Hydrophobic Silane Research Articles

Effect of [Tris(trimethylsiloxy)silyethyl]dimethylchlorosilane on the corrosion protection enhancement of hydrophobic film coated on AISI 304

The effects of Organofunctional moieties and the adhesion properties of hydrophobic [Tris(trimethylsiloxy)silyethyl]dimethylchlorosilane (Alkyl)] coated on AISI 304 to determine the corrosion resistance were investigated and presented. Two different types of adhesion, namely: silicon oxide and plasma silicon oxide films were grown on AISI 304 with the aid of an atomic-layer deposition technique. The effects of the surface preparations on the functionality and the properties of the hydrophobic silane coating were characterized, using the scanning electron microscope (SEM) and the atomic force microscope (AFM) for morphology and topography. X-ray diffraction (XRD) and attenuated Fourier-transform infrared (FTIR-ATR) were used for the chemical composition and the bonding structure, the water contact angle were measured and processed, as well as the determination of electrochemistry of the coated and uncoated surfaces. The results showed that the silicon oxide treated surface improved the durability of the silane film in the corrosive medium; and that has more chemical stability with the coating, when compared with the plasma silicon oxide and base material, which was distinctly discussed.

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.

Fluor-thiol Photocoupling Reaction for Developing High Performance Nucleic Acid (NA) Microarrays.

Spatially controlled anchoring of NA probes onto microscope glass slides by a novel fluor-thiol coupling reaction is performed. By this UV-initiated reaction, covalent immobilization in very short times (30 s at 254 nm) is achieved with probe densities of up to 39.6 pmol/cm2. Modulating the surface hydrophobicity by combining a hydrophobic silane and a hydrophilic silane allows the fabrication of tuned surfaces where the analyte approaches only the anchored probe, which notably reduces nonspecific adsorption and the background. The generated substrates have proven clear advantages for discriminating single-base-pair mismatches, and for detecting bacterial PCR products. The hybridization sensitivity achieved by these high-performance surfaces is about 1.7 pM. Finally, this anchoring reaction is demonstrated using two additional surfaces: polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) membranes. This provides a very interesting pathway for anchoring thiolated biomolecules onto surfaces with C-F motifs via a quick clean UV reaction.

Evaluation of the Durability and the Property of an Asphalt Concrete with Nano Hydrophobic Silane Silica in Spring-Thawing Season

In the spring-thawing season, the high frequency of freeze-soak-scour cycles in the short term is the main cause of pavement damage in the frozen region. One of the methods to improve the durability of asphalt concrete in spring-thawing season is to add suitable modifiers and additives which improve adhesion between asphalt binder and aggregate. This study evaluates the effect of nano hydrophobic silane silica (NHSS) on the performance damage of asphalt concrete (AC) in spring-thawing season. The effectiveness of nano hydrophobic silane silica was evaluated by conducting mixture tests after different freeze-soak-scour cycles, and the damage model of NHSS modified asphalt concrete was established based on the logistic damage model. The results showed that adding NHSS is an effective technique for mitigating freeze-soak-scour cycle damage of asphalt concrete in spring-thawing season. Moreover, the influence of scour, soak, and freeze—three separate factors on NHSS-modified AC in spring-thawing season—was discussed based the gray rational degree theory. The results illustrated that the freeze factor had a more significant impact on the damage process of NHSS modified asphalt concrete compared with the soak and scour factor.

Amine wetting evaluation on hydrophobic silane modified polyvinylidene fluoride/silicoaluminophosphate zeolite membrane for membrane gas absorption

Membrane wetting in membrane gas absorption is undesirable as it reduces the gas transfer in wet pores. This work aims to understand the improvement of membrane hydrophobicity using fluoroalkyl silane and its effects on membrane properties, separation performance and membrane wetting by amine. Polyvinylidene fluoride/silicoaluminophosphate zeolite membranes were prepared using non-solvent induced phase separation technique and then immersed into a mixture of (3,3,3-trifluoropropyl) trimethoxysilane and ethanol solution (volume ratio of 1: 100) for 20 min. The post-modification resulted in a slight improvement of water contact angle and liquid entry pressure. Hence, the highest CO2 absorption flux of 4.48 ± 0.36 × 10−4 mol.m−2. s−1 was achieved using silanated membrane, about 25 % of improvement in comparison to the neat membrane. The absorption flux of humid gas was slightly reduced (-16 %) due to pore wetting. Fluoroalkyl silane could be used to prevent water wetting, resulting improvement of CO2 absorption. The membranes were immersed in diethanolamine solution (2 M) for 50 h before characterization using goniometer, Fourier transform infrared spectroscopy and scanning electron microscope. The incorporation of zeolite reduced membrane wetting because membrane swelling could be prevented. The unfavorable interaction between fluoroalkyl and amine groups induced severe membrane wetting by amine.

Facile fabrication of photoinduced superhydrophobic–superhydrophilic surfaces on cellulose substrate without strength loss

A novel strategy was reported on the design and fabrication of functional photosensitive hybrid sols (FPHSs) by non-alcoholic emulsification in the presence of a TiO2 nanoparticle and photoinitiator via a sol-gel process using tetraethylorthosilicate, γ-methacryloxypropyltrimethoxysilane (MPS) and hydrophobic silane coupling agents as precursors. Smart cellulose substrates with alterable superhydrophobic–superhydrophilic conversion were fabricated using FPHS via the ultraviolet (UV) curing process. The liquid FPHS was photocured into solid gel during UV irradiation for 40 s with MPSs in FPHS, which was verified via Fourier transform infrared spectra. The cellulose substrates were modified with FPHSs, and the water contact angles of the modified cellulose substrates were more than 150°. The superhydrophobicity was improved by the gathering of hydrophobic chains and particle deposition of hybrid gel on the fiber surface. Nevertheless, the water contact angles of the modified cellulose substrates were receded with UV irradiation from 158° to 0° in 200 min, due to TiO2 photoinduction. The irradiated cellulose substrates were placed in the dark, and the water contact angles were recovered to about 130°, gradually. What is more, the reversible process can be repeated more than eight times. The modified cellulose substrate presented excellent washing fastness, even suffering 10 times washing processing. The mechanical properties, including breaking strength and elongation rate, were improved after the coating and UV curing process, which considerably remedied the defects of the heating curing process on the mechanical properties.

Preparation of novel film-forming armoured latexes using silica nanoparticles as a pickering emulsion stabiliser

HypothesisFilm-forming polymer latex particles of diameter <300 nm can be prepared in the complete absence of surfactants, stabilised in part by silica nanoparticles through a Pickering type emulsion polymerisation. Control of the silica wettability through modulation of reaction pH or by reaction of the nanoparticles with a hydrophobic silane results in silica-covered latex particles. ExperimentsThe oil-in-water polymerisation process used methyl methacrylate (MMA) and n-butyl acrylate (BA) as co-monomers, potassium persulphate (KPS) as an initiator and a commercially available colloidal nano-silica (Ludox®-TM40). It was found that pH control before polymerisation using methacrylic acid (MAA) facilitated the formation of armoured latexes, and mechanistic features of this process are discussed. An alternative, more robust protocol was developed whereby addition of vinyltriethoxysilane (VTES) to control wettability resulted in latexes completely armoured in colloidal nano-silica. The latexes were characterised using SEM, cryo-TEM and AFM imaging techniques. The mechanism behind the adsorption was investigated through surface pressure and contact angle measurements to understand the factors that influence this irreversible adsorption. FindingsResults indicate that nanoparticle attachment (but intriguingly not latex size) is dependent on particle wettability, providing new insight into the formation of nanoparticle-armoured latexes, along with opportunities for further development of diversely functionalized inorganic/organic polymer composite particles.

The effect of hydrophobic (silane) treatment on concrete durability characteristics

Hydrophobic (silane) impregnation represents a cost-effective way to increase the durability of concrete structures in cases where insufficient design cover quality and depth have been achieved. The water repellent product lines the internal capillary pore structure and provides a water-repellent concrete surface. Thus, the risk of reinforcement corrosion initiation and subsequent deterioration can be reduced as the ingress of water-dissolved aggressive species (chlorides) is minimised or prevented. The purpose of this study was to investigate the effect of silane impregnation on durability indicators, including penetrability tests and chloride ingress (bulk diffusion). The results indicate that silane impregnation reduces capillary absorption and conductivity of chloride ions. Similarly, chloride ingress in the treated concrete mixes was suppressed.

Waterproof Narrow-Band Fluoride Red Phosphor K2TiF6:Mn4+ via Facile Superhydrophobic Surface Modification.

With unique and efficient narrow-band red emission and broadband blue light absorption characteristics, Mn4+-activated fluoride red phosphors have gained increasing attention in warm white LEDs (WLEDs) and liquid crystal display (LCD) backlighting applications, whereas the intrinsic hygroscopic nature of these phosphors have inevitably limited their practical applications. Herein, a waterproof narrow-band fluoride phosphor K2TiF6:Mn4+ (KTF) has been demonstrated via a facile superhydrophobic surface-modification strategy. With the use of superhydrophobic surface modification with octadecyltrimethoxysilane (ODTMS) on KTF surfaces, the moisture-resistance performance and thermal stability of the phosphor KTF can be significantly improved. Meanwhile, the absorption, and quantum efficiency did not show obvious changes. The surface-modification processes and mechanism, as well as moisture-resistance performances and luminescence properties, of the phosphors have been carefully investigated. It was found that the luminous efficiency (LE) of the modified KTF was maintained at 83.9% or 84.3% after being dispersed in water for 2 h or aged at high temperature (85 °C) and high humidity (85%) atmosphere (HTHH) for 240 h, respectively. The WLEDs fabricated with modified KTF phosphor showed excellent color rendition with lower color temperature (2736 K), higher color rendering index (CRI, Ra = 87.3, R9 = 80.6), and high luminous efficiency (LE = 100.6 lm/W) at 300 mA. These results indicate that hydrophobic silane coupling agent (SCA) surface modification was a promising strategy for enhancing moisture resistance of humidity-sensitive phosphors, exhibiting great potential for practical applications.

Frequency Dependence of Low-Voltage Electrowetting Investigated by Impedance Spectroscopy.

An electrowetting-on-dielectric (EWOD) electrode was developed that facilitates the use of low alternating voltages (≤5 VAC). This allows online investigation of the frequency dependence of electrowetting by means of impedance spectroscopy. The EWOD electrode is based on a dielectric bilayer consisting of an anodic tantalum pentoxide (Ta2O5) thin film (d = 59.35 nm) with a high relative permittivity (εd = 26.3) and a self-assembled hydrophobic silane monolayer. The frequency dependence of electrowetting was studied using an aqueous μL-sized sessile droplet on the planar EWOD electrode in oil. Experiments using electrochemical impedance spectroscopy and optical imaging indicate the frequency dependence of all three variables in the Young-Lippmann equation: the voltage drop across the dielectric layers, capacitance per unit area, and contact angle under voltage. The electrowetting behavior induced by AC voltages is shown to be well described by the Young-Lippmann equation for AC applications below a frequency threshold. Moreover, the dielectric layers act as a capacitor and the stored electrostatic potential energy is revealed to only partially contribute to the electrowetting.

Photopatterning Freestanding Chiral Nematic Mesoporous Organosilica Films

AbstractChiral nematic mesoporous organosilica (CNMO) films are functionalized with a mixture of hydrophobic silanes and spiropyran compounds to create freestanding photochromic films that can be used for reversible photo­patterning. The mesoporosity and interconnected pore structure of the films imparted by the cellulose nanocrystal template enables a large cross‐section of the material to be functionalized. Thus, the materials show intense absorption spectra from the tethered spiropyran and rapid color changes when the porous films are irradiated with UV or white light. The spiropyran‐bound CNMO films behave as reversible sensors where metal binding to the spiropyran results in visible color changes detectable by the naked eye. These metals can be removed in the presence of ethanol and white light, regenerating the metal‐free film. The proof‐of‐concept demonstrated in this paper may help to develop new photochromic displays, security features, and patterns.

Controlling Water Intercalation Is Key to a Direct Graphene Transfer.

The key steps of a transfer of two-dimensional (2D) materials are the delamination of the as-grown material from a growth substrate and the lamination of the 2D material on a target substrate. In state-of-the-art transfer experiments, these steps remain very challenging, and transfer variations often result in unreliable 2D material properties. Here, it is demonstrated that interfacial water can insert between graphene and its growth substrate despite the hydrophobic behavior of graphene. It is understood that interfacial water is essential for an electrochemistry-based graphene delamination from a Pt surface. Additionally, the lamination of graphene to a target wafer is hindered by intercalation effects, which can even result in graphene delamination from the target wafer. For circumvention of these issues, a direct, support-free graphene transfer process is demonstrated, which relies on the formation of interfacial water between graphene and its growth surface, while avoiding water intercalation between graphene and the target wafer by using hydrophobic silane layers on the target wafer. The proposed direct graphene transfer also avoids polymer contamination (no temporary support layer) and eliminates the need for etching of the catalyst metal. Therefore, recycling of the growth template becomes feasible. The proposed transfer process might even open the door for the suggested atomic-scale interlocking-toy-brick-based stacking of different 2D materials, which will enable a more reliable fabrication of van der Waals heterostructure-based devices and applications.

Biocomposite Fiber-Matrix Treatments that Enhance In-Service Performance Can Also Accelerate End-of-Life Fragmentation and Anaerobic Biodegradation to Methane

Biodegradable resins can enhance the environmental sustainability of wood-plastic composites (WPCs) by enabling methane (CH $$_4$$ ) recovery via anaerobic digestion (AD). An under appreciated step in biocomposite AD is the role of cracking and fragmentation due to moisture uptake by the wood fiber (WF) fraction. Here, we use batch microcosms to simulate AD at end-of-life and to assess the effects of fiber-matrix treatments used to retard in-service moisture uptake. The composites evaluated were injection molded poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) with WF (0, 20%) using two fiber-matrix compatibilization treatments: (1) hydrophobic silane treatment of the wood fiber and (2) grafting of hydrophilic maleic anhydride groups to the PHBV matrix. Both treatments accelerated rates of mass loss and CH $$_4$$ production by a factor of 1.2–2.3 compared to neat PHBV. The fragmentation rate, as measured by mass loss, increased significantly for treated samples compared to untreated samples. A ranking of test samples from lowest to highest rates of mass loss gave the following sequence: neat PHBV $$\approx$$ maleated PHBV < PHBV plus untreated WF < maleated PHBV plus untreated WF < PHBV plus silane-treated WF. Compared to the untreated samples, maleic anhydride treatment increased the mass loss rate by 30%, and silane treatment increased the mass loss rate by 92%. Onset of cracking in silane-treated composites was observed at 2 weeks (using X-ray micro-computed tomography). At the same time, solid mass loss and CH $$_4$$ production peaked, implicating cracking and physical disintegration as the rate-limiting step for accelerated anaerobic degradation. When modified to account for bioplastic matrix degradation, a previously derived moisture-induced damage model could predict the onset of composite fragmentation at end-of-life. These results are significant for design of bio-WPCs and demonstrate that treatments designed to improve in-service performance can also improve end-of-life options.

Influence of Surface Silanization on the Physicochemical Stability of Silver Nanocoatings: A Large Length Scale Assessment

We synthesized sub-100 nm “biogenic” protein-capped silver nanoparticles (bio-AgNPs) from a yeast extract (Rhodotorula glutinis) and assessed the chemical stability of their coatings formed on various silane-modified substrates up to the millimeter length scale. Large-field (LF) X-ray imaging was used for scanning AgNPs-coated substrates (5 × 5 mm) after they were immersed in physiological PBS for hours. Striking differences were found in the amount and the structural organization of bio-AgNPs in the coatings depending on the type of surface silanization. The relative amount of bio-AgNPs in the coatings increases due to the assembly of enlarged (8–30 μm2 in area) and chemically stable agglomerates of bio-AgNPs formed on a multilayered aminosilane film (average 230 nm thickness), which was generated with the use of 3-aminopropyltrimethoxysilane (APTMS). In contrast, substantially less bio-AgNPs was found on the hydrophobic silane film generated with the use of trimethoxyphenylsilane (TMPS) and on the films...

The Effect of Hydrophobic Alkyl Silane Self-Assembled Monolayers on Adult Barnacle Adhesion

AbstractAlthough there exists a wide range of nonbiocidal and environmentally friendly surface coatings to reduce biofouling on marine structures, there is still not a fundamental understanding of barnacle adhesion upon reattachment. The purpose of this study is to assess the effect of hydrophobicity on adhesion in the barnacle Amphibalanus amphitrite, an abundant and widespread biofouler. Self-assembled monolayers were made on glass slides from alkyl silanes with methylated and fluorinated terminal groups to produce hydrophobic surfaces. Coated and uncoated glass slides underwent a 2-week barnacle reattachment assay. Barnacles were removed using a force gauge, and critical shear stress was calculated for each substrate. Following reattachment assays, a Coomassie Blue G250 protein stain was used to quantify the amount of glue remaining on substrates by measuring pixel density with ImageJ software on glue scans. Critical shear stress was found to be significantly higher for both hydrophobic surfaces as compared to the hydrophilic uncoated glass, and correspondingly, the density of residual glue was higher on hydrophobic surfaces. Given that hydrophobic substrates can exclude water from the surface, they may provide a protected environment for glue release that is favorable for adhesive bond formation with the substrate as well as inter- and intramolecular bonding within the glue layer. Critical shear stress showed a strong positive correlation with residual glue density, suggesting that barnacle release occurs primarily via cohesive failure. Scanning Electron Microscope (SEM) micrographs confirm morphological differences in the glue remnants, depending on the substrate coating. Among the hydrophobic substrates tested, results suggest that contact angle alone is not enough to predict the critical shear stress of barnacles. The chemical and physical properties of the coating become important parameters to consider in antifouling coating design.

The role of hydrophobic silane coating on Si stamps in nanoimprint lithography.

Hydrophobic silane coatings have been successfully applied to the surface of Si stamps to improve demolding in nanoimprint lithography (NIL). However, the role of the silane coating has only been studied either indirectly, by measuring adhesion or friction coefficients for Si and substrate surfaces without patterns, or collectively, by measuring the overall demolding force that does not differentiate contributions of friction dissipation, stored elastic energy, and adhesion. Here, for the first time, we present experimental evidence on the role of the silane coating in improving demolding in UV-NIL by using different silane coatings. The silane coatings were characterized by x-ray photoelectron spectroscopy, water contact angle, and friction force measurements. Then, the work of demolding was systematically measured for different silane coatings using stamps with the same micropattern but different pattern depths. Comparison of the results to the theoretical model developed for fiber-matrix debonding energy by Sutcu and Hillig [Acta Metall. Mater. 38(12), 2653-2662] indicated that with a hydrophobic silane coating, the main parameter contributing to overall demolding work shifts from adhesion to stored elastic energy and frictional dissipation as surface adhesion keeps decreasing. The results confirm that the main role of the silane coating in reducing the demolding is to reduce surface adhesion rather than friction at the stamp/substrate interface.

Methodology to assess end-of-life anaerobic biodegradation kinetics and methane production potential for composite materials

Composites made with bio-based resins are promising candidates for replacement of conventional plastic composites made with petroleum-based resins in many applications (e.g., decking, paneling, furniture, molded automotive parts). For any such applications, end-of-life management needs consideration. Here, we describe a methodology to assess end-of-life anaerobic degradation to methane (CH4) within landfills or anaerobic digestion (AD) facilities in batch anaerobic microcosms. The core methodology combines stoichiometric considerations, chemical oxygen demand (COD) analysis, a CH4 production assay, and modeling. Additional analyses, such as thermogravimetric analysis (TGA), can complement this core set of analyses. We apply the methodology to injection molded poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) composites with wood fiber (WF) (0%, 20%, 40%) and two fiber-matrix compatibilization treatments that enhance in-service performance: (1) hydrophobic silane treatment of the WF and (2) grafting of hydrophilic maleic anhydride groups to the PHBV matrix. The methodology successfully quantifies process kinetics, ultimate CH4 production capacity, and biodegradability, and allows comparison to reference materials (positive controls).

High steady-state column density of I((2)P3/2) atoms from I2 photodissociation at 532 nm: Towards parity non-conservation measurements.

Steady-state column densities of 1017 cm−2 of I(2P3/2) atoms are produced from photodissociation of I2 vapour at 290.5 K using 5 W of 532 nm laser light. Recombination of the I(2P3/2) atoms at the cell walls is minimized by coating the cell surface with a hydrophobic silane (dimethyldichlorosilane/DMDCS). Operation at room temperature, and at an I2 vapour pressure of ~0.2 mbar, without using a buffer gas, allows relatively low Lorentz and Doppler widths of ~2π × 1.5 (FWHM) and ~2π × 150 (HW at 1/e2) Mrad/s, respectively, at the M1 transition of atomic iodine at 1315 nm. These high column densities and low linewidths are favorable for parity nonconservation optical rotation measurements near this M1 transition. Furthermore, as the cell is completely sealed, this method of production of high-density 127I(2P3/2) atoms is also compatible with using iodine radioisotopes, such as for the production of high-density 129I(2P3/2).

Development of granular expanded perlite/paraffin phase change material composites and prevention of leakage

In this study, granular phase change material (PCM) composites were developed by absorbing paraffin into the pores of expanded perlite particles with two grades of particle size. Because of the different particle sizes and pore structures, the absorption mechanisms of the expanded perlite particles were found to differ. A significant amount of paraffin leakage was found when the PCM composites were applied directly into the cement mixture. To prevent such leakage, a new method by using hydrophobic silane was investigated as surface modification for the PCM composites. The method was then compared with nanosilica deposition method. Although both methods prevented leakage effectively, cement composites incorporating silane-modified PCM composites had lower compressive strength than those incorporating nanosilica modified PCM composites. Thermal performances of expanded perlite/paraffin composites were compared with that of microencapsulated PCM and the results showed expanded perlite/paraffin composites were superior under certain conditions.

Water-based &amp; eco-friendly epoxy-silane hybrid coating for enhanced corrosion protection &amp; adhesion on galvanized steel

Abstract In this current study, epoxy-silane hybrid coatings were designed to investigate their anti-corrosion performance and adhesion on galvanized steel. Silanes with alkoxy group, epoxy group, amine group and thiol group were chosen to understand the role of functionalities in the performance of designed hybrid coatings. Moreover, the silanes were added at three different concentrations into epoxy polymer to asses the effect of concentration on anti-corrosion and adhesion properties of the coating films. From scanning electron microscopic (SEM) images, we observed a uniform coating without any agglomeration of coating particles over galvanized steel substrates. The corrosion performance of casted and cured films was evaluated by using potentiodynamic polarization and AC impedance spectroscopy method. The physical properties, such as, thermal behavior and thermo-mechanical behavior were studied using differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) respectively. The adhesion strength between coating films and galvanized steel substrate was checked by ‘pull off’ adhesion test. It was found that due to the grafting of sol-gel coatings onto organic polymer backbone, the adhesion property and anti-corrosive performance has improved remarkably as compared to non-grafted epoxy polymer. It was observed that amino silane showed superior performance compared to thiol silane. The poor performance of thiol silane grafted epoxy coating could be attributed to some chemical incompatibility of hydrophobic and non-polar sulfur silane moiety and hydrophilic and polar waterborne epoxy polymer backbone. Addition of silane by 1 wt% and 3 wt% into epoxy polymer backbone caused improvement in both anti corrosive property and adhesion strength but further increase of the silane concentration to 5 wt% led to deterioration of protective property of the films. This drop in performance can be attributed to excessive consumption of epoxide groups in epoxy resin by amino and thiol functionalities present in silane.