In-Situ SAXS Studies on the Formation of Silicate/Surfactant Mesophases with Solubilized Benzene under Acidic Conditions

Tiemann, Michael; Goletto, V.; Blum, Raphaël; Babonneau, Florence; Amenitsch, Heinz; Lindén, Mika

doi:10.1021/la026473w

Cited by 27 publications

(27 citation statements)

References 32 publications

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“…Between 400 and 500 seconds after the addition of the silica source, the intensity of the (10) reflection decreases tightly, the (11) and (20) disappear and two other diffraction peaks which can be indexed as the (200) and (210) system where a pure Pm n is obtained at the end. This kind of transformation from a mesostructured phase to another one without dissolution-reprecipitation process has already been reported, from 2D-hexagonal to lamellar as a function of the reaction time 45,46 and from lamellar to 2D-hexagonal 47 or 2D-hexagonal to cubic Ia3d 48 with an increase of the temperature. Nevertheless, an epitaxial correlation between the two ordered phases is rarely encountered.…”

Section: Resultssupporting

confidence: 66%

In Situ Time-Resolved SAXS Study of the Formation of Mesostructured Organically Modified Silica through Modeling of Micelles Evolution during Surfactant-Templated Self-Assembly

et al. 2012

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The mechanisms of formation of organically modified (phenyl, vinyl, and methyl) silica materials with cubic Pm3̅n and hexagonal p6m periodic mesostructures obtained in one step in the presence of the cetyltrimethylammonium bromide (CTA+B) surfactant are reported in this study. Understanding the way these complex materials form is difficult but undoubtedly necessary for controlling the material structure and its properties because of the combined presence of surface organic groups and large surface areas. Here, the mechanism of formation is clarified on the basis of the modeling of time-resolved in situ small angle X-ray scattering (SAXS) experiments, with a specific focus on the micelle evolution during material formation. Their fast self-assembly is followed for the first time with a quick temporal resolution of a few seconds using a third-generation synchrotron radiation source. To better understand the behavior of the complex organic-containing mesostructure, we perform a comparative study with the corresponding organo-free, isostructural materials obtained from three different surfactants (CTA+, CTEA+, and CTPA+) having a constant chain length (C16) and an increasing polar head volume (met-, et-, and prop-). Numerical modeling of SAXS data was crucial to highlighting a systematic sphere-to-rod micellar transition, otherwise undetected, before the formation of the 2D hexagonal phase in both organo-free and organo-containing systems. Then, two different pathways were found in the formation of the cubic Pm3̅n mesostructure: either an ordering transition from concentrated flocs of spherical micelles (from CTEA+ or CTPA+) for pure TEOS systems or a structural transformation from an intermediate 2D hexagonal mesophase in organosilane systems (from CTA+). Combining the comparison between organo-free and organo-containing systems with numerical modeling, we find that the hexagonal-to-cubic phase transition in the organically modified materials seems to be strongly influenced not only by the obvious presence of the organic group but also by the quicker and more massive condensation kinetics of silicate oligomers on the CTA+ micellar surface. Finally, quite unexpectedly, we find a wormlike-to-sphere micellar transition in the CTPA+ system.

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Section: Resultssupporting

confidence: 66%

In Situ Time-Resolved SAXS Study of the Formation of Mesostructured Organically Modified Silica through Modeling of Micelles Evolution during Surfactant-Templated Self-Assembly

et al. 2012

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“…14), a truly cooperative self-assembly of the silicates and surfactants was found to be possible. Firouzi et al [24] showed, through 2 H and 29 Si NMR spectroscopy and neutron scattering, that a micellar solution of CTAB (cetyltrimethylammonium bromide) transforms into a hexagonal phase in the presence of silicate anions. This is consistent with the effect of electrolytes on micellar phase-transi-tions.…”

Section: Inorganic-species-driven Self-assemblymentioning

confidence: 99%

“…The formation of mesoscopically ordered silica/surfactant composites under acidic synthesis conditions was studied by time-resolved in situ small-angle X-ray scattering (SAXS) using synchrotron radiation. [29] The various proposed mechanisms of formation of ordered mesostructured phases have been recently reviewed by Zana et al [30] Recently, Linden et al [31] have followed the initial stages of the formation of SBA-15 by in situ SAXS/XRD using synchrotron radiation. The authors proposed that the first step in the formation of an SBA-15 mesostructure is the liquid-liquid phase sepa-ration of spherical P123-silicate hybrid micelles; nucleation and growth of the 2D hexagonal phase then takes place.…”

Section: Inorganic-species-driven Self-assemblymentioning

confidence: 99%

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Ordered Meso‐ and Macroporous Binary and Mixed Metal Oxides

2004

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A critical review is provided of the principles guiding the synthesis of meso-and macroporous metal oxides on multiple length scales in the presence of surfactant mesophases and colloidal arrays of monodisperse spheres, and correlations between the synthesis conditions and the properties of the resulting meso-and macroporous oxides, such as thermal stability, pore structure, elemental and nanophase compositions of the inorganic wall, etc. The thermal stability of mesostructured metal-oxide phases, in particular, is discussed in terms of charge-matching at the organic-inorganic interface, the strength of interactions between inorganic species and surfactant headgroups, the flexibility of the M-O-M bond angles in the constituent metal oxides, the Tammann temperature of the metal oxide, and the occurrence of redox reactions in the metal-oxide wall. The ordered meso-and

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“…alter micelle shape is one method to achieve this [4][5][6][7]. Incorporation of such species could also result in use of these membranes in encapsulation/release applications, e.g., for hydrophobic species such as scents, pesticides or therapeutic agents.…”

Section: Introductionmentioning

confidence: 99%

Incorporation of sparingly soluble species in mesostructured surfactant–polymer films

O'Driscoll¹,

Hawley²,

Edler³

2008

Journal of Colloid and Interface Science

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In-Situ SAXS Studies on the Formation of Silicate/Surfactant Mesophases with Solubilized Benzene under Acidic Conditions

Cited by 27 publications

References 32 publications

In Situ Time-Resolved SAXS Study of the Formation of Mesostructured Organically Modified Silica through Modeling of Micelles Evolution during Surfactant-Templated Self-Assembly

In Situ Time-Resolved SAXS Study of the Formation of Mesostructured Organically Modified Silica through Modeling of Micelles Evolution during Surfactant-Templated Self-Assembly

Ordered Meso‐ and Macroporous Binary and Mixed Metal Oxides

Incorporation of sparingly soluble species in mesostructured surfactant–polymer films

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