Surface Modification Of Substrates Research Articles

Crystallization Control of Anionic Thiacalixarenes on Silicon Surface Coated with Cationic Poly(ethyleneimine).

Surface modification of solid substrates with organic molecules and polyelectrolytes is a promising strategy toward advanced soft materials due to the control of molecular arrangement and supramolecular organization; however, understanding the nature of interactions within the assembly is challenging. Here a facile approach to the control of the architecture of calixarene macrocycles on soft surfaces is presented through the interplay of weak interactions involving a solid silicon substrate, a cationic polyelectrolyte layer, and anionic sulfonatothiacalix[4]arene (STCA). Topological analysis of atomic force microscopy (AFM) images of STCA on silicon, as well as silicon wafers modified with neutral polyethylenimine (PEI) and cationic PEI-H+, indicates different surface morphology and assembly behavior of STCA on such substrates. Drop-casting a calixarene solution onto silicon induces the formation of chaotically oriented needle crystals. When there is globular PEI, a nucleation point for the STCA crystals is formed on the polyelectrolyte surface, which grows into rosette structures. In contrast, protonated PEI with a chain-like structure alters the self-organization of STCA on silicon surfaces, leading to a dense uniform fiber-like network. Density functional theory modeling of the system components' self-assembly reveals thermodynamically favorable face-to-face antiparallel aggregation of STCA monomers and contribution of H-bonding into PEI(PEI-H+)-STCA and Si-STCA association.

Parametric investigation on surface responses of TIG cladded medium carbon steel substrate with TiO2–SiC powder

The present research work consists of surface modification of a medium-carbon steel substrate with TiO2–SiC powder of the same weight percentage. A Taguchi L9 orthogonal array was used for the design of experiments. Different input process parameters, such as current (A), scan speed (mm/s) and gas flow rate (L/min), have played a significant role in controlling geometrical surface responses. The relationship between different input parameters and response surfaces (clad height, clad width) was plotted and discussed. Diagrams have been utilized to demonstrate the combined impacts of any two process factors on clad height and clad width, such as TIG current–scan speed, TIG current–gas flow rate and gas flow rate–scan speed. Experimental observations revealed that cladding input parameters have a significant influence on response surfaces. TIG current has the maximum impact on clad height. Observations showed that with the increment of current up to a certain amount clad height increased. It was also observed that with an increment of current, clad width increases. Observations revealed that as the gas flow rate rises, clad height decreases but clad width increases. It was further noted that with an increase in scan speed, clad height and clad width follow a downward trend.

Convex structure formation on a Cu substrate by friction stirring using a tool wrapped with Ti foil

The bond strength between Cu substrate and epoxy resin is required to be improved in power modules. Surface modification of the Cu substrate improves the bond strength due to the anchor effect. In this study, we propose a new surface modification method using friction stirring. A convex structure was formed on a Cu substrate by friction stirring using a tool wrapped with Ti foil. The microstructure of the modified surface and adhesion with epoxy resin were evaluated. Friction stirring formed a Ti-derived convex structure on the Cu substrate, and Cu and Ti were mixed at the microscale and bonded strongly. The shear bond strength between the modified surface and epoxy resin was 7.9 ± 1.7 MPa, which was twice as strong as that without surface treatment. The Ti-derived convex structure formed on the Cu substrate improved adhesion with epoxy resin.

Pentaerythritol-DOPA (PE-DOPA): A tetra-catechol derivative for versatile hydrophilic nanocoatings

Pentaerythritol (PE) was modified with 3,4-dihydroxy-L-phenylalanine (L-DOPA) to produce a tetra(catecholamine) tetra-ester derivative (PE-DOPA). Subsequently, PE-DOPA was used to dip-coat glass, stainless steel (SS) and various plastics under alkaline conditions and formed a poly(PE-DOPA) surface coating ranging in thickness between 1.0–3.0 nm on glass and 9.0–12.0 nm on SS, as estimated by X-ray photoelectron spectroscopy (XPS). The as-coated poly(PE-DOPA) showed increased hydrophilicity compared to the bare substrate, as demonstrated by water contact angle (WCA) measurements, whilst subsequent thermal annealing of poly(PE-DOPA) coatings on glass and SS at 120 °C for 6 h reversed the as-coated hydrophilicity through an indole ring formation reaction. The molecular structure of the poly(PE-DOPA) coating was investigated by adsorption studies, suggesting monolayer formation on glass and multilayer on SS. Surface modification of plastic substrates (e.g. Nylon, polyester, polyolefines, PTFE) was also confirmed at the molecular level by XPS and at bulk properties level by WCA. PTFE was the only plastic substrate that didn’t show any altering of its bulk hydrophilicity. Lastly, the fabrication of multilayer structures where poly(PE-DOPA) was coated by bovine serum albumin (BSA) allowed for a first assessment of poly(PE-DOPA) affinity for BSA and the associated possibility of tailoring poly(PE-DOPA) response.

Ni and Ni–P substrates inhibit Bi phase segregation and IMC overgrowth during the soldering process of Sn–Bi solder

In this paper, presents surface modification of Cu substrates by electroplating or chemical plating to obtain high-quality Ni and Ni–P coatings. The Sn58Bi solder reactions with Cu, Ni, and Ni–P UBMs at 180 °C, 250 °C, and 320 °C, respectively. Research has found that Ni and Ni–P substrates can inhibit Bi phase segregation and interfacial IMC overgrowth in Sn–Bi solder joints. Bi phase segregation occurs during the transition from Cu6Sn5 to Cu3Sn. There is Bi segregation at the interface of Sn58Bi/Cu solder joints to Cu3Sn/Cu interface, and IMC grows rapidly. However, Ni/Cu and Ni–P/Cu substrates can not only suppress the Bi phase segregation behavior of Sn58Bi solder joints during soldering, but also slow down the excessive growth of interfacial IMC; Even under the harsh soldering process of up to 320 °C for 600 s, it still has an effective blocking effect. In addition, at 320 °C, when Sn58Bi solder react with Cu, the interface directly crosses Cu6Sn5 to generate Cu3Sn, which exhibits the morphology characteristics of Cu6Sn5 due to high thermal conditions. During the soldering, Ni atoms continuously diffuse towards the interface, and Ni3Sn4 (Ni/Cu) grows from needle like in the early stage of soldering to rod like, and finally to block like; The block like appearance of Ni3Sn4 (Ni–P/Cu) occurs earlier than that of Ni3Sn4 (Ni/Cu), because the presence of columnar Ni3P layers provides a wider diffusion channel for Ni atoms, but the overall growth size is smaller than that on Ni/Cu. A higher undercooling can promote the growth of interfacial IMC, including Cu6Sn5 and Ni3Sn4. At the same time, the Bi phase inside the Sn58Bi solder joint is coarsened, and the substrate Ni/Ni–P can eliminate interfacial brittleness after eliminating Bi segregation.

High‐performance porous transport layers for proton exchange membrane water electrolyzers

AbstractHydrogen is a favored alternative to fossil fuels due to the advantages of cleanliness, zero emissions, and high calorific value. Large‐scale green hydrogen production can be achieved using proton exchange membrane water electrolyzers (PEMWEs) with utilization of renewable energy. The porous transport layer (PTL), positioned between the flow fields and catalyst layers (CLs) in PEMWEs, plays a critical role in facilitating water/gas transport, enabling electrical/thermal conduction, and mechanically supporting CLs and membranes. Superior corrosion resistance is essential as PTL operates in acidic media with oxygen saturation and high working potential. This paper covers the development of high‐performance titanium‐based PTLs for PEMWEs. The heat/electrical conduction and mass transport mechanisms of PTLs and how they affect the overall performances are reviewed. By carefully designing and controlling substrate microstructure, protective coating, and surface modification, the performance of PTL can be regulated and optimized. The two‐phase mass transport characteristics can be enhanced by fine‐tuning the microstructure and surface wettability of PTL. The addition of a microporous top‐layer can effectively improve PTL|CL contact and increase the availability of catalytic sites. The anticorrosion coatings, which are crucial for chemical stability and conductivity of the PTL, are compared and analyzed in terms of composition, fabrication, and performance.

Advanced film/substrate interface engineering for adhesion improvement employing time- and energy-controlled metal ion irradiation

Pre-deposition substrate etching by metal ion bombardment is an efficient and fast cleaning method that ensures improved chemical and topological substrate surface modification. Here, we study the effects of metal ion mass and kinetic energy on etching of industrially-relevant cemented carbide (WC) substrate as well as on adhesion at the Ti0.50Al0.50N/WC interface. Cr+ or W+ ion fluxes are generated by high-power impulse magnetron sputtering (HiPIMS), while their kinetic energy Ekin is tuned by applying negative substrate bias voltage synchronously with the metal ion-rich portion of the flux. The time evolution of ion fluxes at the substrate plane is studied with energy- and time-resolved ion mass spectrometry. The threshold substrate bias voltage required to initiate substrate etching is in the 900–1000 V range for both Cr+ and W+ fluxes. Moreover, we show that the adhesion strength of Ti0.50Al0.50N coatings correlates with Ekin. For Ekin < 900 eV, Cr or W interlayers are grown and no significant improvement in the adhesion strength is observed. Contrary, for Ekin > 900 eV, effective substrate etching with energetic metal ions significantly improves the adhesion strength: we demonstrate an increase of 76–79 % after etching with metal ions as compared to the untreated substrate.

Electrodeposited NiFe‐LDH on the Surface of Ni‐BDC for Electrocatalytic Water Oxidation

AbstractSubstrate surface modification with a functional material can effectively enhance the electrocatalytic performance of an electrode on oxygen evolution reaction (OER). In this work, a functional Ni‐BDC MOF nanosheet layer was in‐situ grown on the surface of nickel foam (NF). Consequently, the NiFe layered double hydroxides (NiFe‐LDH) electrodeposited on the modified layer exhibited an excellent activity and an amazing long‐term stability on electrocatalytic OER. In alkaline electrolyte, the well‐designed NiFe‐LDH/Ni‐BDC/NF drives a current density of 100 mA cm−2 at a small overpotential of 223 mV, with a low Tafel slope of 33.1 mV dec−1 and an outstanding catalytic stability of more than 10 days under continuous electrocatalysis. Such distinguished performances are attributed to the particular hydrophily and electrical conductivity of the Ni‐BDC layer. This work is an important attempt to bring a simple and effective guideline on fabricating a highly efficient catalytic electrode for OER.

An investigation of methods to enhance adhesion of conductive layer and dielectric substrate for additive manufacturing of electronics

Additive manufacturing of conductive layers on a dielectric substrate has garnered significant interest due to its promise to produce printed electronics efficiently and its capability to print on curved substrates. A considerable challenge encountered is the conductive layer’s potential peeling due to inadequate adhesion with the dielectric substrate, which compromises the durability and functionality of the electronics. This study strives to facilitate the binding force through dielectric substrate surface modification using concentrated sulfuric acid and ultraviolet (UV) laser treatment. First, polyetheretherketone (PEEK) and nanoparticle silver ink were employed as the studied material. Second, the surface treatment of PEEK substrates was conducted across six levels of sulfuric acid exposure time and eight levels of UV laser scanning velocity. Then, responses such as surface morphology, roughness, elemental composition, chemical bonding characteristics, water contact angle, and surface free energy (SFE) were assessed to understand the effects of these treatments. Finally, the nanoparticle silver ink layer was deposited on the PEEK surface, and the adhesion force measured using a pull-off adhesion tester. Results unveiled a binding force of 0.37 MPa on unmodified surface, which escalated to 1.99 MPa with sulfuric acid treatment and 2.21 MPa with UV laser treatment. Additionally, cross-approach treatment investigations revealed that application sequence significantly impacts results, increasing binding force to 2.77 MPa. The analysis further delves into the influence mechanism of the surface modification on the binding force, elucidating that UV laser and sulfuric acid surface treatment methods hold substantial promise for enhancing the binding force between heterogeneous materials in the additive manufacturing of electronics.

L-arginine-etched nickel-silver electrocatalyst for low-potential hydrogen evolution

The oxidation of formaldehyde at low potentials to achieve anodic hydrogen production is a crucial focus of current research. Copper-based alloys are prominent electrocatalysts in these reactions but face long-term stability challenges and are susceptible to CO intermediate poisoning. A novel approach that utilizes L-arginine in the surface modification of nickel foam substrates has been developed, enabling the highly dispersed deposition of silver catalysts on the substrates as sub-nanometer particles. This modified electrocatalyst allows formaldehyde oxidation and water electrolysis at a minimal potential of 0.32 VRHE and bipolar hydrogen production with near 100% Faradaic efficiency. This surface modification of substrate material provides a new approach to the design of electrodes.

Antibacterial Zirconia Surfaces from Organocatalyzed Atom-Transfer Radical Polymerization.

Antibacterial coatings are becoming increasingly attractive for application in the field of biomaterials. In this framework, we developed polymer coating zirconia with antibacterial activity using the "grafting from" methodology. First, 1-(4-vinylbenzyl)-3-butylimidazolium chloride monomer was synthesized. Then, the surface modification of zirconia substrates was performed with this monomer via surface-initiated photo atom transfer radical polymerization for antibacterial activity. X-ray photoelectron spectroscopy, ellipsometry, static contact angle measurements, and an atomic force microscope were used to characterize the films for each step of the surface modification. The results revealed that cationic polymers could be successfully deposited on the zirconia surfaces, and the thickness of the grafted layer steadily increased with polymerization time. Finally, the antibacterial adhesion test was used to evaluate the antibacterial activity of the modified zirconia substrates, and we successfully showed the antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa strains.

Growth of Textured Chalcogenide Thin Films and Their Functionalization through Confinement

A number of chalcogenides show a remarkable portfolio of properties, which enables a plethora of applications including thermoelectric power generation and phase change material (PCM)‐based information storage. PCMs exhibit fast and reversible switching between two (typically, amorphous and crystalline) states, characterized by different optical and electrical properties. In the last decade, textured chalcogenide thin films have been investigated to develop a better understanding of structure – property relationships, improve material performance and understand how these properties change upon reducing film thickness. In this review, the present knowledge concerning the textured growth is summarized, focusing on films of GeTe, Sb2Te3, and GeSbTe compounds. In particular, the impact of different deposition methods, substrate surface modifications, and methods to influence film formation is reviewed. In the second part of this review, confinement effects are discussed. Surprisingly pronounced changes in atomic arrangement, that affect film properties, and device performance are presented. These changes are attributed to the unconventional bonding mechanism in these chalcogenides coined metavalent bonding, which is trongly affected by the confinement. Bonding becomes covalent‐like in the two‐dimensional limit, whereas Metavalent Bonding emerges for thicker films, where electron delocalization is increased This explains the pronounced property changes with film thickness.

Nanopatterned Monolayers of Bioinspired, Sequence-Defined Polypeptoid Brushes for Semiconductor/Bio Interfaces.

The ability to control and manipulate semiconductor/bio interfaces is essential to enable biological nanofabrication pathways and bioelectronic devices. Traditional surface functionalization methods, such as self-assembled monolayers (SAMs), provide limited customization for these interfaces. Polymer brushes offer a wider range of chemistries, but choices that maintain compatibility with both lithographic patterning and biological systems are scarce. Here, we developed a class of bioinspired, sequence-defined polymers, i.e., polypeptoids, as tailored polymer brushes for surface modification of semiconductor substrates. Polypeptoids featuring a terminal hydroxyl (-OH) group are designed and synthesized for efficient melt grafting onto the native oxide layer of Si substrates, forming ultrathin (∼1 nm) monolayers. By programming monomer chemistry, our polypeptoid brush platform offers versatile surface modification, including adjustments to surface energy, passivation, preferential biomolecule attachment, and specific biomolecule binding. Importantly, the polypeptoid brush monolayers remain compatible with electron-beam lithographic patterning and retain their chemical characteristics even under harsh lithographic conditions. Electron-beam lithography is used over polypeptoid brushes to generate highly precise, binary nanoscale patterns with localized functionality for the selective immobilization (or passivation) of biomacromolecules, such as DNA origami or streptavidin, onto addressable arrays. This surface modification strategy with bioinspired, sequence-defined polypeptoid brushes enables monomer-level control over surface properties with a large parameter space of monomer chemistry and sequence and therefore is a highly versatile platform to precisely engineer semiconductor/bio interfaces for bioelectronics applications.

Robust underwater superoleophobic coatings based on zwitterionic P(CBMAE‐co‐TMSPMA)/SiO2 with anti‐adhesive behavior

AbstractThis study focuses on the surface modification of substrates using a poly(N,N‐dimethyl‐N‐(ethoxycarbonylmethyl)‐N‐[2′‐(methacryloyloxy) ethyl]‐ammonium chloride‐co‐3‐(trimethoxysilyl)propylmethacrylate) P(CBMAE‐co‐TMSPMA) and ethyl orthosilicate (TEOS). By covalently bonding the Si‐OH pendant of the copolymer with hydroxyl residues on the material's surface, a stable polymer coating is formed. The properties of P(CBMAE‐co‐TMSPMA) coatings were evaluated using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and contact angle (CA) meter. The addition of TEOS allows for the regulation of surface roughness. With the increase of TEOS content, the contact angle of underwater oil first increased and then decreased. The water contact angles were 8°, the underwater superoleophobic contact angle reached 168°, and the number of adherent platelets and Escherichia coli were significantly reduced to 7.5% and 5% on the surface of the coating, respectively. After undergoing simultaneous hydrolysis, the superoleophobic contact angle of P(CBMAE‐co‐TMSPMA)/SiO2 coating further increased to 174°. These interesting and robust properties make them promising candidates for biomedical applications.Highlights The underwater superoleophobic coating (contact angles of 174°). The P(CBMAE‐co‐TMSPMA)/SiO2 coating with excellent resistance to oil adhesion. Solve the hydroxyl residue problem. The coating resistance to E. coli and platelet adhesion.

Hierarchically Multiscale Vertically Oriented NiFeCo Nanoflakes for Efficient Electrochemical Oxygen Evolution at High Current Densities

AbstractCrucial advancements in versatile catalyst systems capable of achieving high current densities under industrial conditions, bridging the gap between fundamental understanding and practical applications, are pivotal to propel the hydrogen economy forward. In this study, vertically oriented hierarchically multiscale nanoflakes of NiFeCo electrocatalysts are presented, developed by surface modification of a porous substrate with nano‐structured nickel. The resulting electrodes achieve remarkably low overpotentials of 139 mV at 10 mAcm−2 and 248 mV at 500 mAcm−2. Further, scaled‐up electrodes are implemented in a water‐splitting electrolyser device exhibiting a stable voltage of 1.82 V to deliver a constant current density of 500 mA cm−2 for over 17 days. Moreover, the role of the unique structures on electrochemical activity is systematically investigated by fractal analysis, involving computation of structure factors such as Minkowski connectivity, fractal dimension, and porosity using scanning electron microscope images. It is found that such structures offer higher surface area than typical layered double hydroxide structures due to morphological coherence that results in a superhydrophilic surface, while the base Ni layer boosts the charge transfer. This study demonstrates a Ni/NiFeCo(OH)x heterostructure with highly porous morphology, a key to unlocking extremely efficient oxygen evolution reaction activity with exceptional stability. Moreover, fractal analysis is presented as a valuable tool to evaluate the electrochemical performance of catalysts for their structured morphology.

Impressive hydrophobic TiO2@Cu mesh for electromagnetic interference shielding

This study investigated the surface modification of copper mesh using modified titanium dioxide (TiO2) coatings to enhance its surface hydrophobic properties while preserving electromagnetic interference (EMI) shielding effectiveness. Silicon-coupling-agent-treated titanium dioxide particles were employed to create micro/nanostructured superhydrophobic coatings. The deposition times were found to influence the coating distribution, pore filling and surface hydrophobicity. S-TiO2@Cu mesh with a single layer of modified titanium dioxide coating exhibited the highest water contact angle compared with T-TiO2@Cu mesh with triple layer coatings and the original O-TiO2@Cu mesh. The superior self-cleaning performance and robust wear resistance of the hydrophobic coatings for S-TiO2@Cu mesh were revealed. In addition, both S-TiO2@Cu mesh and T-TiO2@Cu mesh exhibited satisfactory EMI-shielding efficiency without compromising the intrinsic properties of the copper mesh. These findings provide practical insights into surface modification of copper mesh substrates, emphasizing the balance between surface properties and EMI shielding. The hydrophobic coatings hold promise for multifunctional applications, offering enhanced surface properties without compromising EMI-shielding performance.

Surface modification of paper substrates by a printed UV curing varnish layer and a transferred transparent PEDOT:PSS electrode for paper-based perovskite light-emitting devices in ambient air

Paper, a low-cost and eco-friendly substrate, can be used to prepare flexible electronic devices by resorting to surface modification technology. In this study, we investigated the surface modification of paper substrates, including those that were uncoated or coated with traditional mineral coatings, to analyze the enhancements to surface flatness and water resistance using a UV curing varnish layer. Furthermore, we explored the formation of perovskite films on the surface-modified paper substrates utilizing a PEO-doped perovskite precursor solution in ambient air, and the surface morphology, crystallinity, photoluminescence properties, and absorption properties of the prepared perovskite films were discussed accordingly. Considering the nontransparent feature of paper-based substrates, the inverted perovskite light-emitting device was finally assembled by transfer printing a transparent PEDOT:PSS layer as a top electrode. The conductive and optical properties of the electrode layer were thus analyzed as well. It is found that the surface modification of paper substrates via printing the UV curing varnish can illustrate significant improvements, such as pore-filling on the surface, a more than 10-fold reduction in roughness, and downward penetration. Moreover, prepared perovskite films on the surface-modified coated paper exhibit superior enhancements, including photoluminescence, higher crystallinity, and surface roughness and porosity. Devices fabricated on the surface-modified substrates are less susceptible to short-circuiting. The electroluminescence on the surface-modified coated paper substrate is 2.16 times higher than the prepared device on the surface-modified base paper substrate and even 3.23 times higher than on the PET substrate. Therefore, it is quite feasible to fabricate a perovskite light-emitting device on the modified surface of a paper substrate by using a printed UV curing varnish layer, which is expected to be a promising coating to polish the paper surface in the preparation of electroluminescent devices.

Surface Modification and Bioactivity Improvement of 3Y-TZP Substrate by Spray Coating of Hydroxyapatite/Fosterite Composite Powder

Surface Modification and Bioactivity Improvement of 3Y-TZP Substrate by Spray Coating of Hydroxyapatite/Fosterite Composite Powder

Terahertz Humidity Sensing Based on Surface-Modified Polymer Mesh Membranes with Photografting PEGMA Brush.

A simple and compact intensity-interrogated terahertz (THz) relative humidity (RH) sensing platform is successfully demonstrated in experiments on the basis of combining a porous polymer sensing membrane and a continuous THz electronic system. The RH-sensing membrane is fabricated by surface modification of a porous polymer substrate with hydrophilic and photosensitive copolymer brushes via a UV-induced graft-polymerization process. The intensity interrogation sensing scheme indicated that the power reduction of the 0.4 THz wave is dependent on the grafting density of the copolymer brushes and proportional to the RH percent levels in the humidity-controlled air-sealed chamber. This finding was verified by the water contact angle measurement. Based on the slope of the proportional relation, the best sensitivity of the hydrophilic surface-modified sensing membrane was demonstrated at 0.0423 mV/% RH at the copolymer brush density of 1.57 mg/mm3 grafted on the single side of the sensing membrane. The sensitivity corresponds to a detection limit of approximately 1% RH. The THz RH sensing membrane was proven to exhibit the advantages of low loss, low cost, flexibility, high sensitivity, high RH resolution, and a wide RH working range of 25-99%. Thus, it is a good candidate for novel applications of wearable electronics, water- or moisture-related industrial and bio-sensing.

Patterning of Hydrophilic and Hydrophobic Gold and Magnetite Nanoparticles by Dip Pen Nanolithography (Small 18/2023)

Dip Pen Nanolithography In article number 2208069, Bart Jan Ravoo and co-workers report the surface patterning of nanoparticles using dip pen nanolithography. Metal and metal oxide nanoparticles functionalized with various organic ligands can be patterned in nanosized clusters. Depending on the polarity of the ligand shell, water or toluene is used as ink solvent. No modification of atomic force microscope (AFM) tip or substrate surface is required.