Microporosity and connections between pores in SBA-15 mesostructured silicas as a function of the temperature of synthesis

Galarneau, Anne; Cambon, Hélène; Renzo, Francesco Di; Ryoo, Ryong; Choi, Minkee; Fajula, François

doi:10.1039/b207378c

Cited by 512 publications

(490 citation statements)

References 29 publications

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“…The differences between the native and the functionalized matrixes in regards to the observed reduction of pore size after drug loading might result from differences in the orientation of the adsorbed molecules respect to the pore surface. Also remarkable was the presence of microporosity in the SBA-15 sample, a feature of this structure [39], whereas no microporosity was found in the samples containing CSB. All these facts prove the presence of the biomolecule inside the pores after the adsorption process.…”

Section: Csb Absorptionmentioning

confidence: 94%

A molecular model to explain the controlled release from SBA-15 functionalized with APTES

Sánchez-Montero

Doadrio

Salinas

et al. 2014

Microporous and Mesoporous Materials

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A molecular model with the approximate pore diameter of SBA-15 was constructed for the first time to investigate the effect of functionalize the matrix with 3-aminopropyltriethoxy-silane (APTES) in the release of Chicago Sky Blue 6B (CSB). It was expected that the positively charged amino groups of APTES could interact with the negatively charged sulphonic groups of CSB allowing controlling the release process. Indeed the experimental study showed that the release kinetics of CSB from SBA-15-APTES is two orders of magnitude smaller than from native SBA-15. However molecular modelling calculations investigating the possible interactions of APTES and SBA-15 yield unexpected results. In the model including only the condensation between the silanol groups of SBA-15 and APTES, the calculated interaction energy of CSB was quite similar than with the model of native SBA-15. However when additional electrostatic interactions of the -NH 2 groups of APTES with the mesoporous matrix were modelled the mesoporous channels underwent a considerable deformation. These results point to the structure deformation as the cause of the greater retention of CSB in SBA-15-APTES and warn about the special features of APTES when used to functionalize mesoporous silica materials. The model built in this paper could be used to construct predictive models in analogous drug delivery systems.

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Section: Csb Absorptionmentioning

confidence: 94%

A molecular model to explain the controlled release from SBA-15 functionalized with APTES

Sánchez-Montero

Doadrio

Salinas

et al. 2014

Microporous and Mesoporous Materials

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“…We use here three different MTSs: MCM-41 (26,27), SBA-15 (Santa Barbara Amorphous 15) (28,29), and HMS (Hexagonal Mesoporous Silica) (30,31), which are all shaped in the form of cylindrical pores with a narrow size distribution. Their synthesis, silanization with octyldimethylsilane, and pore size determination with nitrogen sorption at 77 K are described in SI Text, section I.…”

Section: Resultsmentioning

confidence: 99%

“…SBA-15 also has a hexagonal arrangement of cylindrical pores, but depending on the synthesis temperature, these mesopores can be connected by a secondary network of smaller micropores. We chose a temperature of 60°C, which prevents the micropores from growing and creating interconnections (29). The HMS was prepared with C 16 NH 2 as the structuring agent, with a ratio EtOH/H 2 O = 0.19 at an ambient temperature for 24 h (31).…”

Section: Methodsmentioning

confidence: 99%

Activated drying in hydrophobic nanopores and the line tension of water

Guillemot

Biben

Galarneau

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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125

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We study the slow dynamics of water evaporation out of hydrophobic cavities by using model porous silica materials grafted with octylsilanes. The cylindrical pores are monodisperse, with a radius in the range of 1-2 nm. Liquid water penetrates in the nanopores at high pressure and empties the pores when the pressure is lowered. The drying pressure exhibits a logarithmic growth as a function of the driving rate over more than three decades, showing the thermally activated nucleation of vapor bubbles. We find that the slow dynamics and the critical volume of the vapor nucleus are quantitatively described by the classical theory of capillarity without adjustable parameter. However, classical capillarity utterly overestimates the critical bubble energy. We discuss the possible influence of surface heterogeneities, long-range interactions, and high-curvature effects, and we show that a classical theory can describe vapor nucleation provided that a negative line tension is taken into account. The drying pressure then provides a determination of this line tension with much higher precision than currently available methods. We find consistent values of the order of −30 pN in a variety of hydrophobic materials. A remarkable property of water is its ability to form nanosize bubbles, or cavities, on hydrophobic bodies (1). Since their first direct observations through atomic force microscopy about a decade ago (2, 3), surface nanobubbles on hydrophobic surfaces have raised considerable interest, and they are believed to play a major role in surface-driven phenomena, such as boundary slippage of water flows, heat transfer at walls, vaporization and boiling, surface cleaning, etc. (4, 5). In a different context, the evaporation of water in the vicinity of hydrophobic bodies has been studied as a core mechanism for the hydrophobic interaction mediated by water (6-8), which plays a central role in biological matter. The formation of cavities able to bridge hydrophobic units provides a driving force for protein folding and supermolecular aggregation (9). Simulation examples of such drying-induced phenomena include the collapse of a polymer chain, multidomain proteins, and hydrophobic particles (9-13).Despite their direct observation, the easy formation and the high stability of nanobubbles on hydrophobic bodies still raise fundamental questions (5,14,15). Because of significant theoretical work, it is now established that, at the scale of the nanometer, macroscopic concepts apply: hydrophobicity is described by interfacial energies, and the drying transition in hydrophobic confinement is a first-order transition triggered by the nucleation of a critical vapor bubble (1). The energy barrier limiting the kinetics of this transition is a strong signature of nanobubbles properties. Evaporation kinetics has also been pointed out as the most direct measure of the importance of hydrophobic collapse in protein folding (9). However, rate effects in the drying transition have not received much attention. A few numerical studies have addr...

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“…It is to notice that the nanoparticle sizes measured in SEM pictures (60-120 and 10-15 nm for AN001C and AN003C, respectively) are much larger than the ones calculated from the surface area of the materials with the relation d = 6/Sρ (4.3 and 3.1 nm, respectively) (see Section 2.1.3) suggesting that the silica nanoparticles may contain also micropores or small mesopores. The microporosity could arise from the penetration of the polyethylene chains into the silica network, which after calcination gives rise to micropores as it is the case for SBA-15 materials [37]. Solvents extraction of the polymer before calcination were performed with as-synthesized monolith AN001 (y = 178 H 2 O) with 2-propanol or acetone at 40˝C for 24 h (4 times), which resulted in monoliths (S = 615 m 2 /g, V = 1.4 mL/g) which present some cracks after washing, but evidence, in addition to large mesopores of 22 nm, the presence of small mesopores around 4 nm (presence of a large step in nitrogen adsorption between 0.4 < p/p 0 < 0.5 with a volume of 100 mL STP height, not shown).…”

Section: Mesoporous Silica Monolithsmentioning

confidence: 99%

Synthesis and Textural Characterization of Mesoporous and Meso-/Macroporous Silica Monoliths Obtained by Spinodal Decomposition

et al. 2016

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Silica monoliths featuring either mesopores or flow-through macropores and mesopores in their skeleton are prepared by combining spinodal phase separation and sol-gel condensation. The macroporous network is first generated by phase separation in acidic medium in the presence of polyethyleneoxides while mesoporosity is engineered in a second step in alkaline medium, possibly in the presence of alkylammonium cations as surfactants. The mesoporous monoliths, also referred as aerogels, are obtained in the presence of alkylpolyethylene oxides in acidic medium without the use of supercritical drying. The impact of the experimental conditions on pore architecture of the monoliths regarding the shape, the ordering, the size and the connectivity of the mesopores is comprehensively discussed based on a critical appraisal of the different models used for textural analysis.

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Microporosity and connections between pores in SBA-15 mesostructured silicas as a function of the temperature of synthesis

Cited by 512 publications

References 29 publications

A molecular model to explain the controlled release from SBA-15 functionalized with APTES

A molecular model to explain the controlled release from SBA-15 functionalized with APTES

Activated drying in hydrophobic nanopores and the line tension of water

Synthesis and Textural Characterization of Mesoporous and Meso-/Macroporous Silica Monoliths Obtained by Spinodal Decomposition

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