Solid-state silicon-29 NMR and infrared studies of the reactions of mono- and polyfunctional silanes with zeolite Y surfaces

“…From Fig. 10, a minor peak appeared at -14 ppm can be assigned to disubstituted siloxane oligomers (R 2 Si(OSi) 2 ) [64]. The major peak at -22 ppm is due to linear polysiloxane chains (R 2 SiO) x .…”

Section: Solid-state Nmrmentioning

confidence: 99%

Novel organic–inorganic hybrid materials based on epoxy-functionalized silanes

Sitthiracha

Kilmartin

Edmonds

2015

J Sol-Gel Sci Technol

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Hybrid materials comprising inorganic glasses and organic polymers were investigated as potential replacements for diglycidyl ether of bisphenol-A to improve the thermomechanical properties of available composites. An epoxy-functionalized silane, 3-glycidoxypropyltrimethoxysilane (GPTMS), was employed to synthesize organic-inorganic hybrid materials (OIHMs) via a sol-gel process. The oxirane ring in GPTMS was cross-linked by compounds including an aliphatic amine, diethylenetriamine, amine-functionalized silane, n-(2-aminoethyl)-3-aminopropyltrimethoxysilane, tertiary amine, 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), and an acid anhydride, hexahydrophthalic anhydride. OIHMs derived from a difunctional organosilane, (3-glycidoxypropyl)methyldimethoxysilane, were also synthesized to compare the mechanical properties with OIHMs derived from GPTMS. Structural characterization of cured OIHMs was performed using a combination of attenuated total reflectance spectroscopy (FTIR-ATR) and 29 Si solid-state nuclear magnetic resonance. Differential scanning calorimetry and thermogravimetric analysis were used to clarify the thermal properties. The thermomechanical properties and cross-link density were evaluated using dynamic mechanical thermal analysis (DMTA). In this study, it was evident that the presence of inorganic networks provided a significant improvement of the thermomechanical properties, where the glass transition temperature typically increases by 20°C and the storage modulus at 150°C by nearly eight times that of neat epoxy resin. An increase in glass transition temperature, end-use temperature, and the thermomechanical behavior of OIHMs was observed and quantified using DMTA. These results corresponded to calculated increases in cross-link density.

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“…A band at 3740 cm-1, assigned to terminal Si-OH, also significantly decreases in intensity on treatment with HMDS. It is known that these sites in silicas are very reactive with HMDS (20,21). Changes in intensifies of internal frame- work (3640, 3610 cm -~) (4a) hydroxyls on treatment are minimal, which suggests that the terminal Si-OH groups are located primarily on the external surface because they are accessible to the vapor-phase treatment by the named compounds.…”

Section: Characterization Of Surface-treatedmentioning

confidence: 99%

Designing zeolite catalysts for shape-selective reactions: Chemical modification of surfaces for improved selectivity to dimethylamine in synthesis from methanol and ammonia

Corbin

Keane

Abrams

et al. 1990

Journal of Catalysis

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The relative contributions of external and intracrystalline acidic sites of small pore H-RHO zeolite for the selective synthesis of methylamines from methanol and ammonia have been studied. Nonselective surface reactions which produce predominantly trimethylamine can be eliminated by "capping" the external acidic sites with trimethylphosphite (TMP) and other reagents, thus improving the selectivity toward the formation of dimethylamine. For small pore zeolites, neither the zeolite pore size nor the internal acidic sites is significantly affected by this treatment. In situ infrared and MAS-NMR studies show that TMP reacts irreversibly with the zeolite acidic sites via a modified Arbusov rearrangement to form surface-bound dimethylmethylphosphonate.

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Solid-state silicon-29 NMR and infrared studies of the reactions of mono- and polyfunctional silanes with zeolite Y surfaces

Abstract: Structure of the Cobalt(II)-w Capped" Porphyrin, Co(C 3-Cap).3CHCl 3 .

Cited by 48 publications

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Organic-functionalized molecular sieves as shape-selective catalysts

Organic-functionalized molecular sieves as shape-selective catalysts

Novel organic–inorganic hybrid materials based on epoxy-functionalized silanes

Designing zeolite catalysts for shape-selective reactions: Chemical modification of surfaces for improved selectivity to dimethylamine in synthesis from methanol and ammonia

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