Insight into Liquid/Fluid Interfaces

Topic Information

Dear Colleagues,

The reduction of dimensions associated with the presence of a liquid/fluid interface lead to the emergence of specific equilibrium and dynamic features, which are far from those found in traditional 3D systems. Therefore, the understanding of the new physic aspects emerging at liquid/fluid interfaces in relation to bulk liquids is essential for exploiting the entire potential of liquid/fluid interfaces in material science. This is as liquid/fluid interfaces emerge as very good candidates for the design of new functional materials by confining different types of materials, e.g., polymers, surfactants, colloids, or even small molecules, by direct spreading or self-assembly from solutions. However, the development of the potential applications of liquid/fluid interfaces in the fabrication of materials requires a deep understanding of the physico-chemical foundations governing the formation of layers at liquid/fluid interfaces, as well as the characterization of the structures and properties of such interfacial films. This is of paramount importance as the behavior of interfaces is strongly affected by the external perturbations, including additives (e.g., pollutants), mechanical and thermal stresses, or magnetic and electric fields. These affect to the interfacial flows and the exchange of material between the adjacent phases and the interface, governing the equilibrium and dynamic properties of the liquid/fluid interface, which make the exploration of the theoretical and practical aspects involved in the creation of liquid/fluid interfaces essential. This Topic is devoted to the fundamental and applied aspects involved in the study of liquid/fluid interfaces, with the aim of providing a comprehensive perspective on the current status of the research field. It is expected that this will help to provide a bridge between the most fundamental knowledge on fluid interface, and the development of new applications based on it, closing the gap between different views.

Dr. Eduardo Guzmán
Dr. Armando Maestro
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Coatings coatings	2.9	5.0	2011	14.5 Days	CHF 2600
Colloids and Interfaces colloids	2.5	3.9	2017	22 Days	CHF 1600
Gels gels	5.0	4.7	2015	10.8 Days	CHF 2100
Molecules molecules	4.2	7.4	1996	15.1 Days	CHF 2700
Polymers polymers	4.7	8.0	2009	14.5 Days	CHF 2700

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Published Papers (8 papers)

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All Coatings Colloids and Interfaces Gels Molecules Polymers

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32 pages, 4515 KiB  

Open AccessReview

Fluid Interfaces as Models for the Study of Lipid-Based Films with Biophysical Relevance

by Pablo G. Argudo, Armando Maestro and Eduardo Guzmán

Coatings 2023, 13(9), 1560; https://doi.org/10.3390/coatings13091560 - 6 Sep 2023

Cited by 4 | Viewed by 1978

Abstract

This comprehensive review aims to provide a deep insight into the fascinating field of biophysics in living organisms through the study of model fluid interfaces that mimic specific lipid-based structures with biophysical relevance. By delving into the study of these physiological fluid interfaces, [...] Read more.

This comprehensive review aims to provide a deep insight into the fascinating field of biophysics in living organisms through the study of model fluid interfaces that mimic specific lipid-based structures with biophysical relevance. By delving into the study of these physiological fluid interfaces, we can unravel crucial aspects of their behavior, lateral organization, and functions. Through specific examples, we will uncover the intricate dynamics at play and shed light on potential pathogenic conditions that may result from alterations in these interfaces. A deeper understanding of these aspects can lead to the emergence of novel technologies and medical advances, potentially leading to the development of innovative treatments and diagnostic tools. Full article

(This article belongs to the Topic Insight into Liquid/Fluid Interfaces)

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17 pages, 4441 KiB  

Open AccessArticle

The Transport of Charged Molecules across Three Lipid Membranes Investigated with Second Harmonic Generation

by Baomei Xu, Jianhui Li, Shuai Zhang, Johar Zeb, Shunli Chen, Qunhui Yuan and Wei Gan

Molecules 2023, 28(11), 4330; https://doi.org/10.3390/molecules28114330 - 25 May 2023

Cited by 5 | Viewed by 2474

Abstract

Subtle variations in the structure and composition of lipid membranes can have a profound impact on their transport of functional molecules and relevant cell functions. Here, we present a comparison of the permeability of bilayers composed of three lipids: cardiolipin, DOPG (1,2-dioleoyl-sn-glycero-3-phospho-(1′-rac-glycerol), and [...] Read more.

Subtle variations in the structure and composition of lipid membranes can have a profound impact on their transport of functional molecules and relevant cell functions. Here, we present a comparison of the permeability of bilayers composed of three lipids: cardiolipin, DOPG (1,2-dioleoyl-sn-glycero-3-phospho-(1′-rac-glycerol), and POPG (1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1′-rac-glycerol)). The adsorption and cross-membrane transport of a charged molecule, D289 (4-(4-diethylaminostyry)-1-methyl-pyridinium iodide), on vesicles composed of the three lipids were monitored by second harmonic generation (SHG) scattering from the vesicle surface. It is revealed that structural mismatching between the saturated and unsaturated alkane chains in POPG leads to relatively loose packing structure in the lipid bilayers, thus providing better permeability compared to unsaturated lipid bilayers (DOPG). This mismatching also weakens the efficiency of cholesterol in rigidifying the lipid bilayers. It is also revealed that the bilayer structure is somewhat disturbed by the surface curvature in small unilamellar vesicles (SUVs) composed of POPG and the conical structured cardiolipin. Such subtle information on the relationship between the lipid structure and the molecular transport capability of the bilayers may provide clues for drug development and other medical and biological studies. Full article

(This article belongs to the Topic Insight into Liquid/Fluid Interfaces)

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17 pages, 5282 KiB  

Open AccessArticle

Ultrafine Kaolinite Removal in Recycled Water from the Overflow of Thickener Using Electroflotation: A Novel Application of Saline Water Splitting in Mineral Processing

by Felipe M. Galleguillos Madrid, María P. Arancibia-Bravo, Felipe D. Sepúlveda, Freddy A. Lucay, Alvaro Soliz and Luis Cáceres

Molecules 2023, 28(9), 3954; https://doi.org/10.3390/molecules28093954 - 8 May 2023

Cited by 4 | Viewed by 2056

Abstract

The presence of ultrafine clay particles that are difficult to remove by conventional filtration creates many operational problems in mining processing systems. In this work, the removal of clay suspensions has been investigated using an electroflotation (EF) process with titanium electrodes. The results [...] Read more.

The presence of ultrafine clay particles that are difficult to remove by conventional filtration creates many operational problems in mining processing systems. In this work, the removal of clay suspensions has been investigated using an electroflotation (EF) process with titanium electrodes. The results show that EF is a viable and novel alternative for removing ultrafine particles of kaolinite-type clay present in sedimentation tank overflows with low salt concentrations (<0.1 mol/L) in copper mining facilities based on the saline water splitting concept. Maximum suspended solid removal values of 91.4 and 83.2% in NaCl and KCl solutions, respectively, were obtained under the experimental conditions of the constant applied potential of 20 V/SHE, salinity concentration of 0.1 mol/L, and electroflotation time of 10 and 20 min in NaCl and KCl solutions, respectively. Furthermore, the visual evidence of particle aggregation by flocculation during the experiments indicates a synergy between EF and electrocoagulation (EC) that enhances the removal of ultrafine particles of kaolinite. Full article

(This article belongs to the Topic Insight into Liquid/Fluid Interfaces)

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15 pages, 4606 KiB  

Open AccessArticle

Prediction of Slip Velocity at the Interface of Open-Cell Metal Foam Using 3D Printed Foams

by Khairul Azhar Mustapha, Fadhilah Shikh Anuar and Fatimah Al-Zahrah Mohd Saat

Colloids Interfaces 2022, 6(4), 80; https://doi.org/10.3390/colloids6040080 - 12 Dec 2022

Cited by 3 | Viewed by 2718

Abstract

An open-cell metal foam gains a lot of interest from researchers due to its unique porous structure, which provides high surface area and good tortuosity, as well as being lightweight. However, the same structure also induces a massive pressure drop which requires an [...] Read more.

An open-cell metal foam gains a lot of interest from researchers due to its unique porous structure, which provides high surface area and good tortuosity, as well as being lightweight. However, the same structure also induces a massive pressure drop which requires an optimum design to suit applications, for example, a partially filled setup or staggered design. Thus, better attention to the slip velocity at the interface between the porous structure and non-porous region is required to maximize its potential, especially in thermal fluid applications. This study proposed a slip velocity model of an open-cell metal foam by using a reverse engineering method and 3D printing technology. A series of experiments and a dimensionless analysis using the Buckingham-Pi theorem were used to compute the slip velocity model. Results show that the pressure drop increases with decreasing pore size. However, the blockage ratio effects would be more significant on the pressure drop with foams of smaller pore sizes. The proposed slip velocity model for an open-cell metal foam agrees with the experimental data, where the predicted values fall within measurement uncertainty. Full article

(This article belongs to the Topic Insight into Liquid/Fluid Interfaces)

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16 pages, 2815 KiB  

Open AccessArticle

Synergy in Aqueous Systems Containing Bioactive Ingredients of Natural Origin: Saponin/Pectin Mixtures

by Hristina Petkova, Ewelina Jarek, Mitko Doychinov, Marcel Krzan and Elena Mileva

Polymers 2022, 14(20), 4362; https://doi.org/10.3390/polym14204362 - 16 Oct 2022

Cited by 1 | Viewed by 1828

Abstract

Biocompatible and biodegradable ingredients of natural origin are widely used in the design of foam and emulsion systems with various technological applications in the food, cosmetics and pharmaceutical industries. The determination of the precise composition of aqueous solution formulations is a key issue [...] Read more.

Biocompatible and biodegradable ingredients of natural origin are widely used in the design of foam and emulsion systems with various technological applications in the food, cosmetics and pharmaceutical industries. The determination of the precise composition of aqueous solution formulations is a key issue for the achievement of environmentally-friendly disperse systems with controllable properties and reasonable stability. The present work is focused on the investigation of synergistic interactions in aqueous systems containing Quillaja saponins and Apple pectins. Profile analysis tensiometer (PAT-1) is applied to study the surface tension and surface dilational rheology of the adsorption layers at the air/solution interface. The properties and the foam films (drainage kinetics, film thickness, disjoining pressure isotherm, critical pressure of rupture) are investigated using the thin-liquid-film (TLF) microinterferometric method of Scheludko–Exerowa and the TLF-pressure-balance technique (TLF-PBT). The results demonstrate that the structure and stability performance of the complex aqueous solutions can be finely tuned by changing the ratio of the bioactive ingredients. The attained experimental data evidence that the most pronounced synergy effect is registered at a specific saponin:pectin ratio. The obtained information is essential for the further development of aqueous solution formulations intended to achieve stable foams based on mixtures of Quillaja saponins and Apple pectins in view of future industrial, pharmaceutical and biomedical applications. Full article

(This article belongs to the Topic Insight into Liquid/Fluid Interfaces)

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14 pages, 3504 KiB  

Open AccessArticle

A Phase Field Approach to Modeling Heavy Metal Impact in Plasma Spraying

by Mingguang Shen and Ben Q. Li

Coatings 2022, 12(10), 1383; https://doi.org/10.3390/coatings12101383 - 22 Sep 2022

Cited by 1 | Viewed by 1927

Abstract

A phase field model enhanced with the shared memory parallelism OpenMP was proposed, capable of modeling the impact of a heavy metal droplet under practical plasma spraying conditions. The finite difference solution of the Navier-Stokes equations, coupled with the Cahn-Hilliard equation, tracks the [...] Read more.

A phase field model enhanced with the shared memory parallelism OpenMP was proposed, capable of modeling the impact of a heavy metal droplet under practical plasma spraying conditions. The finite difference solution of the Navier-Stokes equations, coupled with the Cahn-Hilliard equation, tracks the gas-liquid interface. The liquid fraction, defined over the computational domain, distinguishes fluid from solid. The model is employed for Ni and YSZ drop impacts after ruling out the effect of mesh size. The model exhibits a reasonable parallel-computing efficiency, and the predicted maximum spread factors agree well with analytical models. Full article

(This article belongs to the Topic Insight into Liquid/Fluid Interfaces)

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17 pages, 3251 KiB  

Open AccessArticle

Oil Droplet Coalescence in W/O/W Double Emulsions Examined in Models from Micrometer- to Millimeter-Sized Droplets

by Nico Leister, Chenhui Yan and Heike Petra Karbstein

Colloids Interfaces 2022, 6(1), 12; https://doi.org/10.3390/colloids6010012 - 8 Feb 2022

Cited by 15 | Viewed by 4501

Abstract

Water-in-oil-in-water (W₁/O/W₂) double emulsions must resist W₁–W₁, O–O and W₁–W₂ coalescence to be suitable for applications. This work isolates the stability of the oil droplets in a double emulsion, focusing on the [...] Read more.

Water-in-oil-in-water (W₁/O/W₂) double emulsions must resist W₁–W₁, O–O and W₁–W₂ coalescence to be suitable for applications. This work isolates the stability of the oil droplets in a double emulsion, focusing on the impact of the concentration of the hydrophilic surfactant. The stability against coalescence was measured on droplets ranging in size from millimeters to micrometers, evaluating three different measurement methods. The time between the contact and coalescence of millimeter-sized droplets at a planar interface was compared to the number of coalescence events in a microfluidic emulsion and to the change in the droplet size distributions of micrometer-sized single and double emulsions. For the examined formulations, the same stability trends were found in all three droplet sizes. When the concentration of the hydrophilic surfactant is reduced drastically, lipophilic surfactants can help to increase the oil droplets’ stability against coalescence. This article also provides recommendations as to which purpose each of the model experiments is suited and discusses advantages and limitations compared to previous research carried out directly on double emulsions. Full article

(This article belongs to the Topic Insight into Liquid/Fluid Interfaces)

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11 pages, 5564 KiB  

Open AccessArticle

The Improvement of the Performance of Sky-Blue OLEDs by Decreasing Interface Traps and Balancing Carriers with PSVA Treatment

by Yijun Ning, Suling Zhao, Dandan Song, Bo Qiao, Zheng Xu, Yuxiang Zhou, Junfei Chen, Wageh Swelm and Ahmed Al-Ghamdi

Polymers 2022, 14(3), 622; https://doi.org/10.3390/polym14030622 - 5 Feb 2022

Cited by 4 | Viewed by 2714

Abstract

The mitigation of interfacial charge accumulation in solution-processed organic light-emitting diodes (s-OLEDs) is an effective method to improve device performance. In this study, the polar solvent vapor annealing (PSVA) method was used to treat two layers in s-OLED, PEDOT:PSS and mCP:DMAC-DPS emitting layers, [...] Read more.

The mitigation of interfacial charge accumulation in solution-processed organic light-emitting diodes (s-OLEDs) is an effective method to improve device performance. In this study, the polar solvent vapor annealing (PSVA) method was used to treat two layers in s-OLED, PEDOT:PSS and mCP:DMAC-DPS emitting layers, separately, to optimize the carrier transmission and balance. After the double-layer PSVA treatment, the current efficiency increased, the lifetime of the device is improved, the efficiency roll-off alleviated from 33.3% to 26.6%, and the maximum brightness increased by 31.3%. It is worth mentioning that the work function of the EML interface reduced by 0.36 eV, and the initial injection voltage of the electrons also reduced. Simulating the solubility of the LUMO and HOMO molecule parts of the mCP and DMAC-DPS, it was found that the LUMO parts had stronger polarity and higher solubility in polar solution than the HOMO parts. By comparing the untreated luminescent layer films, it was found that the PSVA treatment improved the uniformity of the film morphology. We may infer that a more ordered molecular arrangement enhances carrier transport as the LUMO parts tend to be close to the surface and the reduced local state traps on the EML surface promote electron injection. According to the experimental results, the injection of holes and electrons is enhanced from both sides of the EML, respectively, and the charge accumulated at the interface of s-OLEDs is significantly reduced due to the improvement of carrier-transported characteristics. Full article

(This article belongs to the Topic Insight into Liquid/Fluid Interfaces)

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