Infrared and electron diffraction studies of transient stages in very thin Langmuir—Blodgett films

Bonnerot, A.; Chollet, Pierre-Alain; Frisby, H.; Hoclet, M.

doi:10.1016/0301-0104(85)87045-2

Cited by 87 publications

(40 citation statements)

References 15 publications

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“…22,26 Disordered chains have peak positions of 2856 and 2928 cm −1 for υ s (CH 2 ) and υ a -(CH 2 ), respectively. 22 Reported literature values on the υ s (CH 2 ) and υ a (CH 2 ) modes for self-assembled monolayers similar or identical to those used here yield 2852 and 2921 cm −1 for condensed DPPC, 26 2853 and 2920 cm −1 for docosanoic acid, 27 and 2850 and 2917 cm −1 for OTS on silica. 22 These values correlate well with the adsorption behavior of hGH on the different alkyl chains if it is assumed that adsorption is reduced as the less ordered alkyl chains lose entropy upon hGH adsorption.…”

Section: Adsorption and Desorption Kineticssupporting

confidence: 72%

Human Growth Hormone Adsorption Kinetics and Conformation on Self-Assembled Monolayers

1998

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The adsorption process of the recombinant human growth hormone on organic films, created by self-assembly of octadecyltrichlorosilane, arachidic acid, and dipalmitoylphosphatidylcholine, is investigated and compared to adsorption on silica and methylated silica substrates. Information on the adsorption process of human growth hormone (hGH) is obtained by using total internal reflection fluorescence (TIRF). The intensity, spectra, and quenching of the intrinsic fluorescence emitted by the growth hormone's single tryptophan are monitored and related to adsorption kinetics and protein conformation. For the various alkylated hydrophobic surfaces with differences in surface density and conformational freedom it is observed that the adsorbed amount of growth hormone is relatively large if the alkyl chains are in an ordered structure while the amounts adsorbed are considerably lower for adsorption onto less ordered alkyl chains of fatty acid and phospholipid layers. Adsorption on methylated surfaces results in a relatively large conformational change in the growth hormone's structure, as displayed by a 7 nm blue shift in emission wavelength and a large increase in the effectiveness of fluorescence quenching. Conformational changes are less evident for hGH adsorption onto the fatty acid and phospholipid alkyl chains. Adsorption kinetics on the hydrophilic head groups of the self-assembled monolayers are similar to those on solid hydrophilic surfaces. The relatively small conformational changes in the hGH structure observed for adsorption on silica are even further reduced for adsorption on fatty acid head groups.

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Section: Adsorption and Desorption Kineticssupporting

confidence: 72%

Human Growth Hormone Adsorption Kinetics and Conformation on Self-Assembled Monolayers

1998

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“…When the monolayer is cooled well below room temperature, the in-plane lattice distorts to a nonhexagonal arrangement with fine 600 twinning of oriented regions much less than 103 A across (S.G., H. W. Deckman, J. H. Dunsmuir, and M. S. Alvarez, unpublished results). In the second case, in which another layer is deposited on top of the monolayer, the net is again distorted into a nonhexagonal symmetry with 600 twinning now occurring on a larger length scale (on the order of 10 ,tm) (16)(17)(18)(19)(20); S.G., H.W.D., J.H.D., and M.S.A., unpublished results). In fact, a progression from hexagonal to orthorhombic symmetry has been observed as the number of layers is increased from 1 to 10 (19,20).…”

Section: In-plane Ordermentioning

confidence: 92%

“…In the second case, in which another layer is deposited on top of the monolayer, the net is again distorted into a nonhexagonal symmetry with 600 twinning now occurring on a larger length scale (on the order of 10 ,tm) (16)(17)(18)(19)(20); S.G., H.W.D., J.H.D., and M.S.A., unpublished results). In fact, a progression from hexagonal to orthorhombic symmetry has been observed as the number of layers is increased from 1 to 10 (19,20). These few layer structures again do not always exactly fit the known structures of bulk chain molecules but approach this limit as the number of layers is increased.…”

Section: In-plane Ordermentioning

confidence: 92%

“…These "free-volume-allowed" tilts can be much smaller than the ratcheted tilts of the densest phases and must compete with the formation of gauche conformers for excess free volume. In the literature on monolayers, the tilt of the molecules is shown to depend on the particular material under examination (3,4,19,20,(30)(31)(32)36). Often, the molecules of monolayers are reported to be roughly normal to the surface; in multilayer assemblies the larger angles characteristic of the densest structures are reported (16)(17)(18).…”

Section: Tilt Orderingmentioning

confidence: 99%

“…Often, the molecules of monolayers are reported to be roughly normal to the surface; in multilayer assemblies the larger angles characteristic of the densest structures are reported (16)(17)(18). In fact, a slow crossover as a function of number of layers in an LB assembly has been discussed (19,20).…”

Section: Tilt Orderingmentioning

confidence: 99%

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Molecular structure of surfactant-coated surfaces

Garoff

1987

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

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The structure of surfactants on solid surfaces arises from the competition between the molecular forces that drive the formation of bulk phases of these molecules and the constraints of the solid interface. These monolayers exhibit bond-oriented ordering and undergo both reversible and irreversible phase transformations.Historically, the impetus for studying monomolecular layers at interfaces was the dramatic alteration of the interfacial tension of a fluid by such layers (1). This area of research has greatly expanded over the years, and many other macroscopic properties of an interface have been found to be altered by these monolayers. Examples of these interfacial properties include the wetting of a solid by a liquid, the lubrication of two solid surfaces moving past each other, the transport of materials between the bulk phases separated by the monolayer, and the alignment of bulk liquid crystalline phases in contact with the monolayer. In more recent times, similar monolayers have been recognized as potential models for components of cell membranes and as constituents for multilayer assemblies, molecularly engineered to produce electronic and optical devices. These macroscopic interfacial properties which are so greatly affected by these monolayers have tremendous impact on a wide variety of technologies. The search for the origins of these macroscopic interfacial phenomena has led us to a close examination of the structure of the monomolecular films that so dramatically alter them. However, as we have explored these origins, we have found that the intra-and intermolecular order in surfactant monolayers on solid surfaces is a topic of rich scientific interest on its own.The state of ordering in these monolayers on solid surfaces is different than that in bulk lamellar phases (e.g., smectic thermotropic liquid crystals, lamellar lyotropic liquid crystals, and lamellar crystals) of these molecules. This structure arises from a competition between the intermolecular forces responsible for the order in bulk phases and the unique influences and constraints of the interfacial region in which the monolayer lies. Frequently, ordering in monolayers, particularly on the nonideal, hydrophilic substrates usually encountered, is assumed to be some kinetically frozen configuration, far from equilibrium, and on the verge of collapse. Evidence of lattice expansions, reversible phase transitions, and long-term stability indicates that these monolayers are often in deep, metastable states and respond to many thermodynamic stimuli. In fact, the structure of the monolayer is a metastable state governed by the statistical mechanics of the manifold of states existing for the 2-dimensional arrangement of the molecules and only weakly coupled-through a very large energy barrier-to states with a three-dimensional arrangement of the molecules. Therefore, the structure of surfactant monolayers on solid surfaces should be viewed through the models and theories describing the fundamental structure of interfacial phases. Unlike ...

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Reflection–Absorption Spectroscopy of Thin Films on Metallic Substrates

Umemura

2001

Handbook of Vibrational Spectroscopy

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The sections in this article are Introduction Mathematical Treatments and Characteristics of RAS Isotropic Film Uniaxial Film Evaluation of Molecular Orientation Using RAS Comparison with KBr Pellet Spectra Comparison with Transmission Spectra on IR ‐Transparent Substrates RAS Measured with Unpolarized Light Application to the Study of Thin Films L angmuir– B lodgett Films Self‐Assembled Monolayers Vacuum‐Evaporated Films Conclusion

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Infrared and electron diffraction studies of transient stages in very thin Langmuir—Blodgett films

Cited by 87 publications

References 15 publications

Human Growth Hormone Adsorption Kinetics and Conformation on Self-Assembled Monolayers

Human Growth Hormone Adsorption Kinetics and Conformation on Self-Assembled Monolayers

Molecular structure of surfactant-coated surfaces

Reflection–Absorption Spectroscopy of Thin Films on Metallic Substrates

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