Semifluorinated Alkanes at the Air–Water Interface: Tailoring Structure and Rheology at the Molecular Scale

Theodoratou, Antigoni; Jonas, Ulrich; Loppinet, Benoît; Geue, Thomas; Stangenberg, René; Keller, Rabea; Li, Dan; Berger, Rüdiger; Vermant, Jan; Vlassopoulos, Dimitris

doi:10.1021/acs.langmuir.5b04744

Cited by 13 publications

(11 citation statements)

References 31 publications

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“…Also, a similar trend with dispersants was observed in frequency-sweep experiments as shown in Supplementary Material. This response is likely due to phenol molecules disrupting the asphaltene self-association properties, which in turn decreased the elasticity of the asphaltene interface [17,58]. Also, the responses from frequency-sweep experiments showed that the viscoelastic layer (frequency-dependent) was altered to a solid (frequency-independent) film with a higher coverage.…”

Section: B Interfacial Rheology Of Asphaltenes At Air-water Interfacementioning

confidence: 99%

Combined interfacial shear rheology and microstructure visualization of asphaltenes at air-water and oil-water interfaces

Lin

Barman

et al. 2018

Journal of Rheology

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Asphaltenes are surface-active polyaromatic molecules in crude oil that are known to deposit in pipelines or stabilize water droplets by flocculating at interfaces resulting highly viscous emulsions, leading to significant flow assurance problems. Commercial dispersants have been developed to disturb asphaltene aggregation to mitigate deposition, but their role on the interfacial properties of asphaltene films is unclear. In this study, we elucidate asphaltene interfacial rheology at air-water and oil-water interfaces at high and low asphaltene surface coverage and in the presence of dispersants. A modified Langmuir trough with double-wall ring rheometer is used to simultaneously visualize the microstructure of asphaltene interface and measure the rheological responses. Two surface coverages, 0.5 and 4 lg cm À2 , show widely different rheological responses at air-water interfaces. Strong yielding behavior was observed for higher coverage while a less yielding behavior and wider linear viscoelastic regime were observed for the lower coverage. Additionally, asphaltenes at decane-water interfaces were less shear-thinning than at air-water interfaces. Surface pressure-area compression-expansion curves show that the interface is more compressible in the presence of commercial chemical dispersants. This combined imaging and interfacial rheology platform provide an effective method to correlate asphaltene microstructure to interfacial rheological properties. V

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Section: B Interfacial Rheology Of Asphaltenes At Air-water Interfacementioning

confidence: 99%

Combined interfacial shear rheology and microstructure visualization of asphaltenes at air-water and oil-water interfaces

Lin

Barman

et al. 2018

Journal of Rheology

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“…Interfacial rheological measurements are useful because they cleanly decouple contributions of the surface and the bulk and have been extensively used to study liquid–liquid and air–liquid interfaces. − Despite its known benefits, interfacial rheology has yet to be used to probe the viscoelastic properties of liquid metal oxide skins. One study used a bicone geometry as an interfacial rheological tool to measure the viscoelastic properties of oxide skin on Galinstan and the effects of HCl addition on the skin .…”

Section: Introductionmentioning

confidence: 99%

Interfacial Rheology of Gallium-Based Liquid Metals

et al. 2019

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Gallium and its alloys react with oxygen to form a native oxide that encapsulates the liquid metal with a solid "skin". The viscoelasticity of this skin is leveraged in applications such as soft electronics, 3D printing, and components for microfluidic devices. In these applications, rheological characterization of the oxide skin is paramount for understanding and controlling liquid metals. Here, we provide a direct comparison of the viscoelastic properties for gallium-based liquid metals and illustrate the effect of different subphases and addition of a dopant on the elastic nature of the oxide skin. The du Nouÿ ring method is used to investigate the interfacial rheology of oxide skins formed by galliumbased liquid metal alloys. The results show that the oxide layer on gallium, eutectic gallium−indium, and Galinstan are viscoelastic with a yield stress. Furthermore, the storage modulus of the oxide layer is affected by exposure to water or when small amounts of aluminum dopant are added to the liquid metals. The former scenario decreases the interfacial storage modulus of the gallium by 35−85% while the latter increases the interfacial storage modulus by 25−45%. The presence of water also changes the chemical composition of the oxide skin. Scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy suggest that a microstructural evolution of the interface occurs when aluminum preferentially migrates from the bulk to the surface. These studies provide guidance on selecting liquid metals as well as simple methods to optimize their rheological behavior for future applications.

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“…The investigation of interfacial rheology is applied to understand the viscoelastic properties, which provide the modulus and relaxation behaviour [190] and to gain information about the structure-rheology interplay. The two-dimensional properties for a variety of systems like synthetic (co)polymers [115,191,192], mixed protein layers [193], biomolecules [45,194,195] and low molecular weight molecules [196] have been performed. However, investigations on pure protein layers and their interaction with water-soluble molecules are still challenging.…”

Section: Discussionmentioning

confidence: 99%

Evaluating polymeric biomaterial–environment interfaces by Langmuir monolayer techniques

Schöne

Roch

Schulz

et al. 2017

J. R. Soc. Interface.

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Polymeric biomaterials are of specific relevance in medical and pharmaceutical applications due to their wide range of tailorable properties and functionalities. The knowledge about interactions of biomaterials with their biological environment is of crucial importance for developing highly sophisticated medical devices. To achieve optimal performance, a description at the molecular level is required to gain better understanding about the surface of synthetic materials for tailoring their properties. This is still challenging and requires the comprehensive characterization of morphological structures, polymer chain arrangements and degradation behaviour. The review discusses selected aspects for evaluating polymeric biomaterial-environment interfaces by Langmuir monolayer methods as powerful techniques for studying interfacial properties, such as morphological and degradation processes. The combination of spectroscopic, microscopic and scattering methods with the Langmuir techniques adapted to polymers can substantially improve the understanding of their behaviour.

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Semifluorinated Alkanes at the Air–Water Interface: Tailoring Structure and Rheology at the Molecular Scale

Cited by 13 publications

References 31 publications

Combined interfacial shear rheology and microstructure visualization of asphaltenes at air-water and oil-water interfaces

Combined interfacial shear rheology and microstructure visualization of asphaltenes at air-water and oil-water interfaces

Interfacial Rheology of Gallium-Based Liquid Metals

Evaluating polymeric biomaterial–environment interfaces by Langmuir monolayer techniques

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