Modification Of Surface Properties Research Articles

Size Effect of a Piezoelectric Material as a Separator Coating Layer for Suppressing Dendritic Li Growth in Li Metal Batteries.

Li metal has been intensively investigated as a next-generation rechargeable battery anode. However, its practical application as the anode material is hindered by the deposition of dendritic Li. To suppress dendritic Li growth, introducing a modified separator is considered an effective strategy since it promotes a uniform Li ion flux and strengthens thermal and mechanical stability. Herein, we present a strategy for the surface modification of separator, which involves coating the separator with a piezoelectric material (PM). The PM-coated separator shows higher thermal resistance than the pristine separator, and its modified surface properties enable the homogeneous regulation of the Li-ion flux when the separator is punctured by Li dendrite. Furthermore, PM was synthesized in different solvents via solvothermal method to explore the size effect. This strategy would be helpful to overcome the intrinsic Li metal anode problems.

Surface and Physical Properties Modifications of Electron Beam-Irradiated Monolayer MoS2-Au Heterointerface at Nanoscale

Surface and Physical Properties Modifications of Electron Beam-Irradiated Monolayer MoS2-Au Heterointerface at Nanoscale

Surface Protection of Quaternary Gold Alloys by Thiol Self-Assembled Monolayers.

This work deals with a physical and chemical surface characterization of quaternary 18K, 14K, and 9K gold alloys and pure polycrystalline gold substrates. Surface microstructure and composition are evaluated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray fluorescence spectroscopy. Corrosion resistance of 18K gold alloys is explored by potentiodynamic polarization showing the influence of the manufacturing process on materials fabricated as plates and wires. The research is also in the framework of one of the most common strategies on the modification of metallic surface properties, i.e., the building of self-assembled monolayers (SAM) from organic thiols. The metal affinity of the head group to produce the coating of the substrate by covalent binding is approached by using thiol compounds with different molecular structures and functional group chemistries exposed to an electrolyte solution. Therefore, a comparative study on the surface protection of a quaternary 18K gold alloy and pure gold substrates by SAMs of 6-mercaptopurine (6MP), 1-decanethiol (DT), and 11-mercaptoundecanoic acid (MUA) has been carried out. Surface modification and SAM organization are followed by cyclic voltammetry (CV), and the behavior of the double layer of the electrode-electrolyte interface is evaluated by electrochemical impedance spectroscopy (EIS). The study of these materials allows us to extract fundamental knowledge for its potential application in improving the bioactive properties of different jewelry pieces based on 18K gold alloys.

Effects and Mechanisms of Resveratrol on the Adhesion of Lactobacillus acidophilus NCFM.

Based on the adhesion and surface properties of Lactobacillus acidophilus NCFM, five common polyphenols in fruits and vegetables, including resveratrol, epicatechin, quercetin, hesperidin, and caffeic acid, were screened, and the reasons for resveratrol promoting adhesion were systematically explained. The results showed that resveratrol could significantly enhance NCFM adhesion to mucin (1.73 fold), followed by epicatechin (1.47 fold), caffeic acid (1.30 fold), and hesperidin (0.99 fold), while quercetin had a certain degree of inhibition (0.84 fold). The effects of these polyphenols on surface hydrophobicity and auto-aggregation of NCFM were consistent with adhesion results. Then, how resveratrol promotes NCFM adhesion was further explored. The results of the proteomic analysis showed that resveratrol changed the surface layer proteins of NCFM, involving 4 up-regulated proteins and 12 down-regulated proteins. In addition, resveratrol promoted the expression of mucin genes and the glycosylation of mucins on the HT-29 cell surface. Our results indicate that resveratrol changes the surface layer proteins of NCFM to modify surface properties and adhere to mucins. Meanwhile, resveratrol promotes expression and glycosylation of mucins in HT-29 cells. Our findings provide theoretical support for an in-depth explanation of the interaction among resveratrol, NCFM, and the HT-29 cells.

Coupling Plant Polyphenol Coordination Assembly with Co(OH)2 to Enhance Electrocatalytic Performance towards Oxygen Evolution Reaction.

The oxygen evolution reaction (OER) is kinetically sluggish due to the limitation of the four-electron transfer pathway, so it is imperative to explore advanced catalysts with a superior structure and catalytic output under facile synthetic conditions. In the present work, an easily accessible strategy was proposed to implement the plant-polyphenol-involved coordination assembly on Co(OH)2 nanosheets. A TA-Fe (TA = tannic acid) coordination assembly growing on Co(OH)2 resulted in the heterostructure of Co(OH)2@TA-Fe as an electrocatalyst for OER. It could significantly decrease the overpotential to 297 mV at a current density of 10 mA cm-2. The heterostructure Co(OH)2@TA-Fe also possessed favorable reaction kinetics with a low Tafel slope of 64.8 mV dec-1 and facilitated a charge-transfer ability. The enhanced electrocatalytic performance was further unraveled to be related to the confined growth of the coordination assembly on Co(OH)2 to expose more active sites, the modulated surface properties and their synergistic effect. This study demonstrated a simple and feasible strategy to utilize inexpensive biomass-derived substances as novel modifiers to enhance the performance of energy-conversion electrocatalysis.

Efficient Combination of Surface Texturing and Functional Coating for Very Low Secondary Electron Yield Surfaces and Rough Nonevaporable Getter Films

AbstractThe formation of a fissured copper surface by picosecond pulsed laser irradiation is combined with functional coatings consisting of Ti and amorphous carbon layers or a Ti–Zr–V compound film to fabricate surfaces with the maximum of the secondary electron yield being as low as 0.4. By structural and spectroscopic analysis of the formed surfaces it is demonstrated that both coatings enclose the nanostructures generated by redeposition of metal structures from the laser‐induced plasma plume, keeping the initial topography intact. This allows an efficient elimination of secondary electron emission by combining the benefits from structural surface modification and adaption of electronic surface properties to efficiently dissipate the energy of impinging electrons. Thermal activation tests of the Ti–Zr–V nonevaporable getter films revealed that for films on nanostructured substrates, which have a much higher effective surface, a slight diminution of surface activation occurs at 160 and 200 °C, while this effect is completely compensated when heating up to 250 °C indicating promising pumping capabilities. Both examples highlight the benefits from combining 3D substrate patterning with classical 2D deposition technologies.

Selective laser crystallization and amorphization in polymer fibers

Textile finishing is a huge industry for modification of textile surface properties to align with the desired end use spanning medical, engineering, and apparel applications. Laser-induced polymer morphology modification has been studied by researchers, with evidence suggesting a correlation between laser fluence and crystallinity. However, a lack of data has resulted in the mechanism for change remaining unknown. This paper aims to identify the mechanism of initial Young’s modulus control in polyethylene terephthalate (PET) monofilament yarn and explain the relationship between Young’s modulus and the degree of crystallinity using Takayanagi’s model. PET monofilament yarns were treated using a CO2 infrared laser at a 10.6 μm wavelength at fluences up to 0.086 J/mm2. Young’s modulus data obtained from stress-strain curves at 0.2% strain and fraction crystallinities obtained from differential scanning calorimetry were compared with Takayanagi’s series model. Laser surface treatment within a fluence range up to 0.087 J/mm2 on PET resulted in stable Young’s modulus values. A 3.5% reduction in Young’s modulus of PET was seen with a 6.1% reduction in crystallinity, which was in good agreement with Takayanagi’s series model. Lasers offer rapid material processing capable of increasing or decreasing fractional crystallinity selectively along the fiber where desired. Selective amorphization increases chemical absorption, allowing increased surface finishing uptake at milder processing conditions, whereas increasing fractional crystallinity imparts fiber strength. The relationship between fiber crystallinity and Young’s modulus for PET can be described by Takayanagi’s model, allowing a prediction of material properties, which can be extended from fibers to all thin-film polymers.

Copper migration and surface oxidation of in ambient pressure environments

Chemical modifications such as intercalation can be used to modify surface properties or to further functionalize the surface states of topological insulators (TIs). Using ambient pressure x-ray photoelectron spectroscopy, we report copper migration in , which occurs on a timescale of hours to days after initial surface cleaving. The increase in near-surface copper proceeds along with the oxidation of the sample surface and large changes in the selenium content. These complex changes are further modeled with core-level spectroscopy simulations, which suggest a composition gradient near the surface which develops with oxygen exposure. Our results shed light on a new phenomenon that must be considered for intercalated TIs—and intercalated materials in general—that surface chemical composition can change when specimens are exposed to ambient conditions.

Effect of tantalum interlayer on hydroxyapatite biointerface for orthopedic applications

Various attempts have been made during recent decades to improve the functionality, biocompatibility and osseointegration of metallic implants. With technological advancement, modifying superficial properties of orthopedic implants has undergone great evolution. Current efforts of scientists and the orthopedic industry have focused on modifying surface properties to achieve a specific biointerface that can reduce patient's healing time and prevent aseptic loosening. This study investigates the contribution of a protective tantalum interlayer deposited on titanium substrates on the growth of hydroxyapatite (HAp) crystals with hydrothermal synthesis method. We investigated the morphology and structure of the produced coatings, as well as in vitro bioactivity in simulated body fluid and biocompatibility in osteoblast-like cell culture. The hydrothermal method allows to synthesize coating with micro-sized HAp crystallites that exhibit rod-like hexagonal shape. The diameter of HAp crystallites may be controlled and driven by nature of the interlayer (tantalum, tantalum oxide or titanium oxide) previously formed on the titanium substrate. Coatings with smaller diameters of HAp crystals (between 0,3 μm and 0,6 μm) synthesized on tantalum-based films were found to be more favorable for cell viability and attachment. High bioactivity and positive effect on the osteoblast-like cells of the HAp biointerface with a tantalum intermediate layer was observed.

Effects of high energy electron and X-ray irradiation on the morphology, microstructure and reflectivity of cast speculum metal mirror

The effects of irradiation of cast speculum metal mirrors using high-energy electrons (6 MeV and 9 MeV) and X-rays (6 MeV and 10 MeV) from a medical linear accelerator setup are studied in detail for the first time. Analyses using the techniques of X-ray diffraction, atomic force microscopy and Ultraviolet–Visible spectroscopy reveal that the irradiation causes some significant microstructural and morphological changes on the surface of speculum metal leading to the modifications of surface properties and hence the reflectivity of the material. From AFM morphology and XRD pattern, it is evident that the electron beam irradiation affects the surface topography and crystallographic properties of the material more at 6 MeV than 9 MeV. The optical studies suggest a significant reduction in Ultraviolet–Visible reflection after electron irradiation. However, X-ray irradiation of speculum metal provides an enhancement of reflection in the Ultraviolet–Visible region. Irradiation with high-energy electrons affects significantly the amount of absorption in the ultraviolet region. Moreover, an inverse relationship between crystallinity and visible reflectivity is inferred after electron and X-ray irradiations. These results may open up promising possibilities for this alloy to use in future space missions under high-energy irradiation due to its capacity to resist energetic particles and electromagnetic radiation without much material destruction.

Plasmon Inspired 2D Carbon Nitrides: Structural, Optical and Surface Characteristics for Improved Biomedical Applications

In the past few years, noble metal-based 2D nanomaterials particularly Ag and Au enriched carbon nitrides have seen advanced catalytic actions and reactivity. These composite nanostructures’ chemical and physical characteristics have been applied to improve the targeted functionalities in healthcare and medical sciences. Many scientists and experts were inspired to study their foundational technologies in the medicinal industries via architectural and surface modifications by doping of noble nanoparticles. Here, we have provided fundamental ideas for structuring Ag and Au decorated CNs (carbon nitrides) by studying their morphological and modified surface properties for biomedical applications. There is a vast spectrum of publications that discusses the peculiarities of CNs and noble metal’s key discoveries. The impact of surface plasmons resonance (SPR) is an essential factor for noble metals and that is why it is focused extensively for better performance in biomedical sectors. The elemental combinations on the CNs surfaces and their morphological status were found to be much more efficient which is broadly discussed. The fabrication techniques, structural characterizations, and SPR role of Ag and Au are addressed including fundamental concepts followed by many suitable examples under this review.

Small particle size activated carbon enhanced flow electrode capacitive deionization desalination performances by reducing the interfacial concentration difference

Flow electrode capacitive deionization (FCDI) has great advantages in high salinity wastewater desalination. However, due to the limited adsorption capacity of electrode material, membrane concentration polarization would form and increase energy consumption, and affect the continuity of desalination. In this work, milling technology was used to modify original activated carbon (AC), the obtained ball milled activated carbon (BAC) was used as FCDI electrode material. The milling process modified multiple physical and electrochemical characteristics of original AC. The highest average salt removal rate (ASRR) of BAC was 2.2 times of that of AC, which was attributed to the modified surface properties including more oxygenated functional group, larger electrostatic gravitation characteristics and better hydrophilicity. The reduced concentration polarization during the desalination was responsible for the increased adsorption capacity, which was due to larger electrolyte contact area, enhanced ions capacity by more suitable pore structures, and 5 times higher energy normalized removal salt (ENRS) of BAC flow electrode than that of AC. Because of its simple operation and remarkable modification effect, ball milling technology shows great potential in large scale modification of electrode materials.

Modification of Surface Morphology and Surface Properties of Copper-Nickel Alloy by Anodic Treatment in a Deep Eutectic Solvent (Ethaline)

Modification of Surface Morphology and Surface Properties of Copper-Nickel Alloy by Anodic Treatment in a Deep Eutectic Solvent (Ethaline)

Control of the Drying Patterns for Complex Colloidal Solutions and Their Applications.

The uneven deposition at the edges of an evaporating droplet, termed the coffee-ring effect, has been extensively studied during the past few decades to better understand the underlying cause, namely the flow dynamics, and the subsequent patterns formed after drying. The non-uniform evaporation rate across the colloidal droplet hampers the formation of a uniform and homogeneous film in printed electronics, rechargeable batteries, etc., and often causes device failures. This review aims to highlight the diverse range of techniques used to alleviate the coffee-ring effect, from classic methods such as adding chemical additives, applying external sources, and manipulating geometrical configurations to recently developed advancements, specifically using bubbles, humidity, confined systems, etc., which do not involve modification of surface, particle or liquid properties. Each of these methodologies mitigates the edge deposition via multi-body interactions, for example, particle–liquid, particle-particle, particle–solid interfaces and particle–flow interactions. The mechanisms behind each of these approaches help to find methods to inhibit the non-uniform film formation, and the corresponding applications have been discussed together with a critical comparison in detail. This review could pave the way for developing inks and processes to apply in functional coatings and printed electronic devices with improved efficiency and device yield.

Mouse Strain- and Charge-Dependent Vessel Permeability of Nanoparticles at the Lower Size Limit.

Remarkable advancement has been made in the application of nanoparticles (NPs) for cancer therapy. Although NPs have been favorably delivered into tumors by taking advantage of the enhanced permeation and retention (EPR) effect, several physiological barriers present within tumors tend to restrict the diffusion of NPs. To overcome this, one of the strategies is to design NPs that can reach lower size limits to improve tumor penetration without being rapidly cleared out by the body. Several attempts have been made to achieve this, such as selecting appropriate nanocarriers and modifying surface properties. While many studies focus on the optimal design of NPs, the influence of mouse strains on the effectiveness of NPs remains unknown. Therefore, this study aimed to assess whether the vascular permeability of NPs near the lower size limit differs among mouse strains. We found that the vessel permeability of dextran NPs was size-dependent and dextran NPs with a size below 15 nm exhibited leakage from postcapillary venules in all strains. Most importantly, the leakage rate of 8-nm fluorescein isothiocyanate dextran was significantly higher in the BALB/c mouse strain than in other strains. This strain dependence was not observed in slightly positive TRITC-dextran with comparable sizes. Our results indicate that the influence on mouse strains needs to be taken into account for the evaluation of NPs near the lower size limit.

Chemical Bonding of Biomolecules to the Surface of Nano-Hydroxyapatite to Enhance Its Bioactivity

Hydroxyapatite (HA) is a significant constituent of bones or teeth and is widely used as an artificial bone graft. It is often used to replace the lost bones or in reconstructing alveolar bones before dental implantation. HA with biological functions finds its importance in orthopedic surgery and dentistry to increase the local concentration of calcium ions, which activate the growth and differentiation of mesenchymal stem cells (MSC). To make relevant use of HA in bone transplantation, the surfaces of orthopedic and dental implants are frequently coated with nanosized hydroxyapatite (nHA), but its low dispersibility and tendency to form aggregates, the purpose of the surface modification of bone implants is defeated. To overcome these drawbacks and to improve the histocompatibility of bone implants or to use nHA in therapeutic applications of implants in the treatment of bone diseases, various studies suggested the attachment of biomolecules (growth factors) or drugs through chemical bonding at the surface of nHA. The growth factors or drugs bonded physically at the surface of nHA are mostly unstable and burst released immediately. Therefore, reported studies suggested that the surface of nHA needs to be modified through the chemical bonding of biologically active molecules at the surface of bone implants such as proteins, peptides, or naturally occurring polysaccharides to prevent the aggregation of nHA and to get homogenous dispersion of nHA in solution. The role of irradiation in producing bioactive and antibacterial nHA through morphological variations in surfaces of nHA is also summarized by considering internal structures and the formation of reactive oxygen species on irradiation. This mini-review aims to highlight the importance of small molecules such as proteins, peptides, drugs, and photocatalysts in surface property modification of nHA to achieve stable, bioactive, and antibacterial nHA to act as artificial bone implants (scaffolds) in combination with biodegradable polymers.

Electron-beam modification of nitrile butadiene rubber in the fore-vacuum pressure range

We have studied the modification of nitrile butadiene rubber surface properties by pulsed and by continuous electron beams generated in inert (argon, helium) and in chemically active (oxygen, nitrogen, air) gas atmosphere in the fore-vacuum range of pressure (∼10 Pa). Relative measurements of the wear rate, friction coefficient, and contact (wetting) angle of the sample surfaces before and after beam treatment have been made. We have found that the electron-beam treatment of nitrile butadiene rubber does not result in any significant thermal damage to its surface, and that dependencies of the coefficient of friction and the wear rate on the surface treatment duration have a non-monotonic character. For optimal electron beam treatment conditions, the friction coefficient decreases by a factor of about two.

Reduction of the water wettability of Cu films deposited on liquid surfaces by thermal evaporation

We report a facile approach for the wettability control of copper (Cu) films grown on a silicone oil surface by thermal evaporation. Characteristic aggregation of deposited Cu atoms was obtained due to the isotropic and free-sustained liquid substrates. Through the fine adjustment of deposition parameters in the growth process, Cu films with controlled morphology from ramified aggregates to continuous films can be prepared. Accompanied with the evolution of morphology, water wettability was effectively reduced and the hydrophilic-to-hydrophobic transition can be achieved. The relationship between the wettability and microstructure of Cu films was investigated. These films with characteristic morphology and controlled wettability may open lots of application avenues in the development of devices with modified surface properties.

Impact of post‐pyrolysis wash on biochar properties

AbstractWashing biochar modifies its properties for use as a soil amendment. The important biochar properties for use as a soil amendment are hydrophilicity, adsorption, and stability. Biochar was obtained with intermediate pyrolysis at 400°C of three different feedstocks: woodchips, Bayview Flowers Digestate, and Storm Fisher Digestate biomass. A simple wash with an aqueous surfactant solution improved the properties of the biochar for soil amendment, with a non‐ionic surfactant combined with oxidizing hydrogen peroxide being the most effective. The improved properties included the removal of tars and possible modification of surface properties that increased hydrophilicity and adsorption and decreased leaching of any hydrocarbons that could negatively impact the surroundings. As a result, the washed biochar will exhibit better water retention and a more hospitable environment for the growth of beneficial microorganisms. In addition, by making the biochar more hydrophilic, a wash will make its granulation easier, reducing dust emissions during its application and allowing its formulation with enhancement additives. Although many post‐pyrolysis treatments of biochars have been investigated, the proposed wash is simple and effective, with beneficial advantages for downstream processing and application as a soil amendment.

Investigation and correlation between surface modifications and field emission properties of laser-induced silicon plasma ion irradiated stainless steel

Laser-induced silicon (Si) plasma has been used as a source of ion irradiation for modifications in surface, structural and field emission properties of Stainless Steel (SS). Nd:YAG (532 nm, 10 ns) laser at irradiance of 15 GW/cm2 was used to generate Si-plasma ions which were detected by solid-state nuclear track detector (CR-39) and Faraday Cup (FC). Both the energy and fluence of Si ions were measured by FCs. In response to a stepwise increase in the number of laser pulses from 3000 to 12000, the ion fluence varies from 4.6 × 1014 to 18.3 × 1014 ions/cm2 with constant energy of 30 keV. Fourier Transformation Infrared (FTIR) spectroscopy analysis revealed that irradiated silicon makes the stretch band with oxygen Si–O–Si. X-Ray Diffraction (XRD) analysis confirmed the identification of new phase of Si (111) with an anomalous trend in crystallite size, dislocation line density and induced stresses in response to the irradiation with various Si ion fluences. Optical microscopy analysis showed the formation of pits, voids and tracks. Scanning electron microscope (SEM) analysis revealed the formation of nanoscale surface features including pores, craters, embedded particulates and protruded disk-like structures with multiple ablative layers at the fluence of 4.6 × 1014 to 13.7 × 1014 ions/cm2. At the highest ion fluence of 18.3 × 1014 ions/cm2, the flake/flower-like morphology is observed. Field emission (FE) properties were studied under ultra-high vacuum condition in a parallel plate configuration using planar virgin SS as an anode and structured SS as a cathode. The Fowler–Nordheim plots were obtained from I–V characteristics to evaluate the turn-on field, field enhancement factor β and a maximum current density ranging 1.5–4.5 V/µm, 5008–12807 and 96–454 nA/cm2, respectively. The variation in the FE properties is attributed to the different morphological features at varying silicon ion fluences.