Search results for "Silane"
showing 10 items of 173 documents
Synthesis and Characterization of SiC/MC/C Ceramics (M = Ti, Zr, Hf) Starting from Totally Non-oxidic Precursors
2002
The reaction of poly(dimethylsilane) (PDMS) and poly(dimethylcarbosilane) (PCS) with bis(cyclopentadienyl)M dichloride Cp2MCl2 (M ) Ti, Zr, Hf) complexes has been used as a new route to obtain ceramic materials based on SiC-containing M. The reaction is completed at a relatively low temperature, 900 °C, yielding the corresponding amorphous SiC/MC ceramics which have been characterized by means of 29 Si MAS NMR. These amorphous materials have been treated at higher temperatures, 1350 °C, under a purified argon atmosphere, yielding partially crystallized products which have been studied by X-ray powder diffraction and 29 Si MAS NMR. The effect of the composition of the mixture of precursors is
Synthesis of a Hydrothermally Stable, Periodic Mesoporous Material Containing Magnetite Nanoparticles, and the Preparation of Oriented Films
2006
Magnetite nanoparticles modified covalently with triethoxysilane having a quaternary dicetyl ammonium ion are used together with tetraethylorthosilicate as building blocks to prepare a mesoporous material. Cetyltrimethylammonium bromide is used as a structure-directing agent under conditions typically used for mesoporous MCM-41 silicas. The resulting mesoporous material (MAG-MCM-41), containing up to 15 wt % of magnetite is characterized by transmission electron microscopy (TEM), isothermal gas adsorption, and X-ray diffraction. In contrast to siliceous MCM-41, mesoporous MAG-MCM-41 exhibits a remarkable hydrothermal stability. The magnetic properties of MAG-MCM-41 are characterized by DC a…
Effect of Hydration Procedure of Fumed Silica Precursor on the Formation of Luminescent Carbon Centers in SiO 2 :C Nanocomposites
2019
The effect of hydration procedure of fumed silica precursor on photoluminescent properties of carbonized silica (SiO2:C) nanocomposite after chemo/thermal treatments is studied. Main structural effect is the formation of chemical bonding of phenyl groups to silica surface via multiple CSiO bonding bridges. Synthesized samples demonstrate very broad photoluminescence (PL) bands in near ultraviolet and visible ranges with maximum intensity dependent on temperature of thermal annealing. Two main trends in luminescence properties are: 1) hydration-induced blue shift of PL in comparison with PL of unhydrated series; 2) red shift of PL bands with increasing synthesis temperature regardless hydr…
Design of Carbon Dots Photoluminescence through Organo-Functional Silane Grafting for Solid-State Emitting Devices
2017
AbstractAdvanced optical applications of fluorescent carbon dots (C-dots) require highly integrated host-guest solid-state materials with a careful design of C-dots – matrix interface to control the optical response. We have developed a new synthesis based on the grafting of an organo-functional silane (3-glycidyloxypropyltrimethoxysilane, GPTMS) on amino-functionalized C-dots, which enables the fabrication of highly fluorescent organosilica-based hybrid organic-inorganic films through sol-gel process. The GPTMS grafting onto C-dots has been achieved via an epoxy–amine reaction under controlled conditions. Besides providing an efficient strategy to embed C-dots into a hybrid solid-state mat…
The controlled growth of GaN microrods on Si(111) substrates by MOCVD
2015
Abstract In this paper, a selective area growth (SAG) approach for growing GaN microrods on patterned SiN x /Si(111) substrates by metal-organic chemical vapor deposition (MOCVD) is studied. The surface morphology, optical and structural properties of vertical GaN microrods terminated by pyramidal shaped facets (six { 10 1 ¯ 1 } planes) were characterized using scanning electron microscopy (SEM), room temperature photoluminescence (PL) and Raman spectroscopy, respectively. Measurements revealed high-quality GaN microcolumns grown with silane support. Characterized structures were grown nearly strain-free (central frequency of Raman peak of 567±1 cm −1 ) with crystal quality comparable to bu…
Effects of anodizing surface treatment on the mechanical strength of aluminum alloy 5083 to fibre reinforced composites adhesive joints
2021
Abstract In this study, the anodizing process based on the use of tartaric sulfuric acid solution (TSA) was carried out on metal substrate to evaluate for the first time its effect on the adhesion strength and corrosion resistance of aluminium alloy (i.e., AA5083) to fibre (i.e., basalt or glass) reinforced composite adhesive joints for nautical applications. Furthermore, some TSA anodized samples were soaked in a NaOH solution to investigate the influence of this post-immersion step on the joint performances. With the aim to improve the fibre-matrix adhesion in the composite substrate thus further increasing the overall mechanical response of the joint, glass and basalt fibres were treated…
Rapid one-pot synthesis of tapered star copolymers via ultra-fast coupling of polystyryllithium chain ends
2019
Highly efficient stoichiometric coupling of sterically hindered polystyryllithium (PS-Li) chain ends was achieved using tetra[3-(chloro-dimethylsilyl)propyl]silane (TCDMSPS) as the linking agent. Based on the disparate reactivities of isoprene (I, rI = 11.0) and styrene (S, rS = 0.049) in the anionic copolymerization in nonpolar media, poly(isoprene0.5-grad-styrene0.5) (P(I0.5-grad-S0.5)) tapered 4-arm star copolymers were synthesized in only two steps. The tapered 4-arm star copolymers (Mtargetedw = 40 to 160 kg mol−1) were synthesized with high star functionalities f (Mw,star/Mw,arm = 3.68–3.98), low dispersity (Đ = 1.06–1.15) and minimal residual precursor content (2–8 wt%), avoiding fra…
Effect of Polarity of Solvent on Silanization of Halloysite Nanoclay Using (3-Glycidyloxy propyl) Trimethoxy Silane
2021
Abstract: The grafting of silane groups on clay surfaces has been recently investigated in order to fabricate versatile compounds with new potential applications in materials science and ecological engineering. This work explored the influence of variety of solvents with variable polarity on the silanization of halloysite nanoclay (HNT) surface by (3-Glycidyloxy propyl) trimethoxy silane. To this purpose, the functionalization of HNT by 3-Glycidyloxypropyltrimethoxysilane (GOPTMS) has been conducted in Ethanol (polar protic solvent), Tetrahydrofuran (THF) and Acetonitrile (polar aprotic solvents), and Hexane, 1,4-Dioxane and Toluene (non polar solvents). The silane grafted materials were ch…
Proton conductivity through polybenzimidazole composite membranes containing silica nanofiber mats
2019
The quest for sustainable and more efficient energy-converting devices has been the focus of researchers&prime
The impact of different surface treatments on the shear bond strength of orthodontic metal brackets applied to different CAD/CAM composites
2020
Background To investigate the shear bond strength (SBS) of orthodontic metal brackets applied to different CAD/CAM composites treated with different surface treatments. Material and Methods Specimens of two CAD/CAM composites were obtained of Lava Ultimate (LU; n=60) and Brilliant Crios (BC; n=60) which were randomly separated into six subgroups (n=10) according to the surface treatment: control (CTL); sandblasting (SB); sandblasting and silane (SBSL); hydrofluoric acid (HF); hydrofluoric acid and silane (HFSL); and Monobond Etch&Prime (MEP). The mandibular central incisor metal brackets were bonded with a light-cure adhesive. The SBS data were analyzed using the two-way analysis of varianc…