Structural features of silicas prepared in n-heptane/water/ethanol/sodium dodecylsulfate microemulsions

Vicelli, Marcio R.; Awano, Carlos M.; Donatti, D. A.; Ruiz, Alberto; Vicente, F.; Perissinotto, Amanda Pasquoto; Vollet, Dimas R.

doi:10.1016/j.micromeso.2011.12.050

Cited by 4 publications

(4 citation statements)

References 34 publications

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“…12−16 Sodium dodecyl sulfate (SDS) is a very popular anionic surfactant, although one could find only few cases in the literature in which it has been used as a modifier for silica mesoporous structure. 15,17−21 In a previous work, 21 a fixed concentration of SDS was used with varied quantities of an oil phase to produce hydrophobic ambient pressure dried silica aerogels. It was concluded that the typical values of the specific surface of the ambient pressure dried aerogels were comparable with those obtained by supercritical drying, and the pore volume and the mean pore size increased with increasing the oil phase.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Surfactants can form micelles in a variety of forms (spherical, cylindrical, lamellae) and structural organization such as lamellar, cubic, hexagonal, or three-dimensional wormhole, so they have been used as appropriate matrices to prepare and modify a large variety of mesoporous silica with interesting structural properties. − Sodium dodecyl sulfate (SDS) is a very popular anionic surfactant, although one could find only few cases in the literature in which it has been used as a modifier for silica mesoporous structure. ,− In a previous work, a fixed concentration of SDS was used with varied quantities of an oil phase to produce hydrophobic ambient pressure dried silica aerogels. It was concluded that the typical values of the specific surface of the ambient pressure dried aerogels were comparable with those obtained by supercritical drying, and the pore volume and the mean pore size increased with increasing the oil phase.…”

Section: Introductionmentioning

confidence: 99%

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Mass and Surface Fractal in Supercritical Dried Silica Aerogels Prepared with Additions of Sodium Dodecyl Sulfate

et al. 2014

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Silica wet gels were prepared from hydrolysis of tetraethoxysilane (TEOS) with additions of sodium dodecyl sulfate (SDS). The surfactant was removed after gelation. Wet gels exhibited mass-fractal structure with mass-fractal dimension D (typically around 2.25) in a length scale extending from a characteristic size ξ (typically about 10 nm) of the mass-fractal domains to a characteristic size a0 (typically between 0.3 and 0.4 nm) of the primary particles building up the fractal domains. ξ increased while D and a0 diminished slightly as the SDS quantity increased. Aerogels with typical specific surface of 1000 m(2)/g and density of 0.20 g/cm(3) were obtained by supercritical drying of the wet gels after washing with ethanol and n-hexane. The pore volume and the mean pore size increased with the increase of the SDS quantity. The aerogels presented most of the mass-fractal characteristics of the original wet gels at large length scales and exhibited at a higher resolution level at about 0.7 nm a crossover to a mass-surface fractal structure, with apparent mass-fractal dimension Dm ∼ 2.4 and surface-fractal dimension Ds ∼ 2.6, as inferred from small-angle X-ray scattering (SAXS) and nitrogen adsorption data.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mass and Surface Fractal in Supercritical Dried Silica Aerogels Prepared with Additions of Sodium Dodecyl Sulfate

et al. 2014

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“…This suggests that the diffuse boundary could be a more complex structure formed by silica species and hydrophobic organic groups on the silica surface as a result of the overall silylation and APD process. The diffuse-boundary has not been observed earlier in the analogous system studied previously [23] because the maximum q m probed by SAXS there was 2.34 nm À1 , which is below the high-q range showing the effect of the diffuseboundary in Fig. 2.…”

Section: Iðqþ ¼ Apðqþsðqþ;mentioning

confidence: 51%

“…Particularly, sodium dodecyl sulfate (SDS) is an anionic surfactant which has been used in a few cases for this purpose [19e24]. In a previous work [23], a fixed quantity of SDS was used with varied quantities of an oil phase to produce hydrophobic APD silica aerogels. In a more recent work [24], we have obtained SCD aerogels in an autoclave, starting from a set of precursor wet gels prepared using varied quantities of SDS in the hydrolysis step of the process.…”

Section: Introductionmentioning

confidence: 99%

Structure and diffuse-boundary in hydrophobic and sodium dodecyl sulfate-modified silica aerogels

Perissinotto

Awano

Vicente

et al. 2016

Microporous and Mesoporous Materials

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a b s t r a c tSmall-angle X-ray scattering (SAXS) and nitrogen adsorption were used to study ambient pressure drying (APD) silica aerogels prepared from hydrolysis of tetraethoxysilane (TEOS) with additions of sodium dodecyl sulfate (SDS). The surfactant-extracted precursor wet gels have presented mass-fractal structure with typical fractal dimension 2.25 in a SAXS characteristic length scale from~10 nm to~0.35 nm. Hydrophobic APD aerogels with typical specific surface of 800 m 2 /g and bulk density of 0.20 g/cm 3 were obtained after silylation of the precursor wet gels with a mixture of hexamethyldisiloxane (HMDSO) and trimethylchlorosilane (TMCS). The pore volume and the mean pore size of the APD aerogels increased with increasing the SDS quantity. APD aerogels presented most of the mass-fractal characteristics of the precursor wet gels at large length scales. The radius of gyration of the clusters of the APD aerogels (typically 17 nm) increased with increasing the SDS quantity, while the radius of the silica primary particles (typically 2.0 nm) increased at first with the addition of SDS (with respect to the sample without SDS) and decreased regularly afterward with increasing the SDS quantity. The primary particles presented yet some internal inhomogeneity and a diffuse-boundary interface with thickness of about 0.7 nm, according to a linear-gradient model for the diffuse boundary.

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Porous Inorganic Materials as Potential Supports for Ionic Liquids

Schwieger

Selvam

Klumpp

et al. 2014

Supported Ionic Liquids

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Structural features of silicas prepared in n-heptane/water/ethanol/sodium dodecylsulfate microemulsions

Cited by 4 publications

References 34 publications

Mass and Surface Fractal in Supercritical Dried Silica Aerogels Prepared with Additions of Sodium Dodecyl Sulfate

Mass and Surface Fractal in Supercritical Dried Silica Aerogels Prepared with Additions of Sodium Dodecyl Sulfate

Structure and diffuse-boundary in hydrophobic and sodium dodecyl sulfate-modified silica aerogels

Porous Inorganic Materials as Potential Supports for Ionic Liquids

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