Silane Compound Research Articles

Comparing chemical and plasma modification of stainless steel surfaces – Relevance for adsorption of adhesion promotor vinyltrimethoxysilane (VTMS)

Coated stainless steel surfaces with silane compound coupling agent are implemented in many industrial applications. For vinyltrimethoxysilane (VTMS) adsorption optimization, surface modification of stainless steel type V2A was performed with plasma, ozone and in sodium hydroxide (NaOH) solutions. Subsequent a systematic study of a central composite design of experiments (DoE) accomplished with X–ray photoelectron spectroscopy (XPS) data. Similar results in ozone, oxygen (O2)–, and water (H2O)–plasma treatment led to a detailed presentation of the results from the O2–plasma and NaOH treatment. Treatment effects on the surface roughness were determined using atomic force microscopy (AFM) and the functional groups of VTMS on the surface with surface enhanced Raman spectroscopy (SERS). All treatments resulted to a reduction of C and a higher oxidized surface whereas the Fe/Cr–ratio and OH-content were changing significantly after NaOH treatment. Only the root mean squared (RMS)–values calculated from the AFM images of NaOH treated V2A samples indicated an increased coverage of VTMS after longer treatment time in higher concentrated NaOH solutions. The results of this study enable setting the amount of VTMS bonding to the surface of V2A due to NaOH pretreatment.

Alumina lath-like structure-rGO–PVDF hybrid film formation with high-performance corrosion protection for 316L stainless-steel alloy

The susceptibility of stainless steel (SS) to corrosion can necessitate the use of an effective surface coating for application in various industries. In this study, the lath-like structure of aluminium oxide (Al2O3) has been successfully synthesized via a sol–gel process using the ionic liquid, 1-hexyl-3-methylimidazolium hexafluorophosphate. The uniform alumina lath-like structures with a diameter of 105 ± 22 nm and length of 340 ± 66 nm were characterized with various techniques, including X-ray diffraction (XRD), transmission electron microscope (TEM), field emission scanning electron microscopy (FE-SEM), and X-ray photoelectron spectroscopy (XPS). Furthermore, the alumina nanoparticles were functionalized with a silane compound. Composite of reduced graphene oxide (rGO), functionalized Al2O3, and polyvinylidene fluoride (rGO/Al2O3–PVDF) with Al2O3 concentration of 1 wt.% was successfully prepared. The composites were then characterized and utilized for SS protection in a saline solution (3.5% NaCl). Excellent corrosion resistance was conferred to the SS surface using the rGO/Al2O3–PVDF coating with 1% Al2O3 (rGO/Al2O3–1.0–PVDF), which outperformed the other coatings, as indicated by electrochemical characterization using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). The water contact angle of rGO/Al2O3–1.0–PVDF-coated SS was 142.5°, demonstrating good hydrophobicity. The protection mechanism was clarified using both electrochemical and surface characterizations. The remarkable protection performance of rGO/Al2O3–1.0–PVDF is related to the control of charge transfer at the SS/electrolyte interface, which prevents alloy dissolution. Furthermore, the presence of Al2O3 passivates any graphene defects that may be present, which further reduces the corrosion rate, thus providing enhanced protection compared to the rGO/PVDF and neat PVDF coatings.

A comparative study on dry‐sliding wear behavior of graphene oxide/epoxy nanocomposites functionalized by amino‐ and epoxy‐silane coupling agents

AbstractTo enhance the interfacial bonding between the graphene oxide nanoplatelets (GONs) and epoxy (EP) matrix, two different types of silane coupling agents (amino‐ and EP‐silane) were applied to the GONs‐EP nanocomposites. The effects of the silane compound type and silanized GON loading (0.1–0.5 wt% at an interval of 0.2) on the dry‐sliding wear response of GONs‐EP nanocomposites were then studied. The wear tests were conducted under 20 N load and 1000 m sliding distance. The results showed that the wear properties were remarkably improved by the incorporation of silanized GONs to the matrix, and the best wear behavior was obtained at 0.3 wt% silanized GONs. Most importantly, the amino‐silane coupling agent was shown to be more effective in enhancing the wear resistance of the GONs‐EP nanocomposites. After the wear tests, the composite surfaces were studied by scanning electron microscopy to find the predominant mechanisms.

Solution-Based One-Step Preparation of Three-Dimensional Self-Assembled Octadecyl Silica Nanosquare Plate and Microlamella Structures for Superhydrophobic and Icephobic Surfaces.

Icephobic surfaces have gained immense attention owing to their significant roles in decreasing the energy consumption of refrigerators and in improving safety issues by preventing the formation of ice on them. Superhydrophobic surfaces incorporating micro- or nanoscale roughness and hydrophobic functional groups have been shown to prevent ice accumulation. Herein, we report a simple, low-cost, and solution-based one-step process for the production of superhydrophobic surfaces with three-dimensional (3D) self-assembled structures. The controlled hydrolysis and polycondensation of n-octadecyltrichlorosilane (OTS-Cl) in an acetone solution produced a highly uniform superhydrophobic surface on various substrates such as glass, metals, and polymers without the limitation of the surface curvature structure. The as-prepared 3D self-assembled surface exhibited a very high contact angle of 161.7° and a low contact hysteresis of 1.47°. The solvent type, H2O content in acetone, and carbon chain length of the silane compound were critical in the formation of self-assembled nanostructures. The thickness of the superhydrophobic 3D self-assembled structure could be varied by controlling the surface properties of the glass substrate. In addition, a novel octadecyl silica nanosquare plate structure was formed as an intermediate for the microlamella structure. The water drop impact experiments on the 3D self-assembled superhydrophobic glass substrates at low temperatures (T < -25 °C) showed that the as-prepared superhydrophobic glass possessed a high impalement threshold for water contact, resulting in excellent and stable icephobic properties. The preparation method proposed in this study is scalable and can be used on a flat glass surface or in a glass vial inside a glass tube. Moreover, it can be applied to various substrates such as metals and polyurethane surfaces with curvature. Therefore, the solution-based self-assembly method proposed in this study is a promising approach to produce superhydrophobic and icephobic surfaces on a wide range of substrates regardless of their structure and properties.

Adhesive Wet Metallization on TiO2-Coated Glass

In this study, a process for wet metallization on glass substrate involving adhesive electroless plating (ELP) is developed by integrating two material innovations. The first involves functionalizing a polymer-capped Pd nanocluster with amino silane compound to strengthen the adhesion between the ELP metal film and substrate. The second involves an additional nanoscaled TiO2 layer serving as the adhesion promoting layer (APL) coated on glass before metallization. After investigation with various tools, ELP metal film was observed to penetrate the mesoporous structure of TiO2 APL, reinforcing the adhesion of metallized film on glass through the mechanical anchoring effect. The formation of an interlayer between TiO2 APL and glass is not observed. A T-peel strength of 325 N m−1 is achieved. According to fracture analysis, the metal film/TiO2/glass structure breaks inside TiO2 APL, not TiO2 APL/glass, suggesting that further engineering developments are required to improve TiO2 APL coating.

Surface Response to Mechanics of Hardness and Wear Characteristics of Nanoscale Hydrophobic Film

There is an increase in demand for durable and efficient organic nanoscale coatings for modern manufacturing systems and/or components for various applications. In wake of this demand, a new superhydrophobic silane compound was deposited on mild steel, stainless steel and titanium substrates which were pre-treated with alumina via the atomic layer deposition (ALD) method. Three substrates were considered for evolving properties comparison, also, determination of the influence of substrates’ response to films mechanical properties. The mechanical properties and the failure mechanics were investigated through nanoindentation and nanoscratch while the morphologies were examined through a field emission scanning electron microscope. The morphological evolution and mechanical viability indicated that stainless steel showed the most robust properties when compared with other substrates. Therefore, a nanoscale coating’s mechanical strength can be influenced by the substrate’s material compositions.

In-situ thin coating of silica micro/nano-particles on polymeric films and their anti-fogging application

Polymeric films, e.g., polyethylene (PE), coated with a thin layer of silica micro/nano-particles (SiO2 M/NPs) were prepared using a modified Stöber method in the presence of corona treated and non-treated PE films. The obtained films were washed of excess reagents and non-bonded (free) SiO2 M/NPs and dried. Only the corona-treated PE films were coated with a thin layer of SiO2 M/NPs while the non-treated films were almost empty of bound SiO2 particles. PE films composed of bound mesoporous silica NPs were similarly prepared with the addition of cetyltrimethylammonium bromide (CTAB) in the polymerization process. The effect of various polymerization parameters, e.g., tetraethylorthosilicate (TEOS) concentration, ammonium hydroxide concentration and the volume ratio [ethanol]/[water], on the diameter and diameter distribution of the free and surface bound particles were elucidated. Characterization of the SiO2 coated films was accomplished by routine methods such as DLS, HRSEM, water contact angle measurements, AFM and FIB. The SiO2 M/NP coatings on the PE films were found to be durable and did not significantly affect the optical properties of the film. Among the different types of SiO2 coated PE films prepared in our lab only those prepared with CTAB were found to be highly suitable for anti-fogging use.This process of SiO2 coating may be used for many other polymeric films, e.g., PET, PP, PMMA, PC, PVC, etc. as well as for various applications such as superhydrophobic, antimicrobial or UV blocking coatings. This can be done by binding long hydrophobic silane compounds (e.g., octadodecyl trichlorosilane), a positively charged silane compound or a UV absorbing silane, respectively, to the bound SiO2 particle surfaces.

Preparation of Zeolite‐g‐Polyacrylamide using Radiation Induced Grafting and Its Adsorption Isotherms Study on Several Heavy Metal Ions

AbstractZeolite‐g‐polyacrylamide is prepared by using the radiation induced grafting technique. Clinoptilotite, a natural zeolite, is used as the base matrix. In order to increase the degree of grating of polyacrylamide into the zeolite, its surface is modified with silane compound before the grafting reaction and applied a poor solvent method in the grafting reaction, i.e., a mixture of toluene and H2O. The irradiation doses are varied from 10 to 50 kGy. The grafting parameters are 40% w/w acrylamide, temperature 60 °C and 3 h grafting time. The highest degree of grafting is 93% at an irradiation dose of 25 kGy. The zeolite‐g‐polyacrylamide is then characterized with FTIR spectroscopy and SEM observation. Batch experiments are also carried out to investigate the adsorption capacity for ion Cr3+, Pb2+, and Zn2+. The maximum adsorption capacities of zeolite‐g‐polyacrylamide are 544, 345, and 1046 mg g−1 for ion Cr3+, Pb2+, and Zn2+, respectively. The equilibrium data are also tested with Langmuir and Freundlich isotherm to find the best suitable adsorption isotherm system.

New Insights in Adhesive Properties of Hybrid Epoxy-Silane Coatings for Aluminum Substrates: Effect of Composition and Preparation Methods

The sol–gel system has attractive properties both in terms of adhesion to metal substrates and of its great potential to replace the toxic treatments of metal surface currently used, such as chromating and anodization. In this work, hybrid epoxy-silane coatings prepared by the sol–gel method with epoxy resin and tetraethoxysilane (TEOS) were evaluated for the metal–metal bonding of aluminum substrates, based on the influence of different compositions/preparation methods of the coatings in their physical–chemical and adhesive properties. Five variables were studied: time after preparation of the adhesive systems prior to the deposition, the composition of the coating layers, the addition of a silane compound (3-glycidoxypropyltrimethoxysilane-GPTMS), the addition of epoxy resin to the adhesive systems (with or without curing agent) and the pressing method (type C clamp or by marble plates). The samples were characterized by infrared spectroscopy (FT-IR), rheological analyzes (viscosity) and shear test. The FT-IR analysis showed that the presence of epoxy resin in the sol–gel system delayed the gel transition, at the same time that the presence of the sol–gel accelerated the epoxy resin curing process. The rheological analyses showed similar trends, and the viscosity of the epoxy resin and epoxy-sol systems increased after 60 min at 70 °C, while the sol–gel system showed an increase in viscosity after 20 min at 70 °C, indicating that this is the best moment for the deposition. The shear results showed that the system adhesion is stronger when silane is used as a coupling agent between the aluminum substrate and the epoxy resin, probably due to the Si–O–Al bonding and the good cohesion of the epoxy resin with the curing agent.

Bonding of Fused Quartz with an Aromatic Silane Compound and Acidic Functional Monomers with a Tri-n-butylborane Initiated Resin.

Purpose: This study evaluated the effect of an aromatic silane compound and acidic functional monomer on the bond strength of fused quartz. Materials and Methods: A total of 264 disk specimens were fabricated from fused quartz for shear bond testing. Two silane compounds were used: 3-(trimethoxysilyl)propyl methacrylate (3-TMSPMA) and 3-(4-methacryloyloxyphenyl) propyltrimethoxysilane (3-MPPTS). As acidic functional monomers, 4-methacryloyloxyethyl trimellitate (4-MET) and 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) were used. The disks were primed with one of each silane compound with or without the acidic functional monomer of the same molarity. The specimens were bonded with a tri-n-butylborane (TBB) initiated luting material. The shear bond strength was determined before and after 10,000 thermocycles. Bond strength was statistically evaluated with Kruskal-Wallis, Mann-Whitney U-, and Steel- Dwass tests. To test dye penetration, the specimens were immersed in 0.5 wt% fuchsin solution for 24 h after priming with each condition, bonding, and 10,000 thermocycles. The dye penetration area was determined by observing the backside of the bonded specimen with an optical microscope. The relationship between the shear bond strength and dye penetration ratio was analyzed with Spearman’s rank correlation test. Results: The highest post-thermocycling bond strengths in the 1 mol% and 2 mol% groups were 3-TMSPMA + 10- MDP and 3-MPPTS + 10-MDP. Spearman’s rank correlation coefficient between shear bond strength and dye penetration area was γ = -0.7519, indicating a strong negative correlation. Conclusion: The surface treatments of 3-TMSPMA and 3-MPPTS combined with 10-MDP yielded higher bond strength after 10,000 thermocycles than those combined with 4-MET, despite the similarity in molarity. The shear bond strength was negatively correlated with the dye penetration area.

Morphological, physical, and mechanical properties of silanized wood-polymer composite

For investigation on the effect of silane compound on practical properties of poplar wood polymer composite, samples were impregnated using vacuum/pressure method with 3-trimethoxysilyl propyl methacrylate, and subsequently with styrene, methyl methacrylate, and mixtures of styrene/methyl methacrylate. Field emission scanning electron microscopy observations and Fourier transform infrared analysis indicated that styrene/methyl methacrylate copolymerized with 3-trimethoxysilyl propyl methacrylate and the resultant polymer tightly contacted to the wood cell walls without noticeable gaps. Impregnation with styrene resulted in a higher density of wood polymer composite compared to methyl methacrylate, which was more obvious in the presence of 3-trimethoxysilyl propyl methacrylate. Mechanical strength of the wood polymer composites improved and the highest strength was obtained for the 3-trimethoxysilyl propyl methacrylate/styrene/methyl methacrylate-modified samples. Maximum hardness was found in 3-trimethoxysilyl propyl methacrylate/styrene/methyl methacrylate-modified samples due to the cross-link formation between modified cell wall and polymer.

Protective Mechanism of Silane on Concrete upon Marine Exposure

Due to the high chloride ion concentration in marine environments, chloride ions can penetrate into concrete, along with the transportation of water molecules, and thus, cause rebar corrosion. This is an important reason for the decrease in the concrete durability. In this paper, by means of the sol–gel synthesis method, a silane emulsion, a silane compound emulsion, and silane compound gel were prepared by using isobutyl triethoxysilane and ethyl orthosilicate (TEOS) as the main raw materials. These silane materials were coated on a concrete surface and then placed in the marine exposure sites of Wheat Island, in Qingdao, for one year. The results show that these silane materials can effectively inhibit the chloride ions transporting in concrete. Upon the increase of the exposure time, the protection ability of the silane emulsion declined gradually, while the silane compound emulsion had stable protective effects. In comparison with the permeability coefficient of chloride ions in the blank test block, the permeability coefficient of chloride ions in the test block coated with the silane emulsion, the composition of silane emulsion, and silane compound gel fell off around 20%, 30%, and 50%, respectively. The test results indicate that the three kinds of protective materials have good inhibition abilities against chloride ion transportation, on which the compound gel had the best effect.

Graphene‐dispersed silane compound used as a coating to sense immunity from biofilm formation

AbstractBiofilm is a substance that contains organic polymers. It is derived from bacteria, produces slime and forms on material's surfaces. Therefore, it is important to properly evaluate biofilm formation using several types of sensors. Since biofilm forms easily on graphene, it is possible for graphene to serve as a sensor for biofilm formation. In the past, graphene's sensitivity to biofilm formation was confirmed by using CVD (chemical vapour deposition) graphene and by using the tape‐exfoliation method. However, the CVD method was expensive and required special equipment. On the other hand, the exfoliation method was not so expensive, but the precision and reproducibility for graphene formation were problematic. In this experiment, silane‐based resin, with dispersed graphene, was coated on a substrate. This coated substrate can easily be used as a sensor and is an inexpensive way to promote biofilm formation. Glass was used as the substrate, for which various samples were prepared using different concentrations of dispersed graphene. Biofilms formed on the specimens’ surfaces were analysed by using Raman spectroscopy and the crystal violet staining method. The results showed that biofilm formation capability increased with the concentration of dispersed graphene. We confirmed that the sensitivity was evaluated by the colour value for stained surfaces by crystal violet.

Biofilms By E.coli & S.Epidermidis and Its Sensing Possibility By Graphene-Dispersed Silane Coating

We already found that graphene is very sensitive to biofilm formation by bacterial activities. The problem is how to constitute proper sensing systems to detect biofilms in various cases. In this study, we focussed on the silane compound coating in which nano graphene powder would be dispersed in its free volume. The concentration of graphene powders in silane compound coating was changed from 0.1 wt % to 30 wt% and the graphene dispersed silane compounds were coated on glass and pure copper substrates. And biofilms were formed on those specimens in the well plates filled with liquid cultures containing Staphylococcus epidermis (S.epidermidis) as gram-positive bacteria and Escherichia coli (E.coli) as gram-negative ones. And the formation process was checked by the specimens' potential change in liquid cultures, color changes by staining with Crystal violet and some electrical measurement (capacitance etc.). Finally, we compared all of them each other and discussed about the advantage and disadvantage among the methods for the application as sensing method.

Silane modification of layered silicates and the mechanism of network formation from exfoliated layers

The edges of a synthetic layered silicate, Laponite XLG, was successfully modified with various amounts of ethoxytrimethylsilane, a monofunctional silane compound. The occurrence of the reaction was confirmed with various techniques. Thermogravimetric measurements and Fourier-transform infrared spectroscopy (FTIR) carried out on both the treated filler and the reaction medium yielded a saturation like correlation as a function of the amount of the silane used for treatment. The analysis of the bonded amount of silane by FTIR spectroscopy showed that a side reaction takes place during modification. Although the expected dimerization did not occur, the silane hydrolyzed, thus systematically changing the amount of bonded silane determined from the FTIR absorption of oxygen containing groups. Only vibrations related to the absorption of the SiCH3 group can be used for quantitative analysis. X-ray diffraction (XRD) measurements proved that the silane is bonded onto the surface of the silicate and it does not enter the interlamellar space. Approximately 50 mg silane is bonded to 1 g silicate corresponding to almost complete reaction of the surface OH groups. The results of the measurements were supported by model calculations and extremely good agreement was found between the calculated and the measured values. Surface modification did not hinder the formation of a house-of-card structure showing that the generally accepted mechanism of network formation needs revision. An explanation was offered based on the release of hydroxyl ions from the MgOH moiety of the silicate. The modification of the edges of layered silicates may facilitate exfoliation or help functionalization, but does not prevent network formation and cannot be used for the control of rheological properties.

Mechanical Properties of Multiscale Graphene Oxide/Basalt Fiber/Epoxy Composites

This work was carried out to study the effects of silane functionalization of graphene oxide (GO) nanoplatelets and their loadings on the mechanical properties of basalt fiber (BF)/epoxy composites. At first, the GO nanoplatelets were organically modified by grafting of N-(3-trimethoxysilylpropyl)ethylenediamine (3-TMSPED) compound. The Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX), and thermal gravimetric analysis (TGA) results demonstrated that silane compound can be covalently grafted to the surface of GO. The multiscale silanized graphene oxide (SGO)/BF/epoxy composites with various weight percentages of SGO in the matrix (0-0.5 wt.% in the step of 0.1) were fabricated. According to the experimental data, the 0.4 wt.% SGO-filled composite showed the maximum improvement by 18 %, 59 %, and 61 % in the tensile, flexural and compressive strengths of BF/epoxy composite, while the maximum improvement by 46 %, 54 %, and 66 % in the tensile, flexural and compressive moduli, respectively was observed for the 0.5 wt.% SGO-filled composite. Additionally, the SGO was more effective in mechanical property enhancement of fibrous composites in comparison with GO, due to its silane-functionalization. From the fracture surface examination of the specimens, it was found that the incorporation of GO or SGO improved the BF-epoxy interfacial bonding. A theoretical model based on Euler-Bernoulli beam-based method was utilized to predict the compressive properties of composites, which was in an excellent agreement with the experimental data.

Preparation of Water Repellent Layer on Glass Using Hydrophobic Compound Modified Rice Hull Ash Silica

In this study water repellent layered glass has been prepared by coating silica (SiO2) combined with a hydrophobic silane compound. SiO2 was extracted from rice hull ash and two silane compounds, namely hexadecyltrimethoxysilane (HDTMS) and trimethylchlorosilane (TMCS) were used. Coating was performed through two deposition techniques, i.e. one step (mono-layer) and layer by layer (LBL, multi-layer). The effect of silane to SiO2 mole ratio, silane type and layer number on the glass characters was evaluated. Characterization included hydrophobicity, transparency, surface roughness and stability of coating. Results showed that increasing the mole ratio of silane to SiO2 and the layer number increased the hydrophobicity of the glass surface. The optimum mole ratio was 5:1 and the significant increase of contact angle occurred at lower mole ratio, but the stability tends to be increased at higher mole ratio. For HDTMS-SiO2 layer, the technique of LBL technique produced a coating with higher hydrophobicity and transparency than single-stage one. The LBL technique produced the highest water contact angle of 103.7° with transmittance of 96%, while for TMCS-SiO2 layer the one stage technique produced hydrophobic layer with higher water contact angle of 108.0° and transparency about 94.52%. The prepared hydrophobic glasses were relatively stable in polar and non-polar solvents, but unstable to ambient conditions.

Solvent-Dependent Adhesion Strength of Electroless Deposited Ni-P Layer on an Amino-Terminated Silane Compound-Modified Si Wafer.

Amino-terminated silane compound modification was wet-processed on a silicon wafer using four different solvents to investigate the property of the self-assembled monolayer (SAM) and its influence on the adhesion of electroless deposited nickel-phosphorus (Ni-P) films. Analyzed by various tools including dynamic light scattering, the atomic force microscope, X-ray photoelectron spectroscopy, inductively coupled plasma with mass spectroscopy, a proper link between the processing solvent and SAM quality is established. It is found that at least the chemical compatibility, the polarity, and the acidity of solvents can affect the final morphology of the resultant SAM. Unlike toluene and ethanol that are most frequently chosen in literature, we conclude that isopropyl alcohol (IPA) is a superior solvent for amino-terminated silane compounds. Owing to the good SAM quality formed in IPA, the adhesion of electroless deposited Ni-P films is largely strengthened, even as high as the bulk strength of silicon wafers.

Influence of Surface Treatment on Dry Sliding Wear Behavior of Hydrophobic Silane Coating on AISI 304

Henicosyl-1,1,2,2-tetrahydrododecyltricholrosilane is a hydrophobic silane compound coated on AISI 304 substrate. The surface of the substrate was treated in two ways (silicon oxide and plasma oxide) for adhesion and interface between the inorganic substrate and organic coating. The wear performance of the coating as a comparison to the AISI 304 was investigated using vacuum tribometer and characterized by scanning electron microscope and atomic force microscope. The result showed that the silane compound did improve the wear property of the AISI 304 stainless steel. It also proved that silane can be used as wear resistance agent.

Effect of Silane Capping on the Dispersion and Combustion Characteristics of Sub-micrometer Boron Particles Loaded in Jet A-1

The present investigation deals with the surface modification of sub-micrometer boron particles with octadecyltrimethoxysilane (OTMS, a silane compound) to improve the dispersion stability of boron...