Silane-treated Surfaces Research Articles

Adhesive Strength of Glass Fiber-Reinforced Posts with Silane Conditioning Versus Universal Adhesive System Conditioning: An In Vitro Study

Abstract Aim: The current study compared the push-out adhesive strength of glass fiber-reinforced posts with a silane-treated surface versus a universally adhesive-treated surface. In both cases, a universal self-adhesive cement was used. Materials and Methods: Thirty bovine teeth were used in an in vitro experiment. Through cutting, the root and coronal sections were divided. Subsequently, the manufacturer’s recommendations were followed for the placement of glass fiber-reinforced posts through root canal therapy, gutta-percha removal, and canal shaping. On the basis of how the posts were treated prior to cementation, the samples were split into three groups (n = 10). Posts in group A (control) did not get any prior treatment. Posts in group B had previously received a silane treatment. Posts in Group C had previously been coated with universal adhesive. Following the application of RelyX Ultimate universal self-adhesive cementation, the samples were segmented and subjected to a Push-Out test at a speed of 1 mm/min on a universal testing apparatus. Intergroup ANOVA was used to evaluate the adhesive strength means (measured in MPa), and Tukey’s post hoc test was performed afterward, with a significance level of P < 0.05. Results: Compared to the glass fiber-reinforced posts pre-treated with silane (P = 0.003) and the control group (P < 0.001), the adhesive strength of the posts pre-treated with universal adhesive was significantly higher. Similarly, the adhesive strength of the glass fiber-reinforced posts that had been pre-treated with silane was considerably higher than that of the control group (P = 0.012). Conclusion: Posts reinforced with glass fiber and pre-treated with universal adhesive exhibited notably greater adhesive strength compared to those pre-treated with silane. When compared to utilizing universal self-adhesive cement without pre-treatment, both pre-treatment techniques greatly increased the adhesive strength of glass fiber-reinforced posts.

Wetting Patterns of Liquid-Repellent Femtosecond Laser Textured Aluminum Surfaces

Although liquid-repellent surfaces are in demand in many applications, their use is limited by the Cassie state’s sustainability to environmental factors, such as the repellency of liquids with a surface tension lower than that of water. This phenomenon remains not fully understood, despite a well-developed theory. In the current work, wetting of femtosecond laser-textured aluminum surfaces for probe liquids with a surface tension of 72.8–21.2 mN/m was considered. The resulting patterns were an array of pillars at the micro level and fractal-like structures at the nano level. These structured surfaces were treated with alkoxysilanes and oleic acid. All textured samples exhibited a Cassie state with water, and contact angles greater than 150° were achieved with silane-treated surfaces. A decrease in the surface tension of the probe liquid led to а transition to the Wetzel state at 44–46 mN/m for alkoxysilanes and at 52 mN/m for oleic acid. A typical shape of the textured surface wetting curve is proposed. It was shown that the determined values of the surface tension of the Cassie-Wenzel transition were 10–15 mN/m lower than those predicted by the Cassie equations.

Comparison of uncoated vs superhydrophobic copper surfaces for metal spray ionization

In order to evaluate the utility of copper surfaces as spray initiators for mass spectrometric ionization sources, it is necessary to establish how efficient and reproducible the methodology is. To do this, a superhydrophobic and bare copper surface were used to ionize the singly and doubly charged peptides, bradykinin and leucine-enkephalin spiked with substance P as an internal standard, respectively. Both treated and bare copper surfaces were cut to 90, 60, and 30° angles. Calibration curves were constructed for both peptides on a superhydrophobic surface using covalently bonded trichloro(1H, 1H, 2H, 2H-perflourooctyl)silane-treated copper, and bare copper surface. The highest sensitivity for all peptides was observed using a 30 or 60° tip with the silane-treated copper. Limits of detection and quantitation for the 60° silane-treated surface for bradykinin were 6.01 × 10−3 μM and 2.00 × 10−2 μM respectively, with a R2 of 0.9959. Limits of detection and quantitation for the 30° silane-treated surface for leucine-enkephalin were 3.28 × 10−2 μM and 1.09 × 10−1 μM respectively, with a R2 of 0.9993.

Condensation Heat-Transfer Performance of Thermally Stable Superhydrophobic Cerium-Oxide Surfaces.

We introduce a thin (<200 nm) superhydrophobic cerium-oxide surface formed by a one-step wet chemical process to enhance the condensation heat-transfer performance with improved thermal stability compared to silane-treated surfaces. The developed cerium-oxide surface showed a superhydrophobic characteristic with a low (<5°) contact angle hysteresis because of the unique surface morphology and hydrophobicity of cerium oxide. The surface was successfully incorporated to popular engineering materials including copper, aluminum, and steel. Thermal stability of the surfaces was investigated by exposing them to hot (∼100 °C) steam conditions for 12 h. The introduced ceria surfaces could maintain active dropwise condensation after the thermal stability test, whereas silane-treated surfaces completely lost their hydrophobicity. The heat-transfer coefficient was calculated using the thermal network model incorporating the droplet size distribution and morphology obtained from the microscopic measurement. The analysis shows that the suggested cerium-oxide surfaces can provide approximately 2 times and 5 times higher heat-transfer coefficient before and after the thermal stability test, respectively, mainly because of the decrease in the thermal conduction resistance across droplets. The results indicate that the introduced nanostructured cerium-oxide surface is a promising condenser coating to enhance the droplet mobility and the resulting condensation heat-transfer performance for various thermal and environmental applications, especially those being exposed to hot steam conditions.

XPS Analysis of Silane Films on the Surface of a Dental Ceramic

This study was designed to investigate the surface properties and the thickness of organofunctional silane films formed on leucite-reinforced feldspathic (LRF) ceramic surfaces after different methods of silane application using X-ray photoelectron spectroscopy (XPS). Six LRF ceramic discs (Mirage®, Myron Intl., Kansas City, KS, USA) were produced according to the manufacturer's instructions and polished to a 1 μm finish. A silane coupling agent was applied to five ceramic discs using different application methods: (A) immersion in silane solution for 60 s and dried with compressed air spray for 15 s; (B) as method A but heat treated with hot air at 50±5°C for 15 s; (C) silane was applied with a brush for 60 s and dried with compressed air spray for 15 s; (D) as method C but heat treated with hot air at 50±5°C for 15 s; (E) as method C followed by rinsing the specimens with hot water (15 s) and drying with hot air for 30 s. The ceramic surfaces were then analyzed by XPS at 15°–60° take-off angles. The results showed the highest and the lowest increase of C1s (C in the structure of silane) for treatments A and E, respectively. Signals of COO or C–COO in the high resolution spectra of C1s were observed for all silane-treated ceramic surfaces. The proportion of C–Si groups on the silane-treated surfaces compared with the untreated surface was significantly increased. XPS analysis indicates that the thickness of the silane film on a leucite-reinforced feldspathic ceramic surface is a function of the mode of application. The lowest film thickness of silane was found for treatment E, which more closely matches that of a monolayer.

Influence of finite size and wetting on nematic and smectic phase behavior of liquid crystal confined to controlled-pore matrices

The high-resolution calorimetric study was carried out on octylcyanobiphenyl liquid crystal (LC) confined to various controlled-pore glass (CPG) matrices with silane-treated surface. The diameter of the voids cross section ranged between 23.7 and 395 nm. The results are compared to those obtained previously on CPG voids nontreated with silane. We found a striking similarity between the shifts in the isotropic to nematic and nematic to smectic-A phase transition temperatures as a function of the void radius in which order parameter variations at the LC-void interface play the dominant role. Weaker temperature shifts are observed in silane-treated samples, where surface ordering tendency is larger. In nontreated samples, a finite-size scaling law in the maximum value of the heat capacity at the nematic to smectic-A transition was observed for void diameters larger than 20 nm. In silane-treated samples, this behavior is considerably changed by surface wetting interactions.

Characterization and adhesion testing of mixed silane-treated surfaces

Single silanes have been well studied as adhesion promoters, but there are areas of improvement that could use the properties of an additional silane. This research examines the combination of an adhesion promoter with a second silane of different chemical functionality in order, to increase the number of potential applications. Several techniques are investigated for producing mixed silane layers, including solution deposition, microcontact printing and vapor deposition. The second goal of this research is to determine the adhesion between polymers and heterogeneous micropatterned silanes. The two silanes used are n-octadecyltrichlorosilane (ODTS) and 3-aminopropyltriethoxysilane (APS). APS is an adhesion promoter between most polymers and oxide surfaces, while ODTS is very hydrophobic and has insignificant adhesion to polymers. Surfaces are characterized with an Atomic Force Microscope (AFM) with Pulsed Force Mode (PFM), allowing simultaneous topography, adhesion and stiffness measurements of the surface to be generated. In a 180°-peel test between poly(vinyl butyral) (PVB) and glass, the addition of ODTS results in the decrease of the surface energy and a dramatic decrease in adhesion. In a wedge test, the adhesion of APS is found to be proportional to the percent coverage.

Surface modification of an experimental silicone rubber aimed at reducing initial candidal adhesion.

Silicone rubber, which is a widely used biomaterial, is often used to make soft liners for permanent denture. Colonization of denture soft lining materials by Candida albicans can result in clinical problems. The aim of this study was to chemically modify the surface of an experimental silicone rubber in order to produce a silicone that was less susceptible to candidal colonization. Surface modification was carried out with the use of argon-plasma bombardment followed by silane treatment, which caused the incorporation of either hydrophilic or hydrophobic functional groups onto the surface. Changes in water contact angles and chemical analysis of the materials with scanning ion mass spectroscopy confirmed surface changes. In vitro assays were carried out using C. albicans to measure levels of adherence to the surface-modified silicone after 1 h. C. albicans exhibited very low adherence to all silane-treated surfaces, whether hydrophobic or hydrophilic. This led to the conclusion that incorporated long-chain functional groups were inhibiting the adherence of the yeast, possibly by the formation of a barrier between the surface of the material and the yeast. In conclusion, silane surface treatment of an experimental silicone rubber has been successful in reducing candidal adherence.

Surface modification of an experimental silicone rubber aimed at reducing initial candidal adhesion

Silicone rubber, which is a widely used biomaterial, is often used to make soft liners for permanent denture. Colonization of denture soft lining materials by Candida albicans can result in clinical problems. The aim of this study was to chemically modify the surface of an experimental silicone rubber in order to produce a silicone that was less susceptible to candidal colonization. Surface modification was carried out with the use of argon-plasma bombardment followed by silane treatment, which caused the incorporation of either hydrophilic or hydrophobic functional groups onto the surface. Changes in water contact angles and chemical analysis of the materials with scanning ion mass spectroscopy confirmed surface changes. In vitro assays were carried out using C. albicans to measure levels of adherence to the surface-modified silicone after 1 h. C. albicans exhibited very low adherence to all silane-treated surfaces, whether hydrophobic or hydrophilic. This led to the conclusion that incorporated long-chain functional groups were inhibiting the adherence of the yeast, possibly by the formation of a barrier between the surface of the material and the yeast. In conclusion, silane surface treatment of an experimental silicone rubber has been successful in reducing candidal adherence. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 122–128, 2002; DOI 10.1002/jbm.10094

Characterization of hot-dip galvanized (HDG) steel treated with bis-1,2-(triethoxysilyl)ethane and γ-aminopropyltriethoxysilane

The aim of this work was to study the suitability of silane treatments for hot-dip galvanized (HDG) steel. Silane coupling agents were used as adhesion promoters between paint and galvanized steel. The focus was on characterization of the silane-treated surfaces. The adhesion and corrosion performance of the selected silanes in painted galvanized steel systems will be reported separately. In this work, HDG steel was treated with bis-1,2-(triethoxysilyl) ethane (BTSE, Y-11710) and γ-aminopropyltriethoxysilane (γ-APS, A-1100), and the samples were characterized by using various surface analytical methods. The results indicate that if BTSE is deposited onto HDG steel from an ethanol-water solution, hydrolytically stable bonds can be formed between BTSE and HDG steel. Thermodynamically, the film is stable but it has a low total surface energy. FTIR analysis showed that the film contained unhydrolyzed ethoxy groups and unreacted silanol groups, but the surface energy results indicate that the outermost film has hardly any acid or base functionality. ESCA results of the γ-APS treatments indicate that the initial bonds between the deposited γ-APS silanols, and between the silanols and the HDG steel, are not very strong, but upon drying and curing the films the stability of the bonds increases. The FTIR results also show that the γ-APS film deposited at pH 8.5 has a higher degree of amine functionality than the film deposited at pH 10.5. It was also observed that the surface energy of the γ-APS films decreased due to a decrease in surface polarity. The results of a two-step treatment consisting of BTSE and γ-APS on HDG steel showed that the BTSE film affected the orientation of the γ-APS silanols deposited onto it.

Characterization of hot-dip galvanized (HDG) steel treated with γ-UPS, VS, and tetrasulfide

The aim of this work was to study the suitability of silane treatments for hot-dip galvanized (HDG) steel. Silane coupling agents are used as adhesion promoters between paint and galvanized steel. The focus in this paper is on the characterization of the silane-treated surfaces. The adhesion and corrosion performance of the selected silanes in painted galvanized steel systems are reported separately. In this work, HDG steel was treated with γ-ureidopropyltrimethoxysilane (γ-UPS), vinyltrimethoxysilane (VS), and bis-(3-[triethoxysilyl]-propyl)-tetrasulfide (A-1289), and the samples were characterized by surface analytical methods. The treatment technique and the deposition pH affected the amount of silane that could be adsorbed onto HDG steel from the solutions of γ-UPS and VS. The results show that more ureido groups are present on the surface side of the γ-UPS film than near the silane-zinc interface. Better coverage of the treated surface was obtained at the higher pH studied, i.e. pH 8. According to the surface energy results, the γ-UPS films are stable in air. The VS films consisted mainly of low-molecular-weight siloxanes. The rinsed VS films were shown to be stable, whereas a sudden change in the surface basicity was detected in the unrinsed films within 24 h from treatment. The results of A-1289 differed from those obtained with the water-soluble silanes. The chemical and structural compositions of the unrinsed and rinsed films of A-1289 were similar. The films could not be rinsed off by water and were thermodynamically stable.

Conformational transition in DNA on a cold surface.

The contour length of DNA fragments, deposited and imaged on mica under buffer, was measured as a function of deposition temperature. Extended DNA molecules (on Ni- and silane-treated surfaces) contract rapidly with falling temperature, approaching the contour length of A-DNA at 2 degrees C. The contraction is not unique to a specific sequence and does not occur in solution at 2 degrees C or on a surface at 25 degrees C, indicating that it arises from a combination of low temperature and surface contact. It is probably a consequence of reduced water activity at a cold surface.

The Role of Adhesion Promoters on the Molecular and Mesoscopic Structure of the Interphase

Abstract New experimental results are described from Near Edge X-Ray Absorption Fine Structure (NEXAFS) spectroscopy, X-ray photoelectron spectroscopy (XPS) and Atomic Force Microscopy (AFM) on the molecular orientation, chemical composition, and topography of PMDA/ODA Polyimide (PI) deposited by the Langmuir-Blodgett (LB) technique onto Si (100) surfaces covered with a native oxide (SiO x ) and onto SiO x substrates pre-treated with a variety of alkylsilanes. The alkylsilane monolayers used as adhesion promoters were found to be chemically and structurally stable during temperature treatments used to imidize the polymer precursor films. On both the oxidized silicon surface and on the silane-treated surfaces, we find a thickness-dependent, preferential orientation of the pyromellitimide unit in PI, but randomly-oriented oxydianiline fragments. We can not identify any specific chemical bonds between the polymer and the aminosilane film or, in the case of the untreated surface, the SiO x substrate. However,...

Silanization of oxidized silicon and aluminum surfaces with functionalized silanes with characterization by wettability, ellipsometry, XPS and quartz crystal microbalance studies

The synthesis of N-octadecanoyl, N-(12-acetoxydodecanoyl), N-(8-carbomethoxyoctanoyl) and N-(12-nitrododecanoyl) derivatives of 3-triethoxysilylpropanamine ( N-acyl APTES derivatives) along with that of 11-triethoxysilylundecanoic acid t-butyldimethylsilyl ester has been carried out. The covalent binding of all these silanes to oxidized silicon and aluminum surfaces has been effected by both adsorption and Langmuir—Blodgett monolayer transfer techniques. Contact angle and ellipsometric measurements indicate a polarity gradient for the functionalized silane-treated surfaces and variations in orientation with respect to the surface normal compared to similar surfaces treated with octadecyltrichlorosilane and functionalized thiols. Surface coverages of 80–90% are estimated from the Si(2p) silane: Si(2p) substrate binding energy peak ratios determined by XPS. Using the bulk acoustic wave propagation measurements, the reactivity of the silanized surfaces towards 2-propanol and octadecanoic acid is followed. The observed differences in frequency shifts correlate well with the polarities and proposed orientation of the terminal functionalities.