of special interest in manufacturing of lab-on-a-chip, water harvesting, heat-transfer and condensation devices.11,12 In a new original contribution, Zhou et al.3 demonstrate self-propelling movements of water droplets on straight and curved micro-finned silicon-based patterns prepared by photolithography and sputtering coating techniques. The authors show that the droplets in the Wenzel state move spontaneously, and their movement is enhanced when the structures are curved. By analyzing the energy conversion, the authors explain experimental results through theoretical modelling, providing a foundation for a design of heat-transfer condensers.
The fourth paper of this issue, submitted by the research team from Israel, is devoted to the interfacial behavior of ophthalmic drugs administered intravitreally.4 In this interesting contribution, by analyzing phenomena of spreading and interfacial interactions, the authors show that plasma-treated glass successfully imitates animal retinas. They also show that the intravitreal drugs placed in an eye containing a layer of silicon oil as a retinal tamponade agent do not mix with but sink through the oil layer, reaching the retinal surface. When conducting the injection and spreading tests of intravitreal drugs into the thin layer of aqueous fluid present between the silicon oil and retina, the authors found that the drug content must be carefully optimized to avoid its potential toxic effect on the retina.
Functional finish and coloration of fabrics and fibers using natural and eco-friendly chemicals have attracted much research interest in recent years.13,14 In a new contribution, Adeel et al.5 describe extraction of natural dyes from Butea monosperma plants using aqueous and acidic solutions under microwave treatment. The authors also describe a novel dyeing method for silk fabric through mordant dyeing and microwave irradiation. The natural dyes and coloration technology offered provide a sustainable alternative to synthetic chemicals currently used in the textile industry to produce brownish and yellowish shades of silk fabric.
In the final article of this issue, Abdelhamid et al.6 describe changes in structural, optical and electric properties of amorphous semiconducting Ge10Se70Bi20 thin films deposited on glass substrates using the thermal evaporation method after irradiation with nitrogen (N+), argon (Ar+), hydrogen (H+) and oxygen (O+) ion beams. The authors demonstrate that the optical absorbance of the Ge10Se70Bi20 thin films increases, the optical bandgap decreases, and the electrical conductivity increases after irradiation. It is concluded that the Ge10Se70Bi20 thin films irradiated with nitrogen and argon ions could find applications in solar cells, chemical sensors and optical data storage systems, whereas films irradiated with hydrogen and oxygen ions are attractive for infrared detectors. The ion irradiation and its benefits were also described by the same research group in several previous papers that we recommend to everyone who is exploring surface and thin film modifications through ion beam treatments.15,16
We would appreciate any feedback and valuable suggestions from contributing authors and readers on any developments to the Surface Innovations journal that could make it more appealing to them in the years to come.
