Étude par des expériences HETCOR 1H–29Si des interfaces tensioactif/silice dans des matériaux mésostructurés à porosité ordonnée

Baccile, Niki; Maquet, Jocelyne; Babonneau, Florence

doi:10.1016/j.crci.2005.06.021

Cited by 10 publications

(8 citation statements)

References 31 publications

(48 reference statements)

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“…The 29 Si MAS NMR spectra present peaks due to the three different silicon sites : Q4= SiO2, Q3 = SiO1,5Ot, Q2 = SiO(Ot)2 (Ot : Non-bridging oxygen). 31 The number of Q3 sites is high in both samples, because of the rather short aging time of the powder after precipitation (3 h); 13 C MAS-NMR spectra (not shown) have confirmed the absence of any residual ethoxy groups. One might expect that under acidic conditions, the Q3 units thus correspond to the presence of Si-OH groups, 0.64 per Si (including Q3 and Q2 contributions).…”

Section: -Characterization Of the Silica/surfactant Bulk Powdersmentioning

confidence: 83%

“…Preliminary 2D-29 Si{ 1 H} HETCOR experiments have been recorded on both types of samples and different NMR responses were obtained. 31 Two contact times -time during which the magnetisation transfer occurs between the 1 H and 29 Si spin systems -were used to explore increasing inter-nuclei distances; these 2D-experiments are quite time-consuming especially with a moderate static magnetic field, which limits the number of possible contact times. Indeed, in most of the previous publications, only one experiment recorded at only one contact time has been presented.…”

Section: Introductionmentioning

confidence: 99%

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Solid-State NMR Characterization of the Surfactant−Silica Interface in Templated Silicas: Acidic versus Basic Conditions

et al. 2007

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Combination of one-dimensional and two-dimensional solid state magic angle spinning nuclear magnetic resonance (MAS NMR) experiments has been used to investigate the hybrid organicinorganic interfaces in surfactant templated silicas. Samples prepared with cetyltrimethylammonium 2 bromide (CTAB) under acidic (HCl) and basic (NaOH) conditions have been compared. The use of sequences based on the 29 Si-1 H heteronuclear dipolar interactions allows us to selectively filter the NMR response of the protons close to the Si surface sites showing directly the clear difference between the two systems. The basic sample is characterised by a small amount of Si-OH groups, and a short distance between the Si-Osurface groups and the surfactant polar head group, while the acidic sample exhibits a silanol-rich surface with a longer distance between the Si surface sites and the polar head groups. The nature of the interface induces consequent differences in the structure of the adsorbed water layers present at the interface, and this has been revealed by near infrared experiments, as well as 1 H MAS NMR spectra recorded on dehydrated and partially re-hydrated samples. One objective of this work was also to show that the use of standard solid state NMR conditions (magnetic field of 7 T and magic angle spinning frequency less than 15 kHz) can be largely sufficient to get extremely valuable information regarding the silica/surfactant interfaces.

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Section: -Characterization Of the Silica/surfactant Bulk Powdersmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Solid-State NMR Characterization of the Surfactant−Silica Interface in Templated Silicas: Acidic versus Basic Conditions

et al. 2007

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“…Then the behaviour and eventual interactions between the pollutant and the host matrix will be characterised by means of solid state Nuclear Magnetic Resonance (NMR), which revealed elsewhere [6,33,34] to be a powerful technique to explore short range order interactions at the inorganic/organic interface in mesostructured silica-based materials. Knowledge of interactions between the adsorbed guest molecules and the host porous matrix is an important issue to evaluate the possibility for the materials to be further recycled and for the pollutant to be post-treated.…”

Section: Introductionmentioning

confidence: 99%

Organo-modified mesoporous silicas for organic pollutant removal in water: Solid-state NMR study of the organic/silica interactions

Baccile

Babonneau

2008

Microporous and Mesoporous Materials

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“…The solid-state two-dimensional (2D) 1 H− 29 Si heteronuclear NMR correlation (HETCOR) sequence is a key NMR technique for investigating the organic and inorganic interfaces at a molecular level . It relies on dipolar coupling between silicon atoms and protons and has recently provided detailed characterization of the surface of mesoporous silicas. , In particular, the spatial connectivities between species at the interface can be established (on the order of 0.5 nm) by using the dipolar through-space interactions, with the relative vicinity being inferred from the contact time (τ C ) employed for the HETCOR sequence. The use of short contact time (τ C = 0.5 ms) allows the selective observation of silicon and proton nuclei which are spatially very close.…”

Section: Resultsmentioning

confidence: 99%

Silica Nanoparticles Grown and Stabilized in Organic Nonalcoholic Media

et al. 2009

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This work features an alternative approach to the well-documented preparation of silica nanoparticles in protic media. We present here the one-pot synthesis of silica nanoparticles of adjustable size (between 18 and 174 nm), prepared and stabilized in organic nonalcoholic solvents. This novel route is based on hydrolysis and condensation of tetraethoxysilane, using water as reactant and different primary amines (butylamine, octylamine, dodecylamine, hexadecylamine) as catalysts in tetrahydrofuran or dimethoxyethane. The growth rate can be finely adjusted, and the first stages of the formation are observed by transmission electronic microscopy, revealing a silicated network in which the silica particles are formed and then released in solution. The amine plays not only a catalyst role but is also implied, as well as the solvent, in the stabilization process and the size control of the particles. A detailed NMR study demonstrates a core-shell structure in which the silica core is surrounded by a layer of alkylammonium ions together with solvent.

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Étude par des expériences HETCOR 1H–29Si des interfaces tensioactif/silice dans des matériaux mésostructurés à porosité ordonnée

Cited by 10 publications

References 31 publications

Solid-State NMR Characterization of the Surfactant−Silica Interface in Templated Silicas: Acidic versus Basic Conditions

Solid-State NMR Characterization of the Surfactant−Silica Interface in Templated Silicas: Acidic versus Basic Conditions

Organo-modified mesoporous silicas for organic pollutant removal in water: Solid-state NMR study of the organic/silica interactions

Silica Nanoparticles Grown and Stabilized in Organic Nonalcoholic Media

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