X-ray reflectivity of a Langmuir monolayer on water

Bosio, L.; Benattar, J. J.; Rieutord, F.

doi:10.1051/rphysap:01987002208077500

Cited by 39 publications

(20 citation statements)

References 6 publications

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“…Similar binding has been shown for a range of divalent cations (Richardson & Roser 1987;Gordziel et al 1981). Recently, Xray reflectivity studies have shown that Pb11 ions bind to stearic acid films with the stoichiometry Pb(stearate)2 (Bosio et al 1987), and it is reasonable to propose that Ca binds in a similar manner. Because the pK of stearic acid in the presence of Ca is ca.…”

Section: Discussionsupporting

confidence: 66%

Interfacial control of nucleation of calcium carbonate under organized stearic acid monolayers

Mann

Heywood

Rajam

et al. 1989

Proc. R. Soc. Lond. A

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The nucleation and crystal growth of calcium carbonate from supersaturated bicarbonate solutions in the presence of stearic acid monolayers has been studied by electron microscopy and electron and X-ray diffraction. Whereas rhombohedral crystals of calcite are randomly deposited in the absence of the monolayer, regiospecific crystallization of vaterite florets occurs at the organic surface. The florets develop initially as single crystalline biconvex discs oriented with respect to the negatively charged headgroups of the organic membrane such that the radial axis, which corresponds to the crystallographic [0001] direction, is aligned perpendicular to the monolayer interface. Subsequent radial outgrowth results in the polycrystalline floret morphology. The degree of compression of the monolayer results in significant changes in nucleation. Solid-phase films are highly catalytic and generate vaterite discs with a wide size distribution. In contrast, nucleation on liquid-phase monolayers results in discs of more uniform particle diameter. Increased supersaturation and uncompressed films gave both calcite and vaterite polymorphs. Preferential orientation of the ab vaterite crystal face parallel to the monolayer surface is discussed in terms of the electrostatic accumulation of a Stern layer of Ca ions. Polymorph selectivity is determined by kinetic factors involving charge accumulation and possibly stereochemical recognition between the alignment of the stearic acid carboxylates and the orientation of carbonate anions in the vaterite unit cell. Geometric (epitaxial) matching at the interface is not a primary factor in regulating nucleation.

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Section: Discussionsupporting

confidence: 66%

Interfacial control of nucleation of calcium carbonate under organized stearic acid monolayers

Mann

Heywood

Rajam

et al. 1989

Proc. R. Soc. Lond. A

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“…[18,19] Specular reflection provides information on the electron-density variation (scattering length density variation) perpendicular to the surface with ngström-level resolution. Due to the loss of the phase information in conventional X-ray reflectivity experiments, the data analysis is generally based on finding proper electrondensity functions, whose reflectivity properties retrospectively best match the observed reflectivity data.…”

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confidence: 99%

Hydrophilic/Hydrophobic Nanostripes in Lipopolymer Monolayers

et al. 2000

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“…The profile of the film in which a trilayer is expected features more peaks than were observed for trilayers of X-shaped molecules. In fittings of the XRR profiles to the theoretical equations, 43,44 a vertical orientation of the molecules was assumed and the electron density profile consisting of more slabs of different density than in the case of the X-shaped molecules was taken into consideration. The A 3 /A 1 ratio equals 2.65, indicating partial interdigitation of the molecules between the layers.…”

Section: T-shaped Bolaamphiphilementioning

confidence: 99%

Stable, ordered multilayers of partially fluorinated bolaamphiphiles at the air–water interface

et al. 2012

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The article presents systematic research on Langmuir films of partially fluorinated bolaamphiphiles of different shapes. Such films exhibit a layering transition from a monolayer to a trilayer during compression on the air-water interface. Further compression gives different results depending on the shape and degree of fluorination of the molecules. Partially fluorinated compounds form well defined multilayers in a reversible process. The balance between rigidity and flexibility of the molecules, adjusted by the fluorination and shape of the molecules, seems to be the key factor in avoiding irreversible aggregation of the molecules and creating ordered multilayer structures. Anchor-shaped bolaamphiphiles form a trilayer and, subsequently, a 9-layer film due to a double roll-over mechanism. In contrast, when trilayer films of X-shaped bolaamphiphiles are compressed, 5-and 7-layer films are created according to a different mechanism. Films of thickness of up to nine layers were transferred from the water surface to solid substrates in a single step procedure without any distortion in the structure of the layers. X-ray reflectometry (XRR) was used to measure the thickness of the layers. Perfect fits of the XRR data to theoretical equations allowed for a conclusion that the multilayers are well-ordered lamellar structures. These investigations lead to an improvement in the general understanding of trilayer and multilayer formation and indicate that only in exceptional cases it happens due to a roll-over process.

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X-ray reflectivity of a Langmuir monolayer on water

Cited by 39 publications

References 6 publications

Interfacial control of nucleation of calcium carbonate under organized stearic acid monolayers

Interfacial control of nucleation of calcium carbonate under organized stearic acid monolayers

Hydrophilic/Hydrophobic Nanostripes in Lipopolymer Monolayers

Stable, ordered multilayers of partially fluorinated bolaamphiphiles at the air–water interface

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