X-ray reflectivity measurements of liquid/solid interfaces under high hydrostatic pressure conditions

Wirkert, Florian J.; Paulus, Michael; Nase, Julia; Möller, Johannes; Kujawski, Simon; Sternemann, Christian; Tolan, Metin

doi:10.1107/s1600577513021516

Cited by 30 publications

(23 citation statements)

References 45 publications

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“…The depletion is due, arguably [41][42][43][44] , to the monolayer's lower-density CH 3 terminal group, found also for surface-frozen alkanes 36 and alcohols 45 , at and at SAM/water interfaces. [46][47][48][49] As previously demonstrated 36,41 , the strong coupling between ρ and d in a thin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 slab does not allow their independent fit, only that of their product. Thus, the depletion layer's density was fixed at ρ 4 = 0.1 e/Å 3 and only d 4 and σ 4 were refined.…”

Section: Surface Normal Structurementioning

confidence: 99%

Order and Melting in Self-Assembled Alkanol Monolayers on Amorphous SiO₂

et al. 2015

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Molecular self-assembly is a key to wide-ranging nano-and micro-scale applications in numerous fields. Understanding its underlying molecular level science is therefore of prime importance. This study resolves theÅ-scale structure of the earliest and simplest self-assembled monolayer (SAM): octadecanol on amorphous-SiO 2 -terminated Si (001) substrate, and determines the structure's temperature evolution. At low temperatures lateral hexagonal order exists, with close-packed, surface-normal molecules. ∼ 12 • C above the alkanol's bulk melting a fully-reversible disordering transition occurs to a novel "stretched liquid" phase, laterally disordered, but only ∼ 15% thinner SAM than the crystalline phase. The SAM persists to ≥ 100 • C. A thermodynamic model yields here a headgroup-substrate bond energy ∼ 40% lower than on crystalline sapphire, highlighting the importance of the substrate's order, and near-epitaxy, for the SAM's ordering and stability.

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Section: Surface Normal Structurementioning

confidence: 99%

Order and Melting in Self-Assembled Alkanol Monolayers on Amorphous SiO₂

et al. 2015

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“…For the measurements a reflectivity sample cell developed for applying hydrostatic pressure was used [32]. The experiments were performed with an X-ray wavelength of k = 0.452 Å.…”

Section: X-ray Reflectivity Xrr Measurementsmentioning

confidence: 99%

The effect of temperature on supported dipalmitoylphosphatidylcholine (DPPC) bilayers: Structure and lubrication performance

Wang

Zander²,

Liu

et al. 2015

Journal of Colloid and Interface Science

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Phospholipids fulfill an important role in joint lubrication. They, together with hyaluronan and glycoproteins, are the biolubricants that sustain low friction between cartilage surfaces bathed in synovial fluid. In this work we have investigated how the friction force and load bearing capacity of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers on silica surfaces are affected by temperature, covering the temperature range 25-52°C. Friction forces have been determined utilizing the AFM colloidal probe technique, which showed that DPPC bilayers are able to provide low friction forces over the whole temperature interval. However, the load bearing capacity is improved at higher temperatures. We interpret this finding as being a consequence of lower rigidity and higher self-healing capacity of the DPPC bilayer in the liquid disordered state compared to the gel state. The corresponding structure of solid supported DPPC bilayers at the silica-liquid interface has been followed using X-ray reflectivity measurements, which suggests that the DPPC bilayer is in the gel phase at 25°C and 39°C and in the liquid disordered state at 55°C. Well-defined bilayer structures were observed for both phases. The deposited DPPC bilayers were also imaged using AFM PeakForce Tapping mode, and these measurements indicated a less homogeneous layer at temperatures below 37°C.

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“…XRR experiments were performed in a custom‐built pressure cell . The sample system consisted of OTS‐covered silicon wafers with a surface of 7.8×7.8 mm 2 in 350 μl of ultrapure water (MilliQ, resistance R= 18.2 MΩcm).…”

Section: Figurementioning

confidence: 99%

The Hydrophobic Gap at High Hydrostatic Pressures

et al. 2017

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We have gained new insight into the so-called hydrophobic gap,amolecularly thin region of decreased electron density at the interface between water and as olid hydrophobic surface,b yX -rayr eflectivity experiments and molecular dynamics simulations at different hydrostatic pressures.P ressure variations show that the hydrophobic gap persists up to apressure of 5kbar.The electron depletion in the interfacial region strongly decreases with an increase in pressure,i ndicating that the interfacial region is compressed more strongly than bulk water.The decrease is most significant up to 2kbar;b eyond that, the pressure response of the depletion is less pronounced.

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X-ray reflectivity measurements of liquid/solid interfaces under high hydrostatic pressure conditions

Cited by 30 publications

References 45 publications

Order and Melting in Self-Assembled Alkanol Monolayers on Amorphous SiO₂

Order and Melting in Self-Assembled Alkanol Monolayers on Amorphous SiO₂

The effect of temperature on supported dipalmitoylphosphatidylcholine (DPPC) bilayers: Structure and lubrication performance

The Hydrophobic Gap at High Hydrostatic Pressures

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X-ray reflectivity measurements of liquid/solid interfaces under high hydrostatic pressure conditions

Cited by 30 publications

References 45 publications

Order and Melting in Self-Assembled Alkanol Monolayers on Amorphous SiO2

Order and Melting in Self-Assembled Alkanol Monolayers on Amorphous SiO2

The effect of temperature on supported dipalmitoylphosphatidylcholine (DPPC) bilayers: Structure and lubrication performance

The Hydrophobic Gap at High Hydrostatic Pressures

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Product

Resources

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Order and Melting in Self-Assembled Alkanol Monolayers on Amorphous SiO₂

Order and Melting in Self-Assembled Alkanol Monolayers on Amorphous SiO₂