Surface Modification Of Substrates Research Articles

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.

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.

Recent Progress in Development and Application of DNA, Protein, Peptide, Glycan, Antibody, and Aptamer Microarrays.

Microarrays are one of the trailblazing technologies of the last two decades and have displayed their importance in all the associated fields of biology. They are widely explored to screen, identify, and gain insights on the characteristics traits of biomolecules (individually or in complex solutions). A wide variety of biomolecule-based microarrays (DNA microarrays, protein microarrays, glycan microarrays, antibody microarrays, peptide microarrays, and aptamer microarrays) are either commercially available or fabricated in-house by researchers to explore diverse substrates, surface coating, immobilization techniques, and detection strategies. The aim of this review is to explore the development of biomolecule-based microarray applications since 2018 onwards. Here, we have covered a different array of printing strategies, substrate surface modification, biomolecule immobilization strategies, detection techniques, and biomolecule-based microarray applications. The period of 2018-2022 focused on using biomolecule-based microarrays for the identification of biomarkers, detection of viruses, differentiation of multiple pathogens, etc. A few potential future applications of microarrays could be for personalized medicine, vaccine candidate screening, toxin screening, pathogen identification, and posttranslational modifications.

Flexible Microspectrometers Based on Printed Perovskite Pixels with Graded Bandgaps.

Miniaturized spectrometers have attracted much attention due to their capability to detect spectral information within a small size. However, such technology still faces challenges including large-scale preparation and performance repeatability. In this work, we overcome these challenges by demonstrating a microspectrometer constructed with a series of pixelized graded-bandgap perovskite photodetectors fabricated with inkjet printing. High-quality perovskite films with minimal pinholes and large grains are deposited by optimizing printing conditions including substrate temperature and surface modification. The resulting perovskite photodetectors show decent photosensing performance, and the different photodetectors based on perovskite films with different bandgaps exhibit various spectral responsivities with different cutoff wavelength edges. Microspectrometers are then constructed with the array of the pixelized graded-bandgap perovskite photodetectors, and incident spectra are algorithmically reconstructed by combining their output currents. The reconstruction performance of the miniaturized spectrometer is evaluated by comparing the results to the spectral curve measured with a commercial bulky spectrometer, indicating a reliable spectral reconstruction with a resolution of around 10 nm. More significantly, the miniaturized spectrometers are successfully fabricated on polymer substrates, and they demonstrate excellent mechanical flexibility. Therefore, this work provides a flexible miniaturized spectrometer with large-scale fabricability, which is promising for emerging applications including wearable devices, hyperspectral imaging, and internet of things.

3D printing of drug-eluting bioactive multifunctional coatings for orthopedic applications.

Three-dimensional (3D) printing is implemented for surface modification of titanium alloy substrates with multilayered biofunctional polymeric coatings. Poly(lactic-co-glycolic) acid (PLGA) and polycaprolactone (PCL) polymers were embedded with amorphous calcium phosphate (ACP) and vancomycin (VA) therapeutic agents to promote osseointegration and antibacterial activity, respectively. PCL coatings revealed a uniform deposition pattern of the ACP-laden formulation and enhanced cell adhesion on the titanium alloy substrates as compared to the PLGA coatings. Scanning electron microscopy and Fourier-transform infrared spectroscopy confirmed a nanocomposite structure of ACP particles showing strong binding with the polymers. Cell viability data showed comparable MC3T3 osteoblast proliferation on polymeric coatings as equivalent to positive controls. In vitro live/dead assessment indicated higher cell attachments for 10 layers (burst release of ACP) as compared to 20 layers (steady release) for PCL coatings. The PCL coatings loaded with the antibacterial drug VA displayed a tunable release kinetics profile based on the multilayered design and drug content of the coatings. Moreover, the concentration of active VA released from the coatings was above the minimum inhibitory concentration and minimum bactericidal concentration, demonstrating its effectiveness against Staphylococcus aureus bacterial strain. This research provides a basis for developing antibacterial biocompatible coatings to promote osseointegration of orthopedic implants.

Actinide and lanthanide thin-layer developments using a drop-on-demand printing system

Actinide and lanthanide thin layers with specific requirements regarding thickness, homogeneity, chemical purity, mechanical stability, and backing properties are applied in a multitude of physics and chemistry experiments. A novel target preparation method, the so-called “Drop-on-Demand” (DoD) technique, based on a commercial nanoliter (nL) dispenser is applied since a few years in the Nuclear Chemistry unit at Johannes Gutenberg University Mainz. The wetting behaviour of the nL droplets on the substrate’s surface is a key parameter determining the spatial distribution of the deposited material after evaporation. By switching from aqueous to organic solvents as well as by substrate surface modifications, the wetting behaviour can be influenced. Recent investigations on this influence and applications of the DoD method are presented. The produced actinide deposits were characterized by optical and scanning electron microscopy, by α spectroscopy as well as by radiographic imaging.

Recent Advances in Graphene Epitaxial Growth: Aspects of Substrate Surface Modification Using Coatings

Since the discovery of graphene in 2004 [...]

Differentiation and identification structural similar chemicals using SERS coupled with different chemometric methods: The example of fluoroquinolones

Surface-enhanced Raman spectroscopy (SERS) stands out in chemical analysis due to its rich molecular information, fast analysis speed, and high sensitivity. However, the differentiation of structural-similar chemicals is still challenging due to their similar SERS profiles. In this work, multivariate analysis (PCA and SCA) was combined with SERS for the differentiation and identification of highly similar chemicals using surface-modified SERS nanomaterials (MUO@Ag NPs), where three structural similar fluoroquinolone antibiotics (Norfloxacin, Ofloxacin, and Ciproflxacin) were used as examples. Due to their close molecular structure, the three chemicals showed very similar SERS spectra, with main feature located at 1394 cm−1. Introducing surface modification of the SERS substrate (MUO@Ag NPs) brought richer spectral information than the pristine ones. The performance of the two chemometric methods (PCA and SCA)was then compared using the MUO@Ag NPs as SERS substrate. SCA was found superior in identifying and differentiating these chemicals compared with widely adopted PCA analysis.