The interfacial structure of water droplets in a hydrophobic liquid

Smolentsev, Nikolay; Smit, Wilbert J.; Bakker, Huib J.; Roke, Sylvie

doi:10.1038/ncomms15548

Cited by 65 publications

(86 citation statements)

References 60 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This report provides important insights into the interfacial bonding and structure at the aqueous-hydrophobic droplet interface where contaminants or other added surfactants have been minimized. Instead of relying on indirect phase interference arguments and surfactant-coated water droplets (9,10,29), this study provides direct measurements of the interfacial aqueous layer in contact with the bare nanoemulsion surface. Success in preparing and characterizing the bonding interactions at these bare droplet surfaces have also provided a more accurate understanding of how interfacial bonding and solvent orientation are altered by the presence of surfactants.…”

Section: Discussionmentioning

confidence: 99%

“…As discussed later, we conclude this higher charge is a potential contributor to the absence of a free OD at nanoemulsion surfaces. Another VSFSS study of reverse nanoemulsions stabilized by 5 mM Span 80 was able to access much more of the OD stretching region of the interfacial water (29). No free OD mode was observed in those spectra either.…”

Section: Water Bonding and Hydrophobic Structuring At The Lcne Surfacementioning

confidence: 98%

See 1 more Smart Citation

Formation and surface-stabilizing contributions to bare nanoemulsions created with negligible surface charge

Carpenter

Tran

Altman

et al. 2019

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

View full text Add to dashboard Cite

The stabilization of nanoemulsions, nanosized oil droplets dispersed in water, is commonly achieved through the addition of surfactants and polymers. However, nanoemulsions in the absence of emulsifiers have been observed to acquire a significant negative charge at their surface, which ultimately contributes to their stability. While the source of this negative charge is disputed to this day, its presence is taken as an inherent property of the aqueous–hydrophobic interface. This report provides a look at the molecular structure and bonding characteristics of bare aqueous–hydrophobic nanoemulsion interfaces. We report the creation of bare nanoemulsions with near zero surface charge, which are marginally stable for several days. The process of creating these low-charge nanoemulsions (LCNEs) required rigorous cleaning procedures and proper solvent storage conditions. Using vibrational sum-frequency scattering spectroscopy, we measure the structure and bonding of the interfacial aqueous and hydrophobic phases. The surfaces of these LCNE samples possess a measurable free OH vibration, not found in previous studies and indicative of a clean interface. Tuning the nanoemulsion charge through addition of anionic surfactants, modeling potential surface-active contaminants, we observe the free OH to disappear and a reorientation of the interfacial hydrophobic molecules at micromolar surfactant concentrations. Notably, the free OH vibration provides evidence for stronger dispersion interactions between water molecules and the hydrophobic phase at the LCNE surface compared with similar planar water–alkane interfaces. We propose the stronger bonding interactions, in addition to an ordered interfacial aqueous layer, contribute to the delayed droplet coalescence and subsequent phase separation.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Water Bonding and Hydrophobic Structuring At The Lcne Surfacementioning

confidence: 98%

Formation and surface-stabilizing contributions to bare nanoemulsions created with negligible surface charge

Carpenter

Tran

Altman

et al. 2019

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

View full text Add to dashboard Cite

show abstract

“…There are ample experimental evidences and computational results, indicating that water molecules around a hydrophobe are tangentially oriented with respect to its surface. Therefore in the construction of the hydration shell we cannot avoid considering the structure of the clathrate hydrates of gases .…”

Section: Methodological Frameworkmentioning

confidence: 99%

“…The fact that regular clathrate cages do not exist in solution on a long scale time it is a well‐established issue . On the other hand, there are evidences that the hydrophobe imposes some geometrical constraints to water molecules in the immediate neighbors that reduce the configurational space with respect to water molecules in the bulk . Very recently, THz/FIR absorption spectroscopy studies suggested that hydration water layer around hydrophobes might contain clathrate‐like structural motifs …”

Section: Methodological Frameworkmentioning

confidence: 99%

The water molecule arrangement over the side chain of some aliphatic amino acids: A quantum chemical and bottom‐up investigation

Lanza

Chiacchio

2020

Int J of Quantum Chemistry

View full text Add to dashboard Cite

The geometry of surrounding water molecules on the side chain of glycine, alanine, α‐aminoisobutyric acid, α‐aminobutyric acid, valine, and related hydrocarbons has been analyzed combining bottom‐up and quantum chemical methodologies. To minimize the cavity size and to prevent water‐water hydrogen bonding loss, the water molecules adopt a shape, resembling the one found in crystal structure of gas clathrate hydrates, with water molecules tangentially oriented to the surface of hydrophobic side chain. The cage is directly hydrogen bonded to the backbone's polar groups, thus hydration shells around hydrophobic and hydrophilic groups are folded together in amphiphilic molecules. The hydrophobe enclathration implies a substantial freedom degree reduction which makes it entropically disfavored. This disadvantageous entropic contribution is partially compensated by the favorable van der Waals interactions with guest in stabilizing clathrate hydrate formation. The water shell around the side chain relates intimately with the side‐chain rotational isomerism. Present data are correlated with the experimental determined populations of the three rotamers, yielding promising results for both α‐aminobutyric acid and valine.

show abstract

“…However, water droplet size is dependent on the surrounding medium. For example, in a hydrophobic liquid, the water droplets can be as small as 100 nm . Moreover, water trapped within specific micro emulsions can reach diameters below 4 nm at low droplet mass fractions .…”

Section: Introductionmentioning

confidence: 99%

Effects of glycol on adsorption dynamics of idealized water droplets on LTA‐3A zeolite surfaces

Olsen

Kvamme

2019

AIChE Journal

View full text Add to dashboard Cite

During production of natural gas, glycol may follow the gas stream due to hydrate prevention or glycol dehumidification. Further dehumidification can be achieved by Linde Type A‐3A zeolite. Local glycol concentrations can form through adsorption to surrounding clay material or zeolite, thus blocking zeolite windows or contaminating condensed water droplets close to the surface. Idealized nanoscale water droplets and their adsorption dynamics onto zeolite structures were simulated, with and without glycol contamination. Blockage of the zeolite windows was also investigated. Water from contaminated droplets adsorbed slower than uncontaminated droplets due to hindrance caused by glycols adsorbed to the zeolite surfaces, thus decreasing initial water loading rates. The adsorption free energy barrier of water was higher for D4R‐terminated zeolite than for alpha cavity‐terminated zeolite. Adsorbed glycols blocked zeolite cavities. However, temperature increase resulted in partial desorption of the glycols, while water desorbed at a lower temperature than for glycol.

show abstract

The interfacial structure of water droplets in a hydrophobic liquid

Cited by 65 publications

References 60 publications

Formation and surface-stabilizing contributions to bare nanoemulsions created with negligible surface charge

Formation and surface-stabilizing contributions to bare nanoemulsions created with negligible surface charge

The water molecule arrangement over the side chain of some aliphatic amino acids: A quantum chemical and bottom‐up investigation

Effects of glycol on adsorption dynamics of idealized water droplets on LTA‐3A zeolite surfaces

Contact Info

Product

Resources

About