Erratum: X-ray grazing incidence diffraction from alkylsiloxane monolayers on silicon wafers [J. Chem. Phys. <b>95</b>, 2854 (1991)]

Tidswell, I. M.; Rabedeau, T. A.; Pershan, Peter S.; Kosowsky, S. D.; Folkers, John P.; Whitesides, George M.

doi:10.1063/1.465126

Cited by 8 publications

(9 citation statements)

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“…The reflectivity shows sharp dips and oscillations owing to interference between x rays reflected at the silicon-organic and organic-air interfaces, and is thus highly sensitive to the monolayer thickness D. The first intensity dip gives a rough estimate of the thickness D: D =Q min [24][25] A, where the range depends on the sample. This is in excellent agreement with the landmark study by Tidswell et al of octadecylsilane monolayers in air [27]. Figure 1 shows the derived electron density profile corresponding to the best-fit reflectivity.…”

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confidence: 85%

“…For quantification, least-squares comparisons between experimental and calculated reflectivities were made using the widely used PARRAT formalism [28], in which interfacial electron density is modeled with a series of error function profiles [26,27]. Fits of monolayers in air fixed parameters used to fit reflectivity of these same monolayers immersed in water, including the thicknesses, scattering length densities, and roughnesses for silicon oxide and bulk silicon layers.…”

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confidence: 99%

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How Water Meets a Hydrophobic Surface

et al. 2006

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Synchrotron x-ray reflectivity measurements of the interface between water and methyl-terminated octadecylsilane monolayers with stable contact angle >100 degrees conclusively show a depletion layer, whether or not the water is degassed. The thickness is of order one water molecule: 2-4 Angstrom with electron density <40% that of bulk water. Considerations of coherent and incoherent averaging of lateral inhomogeneities show that the data cannot be explained by "nanobubbles." When the contact angle is lower, unstable in time, or when monolayers fail to be sufficiently smooth over the footprint of the x-ray beam, there is no recognizable depletion.

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How Water Meets a Hydrophobic Surface

et al. 2006

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“…Consequently, we expect that for SAMs of OTS either the solvent is not excluded significantly from the compressed region under the tip or that solvent may ''channel'' through the SAM via a network of defects. ''Channeling'' that results in a larger diffusion coefficient is plausible because the molecular areas achieved in SAMS of OTS 0.21-25 nm 2 /chain 35,36,53 are larger than the molecular area of the 0.19 nm 2 /chain of the LB films of arachidic acid used by Vanderlick and coworkers. Also, SAMs of OTS do not display a long-range, quasicrystalline structure.…”

Section: Influence Of Load On Friction Maxima Changes With Chain Densitymentioning

confidence: 99%

The effect of chain density on the frictional behavior of surfaces modified with alkylsiloxanes and immersed in n-alcohols

Clear

Nealey

2001

The Journal of Chemical Physics

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Concepts of viscoelastic behavior of bulk polymer systems were used to describe maxima in the friction behavior of self-assembled monolayers ͑SAMs͒ measured with lateral force microscopy ͑LFM͒ as a function of sliding velocity and applied normal load in the presence of solvents ͑plasticizers͒. The objective of this study was to investigate whether decreases in the chain density of the SAMs caused maxima in the friction force to shift to higher sliding velocities; such a shift is indicative of shorter chain relaxation times in less dense, less ordered SAMs. Complete SAMs were formed from octadecyltrichlorosilane ͑OTS͒ and partial SAMs were formed from n-octadecylmethyldichlorosilane ͑2Cl͒ and n-octadecyldimethyldichlorosilane ͑1Cl͒, all on silicon/silicon dioxide substrates. With decreasing chain density, solvent partitioning into the monolayer should increase as OTSϽ2ClϽ1Cl. In butanol and pentanol, the maxima in the friction force shifted to higher sliding velocities with decreasing chain density, and the relaxation times calculated for the partial 2Cl films were an order of magnitude shorter than those for SAMs of OTS. For both SAMs of OTS and 2Cl films, maxima shifted to lower sliding velocities with increases in the applied normal load and with increases in the chain length n of the solvent. The higher compressibility of 2Cl films caused greater shifts in the maxima for similar increases in the applied normal load. The increase with n was consistent with both a mechanism of solvent partitioning controlled by the free volume distribution in the SAM and a mechanism of insertion. The relaxation times of the alkyl chains were related to a molecular model of energy dissipation involving the adsorption and desorption of the chain ends to and from the surface of the probe tip.

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“…We can measure diffraction data from the thin film without peeling it from the substrate. As the use of synchrotron radiation increases, this method has been applied to a wide variety of thin‐film samples, such as monolayers at the water–air interface,11, 12 self‐assembled monolayers,13, 14 polymer surfaces,15, 16 and liquid‐crystalline polymers 17. It is also advantageous that the in‐plane structure, which cannot be detected with the conventional X‐ray diffraction method at reflection mode, can be measured with the TRXD system.…”

Section: Introductionmentioning

confidence: 99%

Total-reflection X-ray diffraction study of friction-transferred poly(tetrafluoroethylene) film

Tanigaki¹,

Yoshida²,

Kaito³

et al. 2001

J. Polym. Sci. B Polym. Phys.

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The orientational structure of the friction‐transferred poly(tetrafluoroethylene) (PTFE) film, which consists of highly oriented polymer strands, was evaluated with energy‐dispersive total‐reflection X‐ray diffractometry. In the film, each PTFE molecule is oriented along the friction direction, and PTFE crystallites have a preferred orientation with respect to the substrate surface. The orientational distribution of the chain direction was quantitatively evaluated. The half‐width of the distribution was determined to be about 3°. The dependence of the orientational distribution on temperature is discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 432–438, 2001

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Erratum: X-ray grazing incidence diffraction from alkylsiloxane monolayers on silicon wafers [J. Chem. Phys. 95, 2854 (1991)]

Cited by 8 publications

References 0 publications

How Water Meets a Hydrophobic Surface

How Water Meets a Hydrophobic Surface

The effect of chain density on the frictional behavior of surfaces modified with alkylsiloxanes and immersed in n-alcohols

Total-reflection X-ray diffraction study of friction-transferred poly(tetrafluoroethylene) film

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