Spray-On Nanocomposite Coatings: Wettability and Conductivity

Conductive hydrophobic graphene oxide films via laser-scribed surface modification

Graphene oxide (GO) can be surface modified for various purposes, including enhancing its properties or tailoring its behaviour for specific applications such as biosensing. Herein we report the behaviour of a carboxylate functionalized graphene oxide that is both water repellent and electrically conductive. The GO is first produced using a modified Hummers method and then functionalized with a hyperbranched isostearic alcohol through an esterification reaction. The as-deposited functionalized GO films were observed to cause "petal-like" wetting of water, whereby droplets exhibited contact angles (CAs) greater than 150° and remaining pinned to the surface. To improve their conductivity, films of the functionalized GO deposited onto glass were laser-scribed to reduce some of the specific, adjoining regions of oxidic carbon to partially restore some of the sp2 C network. This improved the conductivity of the as-deposited GO films by approximately four orders of magnitude from 0.002 to ∼20 S/m using the low laser scan speed of 250 mm/min. It was observed that with a high laser scan speed of 500 mm/min some of the hydrophobic character was retained (CAs ∼110°), whilst maintaining conductivities of up to 0.17 S/m. Consequently, these materials show promise for applications such as biosensing materials, where tuneable hydrophobicity combined with conductivity are required characteristics.

Component Effects on Agricultural Spray

Regulating the spray behavior of liquids is of great importance in various practical applications, especially in improving pesticide utilization efficiency because the spray states are directly related to the spray drift and deposition efficiency. The components of pesticides, including surfactants, polymers, and active ingredients, were found to influence spray behavior significantly. However, because of both the complexity of interactions in sprayed liquids and the technology limit, only a few specific aspects of the formation of droplets have been studied, and a comprehensive and general understanding is still lacking. This brief review summarizes the effects of surfactants, polymers, and active ingredients on spray and highlights the underlying mechanisms related to sheet breakup and droplet formation. Other factors that warrant detailed exploration in the future are proposed, including dilatational viscoelasticity, zeta potential, aggregation, and sheet thickness. Finally, insights into the design of spray additives for agricultural applications are provided.

Research into the Influence of Filtration Media Microstructure on Oil-Water Separation Performance

Oil-water separation materials with specialized wettability have garnered significant attention in the field of oil-water separation due to the advantages of simple use and no secondary pollution. However, the adsorptive contamination of the filter surface by impurity phases and surfactants can cause a shift in the wettability of the filter surface. For efficient oil-water separation and improved resistance to adherent contamination on the oil-water separation membrane surface, herein, superwetted Cu nanofilms and smooth hydrophobic surfaces were prepared on SSM substrates by one-step electrodeposition and immersion methods, respectively. For water-in-oil/oil-in-water emulsions, nano-Cu has high separation efficiency. Experimentally, it was analyzed that the smaller spacing between the pores of the mesh membrane and the micro-nanostructures makes the separation effect better, but the flux will be reduced accordingly. By studying the separation images during the actual separation process through optical microscopy, it was found that the increase in the efficiency of the mesh membrane during the oil-water separation process and the decrease in the flux were due to the impurity phases aggregating and clogging the pores during the separation process to achieve a reduction in the pore size and the spacing of the micro-nanostructures. And further verification of the stability and mechanism correctness of the nano-Cu mesh film was conducted using cyclic experiments. The surface adhesion mechanism of filtration materials was analyzed by studying the phenomenon of water droplet adhesion on different mesh membranes and the ratio of adhesion. The research findings provide a comprehensive analysis of oil-water separation materials, focusing on both separation effectiveness and antiadhesion properties. This study offers new insights into the design of efficient oil-water separation materials and holds significant implications for advancing the practical application of oil-water separation membranes.

Enhancing soot oxidation using microtextured surfaces

Biomass combustion provides energy needs for millions of people worldwide. However, soot accumulation on the combustors' walls significantly reduces heat transfer efficiency. Herein, we demonstrate how microtextured surfaces minimize soot accumulation by enhancing soot oxidation. We investigate soot layers from the combustion of paraffin wax as a model for wood-based soot, and find that randomly microtextured glass obtained by sandblasting shows a 71% reduction in the time taken to oxidize 90% of surface soot coverage when compared to smooth glass at 530 °C. We also study grooved microtextures fabricated via laser ablation and find that grooves with widths between 15 and 50 µm enhance soot oxidation, while the expedited advantage is lost when the groove width is 85 µm. X-ray photoelectron spectroscopy validates the superior extent of soot removal on microtextures down to a sub-nanometer length-scale. The high density of sharp features such as peaks and edges on microtextures, and the conformality of the soot layer to the microtextures contribute to increased soot oxidation. We also demonstrate enhanced soot oxidation on microtextured stainless steel, the principal material of construction in biomass combustors. Microtextured surfaces that facilitate soot oxidation upon contact could significantly improve performance and longevity in various combustion applications.

Preparation and properties of oxidized multi-walled carbon nanotube superhydrophobic composites modified by bio-fatty acids

In this paper, a preparation method of superhydrophobic composites of oxidized multi-walled carbon nanotubes modified by stearic acid (SA) is proposed. Hydroxylated multi-walled carbon nanotubes (HMWCNTs) were obtained by oxidizing multi-walled carbon nanotubes with potassium dichromate to give them hydroxyl groups on the surface. Subsequently, the carboxyl group in the SA molecule was esterified with the hydroxyl group on the HMWCNTs. SA molecules were grafted onto the surface of multi-walled carbon nanotubes. SA modified oxidized multi-walled carbon nanotubes (SMWCNT) superhydrophobic composites were obtained. The results show that the water contact angle (WCA) of superhydrophobic composites can reach up to 174°. At the same time, the modified nanocomposites have good anti-icing and corrosion resistance. After low temperature delayed freezing test, the freezing extension time of the nanocomposite film is 30 times that of the smooth surface. Under strong acid and alkali conditions, the superhydrophobic nanocomposites still maintain good superhydrophobicity. The nanocomposites may have potential applications in the preparation of large-scale superhydrophobic coatings.

Osteoimmunomodulatory Nanoparticles for Bone Regeneration

Treatment of large bone fractures remains a challenge for orthopedists. Bone regeneration is a complex process that includes skeletal cells such as osteoblasts, osteoclasts, and immune cells to regulate bone formation and resorption. Osteoimmunology, studying this complicated process, has recently been used to develop biomaterials for advanced bone regeneration. Ideally, a biomaterial shall enable a timely switch from early stage inflammatory (to recruit osteogenic progenitor cells) to later-stage anti-inflammatory (to promote differentiation and terminal osteogenic mineralization and model the microstructure of bone tissue) in immune cells, especially the M1-to-M2 phenotype switch in macrophage populations, for bone regeneration. Nanoparticle (NP)-based advanced drug delivery systems can enable the controlled release of therapeutic reagents and the delivery of therapeutics into specific cell types, thereby benefiting bone regeneration through osteoimmunomodulation. In this review, we briefly describe the significance of osteoimmunology in bone regeneration, the advancement of NP-based approaches for bone regeneration, and the application of NPs in macrophage-targeting drug delivery for advanced osteoimmunomodulation.

Scalable Paper Supercapacitors for Printed Wearable Electronics

Printed paper-based electronics offers solutions to rising energy concerns by supplying flexible, environmentally friendly, low-cost infrastructure for portable and wearable electronics. Herein, we demonstrate a scalable spray-coating approach to fabricate tailored paper poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/cellulose nanofibril (CNF) electrodes for all-printed supercapacitors. Layer-by-layer spray deposition was used to achieve high-quality electrodes with optimized electrode thickness. The morphology of these electrodes was analyzed using advanced X-ray scattering methods, revealing that spray-coated electrodes have smaller agglomerations, resulting in a homogeneous film, ultimately suggesting a better electrode manufacturing method than drop-casting. The printed paper-based supercapacitors exhibit an areal capacitance of 9.1 mF/cm², which provides enough energy to power electrochromic indicators. The measured equivalent series resistance (ESR) is as low as 0.3 Ω, due to improved contact and homogeneous electrodes. In addition, a demonstrator in the form of a self-powered wearable wristband is shown, where a large-area (90 cm²) supercapacitor is integrated with a flexible solar cell and charged by ambient indoor light. This demonstration shows the tremendous potential for sequential coating/printing methods in the scaling up of printed wearables and self-sustaining systems.

Molecule-to-Material-to-Bio Nanoarchitectonics with Biomedical Fullerene Nanoparticles

Nanoarchitectonics integrates nanotechnology with various other fields, with the goal of creating functional material systems from nanoscale units such as atoms, molecules, and nanomaterials. The concept bears strong similarities to the processes and functions seen in biological systems. Therefore, it is natural for materials designed through nanoarchitectonics to truly shine in bio-related applications. In this review, we present an overview of recent work exemplifying how nanoarchitectonics relates to biology and how it is being applied in biomedical research. First, we present nanoscale interactions being studied in basic biology and how they parallel nanoarchitectonics concepts. Then, we overview the state-of-the-art in biomedical applications pursuant to the nanoarchitectonics framework. On this basis, we take a deep dive into a particular building-block material frequently seen in nanoarchitectonics approaches: fullerene. We take a closer look at recent research on fullerene nanoparticles, paying special attention to biomedical applications in biosensing, gene delivery, and radical scavenging. With these subjects, we aim to illustrate the power of nanomaterials and biomimetic nanoarchitectonics when applied to bio-related applications, and we offer some considerations for future perspectives.

On the Development of Ultradurable Extremely Water-Repellent and Oleophobic Soot-Based Fabrics with Direct Relevance to Sperm Cryopreservation

Nowadays, the tremendous progress of nanotechnologies and materials science facilitates the fabrication of universal and multifunctional superhydrophobic surfaces on a large scale. Yet, integrating icephobic and anti-bioadhesive properties in an individual water-repellent functional coating, for addressing the difficulties faced by cryobiologists, aircraft, and seacraft manufacturers, is quite tricky but feasible if using nonpolar soot nanoparticles, whose fragility, however, impedes their industrial applicability. Here, we advance the current state-of-the-art to an extent, permitting the introduction of economically affordable and ultradurable non-wettable soot-based coatings. The deposition of rapeseed oil soot, cyanoacrylate glue and fluorine compounds onto different fabrics confers the latter with superior tolerance to harsh mechanical and thermal interventions [e.g., scratching, blade scraping, liquid nitrogen immersion (T ∼ -196 °C), torsion and water jetting], while in the meantime retaining water repellency and oleophobicity. The as-prepared soot fabrics can stick continuously to the selected host surface and favor the recovery of ∼60% of the initial motility of human spermatozoa subjected to cryopreservation or being detached and utilized as standalone non-wettable membranes. Our invention may be considered as the first fundamental stage of safely (without any health concerns) transferring the soot in reproductive medicine and developing enhanced cryogenic and antibacterial medical devices.

Poly(Lactic-co-glycolic) Acid and Phospholipids Hybrid Nanoparticles for Regeneration of Biological Tissue

In tissue regeneration, biomaterials facilitate biological processes. However, a treatment with biomaterials will be successful only if supported by simple and inexpensive technologies which stimulate the regenerative processes. The present study focused on the possibility of creating formulations from which then to obtain suitable materials for the regeneration of heart tissue. The experimental procedure for precipitation of polymer- nanoparticles was modified ad hoc to obtain hybrid poly lactic-co-glycolic acid (PLGA)-phospholipid nanoparticles. The properties of the formulations produced by direct PLGA-phospholipid co-precipitation depend on the mass ratio R= polymer mass/phospholipid mass. The value of this parameter allows us to modulate the properties of the formulations. Formulations with R = 1.5, 2.3, 4, and 9 were prepared, and for each of them the particle-size distribution obtained by dynamic light scattering was studied. All samples showed that the hydrodynamic diameter decreases with increasing R value. This behavior is interpreted as polymer coil shrinkage due to contacts with the non-solvent. The spreadability and ease of obtaining thin sheets were evaluated for each formulation. The formulation with R=4 resulted in a homogeneous and easily workable material in thin sheets.

Transport and Separation of the Silver Ion with n-decanol Liquid Membranes Based on 10-undecylenic Acid, 10-undecen-1-ol and Magnetic Nanoparticles

This paper presents a transport and recovery of silver ions through bulk liquid membranes based on n-decanol using as carriers 10-undecylenic acid and 10-undecylenyl alcohol. The transport of silver ions across membranes has been studied in the presence of two types of magnetic oxide nanoparticles obtained by the electrochemical method with iron electrodes in the electrolyte with and without silver ions, which act as promoters of turbulence in the membrane. Separation of silver ions by bulk liquid membranes using 10-undecylenic acid and 10-undecylenyl alcohol as carriers were performed by comparison with lead ions. The configuration of the separation module has been specially designed for the chosen separation process. Convective-generating magnetic nanoparticles were characterized in terms of the morphological and structural points of view: scanning electron microscopy (SEM), high-resolution SEM (HR-SEM), energy dispersive spectroscopy analysis (EDAX), Fourier Transform InfraRed (FTIR) spectroscopy, thermal gravimetric analysis (TGA), differential scanning calorimetry and magnetization. The process performance (flux and selectivity) was tested were tested for silver ion transport and separation through n-decanol liquid membranes with selected carriers. Under the conditions of the optimized experimental results (pH = 7 of the source phase, pH = 1 of the receiving phase, flow rate of 30 mL/min for the source phase and 9 mL/min for the receiving phase, 150 rot/min agitation of magnetic nanoparticles) separation efficiencies of silver ions of over 90% were obtained for the transport of undecenoic acid and about 80% for undecylenyl alcohol.

Superhydrophobic materials used for anti-icing Theory, application, and development

The accumulation of ice will reduce the performance of the base material and lead to all kinds of damage, even a threat to people's life safety. Recent increasing studies suggest that superhydrophobic surfaces (SHSs) originating from nature can remove impacting and condensing droplets from the surface before freezing to subzero temperatures, and it can be seen that hydrophobic/SH coating has good freezing cold resistance. But such anti-icing performances and developments in practical applications are restricted by various factors. In this paper, the mechanism and process of surface icing phenomenon are introduced, as well as how to prevent surface icing on SHS. The development of SH materials in the aspect of anti-icing in recent years is described, and the existing problems in the aspect of anti-icing are analyzed, hoping to provide new research ideas and methods for the research of anti-icing materials.

Recent Advances in Multi-Functional Coatings for Soft Magnetic Composites

During the past 50 years, the aim to reduce the eddy current losses in magnetic cores to a minimum led to the formulation of new materials starting from electrically insulated iron powders, today called Soft Magnetic Composites (SMC). Nowadays, this promising branch of materials is still held back by the mandatory tradeoff between energetic, electrical, magnetic, and mechanical performances. In most cases, the research activity focuses on the deposition of an insulating/binding layer, being one of the critical points in optimizing the final composite. This insulation usually is achieved by either inorganic or organic layer constituents. The main difference is the temperature limit since most inorganic materials typically withstand higher treatment temperatures. As a result, the literature shows many materials and process approaches, each one designed to meet a specific application. The present work summarizes the recent advances in state of the art, analyzing the relationship among material compositions and magnetic and mechanical properties. Each coating shows its own processing sets, which vary from simple mechanical mixing to advanced chemical methods to metallurgical treatments. From state of the art, Aluminum coatings are characterized by higher current losses and low mechanical properties. In contrast, higher mechanical properties are obtained by adopting Silicon coatings. The phosphates coatings show the best-balanced overall properties. Each coating type was thoroughly investigated and then compared with the literature background highlighting. The present paper thus represents a critical overview of the topic that could serve as a starting point for the design and development of new and high-performing coating solutions for SMCs. However, global research activity continuously refines the recipes, introducing new layer materials. The following steps and advances will determine whetherthese materials breakthrough in the market.

Biochar Nanocomposite Derived from Watermelon Peels for Electrocatalytic Hydrogen Production

Water splitting is the most potential method to produce hydrogen energy, however, the conventional electrocatalysts encounter the hindrances of high overpotential and low hydrogen production efficiency. Herein, we report a carbon-based nanocomposite (denoted as CCW-x, x stands for the calcination temperature) derived from watermelon peels and CoCl₂, and the as-synthesized CCW-x is used as the electrocatalyst. The overpotential and the Tafel slope of CCW-700 for oxygen evolution reaction (OER) is 237 mV at 10 mA cm^-2 and 69.8 mV dec^-1, respectively, both of which are lower than those of commercial RuO₂. For hydrogen evolution reaction (HER), the overpotential of CCW-700 (111 mV) is higher than that of the widely studied Pt/C (73 mV) but still lower than those of lots of carbon-based nanomaterials (122-177 mV). In the light of CCW-700 is highly active for both OER and HER, we assembled a water-splitting electrocatalyst by employing nickel foam loaded with CCW-700 as the anode and cathode in 1 M KOH. The water-splitting voltage is only 1.54 V for the CCW-700//CCW-700 electrodes and 1.62 V for the RuO₂//Pt/C ones. Therefore, the so-denoted CCW-x powder possesses good electrocatalytic hydrogen production efficiency.

Study of aerodynamic focusing lens stacks (ALS) for long focal length aerosol-assisted focused chemical vapor deposition (AAFCVD)

Mask-free direct printing can alleviate the high cost and high consumption involved in photo-lithography for chip processing. Most of their technical routes are based on the traditional short focal length nozzles, which is suffered from higher probability of nozzle retardation or clogging as well as the higher mechanical burdens. While aerosol-assisted chemical vapor deposition (AACVD) has better deposition adaptability but usually lack of focused printing. In this study, a system that combines of long focal length ALS with AACVD, so called AAFCVD printing system has been developed. The single-point printing capability and aerosol precursor adaptability were verified, and the relationship between the single spot printing performance and the chemical reaction mechanisms were studied. Furthermore, a unique carbon injection effect brought by ALS was discovered. Finally, the linear graphics printing performances of the system were evaluated. This system is expected to become a new generation of high-performance mask-free printing system for chip manufacturing.

A new generation system so called AAFCVD printing system has been developed. It is a mask-free printing system with longer focal length and compatibility for AACVD.