Great Improvement of Chromatographic Performance Using MCM-41 Spheres as Stationary Phase in HPLC

Martin, Thierry; Galarneau, Anne; Renzo, Francesco Di; Brunel, Daniel; Fajula, François; Heinisch, Sabine; Crétier, G.; Rocca, Jean‐Louis

doi:10.1021/cm030443c

Cited by 126 publications

(90 citation statements)

References 25 publications

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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%

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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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Section: Resultsmentioning

confidence: 99%

“…27. MCM-41 is a model material presenting independent cylindrical pores that are hexagonally ordered and have a smooth internal surface.…”

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.

Self Cite

125

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“…Im Jahr 2004 folgte eine Veröffentlichung, in der die Anwendung von sphäri-schen MCM-Partikeln als Säulenmaterial in der Hochleistungsflüssigkeitschromatographie (HPLC) beschrieben wurde [2,10,11]. Durch die großen Oberflächen und die geordnete Porenstruktur konnten die Retentionszeiten verlängert werden, was zu einer besseren Auflösung der Peaks von Stoffgemischen führt und die Effizienz chromatographischer Systeme erhöht.…”

Section: Introductionunclassified

Charakterisierung von Kieselgelen mit bimodaler Porenstruktur mittels Positronenlebensdauer‐Spektroskopie

Uhlig

Zieger

Bluhm

et al. 2016

Chemie Ingenieur Technik

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Characterization of Hierarchical Silica Gels with Positron Annihilation Lifetime SpectroscopyIn this study the results of the characterization of hierarchical silica-gel samples with nitrogen adsorption and positron annihilation lifetime spectroscopy (PALS) were compared. The hierarchical silica-gel samples were synthesized by pseudomorphic transformation of a meso porous silica gel with CTAOH. The results of the PALS measurements clearly indicate the hierarchical pore structure of the materials. Two individual pore systems can be detected with a good resolution. The peak area of the signals can be calculated and compared with the pore volumes determined by nitrogen adsorption.

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“…However, the preparation and characterization of long alkyl chain modified MgO have not been reported until now, except for the modification of MgO with ethylene glycol [14]. Due to the higher stability and surface coverage of the obtained products by using polyfunctional silanes than by using monofunctional silanes [15][16][17][18], n-octadecyltrichlorosilane, a trifunctional silylation agent, was used to modify the surface of MgO microspheres.…”

Section: Introductionmentioning

confidence: 99%