Agent 3-aminopropyltriethoxysilane Research Articles

Fluorinated Nanodiamond as a Wet Chemistry Precursor for Diamond Coatings Covalently Bonded to Glass Surface

The chemical reaction between fluoro-nanodiamond (F-ND) powder, solubilized in o-dichlorobenzene, and a glass surface, functionalized with the silane coupling agent, 3-aminopropyltriethoxysilane (APTES), was found to proceed under heating at 130 degrees C for 24-40 h and to result in covalent bonding of F-ND particles to a glass substrate, forming a 10-40 nm thick nanocrystalline film. The observed process presents a novel and cost-effective approach to fabrication of diamond coatings on glass by using wet chemistry instead of CVD and can be extended to other materials.

Complementary characterization by fluorescence and AFM of polyaminosiloxane glass fibers coatings

AR-Glass fibers were coated with the coupling agent 3-aminopropyltriethoxysilane. The polyaminosiloxane coating obtained was characterized: (i) at a molecular scale by using the fluorescence response of pyrene moiety chemically attached (PSA) to the polymer coating and (ii) at a nanoscopic scale by using Atomic Force Microscopy (AFM). After modifying the polymer structure of the coating by the action of different solvents, the data obtained from both techniques were jointly discussed. It was confirmed by AFM that the deposition of the coupling agent on the fibers is in the form of homogeneously distributed ‘islands’. Furthermore, differences in the size of the silane islands were observed when the silanized fibers are subjected to the effect of different solvents. The fluorescence emission from PSA showed that the solvents exert an important structural change in the polyaminosiloxane coating. The correlation between information at a nanoscopic scale (morphology) and at molecular scale (structure) suggested that certain solvents under a subsequent specific evaporation rate rearrange the polymer chains of the glass fibers coating. This rearrangement seems to be a kind of solvophobic effect whose degree depends on the quality of the solvent and the evaporation rate.

The effect of interfacial interactions on the mechanical properties of polypropylene/natural zeolite composites

Abstract The effect of interfacial interactions on the mechanical properties of polypropylene (PP)/natural zeolite composites was investigated under dry and wet conditions. Interfacial interactions were modified to improve filler compatibility and mechanical properties of the composites by surface treatment of natural zeolite with a non-ionic surface modifier; 3 wt% polyethylene glycol (PEG) and three different types of silane coupling agents; 3-aminopropyltriethoxysilane (AMPTES), methyltriethoxysilane (MTES) and 3-mercaptopropyltrimethoxysilane (MPTMS), at four different concentrations (0.5–2 wt%). PP composites containing (2–6 wt%) zeolite were prepared by an extrusion technique. The tensile properties of the composites determined as a function of the filler loading and the concentration of the coupling agents were found to vary with surface treatment of zeolite. Silane treatment indicated significant improvements in the mechanical properties of the composites. According to the dry and wet tensile test results, the maximum improvement in the mechanical properties was obtained for the PP composites containing 1 wt% AMPTES treated zeolite. The improvement in the interfacial interaction was confirmed using a semi-empirical equation developed by Pukanszky. Good agreement was obtained between experimental data and the Pukanszky model prediction. Scanning electron microscopy studies also revealed better dispersion of silane treated filler particles in the PP matrix.

Epoxy-silica polymers as restoration materials. Part II

Room temperature reaction of the epoxy resin poly(bisphenolA-co-epichlorohydrin), glycidyl end-capped with the coupling agent (3-aminopropyl)triethoxysilane, in 1:2 (1), 1:1 (2) and 2:1 (3) molar ratios, leads, after curing for three months at room temperature, to glassy, transparent, crack-free solids which were investigated by SEM, TGA, DSC, NIR and Raman spectroscopy. SEM investigations show substantially a great homogeneity over the entire area with absence of cracks, veins and/or fissures and without formations of clusters and/or aggregates. The conversion of oxirane rings, as found by Raman spectroscopy, decreases by increasing the epoxy/amine ratio, with conversion percentages ranging from 95.3 to 81.3%. As a common feature, the presence in 1, 2 and 3 of Si–O–Si linkages increases the polymer degradation temperature and thermal oxidative stability relative to the parent epoxy resin by shifting the weight loss to higher temperatures. Differently from mixtures 2 and 3, which show the Tg at 90 °C, the mixture 1 does not exhibit any detectable glass transition.

Controlling Subcritical Crack Growth at Epoxy/Glass Interfaces

The resistance of silane bonded epoxy/glass interfaces to subcritical crack growth was studied as a function of the density of primary bonds between the silane and epoxy using the double-cleavage drilled compression test (DCDC). The silane coupling agents propyltriethoxysilane (PES), 3-aminopropyltriethoxysilane (3-APES) and various mixtures of 3-APES and PES were used to systematically control the bonding density since 3-APES can form primary bonds with both the glass and the epoxy, while PES forms primary bonds only with the glass. The resistance of these interfaces to crack growth was tested under both static and cyclic loading in high and low humidity test environments. These tests allowed the separation of the effects on crack growth due to stress corrosion and cyclic fatigue. Experimental results showed that the density of primary bonding between the silane layer and the epoxy controls the cyclic fatigue resistance of the silanized interfaces. Additionally, for 3-APES bonded epoxy/glass interfaces cyclic fatigue crack growth predominates at both high and low humidities but for PES bonded interfaces, crack growth by stress corrosion dominates at high humidity and by cyclic fatigue at low humidities. For a 50% 3-APES/50% PES bonded interface, stress corrosion effects are somewhat greater than cyclic fatigue effects at high humidities but at low humidities the two effects are comparable. When testing the interfaces for durability, PES bonded interfaces showed spontaneous delamination when aged in distilled water for 36h at 94°C. On the other hand, 3-APES and mixtures of 3-APES bonded interfaces did not show any detrimental effect of the cyclic fatigue resistance when aged in distilled water at temperatures up to 98°C.

Fatigue resistance of silane-bonded epoxy/glass interfaces using neat and rubber-toughened epoxies

The influence that the energy absorbing ability of an epoxy has on the cyclic fatigue resistance of a silane-bonded epoxy/glass interface in moist air was studied using the double cleavage drilled compression (DCDC) test. The material properties of two epoxies with similar chemical structures were controlled through the manipulation of the molecular weight between cross-links, Mc, of the epoxy network. Two rubber-toughened epoxies with different nominal particle sizes (10–40 μm and 1–2 μm) were fabricated by adding a liquid butadiene/acrylonitrile copolymer to the epoxy resins. Mixtures of the silane-coupling agents 3-aminopropyltriethoxysilane (3-APES) and propyltriethoxysilane (PES) were used to treat the glass substrate in order to control the number of covalent bonds between epoxy and the glass. 3-APES has the ability to form primary bonds with both the epoxy and the glass, while PES forms primary bonds with only the glass. Experimental results showed that the manipulation of Mc had little effect on the cyclic fatigue resistance of the epoxy/glass interface. However, incorporation of rubber particles gave a significant improvement in the fatigue resistance. The rubber particles allowed the microscopic, non-linear deformation mechanisms of cavitation and shear yielding to dissipate energy during fatigue crack growth. Smaller particles gave the greatest improvement to fatigue resistance; about a 75% improvement compared to the neat (non-modified) epoxy. Adjustment of the number of silane bonds between the neat epoxies and the glass had little effect within experimental scatter on the fatigue resistance of the interfaces, suggesting that the energy dissipated through the breaking of bonds at the interface was insignificant compared to the energy dissipated through plastic and other inelastic deformation mechanisms in the epoxy.

Fatigue and Durability of Silane-Bonded Epoxy/Glass Interfaces

Fatigue (slow) crack growth in epoxy/glass interfaces bonded with the silane coupling agent 3-aminopropyltriethoxysilane was studied under static and cyclic loading at 23°C, 95% RH using the double cleavage drilled compression test. Crack growth rates under cyclic loading were significantly greater than under static loading, in contrast to crack growth rate results in monolithic glass. After aging up to 34 h at 94°C in distilled water, the silane-bonded epoxy/glass specimens exhibited somewhat greater resistance to fatigue crack growth than the unaged samples; however, after aging at 98°C in distilled water and at 70°C in an aqueous KOH solution at pH 10, crack growth became cohesive and exhibited fractal behavior. Mechanisms for fatigue crack growth at silane-bonded epoxy/glass interfaces are proposed.

Preparation of poly(methyl acrylate-co-itaconic anhydride)/SiO2 hybrid materials via the sol-gel process?The effect of the coupling agent, inorganic content, and nature of the catalyst

Transparent poly(methyl acrylate-co-itaconic anhydride)/SiO2 hybrid materials were prepared from methyl acrylate-itaconic anhydride copolymer and tetraethoxysilane (TEOS) with the coupling agent (3-aminopropyl)triethoxysilane (APTES) via a sol–gel process. The covalent bonds between the organic and inorganic phases were introduced by the in situ aminolysis of the itaconic anhydride units with APTES forming a copolymer bearing a triethoxysilyl group. These groups subsequently were hydrolyzed with TEOS and allowed to form a network. These reactions were monitored by Fourier transform infrared analysis. The amount of APTES had a dramatic influence on the gel time and sol fraction. The effect of APTES, the inorganic content, and the nature of the catalyst on the thermal properties and morphology of the hybrid materials were studied by differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and atomic force microscopy. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 321–328, 2000

Adhesion and Reliability of Epoxy/Glass Interfaces

The reliability of microelectronic components is profoundly influenced by the fracture resistance of the polymer/inorganic interfaces and by the progressive debonding of these interfaces in aqueous environments. Consequently, fatigue (slow) crack growth in epoxy/glass interfaces bonded with the silane coupling agent 3-aminopropyltriethoxysilane (3-APES) was studied under static and cyclic loading at 23°C and in either dry or humid conditions using the double cleavage drilled compression (DCDC) test. Crack growth rates under cyclic loading were significantly greater than under static loading, indicating that stress corrosion effects are negligible and that crack tip plasticity controls cyclic fatigue crack growth at silane (3-APES) bonded epoxy/glass interfaces. After aging at 94°C in water, these silane bonded epoxy/glass interfaces exhibited somewhat greater resistance to cyclic fatigue crack growth than the unaged samples; however, after aging at 98°C in water cyclic fatigue crack growth became cohesive and fractal in nature. Mechanisms for fatigue crack growth at silane (3-APES) bonded epoxy/glass interfaces are discussed.

Spectroelectrochemical Sensing Based on Multimode Selectivity Simultaneously Achievable in a Single Device. 4. Sensing with Poly(vinyl alcohol)−Polyelectrolyte Blend Modified Optically Transparent Electrodes

The feasibility of using polymer blend thin films covalently attached to indium tin oxide-glass, via the silane coupling agent (3-aminopropyl)triethoxysilane, for performing spectroelectrochemical modulation is demonstrated in aqueous solutions. The polymer blends were formulated by entrapping three polyelectrolytes-poly(vinylbenzyltrimethylammonium chloride) (PVTAC), poly(acrylic acid), and Nafion-in cross-linked poly(vinyl alcohol) (PVA) matrix for the purpose of selectively incorporating solution-phase anions and cations. Ru(BiPy) 3 2+ (BiPy = 2,2'-bipyridine), Ru(CN) 6 4- , and Fe(CN) 6 3- were chosen as the analytes for their suitable optical and electrochemical properties. Peak current enhancements, compared with the bare electrode under the same conditions, ranging from 2 to 7 were observed for these systems with the largest being for Fe(CN) 6 3- at an electrode coated with PVA-PVTAC blend. The optical absorbance change under attenuated total reflection during cyclic voltammetry (spectroelectrochemical modulation) was observed for all systems. The effects of potential window, electrochemical reversibility of the analyte, and potential scan rate on the resulting absorbance-time plot for modulation by cyclic voltammetry are reported for the different analyte-polymer blend systems. The modulation transfer ratios of analyte-polymer systems were studied. Modulation at 450 nm resulting from oxidation/reduction of the Ru(BiPy) 3 2+/3+ couple at 1.30 and 0.90 V vs Ag/AgCl with varying concentrations was used to construct analytical working curves for the spectroelectrochemical sensor.

Preparation and properties of poly (styrene-co-maleic anhydride) / silica hybrid materials by the in situ sol-gel process

Poly( styrene-co-maleic anhydride )/silica hybrid material has been successfully prepared from styrene-maleic anhydride copolymer and tetraethoxysilane (TEOS) in the presence of a coupling agent (3-aminopropyl)triethoxysilane (APTES) by an in situ sol-gel process. It was observed that the gel time of sol-gel solution was dramatically influenced by the amount of APTES. The hybrid material exhibits optical transparency almost as good as both silica gel and the copolymer. The covalent bonds between organic and inorganic phases were introduced by the aminolysis reaction of the amino group with maleic anhydride units of copolymer to form a copolymer bearing trimethoxysilyl groups, which undergo hydrolytic polycondensation with TEOS. The differential scanning calorimetry ( DSC ) showed that the glass transition temperature of the hybrid materials increases with increasing of SiO 2 composition. Photographs of scanning electron microscopy ( SEM ) and atomic force microscopy (AFM) inferred that the size of the inorganic particles in the hybrid materials was less than 20 nm.

DETECTING PLANT SILICA FIBRES IN ANIMAL TISSUE BY CONFOCAL FLUORESCENCE MICROSCOPY

Silica fibres from the inflorescence bracts of the grass Phalaris canariensis L. cause dermatitis, and have been implicated in the aetiology of oesophageal cancer in northeastern Iran. Here we describe a method for labelling these fibres so that they can be located in mammalian tissue. Fluorescein was covalently linked to isolated, purified fibres with the silane coupling agent 3-aminopropyl triethoxysilane. The labelled hairs were then rubbed into the backs of mice. These were later killed and their skin fixed, stained and sliced at a thickness of 250 microns. A confocal laser scanning microscope gave brilliant images of the fibres at any depth up to 100 microns or more beneath the surface of the slice. Fibres penetrated deeply into the dermis. Several cubic millimetres of tissue could be surveyed in 1 h. The number of fibres present was approximately 2 mm-3 initially, falling to 0.1 mm-3 after 7 days.

Synthesis and Characterization of Monodisperse Colloidal Organo-silica Spheres

Monodisperse, colloidal silica spheres were prepared from tetraethoxysilane (TES) in mixtures of ammonia, water, and ethanol. The surface of the particles could be coated through a subsequent chemical reaction with the silane coupling agent 3-aminopropyltriethoxysilane (APS). Also, a new kind of monodisperse, colloidal silica spheres (organo-silica spheres) was prepared starting from mixtures of APS and TES. Organo-silica spheres synthesized with equal amounts of APS and TES were found to contain as much as 37% of the total amount of APS. The amount taken up by the particles, and therefore also the particle properties, depended on the initial composition of the mixture of alkoxides. It is argued that the most important reaction by which APS is incorporated into the particles is through an alcohol-producing condensation reaction with a silanol group bonded to a silicon atom that was part of a TES molecule. Because of this proposed mechanism, it is argued that this base-catalyzed method of making hybrid organic-silica particles will also be applicable to mixtures of other organoalkoxides. The organo-silica spheres differed from silica spheres prepared with TES alone in the following aspects: The negative surface charge in the mixture of water, ammonia and ethanol was reduced, the mass density was lower (e.g., 1.51 g/cm 3 compared to 1.98 g/cm 3), the microporosity was larger, and the siloxane structure was less condensed. The particle refractive index was higher, but the differences were small (around 0.02). It was shown that particles with APS on the surface could be grown larger with a silica layer prepared from TES. Organo-silica particles and silica-coated organo-silica particles were surface coated with stearyl alcohol. The resulting stability in several solvents was assessed. The different colloidal systems were characterized by static and dynamic light scattering, transmission electron microscopy, elemental analysis, nitrogen adsorption measurements, electrophoresis, and qualitative 13C and quantitative 19 Si solid-state nuclear magnetic resonance spectroscopy.

Interactions of aminosilane with alumina and silica substrates deposited from nonaqueous and aqueous media

N-15 (Nitrogen-15) NMR studies of the widely-used coupling agent 3-aminopropyltriethoxysilane (APS) deposited onto native-oxide alumina and silica in submonolayers from nonaqueous and aqueous solut...