Additional Silane Research Articles

Effect of silane pretreatment on the immediate bonding of universal adhesives to computer-aided design/computer-aided manufacturing lithium disilicate glass ceramics.

The aim of this study was to investigate the effect of silane pretreatment on the universal adhesive bonding between lithium disilicate glass ceramic and composite resin. IPS e.max ceramic blocks etched with hydrofluoric acid were randomly assigned to one of eight groups treated with one of four universal adhesives (two silane-free adhesives and two silane-containing adhesives), each with or without silane pretreatment. Bonded specimens were stored in water for 24 h. The shear bond strength (SBS) of the ceramic-resin interface was measured to evaluate bond strength, and the debonded interface after the SBS test was analysed using field-emission scanning electron microscopy to determine failure mode. Light microscopy was performed to analyse microleakage and marginal sealing ability. Silane pretreatment significantly and positively influenced SBS and marginal sealing ability. For all the universal adhesive groups, SBS increased and the percentage of microleakage decreased after the pretreatment. Without the pretreatment, SBS and the percentage of microleakage were not significantly different between the silane-containing universal adhesive groups and the silane-free groups. Cohesive failure was the main fracture pattern. The results suggest that additional silane pretreatment can effectively improve the bonding strength and marginal sealing of adhesives to lithium disilicate glass ceramics. The bonding performance of silane-containing universal adhesives without pretreatment is similar to that of silane-free adhesives.

A Convenient Palladium‐Catalyzed Reductive Carbonylation of Aryl Iodides with Dual Role of Formic Acid

Palladium-catalyzed reductive carbonylation of aryl halides represents a straightforward pathway for the synthesis of aromatic aldehydes. The known reductive carbonylation procedures either require CO gas or complexed compounds as CO sources. In this communication, we developed a palladium-catalyzed reductive carbonylation of aryl iodides with formic acid as the formyl source. As a convenient, practical, and environmental friendly methodology, no additional silane or H2 was required. A variety of aromatic aldehydes were isolated in moderate to excellent yields under mild reaction conditions. Notably, this is the first procedure on using formic acid as the formyl source.

Resin bond to indirect composite and new ceramic/polymer materials: a review of the literature.

Resin bonding is essential for clinical longevity of indirect restorations. Especially in light of the increasing popularity of computer-aided design/computer-aided manufacturing-fabricated indirect restorations, there is a need to assess optimal bonding protocols for new ceramic/polymer materials and indirect composites. The aim of this article was to review and assess the current scientific evidence on the resin bond to indirect composite and new ceramic/polymer materials. An electronic PubMed database search was conducted from 1966 to September 2013 for in vitro studies pertaining the resin bond to indirect composite and new ceramic/polymer materials. The search revealed 198 titles. Full-text screening was carried out for 43 studies, yielding 18 relevant articles that complied with inclusion criteria. No relevant studies could be identified regarding new ceramic/polymer materials. Most common surface treatments are aluminum-oxide air-abrasion, silane treatment, and hydrofluoric acid-etching for indirect composite restoration. Self-adhesive cements achieve lower bond strengths in comparison with etch-and-rinse systems. Thermocycling has a greater impact on bonding behavior than water storage. Air-particle abrasion and additional silane treatment should be applied to enhance the resin bond to laboratory-processed composites. However, there is an urgent need for in vitro studies that evaluate the bond strength to new ceramic/polymer materials. This article reviews the available dental literature on resin bond of laboratory composites and gives scientifically based guidance for their successful placement. Furthermore, this review demonstrated that future research for new ceramic/polymer materials is required.

Effect of incorporation of silane in the bonding agent on the repair potential of machinable esthetic blocks.

Objective:To investigate the repair potential of CAD/CAM (computer-aided design/computer-aided manufacturing) ceramic and composite blocks using a silane-containing bonding agent with different repair protocols.Materials and Methods:Twenty-four discs were constructed from CAD/CAM ceramic and composite blocks. The discs were divided into six groups according to surface pre-treatment employed; GI: Diamond stone roughening (SR), GII: SR+ silanization (SR+S), GIII: Hydrofluoric acid etching (HF), GIV: HF+ silanization (HF+S), GV: Silica coating (SC), GVI: SC+ silanization (SC+S). Silane-containing bonding agent (Single Bond Universal adhesive, 3M ESPE) was applied to the pre-treated discs. Prior to light curing, irises were cut from tygon tubes (internal diameter = 0.8 mm and height = 0.5 mm) and mounted on each treated surface. Nanofilled resin composite (Filtek Z350XT, 3M ESPE) was packed into the cylinder lumen and light-cured (n = 10). The specimens were subjected to microshear bond strength testing (μ-SBS) using universal testing machine. Failure modes of the fractured specimens were analyzed using field emission scanning electron microscope (FESEM). Eight representative discs were prepared to analyze the effect of surface treatments on surface topography using FESEM. μ-SBS results were analyzed using ANOVA and Tukeys post-hoc test.Results:Three-way ANOVA results showed that the materials, surface pre-treatment protocols, and silanization step had a statistically significant effect on the mean μ-SBS values at P ≤ 0.001. For ceramic discs, the groups were ranked; GIV (24.45 ± 7.35)> GVI ((20.18 ± 2.84)> GV (7.14 ± 14)= GII (6.72 ± 1.91)=GI (6.34 ± 2.21)=GIII (5.72 ± 2.18). For composite discs, groups were ranked; GI (24.98 ± 7.69)=GVI (24.84 ± 7.00) >GII (15.85 ± 5.29) =GV (14.65 ± 4.5)= GIV (14.24 ± 2.95)≥ GIII ((9.37 ± 2.78).Conclusion:The additional silanization step cannot be omitted if the repair protocol comprises of either hydrofluoric acid etching or silica coating for both CAD/CAM esthetic restorative materials. However, this step can be suppressed by using silane-containing adhesive with diamond stone roughened repair protocol.

Adhesion of veneering resins to polymethylmethacrylate-based CAD/CAM polymers after various surface conditioning methods

Objectives. The aims of this study were to test whether the bond strength of a hybrid composite and a PMMA-based veneer to CAD/CAM polymers would improve after pre-treatment and to evaluate the failure types after debonding. Materials and methods. Three types of PMMA-based (CAD-Temp, artBloc Temp and TelioCAD) CAD/CAM blocks were obtained (N = 360, n = 15 per test group). They were divided into four groups to be conditioned with the following methods: (a) no-treatment, (b) air-abrasion (50 μm Al2O3), (c) air-abrasion (50 μm Al2O3) + MPS-Silane (Monobond S) + Adhesive resin (StickResin) (for Gradia)/MMA (for Integral Esthetic Press) application, (d) Silica coating and silanization (CoJet-System). The conditioned surfaces were veneered with a hybrid composite (Gradia) or a PMMA-based resin (Integral esthetic press). After water storage (1 week, 37°C), the bond strength was measured. Data were analyzed using 3-way ANOVA and post-hoc Scheffé test (α = 0.05). Results. Surface-conditioning method, veneer type and CAD/CAM polymers significantly affected the results. Hybrid composite did not bond to non-conditioned CAD/CAM polymers. Regardless of the conditioning method, PMMA-based resin showed significantly higher bond strength to all CAD/CAM polymers compared to hybrid composite. Air-abrasion increased the bond strength in all tested groups. Additional silane application after air-abrasion did not significantly increase the bond strength of hybrid composite. While exclusively adhesive failures were observed between the hybrid composite and the CAD/CAM polymers, PMMA veneer demonstrated cohesive failures in the CAD/CAM polymers. Conclusion. CAD/CAM polymers could be veneered with only a PMMA-based veneer with and without air-abrasion.

Efficacy of air-abrasion technique and additional surface treatment at titanium/resin cement interface.

To evaluate the effect of surface treatments on the shear bond strength (SBS) of a resin cement to commercially pure titanium (CP Ti). Two hundred cast CP Ti disks were divided into 5 groups (n = 40), which were treated with one of the following air-abrasion techniques: (1) 50-µm Al2O3 particles; (2) 120-µm Al2O3 particles; (3) 250-µm Al2O3 particles; (4) 30-µm silica-modified Al2O3 particles (Cojet Sand); (5) 50-µm Al2O3 particles followed by 110-µm silica-modified Al2O3 particles (Rocatec Plus). For each air-abrasion technique, the following additional surface treatments were used (n = 10): (1) none; (2) adhesive Adper Single Bond 2; (3) silane RelyX Ceramic Primer; (4) silane plus adhesive. RelyX ARC resin cement was bonded to CP Ti surfaces. All specimens were thermocycled (5,000 cycles) before being tested in shear mode. Data (MPa) were analyzed using two-way ANOVA and Tukey's test (α = 0.05). Failure mode was determined with a stereomicroscope (20X). The results revealed that the air-abrasion technique (p < 0.001), additional surface treatment (p < 0.001) and their interaction were significant (p < 0.001). Except for the 50-µm Al2O3 + adhesive group, 250-µm Al2O3 particles promoted significantly higher SBS than 50-µm Al2O3 particles (p < 0.001), while Rocatec Plus provided bond strengths that were similar to or higher than those of Cojet Sand. Of the additional surface treatments, the adhesive provided the best results in combination with the 3 air-abrasion techniques (50-µm, 120-µm, and 250-µm Al2O3), whereas in the groups abraded with silica-modified Al2O3 particles (Cojet Sand and Rocatec Plus), the best results were obtained with additional silane. The two combinations that promoted the highest SBS were 250-µm Al2O3 + adhesive and Rocatec Plus + silane. All groups showed 100% adhesive failure. The selection of the best additional surface treatment varied according to the air-abrasion technique. Particle size was the decisive factor in determining the bond strength when micromechanical retention was the only bonding mechanism. When both mechanisms were present, in addition to particle size, the material applied as the additional surface treatment also contributed to determining the bond strength.

Bond strength of composite resin to glass ceramic after saliva contamination

Purpose of this study was to investigate the effect of cleaning methods of glass ceramic specimens contaminated with saliva on tensile bond strength (TBS) to composite resin. Additionally, effect of water storage on bond strength was evaluated. Glass ceramic discs (IPS Empress, Ivoclar-Vivadent, FL) distributed among five groups (n = 28) were etched with hydrofluoric acid, silanized, contaminated with human saliva, and in group W rinsed with water, group WS additionally silanized, group E rinsed with water and cleaned with ethanol, and group ES additionally silanized. Group C served as a control without contamination. Plastic screws were bonded to the glass ceramic discs using Variolink II (Ivoclar-Vivadent). TBS was measured after 24h and after 150days of storage. Failure modes were examined. ANOVA was applied to explore group effect on TBS. Pair-wise comparisons were calculated. The mean TBS [in megapascals] were for W 46 ± 14, WS 55 ± 8, E 48 ± 11, ES 52 ± 10, and C 50 ± 8 after 24h, and W 39 ± 11, WS 53 ± 9, E 48 ± 8, ES 48 ± 11, and C 50 ± 8 after 150days. After 150days specimens of group W showed significantly lower TBS compared to group C (p = 0.05). Additional silanization in group WS led to a significant increase of TBS compared to specimens of group W (p = 0.003). Adhesive fractures were observed only in specimens without second application of silane. The cleaning of the contaminated glass ceramic surface by rinsing only did not result in a durable bond. Pre-silanized glass ceramic restorations need to be rinsed and treated with a fresh layer of silane after saliva contamination.

The influences of the transfer method and particle surface chemistry on the dispersion of nanoparticles in nanocomposites

The synthesis via in situ polymerization and characterization of nanocomposites (NCs) made from silica (SiO(2)) nanoparticles in a methyl methacrylate (MMA) monomer matrix is reported. We first investigate the transfer of well-defined spherical silica nanoparticles (NPs) (average radius R = 24.2 ± 3.2 nm) into the monomer solvent. We study the influence of two transfer methods and different surface chemistries on the resulting colloidal stability. The first transfer method consists of drying the silica particles into powder before dispersing them via ultrasonication in the MMA matrix. The second is based on repetitive centrifugations to exchange NPs from their synthetic milieu to pure MMA, avoiding the dried powder state. These transfer methods are compared for two kinds of NP surface chemistry, natural silanol (Si-OH) groups of the silica NPs and an additional silane coupling agent, namely 3-(trimethoxysilyl)propyl methacrylate (TPM), which mimics the monomeric group of the MMA dispersing milieu. We then characterize the morphology of the resulting nanocomposites prepared via in situ polymerization at a fixed amount of dispersed NPs (2.2 wt%; 1 vol%) using a combination of transmission electron microscopy (TEM) from ultramicrotomed nanocomposite films, thermogravimetry (TGA) and small angle X-ray scattering (SAXS).

Effects of organoclay modifiers on the flammability, thermal and mechanical properties of polycarbonate nanocomposites filled with a phosphate and organoclays

Polycarbonate was melt blended with solid bisphenol A bis(diphenyl phosphate), and a series of organoclays. Effects of the organoclay modifiers on the flammability, thermal and mechanical properties of the nanocomposites were studied by limiting oxygen index, UL-94 burning test, thermogravimetric analysis, differential scanning calorimetry, tensile test and dynamic mechanical analysis. Although all the nanocomposites exhibit an intercalated-exfoliated morphology, they vary in the magnitude of intercalation revealed by X-ray diffraction and transmission electron microscopy. Flammability of the nanocomposites is strongly related to the thermal stability rather than the morphology. Glass transition temperature ( T g) and mechanical properties are controlled by both the morphology and the affinity of the organoclays with the matrix. The modifier containing hydroxyl moiety has stronger interactions with the matrix but it can promote its degradation, thus the corresponding nanocomposite exhibits a better intercalated morphology, higher T g, superior strength and modulus however a worse thermal stability and flame retardancy. An additional silane within the organoclays would make the organoclays more compatible with the matrix but be a steric obstacle to the intercalation of the matrix chains; however, flame retardancy of the corresponding nanocomposite is enhanced due to the flame retardant nature of the silane. Similarly, the modifier bearing two long alkyl tails shows stronger affinity with the matrix than the one bearing a single tail, but it would hinder the intercalation due to the steric effect. These establishments between organoclay modifiers and the properties of nanocomposites might be guidance for developing materials with practical applications.

Vapor phase adsorption of organic compounds on octyl silicas

The influence of the modification of silica by octyltrichlorosilane with the formation of an oligomeric grafted layer (sample C8(II)) and additional silanization (sample C8(III)) on the thermodynamic adsorption characteristics (TACs) of different classes of organic compounds was investigated by gas chromatography. It was shown that the modification leads to decreased adsorption values for most of the investigated compounds (with the exception of alkanes, for which TACs on sample C8(II) approach the values observed on the initial support, due probably to additional interactions with silanol groups formed in modifying the surface with octyltrichlorosilane). It was established that blocking these silanol groups during additional silanization with trimethylsilane resulted in inert surfaces whose adsorption properties with respect to many compounds (including some capable of participating in strong specific interactions) approaches to the properties of octyl-silica with a close-packed grafted monolayer.

Development of stable DNA microarray platforms suitable for quantitative analysis

DNA microarray has become one of the most indispensable tools for genome analysis, medical diagnosis and molecular biological studies. In this study, to make DNA microarray more reliable and efficient, we employed additional silanization modification on aminoalkoxysilane-treated surface. In addition, oxanine was used as a linker of DNA probe, which does not require any chemical activation step in probe immobilization. These strategies were practically convenient in DNA microarray fabrication, and the newly developed system showed enhanced stability for the immobilized DNA probes that could be useful for quantitative analysis.

Development of an efficient amine-functionalized glass platform by additional silanization treatment with alkylsilane

Aminosilane-treated molecular layers on glass surfaces are frequently used as functional platforms for biosensor preparation. All the amino groups present on the surface are not available in reactive forms, because surface amino groups interact with remaining unreacted surface silanol groups. Such nonspecific interactions might reduce the efficiency of chemical immobilization of biomolecules such as DNA, enzymes, antibodies, etc., in biosensor fabrication. To improve immobilization efficiency we have used additional surface silanization with alkylsilane (capping) to convert the remaining silanol groups into Si-O-Si linkages, thereby liberating the amino groups from nonspecific interaction with the silanol groups. We prepared different types of capped amine surface and evaluated the effect of capping on immobilization efficiency by investigating the fluorescence intensity of Cy3-NHS (N-hydroxysuccinimide) dye that reacted with amino groups. The results indicate that most of the capped amine surfaces resulted in enhanced efficiency of immobilization of Cy3-NHS compared with the untreated control amine surface. We found a trend that trialkoxysilanes had greater capping effects on immobilization efficiency than monoalkoxysilanes. It was also found that the aliphatic chain of alkylsilane, which does not participate in the capping of the silanol, had an important function in enhancing immobilization efficiency. These results would be useful for preparation of an amine-modified surface platform, with enhanced immobilization efficiency, which is essential for developing many kinds of biosensors on a silica matrix.

Microcalorimetric Study of Methanol Adsorption on Initial Silica and Silica Modified with Polyfluoroalkyl Groups

The adsorption of methanol on initial silica and modified silica samples containing large mesopores is studied by the adsorption–calorimetric method. The grafted tridecylfluoroalkyl groups have a tilted orientation on the silica and physically screen the part of the surface OH groups that have not been involved in the reaction with a modifier. Adsorbed methanol makes the modifying layer looser, thus facilitating the accessibility of methanol molecules to these hydrophilic adsorption sites. Concentrations of OH groups involved in the chemical interaction with molecules of the modifier, OH groups physically screened by its organofluoric radicals, and OH groups located on the surface areas free of the modifier are quantitatively estimated. An additional silanization of the modified silica leads to coverage of silica surface areas that are free of organofluoric modifier with trimethylsilyl radicals. The heat of interaction between the methanol molecules and silica surface hydroxyl groups is determined; it is equal to 60 kJ/mol. The structure of the modifying organofluoric layer and changes in this structure that resulted from additional silanization of the surface and from the methanol adsorption are discussed.

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.

Characteristics of nitrile–butadiene rubber layered silicate nanocomposites with silane coupling agent

AbstractNanocomposites of organophilic montmorillonite (C18‐MMT), nitrile–butadiene rubber (NBR), and a coupling agent were produced during a melt compounding process at room temperature. During the process, it was clearly observed that organo‐MMT particles were exfoliated into nanoscale layers of approximately 1–30 nm thickness, in addition to their original 40 μm thickness. These MMT layers were uniformly dispersed in the NBR matrix. The effects of a coupling agent such as 3‐(mercaptopropyl)trimethoxy silane in C18‐MMT/NBR nanocomposites were studied. The C18‐MMT/NBR nanocomposites in the presence of the coupling agent were identified and characterized by X‐ray diffraction, transmission electron microscopy, a universal testing machine, thermogravimetric analysis, and IR spectroscopy. It was observed that an additional silane coupling agent, 3‐(mercaptopropyl)trimethoxy silane, enhanced the chemical interaction and was accompanied by the formation of SiOSi coupling bonds between C18‐MMT and the coupling agent and SiC coupling bonds between NBR and the coupling agent. This work resulted in improved properties of organo‐MMT/NBR nanocomposites because of the nanoscale effects and strong interaction of the coupling bonds between NBR and organo‐MMT. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2633–2640, 2003

Hydrosilylation of a Dinuclear Tantalum Dinitrogen Complex: Cleavage of N2 and Functionalization of Both Nitrogen Atoms

Hydrosilylation of the ditantalum dinitrogen complex ([NPN]Ta)2(mu-H)2(mu-eta1:eta2-N2) proceeds via an addition reaction to produce ([NPN]TaH)(mu-H)2(mu-eta1:eta2-N-NSiH2Bu)(Ta[NPN]), which contains a new N-Si bond and a terminal tantalum hydride; this species has been characterized by NMR spectroscopy and X-ray diffraction. This complex undergoes reductive elimination of H2 followed by N-N bond cleavage to generate a new intermediate with the formula ([NPN]TaH)(mu-N)(mu-NSiH2Bu)(Ta[NPN]); confirmation of N-N bond cleavage is evident from the 15N-labeled isotopomer that displays an absence of 15N-15N scalar coupling in the 15N NMR spectrum. In the presence of additional silane, a second hydrosilylation and reductive elimination results to give ([NPN]Ta)2(mu-NSiH2Bu)2, a species in which each dinitrogen-derived N atom has been converted to a bridging silylimide ligand. This latter complex displays C2h symmetry both in solution and in the solid state.

The role of additional silane coupling agent treatment in oxygen plasma-treated UHMPE fiber/vinylester composites

Ultra-high modulus polyethylene (UHMPE) fiber was treated with oxygen plasma and a silane coupling agent in order to improve the interfacial adhesion between the UHMPE fiber and vinylester resin. The oxygen plasma and γ-methylmethacryloxypropyltrimethoxysilane (γ-MPS)-treated UHMPE fiber/vinylester composites showed a slightly higher interlaminar shear strength than the oxygen plasma-treated UHMPE fiber/vinylester composites. The interfacial adhesion of the oxygen plasma-treated UHMPE fiber/vinylester composites in this study is mainly due to mechanical interlocking between the micropits formed by the oxygen plasma treatment and the vinylester resin. The γ-MPS molecules adsorbed onto the UHMPE fiber surface neither affected the morphology of the UHMPE fiber surface, nor reduced the extent of mechanical interlocking. The improved interfacial adhesion by the γ-MPS treatment is due to enhanced wettability and chemical interaction through the chemically adsorbed γ-MPS molecules, as detected by Fourier-transform infrared (FT-IR) spectroscopy. The γ-MPS molecules adsorbed onto the ultra-high molecular weight polyethylene (UHMWPE) plate surface also reduced the aging effect of the oxygen plasma-treated UHMWPE surface.

The adsorption and decomposition of silane on Cu(111)

The adsorption and decomposition of silane, SiH 4, on Cu(111) was studied by low energy electron diffraction, Auger electron spectroscopy, electron energy loss spectroscopy and reflection-absorption infrared spectroscopy. Silane adsorbs as SiH 3fragments below 150 K. These decompose at 150 K to give elemental silicon and μ 2-bridging hydrogen on the copper surface. The hydrogen is completely desorbed at 273 K, to leave a (√3 × √3)R30° LEED pattern for silicon on copper. This surface structure was also observed when silane was adsorbed on the surface at temperatures in excess of 273 K, as elemental silicon. The resulting surface was almost completely passive and would not adsorb additional silane, CO or atomic hydrogen.