Surface Modification Of Substrates Research Articles

Directional Self‐Assembly of Fluorinated Star Block Polymer Thin Films Using Mixed Solvent Vapor Annealing

ABSTRACTWe demonstrate the directional alignment of perpendicular‐lamellae domains in fluorinated three‐armed star block polymer (BP) thin films using solvent vapor annealing with shear stress. The control of orientation and alignment was accomplished without any substrate surface modification. Additionally, three‐armed star poly(methyl methacrylate‐block‐styrene) [PMMA‐PS] and poly(octafluoropentyl methacrylate‐block‐styrene) were compared to their linear analogues to examine the impact of fluorine content and star architecture on self‐assembled BP feature sizes and interdomain density profiles. X‐ray reflectometry results indicated that the star BP molecular architecture increased the effective polymer segregation strength and could possibly facilitate reduced polymer domain spacings, which are useful in next‐generation nanolithographic applications. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 1663–1672

Surface Assembly Strategy for the Fabrication of MoS2 Thin-Film Patterns

Molybdenum disulfide (MoS2) is a novel material with remarkable properties that is widely investigated for future applications in electronics, sensors, and smart materials. In this respect, a low cost, easy process, large-area mass production process is needed to obtain diverse structures and surface patterns of MoS2. Here, we demonstrate an effective MoS2 patterning process using substrate surface modification that can solve the difficulties encountered in previous studies. This technique utilizes the sulfur vacancies introduced during chemical exfoliation of MoS2 flakes. The MoS2 patterning is performed via surface modification with thiol molecules on the substrate in pre-designed shapes. The thiol (???SH) group required to bond MoS2 to the surface-modified substrate using (3-mercaptopropyl)trimethoxysilane was confirmed by FT-IR and the patterned MoS2 was confirmed by Raman shift. Through this process, a gas sensor was fabricated and its feasibility was confirmed to show its applicability to various applications MoS2.

Air-plasma surface modification of epoxy resin substrate to improve electroless copper plating of printed circuit board

In this work, air plasma was employed to modify the surface of epoxy resin substrate for subsequent electroless copper plating. The influence of plasma modification on the interface performance of epoxy resin substrate was analyzed by multiple characterizations including morphological, chemical and surface tension-based measurements. The results show that the wettability and roughness of epoxy resin substrate are substantially increased after air plasma modification. The roughened shape and the oxidized chemical groups at surface are the major causes of modified interface properties of epoxy resin substrate. Subsequent electroless copper plating tests demonstrate that this air plasma treatment significantly improves the quality of copper deposition for printed circuit board manufacture.

Effect of Swelling of Chemical Reagents and the Sulfuric-Chromic Acid Bath on Surface Texturizing of Poly(Acrylonitrile-Butadiene-Styrene)

The surface modification of copolymer substrates of Acrylonitrile-Butadiene-Styrene (ABS) is significant for the electroplating industry. The sulfuric-chromic acid bath, used in the Electroless process, conditioning the ABS surface by selective oxidation of poly(butadiene) creating interconnected micro-holes, which allows an excellent mechanical adherence between the metallic film and the substrate. The chromium in its hexavalent form Cr(VI) is harmful to human beings and the environment being a carcinogenic element. This work shows a surface alteration effect with different types of chemical reagents on ABS surface and its treatment with the sulfuric-chromic acid bath in concentrations below those of the normal process, to analyze the possible application of the electroless process. The use of the different chemical reagents studied favored the alteration of the ABS surface causing various types of surface reactions, which could be shown spontaneously or during the conditioning step.

Real-Time Monitoring of Cellular Cultures with Electrolyte-Gated Carbon Nanotube Transistors.

Cell-based biosensors constitute a fundamental tool in biotechnology, and their relevance has greatly increased in recent years as a result of a surging demand for reduced animal testing and for high-throughput and cost-effective in vitro screening platforms dedicated to environmental and biomedical diagnostics, drug development, and toxicology. In this context, electrochemical/electronic cell-based biosensors represent a promising class of devices that enable long-term and real-time monitoring of cell physiology in a noninvasive and label-free fashion, with a remarkable potential for process automation and parallelization. Common limitations of this class of devices at large include the need for substrate surface modification strategies to ensure cell adhesion and immobilization, limited compatibility with complementary optical cell-probing techniques, and the need for frequency-dependent measurements, which rely on elaborated equivalent electrical circuit models for data analysis and interpretation. We hereby demonstrate the monitoring of cell adhesion and detachment through the time-dependent variations in the quasi-static characteristic current curves of a highly stable electrolyte-gated transistor, based on an optically transparent network of printable polymer-wrapped semiconducting carbon-nanotubes.

Effects of irradiation atmosphere on vacuum ultraviolet-induced surface modification of cyclo-olefin polymer substrates

The surface of a cyclo-olefin polymer was modified using vacuum ultraviolet (VUV) light to obtain a wettable surface. We found that the surface hydrophilicity is dependent on both VUV irradiation distance and irradiation time, which affected the concentration of oxygen functional groups. We investigated the effects of the VUV irradiation atmosphere and aging of the treated surfaces. We concluded that VUV treatment in low-humidity air (1% relative humidity) was the most effective condition for introducing oxygen functional groups on the surface; the concentration of these groups decreased over time (a drop of 11% over 5 d).

Fabrication of Silica Nanoparticle Monolayer Arrays Using an Anodic Aluminum Oxide Template.

Non-close-packed (NCP) silica nanoparticle monolayer arrays (SNMA) on ordered porous anodic aluminum oxide (AAO) templates were fabricated for the first time by a novel two-step spin-coating technique. The obtained NCP-SNMA-AAO was composed of silica nanoparticles (average primary particle size of 440 nm) and well-organized nanopores on the AAO substrates. NCP-SNMA-AAO with a supporting ratio of 87% silica nanoparticles showed a hydrophilic surface (water contact angle of 51.0°), while the original AAO substrate shows a hydrophobic surface (water contact angle of 107.9°). The maximum coefficient of static friction was decreased by 29% (0.327 → 0.233). The coefficient of dynamic friction was also decreased by 20% (0.281 → 0.226). We found that controlling the silica supporting ratio using the two-step spin-coating technique is an effective approach for surface modification of an AAO substrate.

Surface modification of β-type titanium with multi-walled CNTs/ μ-HAp powder mixed Electro Discharge Treatment process

The present study addresses the surface modification of β-type titanium substrate by the Electro Discharge Treatment (EDT). This technique incorporates multi-walled carbon nanotubes (MWCNTs), and μ-hydroxyapatite (μHAp) powders in the dielectric medium to achieve bio-favorable substrate. The L18 array is employed to conduct the experiments considering tool polarity, peak current, pulse duration, dielectric medium, and electrode tool material as a process parameters. The treated surface is scrutinized in terms of cell viability and hemolysis which concludes that the presence of MWCNTs on the surface promotes cell proliferation. Surface morphology also confirmed that powder mixed electro-discharge treatment elevates the porosity that is advantageous for bone grafting. X-Ray pattern revealed the formation of biocompatible phases of oxides, carbide, and hydride for the surface treated in the presence of MWCNTs mixed dielectric medium. The positive polarity of the graphite tool electrode at 15 A is the most desirable process parameter developing the bioactive surface.

Advancing Metal-Phenolic Networks for Visual Information Storage.

We report a facile inking strategy for visual information storage (e.g., writing, printing, and beyond) via surface modification of substrates with polyphenols and subsequent in situ formation of metal-phenolic networks (MPNs) on the substrates. The reported technique has several advantages compared with current printing techniques. Diverse substrates can be used to fulfill the requirements for different applications (e.g., printing, writing, painting, and stamping). A range of colors (e.g., yellow, blue, and green) can be realized using different polyphenols (e.g., tannic acid, gallic acid, and pyrogallol) and metal ions (e.g., CuII, FeIII, and TiIV). The disadvantages (e.g., ink precipitation, color fading) associated with writing or printing using traditional ink can be overcome. The obtained paintings can be easily removed by acids enabling the recycling of substrates. The reported strategy provides a new avenue for the development of portable, nontoxic, and green technologies for writing, printing, and beyond, which expands the applications of MPN-based materials.

The Surface Science of Microarray Generation–A Critical Inventory

Microarrays are powerful tools in biomedical research and have become indispensable for high-throughput multiplex analysis, especially for DNA and protein analysis. The basis for all microarray processing and fabrication is surface modification of a chip substrate and many different strategies to couple probe molecules to such substrates have been developed. We present here a critical assessment of typical biochip generation processes from a surface science point of view. While great progress has been made from a molecular biology point of view on the development of qualitative assays and impressive results have been obtained on the detection of rather low concentrations of DNA or proteins, quantitative chip-based assays are still comparably rare. We argue that lack of stable and reliable deposition chemistries has led in many cases to suboptimal quantitative reproducibility, impeded further progress in microarray development and prevented a more significant penetration of microarray technology into the diagnostic market. We suggest that surface-attached hydrogel networks might be a promising strategy to achieve highly sensitive and quantitatively reproducible microarrays.

Coating Architects: Manipulating Multiscale Structures To Optimize Interfacial Properties for Coating Applications

Polymeric coatings are ideal materials for the surface modification of many solid substrates. The interfacial properties of these coatings, i.e., surface energy and tribological features, impact a ...

Surface modification of polyethylene naphthalate substrates by ultraviolet light-irradiation and assembling multilayers and their application in electroless deposition: The chemical and physical properties of the stratified structure

Electroless metal deposition on polymer surface is useful for fabricating metallic patterns. The surfaces of polyethylene naphthalate (PEN) substrates were modified by ultraviolet (UV) light -irradiation and layer-by-layer assembly of polyelectrolyte multilayer thin films, and then nickel and copper films were electrolessly deposited on the substrate surfaces to form the stratified structure, PEN-substrate/multilayer/metal-film. The chemical and physical properties of the modified layer in the substrate surfaces were studied by X-ray photoelectron spectroscopy, nanoindentation test, and measuring contact angle. The properties of the UV-irradiated surface layer depended on the condition of surface modification and affected the adhesion of the deposited metal film. Adhesive nickel films were deposited on the UV (254 nm)-irradiated PEN substrates that have thin modified layers compatible with the multilayers. In contrast, no adhesive nickel films were deposited on the substrate surfaces having thicker and fragile modified layers. These contrasting results are originated from the oxygenation and crosslinking of the polymer chains in the substrate surface layers, and reactive species formed by the UV irradiation induce the oxygenation and crosslinking. The properties of the modified substrate-surface play an important role for depositing adhesive metal films.

Coating the porous Al2O3 substrate with a natural mineral of Nontronite-15A for fabrication of hydrogen-permeable palladium membranes

Substrate surface modification is a key pretreatment during fabrication of composite palladium membranes for hydrogen purification in hydrogen energy applications. The suspension of a natural porous material, Nontronite-15A mineral, without any organic additives was employed in dip-coating of the porous Al2O3 substrate. The Nontronite-15A mineral was characterized by SEM, XRD, TG−DSC and granulometry analysis. The surface and cross-section of the coated porous Al2O3 tubes were observed by SEM, and their pore size distribution and nitrogen flux were also measured. Palladium membranes were fabricated over the coated Al2O3 tubes by a suction-assisted electroless plating. The optimal loading amount of the Nontronite-15A mineral is just to fill in and level up the surface cavities of the Al2O3 substrate rather than to form an extra continuous layer. A thin and selective palladium membrane was successfully obtained, and its permeation performances were tested. The kinetic analyses on the hydrogen flux indicate that the hydrogen permeation behavior exhibits typical characteristics for most of the palladium membranes. During the stability test at 450 °C for 192 h, no membrane damage was detected, and the hydrogen flux increased slightly.

Surface Functionalization of Polyester Fibers via One-step Green Formation and Assembling of Iron Oxide Nanoparticles with Photo and Magneto Activities

In this research for the first time, surface functionalization of polyester fibers was performed via one-step, facile and clean strategy through green synthesis and deposition of iron oxide nanoparticles for photocatalytic and magnetic applications. The commercial ash of Seidlitzia Rosmarinus plant was used as a natural alkaline source for nanoparticles synthesis as well as surface modification of polyester substrate and iron sulfate as metal precursor. The presence of iron oxide nanoparticles on polyester fibers was proved by X-ray diffraction analysis, energy-dispersive X-ray spectroscopy, mapping, field-emission scanning electron microscope images and Fourier transform infrared spectra. The fabricated samples exhibited very good photocatalytic activities toward methylene blue decoloration about 95.45% after 48 h exposing to sunlight irradiation. In addition, they indicated appropriate magnetic properties with saturated magnetization of 2.30 and 1.69 emu/g at room temperature. The coloring effect, weight change and wettability behavior of the fabricated samples were also investigated. The mentioned route in this paper can simply be scaled up as an eco-friendly and scalable route for surface functionalization of polymeric substrates via synthesis and deposition of iron oxide nanoparticles to acquire durable photo and magneto activities on polymers for different applications.

Polyethylene-Glycol-Added Water-Droplet Evaporative Cooling for Fast Cooling Operations

The surface modification of the hot substrate and the alteration of thermophysical properties at the interface in the favorable direction of heat transfer significantly reduce the film boiling effect. The exact methodology describing the simultaneous attainment of the aforementioned variations has not been addressed in the literature. Therefore, in the current work, an attempt has been made to propose a process depicting enhanced dropwise evaporation due to simultaneous variation of the aforementioned parameters, and this is achieved by using polyethylene glycol (PEG) as an additive, which modifies the surface to hydrophilic at a very high temperature () and alters the thermophysical properties in the positive direction of heat transfer. The scanning electron microscope analysis confirms the deposition over the surface of the substrate that contributes hydrophilicity to the surface, and the Fourier-transform infrared (spectroscopy) analysis asserts the unaltered functional groups present in the PEG forming a coating over the surface. The heat transfer analysis depicts that the droplet lifetime decreases with increasing PEG concentrations and substrate temperature, and the dropwise evaporative cooling also follows the same trend line. The droplet impact mapping reveals the transition of the Leidenfrost point from 200 to 400°C. The nature of the boiling curve confirms the elimination of film boiling.

Enhanced electrical conductivity of silver nanoparticles decorated fabrics with sandwich micro-structure coating layer based on “silver colloid effect”

Surface modification of nonconductor fabric substrate for enhancing electrical conductivity is a desirable work of flexible wearable devices. In our work, silver conductive layer with sandwich micro-structure was decorated on polyester fabric, and such a sandwich micro-structure layer is composed of the inner polyurethane (PU) as the interface binder, the filling layer of the precipitating silver nanoparticles (AgNPs) as the conductive path via in-situ chemical synthesis, the outer PU layer as the shielding layer. The obtained sandwich micro-structure PET fabric possessed six orders of magnitude higher conductivity than that of the case without sandwich micro-structure. Such marvelous increasing conductivity can be attributed to the “silver colloid effect” which is deemed as approximation of conductive principle of silver conductive adhesives. The present study provides a potential strategy and theoretical basis for the preparation of low concentration silver conductive fabrics.

Shedding Light on the Dark Corners of Metal-Organic Framework Thin Films: Growth and Structural Stability of ZIF-8 Layers Probed by Optical Waveguide Spectroscopy.

Metal-organic framework (MOF) thin films are promising materials for multiple technological applications, such as chemical sensing. However, one potential limitation for their widespread use in different settings is their stability in aqueous environments. In the case of ZIF-8 (zeolitic imidazolate framework) thin films, their stability in aqueous media is currently a matter of debate. Here, we show that optical waveguide spectroscopy (OWS), in combination with surface plasmon resonance (SPR) spectroscopy, offers a convenient way for answering intriguing questions related to the stability of MOF thin films in aqueous solutions and, eventually provide a tool for assessing changes in MOF layers under different environmental conditions. Our experiments relied on the use of ZIF-8 thin films grown on surface-modified gold substrates, as optical waveguides. We have found a linear thickness increase after each growing cycle and observed that the growing characteristics are strongly influenced by the nature of the primer layer. One of our findings is that substrate surface modification with a 3-mercapto-1-propanesulfonate (MPSA) primer layer is critical to achieve ZIF-8 layers that can effectively act as optical waveguides. We observed that ZIF-8 films are structurally stable upon exposure to pure water and 50 mM NaCl solutions but they exhibit a slight swelling and an increase in porosity probably due to the permeation of the solvent in the intergrain mesoporous cavities. However, OWS revealed that exposure of ZIF-8 thin films to phosphate-buffered saline solutions (pH 8) promotes significant film degradation. This poses an important question as to the prospective use of ZIF-8 materials in biologically relevant applications. In addition, it was demonstrated that postsynthetic polyelectrolyte modification of ZIF-8 films has no detrimental effects on the structural stability of the films.

Surface modification of zirconia substrate by silicon-substituted hydroxyapatite coating for enhanced bioactivity

Surface modification of zirconia substrate by silicon-substituted hydroxyapatite coating for enhanced bioactivity

Ultra-thin carbon fiber mirrors: nickel plated, optical fabrication and thermal deformation test

The aperture of space remote sensing camera is increasing, and the demand for lighter weight is getting higher and higher. With the advancement of active optics, the thickness of optical components has gradually grown to light and thin. It is extremely difficult to develop ultrathin mirrors using brittle materials such as traditional optical glass and silicon carbide. Due to advantages such as low density, high specific stiffness, low thermal expansion coefficient, toughness, and additive rapid manufacturing properties, carbon fiber reinforced plastic (CFRP) is one of potential applications for large-diameter ultra-thin mirrors. However, the carbon fiber composite material is a two-phase material that cannot be used as optical surface and must be surface-modified. In this paper, the surface modification of CFRP substrate was carried out by chemical nickel plating and nickel electroplating. The modified nickel layer covers all surfaces of CFRP substrate, and nickel layers satisfying the thickness, bonding force, and internal stress requirements. A Φ100 mm aperture ultra-thin carbon fiber mirror developed, after optical fabricating, its surface accuracy RMS is better than λ/15. Thermal deformation analysis and test show that the thermal deformation of ultra-thin carbon fiber mirrors is mainly manifested by the change of radius of curvature, which is caused by the thickness error of the nickel layer on the front and rear faces. In addition, although thermal deformation caused by the lamination angle error of CFRP substrate is relatively small in value, it should still be given enough attention, because the astigmatic error produced is hard to eliminate.

Laser induced periodic surface structures on nano metal oxide filled polyvinylidene fluoride nanocomposites

The ability of polarized pulsed laser in surface modification of substrate surfaces without thermally destroying them is a well-established concept of scientific procedure. In this work, we report the laser induced surface structures that are created on the semi crystalline polyvinylidene fluoride (PVDF) polymer and its composites containing transition metal oxides-zinc oxide of 100 nm and iron oxide of 30 nm diameter. The PVDF nanocomposites are fabricated by solution casting method and films of 0.2 mm thickness are used for laser treatment. The periodic structures formed are demonstrated by atomic force microscopy and profilometry investigations. Influence of laser pulses on the material properties is also addressed by means of Fourier transform infrared spectroscopy, contact angle measurements and thermogravimetric/differential scanning calorimetric studies.