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Yang S, Kumar S, Dutcher CS. Rupture of thin liquid trilayer films with soluble surfactants: fundamentals and applications to droplet coalescence. SOFT MATTER 2024; 20:4972-4987. [PMID: 38874504 DOI: 10.1039/d4sm00562g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
Understanding the stability of thin liquid trilayer films is of direct relevance to applications such as multilayer coatings and polymer processing. The stability of trilayer films can also be used to provide insights into emulsion dynamics, such as the rupture of the thin film formed between two droplets during coalescence. Often, emulsions are laden with surfactants and other additives, which can be present in one or both phases as well as at the interfaces between the liquids. In experimental studies, complicating factors such as variations in droplet sizes, curvatures, and collision processes make it difficult to specifically isolate the influence of surfactant transport on droplet coalescence and film rupture. The present work addresses this issue by systematic consideration of a model problem involving a thin liquid trilayer film. Surfactant is soluble in either the outer layers or the inner layer, corresponding to surfactant soluble in the droplets or the continuous phase. Rupture of the inner layer is driven by van der Waals forces. Lubrication theory is applied to derive coupled nonlinear evolution equations describing the perturbations to the interface positions and the surfactant concentrations. Our findings reveal that surfactant better stabilizes the film when soluble in the inner layer, and the stabilizing effect is more pronounced when the outer layers are thicker. These findings are consistent with experimental observations involving emulsions, where emulsions tend to be more stable when surfactant is in the continuous phase rather than in the droplets, with the distinction being more pronounced when droplets are larger.
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Affiliation(s)
- Shu Yang
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Satish Kumar
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Cari S Dutcher
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
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2
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Herchenbach PJ, Layman BR, Dick JE. Quantifying the interfacial tension of adsorbed droplets on electrified interfaces. J Colloid Interface Sci 2024; 674:474-481. [PMID: 38941939 DOI: 10.1016/j.jcis.2024.06.141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 06/16/2024] [Accepted: 06/19/2024] [Indexed: 06/30/2024]
Abstract
HYPOTHESIS This paper develops a new measurement method to answer the question: How does one measure the interfacial tension of adsorbed droplets? EXPERIMENTS This measurement is based on the placement of a bubble at a water|organic interface. To prove the concept, a bubble was formed by pipetting gas below the water|1,2-dichloroethane interface. Our values agree well with previous reports. We then extended the measurement modality to a more difficult system: quantifying interfacial tension of 1,2-dichloroethane droplets adsorbed onto conductors. Carbon dioxide was generated in the aqueous phase from the electro-oxidation of oxalate. Given carbon dioxide's solubility in 1,2-dichloroethane, it partitions, a bubble nucleates, and the bubble can be seen by microscopy when driving the simultaneous oxidation of tris(bipyridine)ruthenium (II), a molecule that will interact with CO2.-. and provide light through electrochemiluminescence. We can quantify the interfacial tension of adsorbed droplets, a measurement very difficult performed with more usual techniques, by tracking the growth of the bubble and quantifying the bubble size at the time the bubble breaks through the aqueous|1,2-dichloroethane interface. FINDINGS We found that the interfacial tension of nanoliter 1,2-dichloroethane droplets adsorbed to an electrified interface in water, which was previously immeasurable with current techniques, was one order of magnitude less than the bulk system.
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Affiliation(s)
- Patrick J Herchenbach
- James Tarpo Jr. & Margaret Tarpo Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Brady R Layman
- James Tarpo Jr. & Margaret Tarpo Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Jeffrey E Dick
- James Tarpo Jr. & Margaret Tarpo Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA; Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907, USA.
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3
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Britel A, Tomagra G, Aprà P, Varzi V, Sturari S, Amine NH, Olivero P, Picollo F. 3D printing in microfluidics: experimental optimization of droplet size and generation time through flow focusing, phase, and geometry variation. RSC Adv 2024; 14:7770-7778. [PMID: 38444974 PMCID: PMC10913413 DOI: 10.1039/d4ra00752b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Accepted: 02/26/2024] [Indexed: 03/07/2024] Open
Abstract
Droplet-based microfluidics systems have become widely used in recent years thanks to their advantages, varying from the possibility of handling small fluid volumes to directly synthesizing and encapsulating various living forms for biological-related applications. The effectiveness of such systems mainly depends on the ability to control some of these systems' parameters, such as produced droplet size and formation time, which represents a challenging task. This work reports an experimental study on tuning droplet size and generation time in a flow-focusing geometry fabricated with stereolithography 3D printing by exploring the interplay of phase and geometrical parameters. We produced droplets at different low flow rates of continuous and dispersed phases to assess the effect of each of these phases on the droplets' size and formation time. We observed that smaller droplets were produced for high viscosity oil and water phase, along with high flow rates. In addition, changing the microfluidics channels' width, and morphology of the orifice has shown a similar effect on droplet size, as shown in the case of high-viscosity solutions. The variation of the bifurcation angle shows a noticeable variation in terms of the achieved droplet size and formation time. We further investigated the impact of modifying the width ratio of the continuous and dispersed phases on droplet formation.
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Affiliation(s)
- Adam Britel
- Department of Physics, "NIS" Inter-departmental Centre, University of Torino, National Institute of Nuclear Physics Sect. Torino, Via Pietro Giuria 1 10125 Torino Italy
| | - Giulia Tomagra
- Department of Drug and Science Technology, NIS Interdepartmental Centre, University of Torino Corso Raffaello 30 10125 Torino Italy
| | - Pietro Aprà
- Department of Physics, "NIS" Inter-departmental Centre, University of Torino, National Institute of Nuclear Physics Sect. Torino, Via Pietro Giuria 1 10125 Torino Italy
| | - Veronica Varzi
- Department of Physics, "NIS" Inter-departmental Centre, University of Torino, National Institute of Nuclear Physics Sect. Torino, Via Pietro Giuria 1 10125 Torino Italy
| | - Sofia Sturari
- Department of Physics, "NIS" Inter-departmental Centre, University of Torino, National Institute of Nuclear Physics Sect. Torino, Via Pietro Giuria 1 10125 Torino Italy
| | - Nour-Hanne Amine
- Department of Physics, "NIS" Inter-departmental Centre, University of Torino, National Institute of Nuclear Physics Sect. Torino, Via Pietro Giuria 1 10125 Torino Italy
| | - Paolo Olivero
- Department of Physics, "NIS" Inter-departmental Centre, University of Torino, National Institute of Nuclear Physics Sect. Torino, Via Pietro Giuria 1 10125 Torino Italy
| | - Federico Picollo
- Department of Physics, "NIS" Inter-departmental Centre, University of Torino, National Institute of Nuclear Physics Sect. Torino, Via Pietro Giuria 1 10125 Torino Italy
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4
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Gu P, Luo X, Zhou S, Wang D, Li Z, Chai Y, Zhang Y, Shi S, Russell TP. Stabilizing Liquids Using Interfacial Supramolecular Assemblies. Angew Chem Int Ed Engl 2023; 62:e202303789. [PMID: 37198522 DOI: 10.1002/anie.202303789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/17/2023] [Accepted: 05/17/2023] [Indexed: 05/19/2023]
Abstract
Stabilizing liquids based on supramolecular assembly (non-covalent intermolecular interactions) has attracted significant interest, due to the increasing demand for soft, liquid-based devices where the shape of the liquid is far from the equilibrium spherical shape. The components comprising these interfacial assemblies must have sufficient binding energies to the interface to prevent their ejection from the interface when the assemblies are compressed. Here, we highlight recent advances in structuring liquids based on non-covalent intermolecular interactions. We describe some of the progress made that reveals structure-property relationships. In addition to treating advances, we discuss some of the limitations and provide a perspective on future directions to inspire further studies on structured liquids based on supramolecular assembly.
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Affiliation(s)
- Peiyang Gu
- Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou, 213164, P. R. China
| | - Xiaobo Luo
- Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou, 213164, P. R. China
| | - Shiyuan Zhou
- Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou, 213164, P. R. China
| | - Danfeng Wang
- Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou, 213164, P. R. China
| | - Zhongyu Li
- Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou, 213164, P. R. China
- School of Environmental and Safety Engineering, Changzhou University, Changzhou, 213164, P. R. China
| | - Yu Chai
- Department of Physics, City University of Hong Kong, Kowloon, P. R. China
| | - Yuzhe Zhang
- School of Environmental and Safety Engineering, Changzhou University, Changzhou, 213164, P. R. China
| | - Shaowei Shi
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
| | - Thomas P Russell
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China
- Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
- Polymer Science and Engineering Department, University of Massachusetts, Amherst, MA 01003, USA
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aoba, Sendai, 980-8577, Japan
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Yang S, Kumar S, Dutcher CS. Instability and rupture of surfactant-laden bilayer thin liquid films. SOFT MATTER 2023; 19:5737-5748. [PMID: 37462060 DOI: 10.1039/d3sm00463e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/03/2023]
Abstract
The stability of surfactant-laden bilayer thin films, where the top layer is subject to van der Waals driven breakup, is of particular relevance to applications where one thin liquid layer is spread on another, such as film-forming firefighting foams and multilayer coatings. Although there has been much prior modeling work on the stability of thin liquid bilayers, additional physical effects and assumptions were incorporated in those studies, making it difficult to isolate the influence of surfactant on the rupture of the top layer. The present work addresses this issue through application of the lubrication approximation to derive a coupled system of nonlinear evolution equations describing the perturbations to the liquid-liquid and liquid-air interfaces and the surfactant interfacial concentrations. The surfactant is assumed to be insoluble and can be present at each interface. Linear stability analysis suggests, and nonlinear simulations confirm, that by using surfactant that adsorbs to both interfaces, the rupture time can be increased by an order of magnitude relative to the surfactant-free case. However, we find it crucial to have the right amount of surfactant to generate strongly stabilizing Marangoni stresses without reducing the interfacial tension too much. Nonlinear simulations and linear stability analysis provide insight into the mechanisms of the delayed rupture and show how the direction and strength of the Marangoni stresses strongly depend on the viscosity ratio of the layers. These results can help guide the choice and design of surfactants to achieve more effective firefighting foams and more stable liquid coatings.
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Affiliation(s)
- Shu Yang
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Satish Kumar
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Cari S Dutcher
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA.
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
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Raynel G, Marques DS, Al-Thabet M. The influence of water droplet packing on crude oil emulsion. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2023; 46:53. [PMID: 37450063 DOI: 10.1140/epje/s10189-023-00311-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 06/15/2023] [Indexed: 07/18/2023]
Abstract
To assure a smooth and cost-efficient flow of crude oil emulsion from wells to a production facility, the oil industry relies heavily on the prediction of viscosity in pipe. The physical expression of this viscosity depends on a subjective estimate of a maximum packing volume fraction (compacity), ranging between 58 and 74 vol%. This inaccurate practice can lead to catastrophic loss of pump efficiency. Two new concepts were defined to describe the emulsion: its compacity; and the occupancy of water droplets at the oil-water interface. This development leads to a better understanding of the formation and disappearance of a suspension, and can assist in building a reliable phenomenological model of the sedimentation and coalescence of an emulsion. Theoretical and experimental approaches were conducted to investigate the packing of water droplets in emulsions. A 3D packing model was developed to explain the observations made during emulsification experiments. It was found that below a water volume fraction of 34 vol%, water droplets settle, under the effect of gravity, in a loose-packed zone; and then sediment in a dense-packed zone (DPZ). The DPZ exists between a water volume fraction of 34 vol% and 60 vol%. The maximum compacity is the upper limit of this zone; and has a value of 60.46%. Knowing this objective value, other parameters affecting the viscosity can be better studied.
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Affiliation(s)
- Guillaume Raynel
- Saudi Aramco, Research and Development Center, Dhahran, Saudi Arabia.
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Park W, Park J, Im S, Choi SJ. Influence of the type and concentration of hydrocolloids on Ostwald ripening of emulsions stabilized with small molecular and non-ionic surfactants. Food Chem 2023; 411:135504. [PMID: 36682162 DOI: 10.1016/j.foodchem.2023.135504] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 01/10/2023] [Accepted: 01/15/2023] [Indexed: 01/19/2023]
Abstract
The effects of hydrocolloid gum, gum arabic, carrageenan, and xanthan on the Ostwald ripening of emulsions fabricated using Brij or Tween surfactants were examined. Emulsions prepared using pure n-decane exhibited low stability to Ostwald ripening, and modifying the oil composition by mixing corn oil improved the stability to Ostwald ripening. When gums were added to emulsions prepared using pure n-decane, the stability to Ostwald ripening decreased further, except for xanthan in emulsions stabilized using Tween surfactant. This could be because gums may affect interactions between water molecules and the hydrophilic head of the surfactant, increasing the water solubility of n-decane. However, gum addition (or viscosity increment) increased the stability of emulsions prepared using the modified oil composition (90% n-decane and 10% corn oil). In conclusion, emulsions unstable to Ostwald ripening may be negatively affected by gum addition, whereas emulsions relatively stable to Ostwald ripening may be positively affected.
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Affiliation(s)
- Woojin Park
- Department of Food Science and Technology, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | - Joonwoo Park
- Department of Food Science and Technology, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | - Sohyeon Im
- Department of Food Science and Technology, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | - Seung Jun Choi
- Department of Food Science and Technology, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea; Center for Functional Biomaterials, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea.
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8
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A microfluidic study of bubble formation and coalescence tuned by dynamic adsorption of SDS and proteins. Food Hydrocoll 2023. [DOI: 10.1016/j.foodhyd.2023.108663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2023]
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9
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Ciutara CO, Barman S, Iasella S, Huang B, Zasadzinski JA. Dilatational and shear rheology of soluble and insoluble monolayers with a Langmuir trough. J Colloid Interface Sci 2023; 629:125-135. [PMID: 36063630 PMCID: PMC10038177 DOI: 10.1016/j.jcis.2022.08.051] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/31/2022] [Accepted: 08/09/2022] [Indexed: 10/15/2022]
Abstract
HYPOTHESIS The surface dilatational and shear moduli of surfactant and protein interfacial layers can be derived from surface pressures measured with a Wilhelmy plate parallel, ΔΠpar and perpendicular ΔΠperp to the barriers in a Langmuir trough. EXPERIMENTAL Applying area oscillations, A0+ ΔAeiωt, in a rectangular Langmuir trough induces changes in surface pressure, ΔΠpar and ΔΠperp for monolayers of soluble palmitoyl-lysophosphatidylcholine (LysoPC), insoluble dipalmitoylphosphatidylcholine (DPPC), and the protein β-lactoglobulin to evaluate Es∗+Gs∗=A0ΔΠparΔA and Es∗-Gs∗=A0ΔΠperpΔA. Gs∗ was independently measured with a double-wall ring apparatus (DWR) and Es∗ by area oscillations of hemispherical bubbles in a capillary pressure microtensiometer (CPM) and the results were compared to the trough measurements. FINDINGS For LysoPC and DPPC, A0ΔΠparΔA≅A0ΔΠperpΔA meaning Es∗≫Gs∗ and Es∗≅A0ΔΠparΔA≅A0ΔΠperpΔA. Trough values for Es∗ were quantitatively similar to CPM when corrected for interfacial curvature. DWR showed G∗ was 4 orders of magnitude smaller than Es∗ for both LysoPC and DPPC. For β-lactoglobulin films, A0ΔΠparΔA>A0ΔΠperpΔA and Es∗ and Gs∗ were in qualitative agreement with independent CPM and DWR measurements. For β-lactoglobulin, both Es∗ and Gs∗ varied with film age and history on the trough, suggesting the evolution of the protein structure.
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Affiliation(s)
- Clara O Ciutara
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Sourav Barman
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Steven Iasella
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Boxun Huang
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
| | - Joseph A Zasadzinski
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
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10
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Onsite coalescence behaviour of whey protein-stabilized bubbles generated at parallel microscale pores: Role of pore geometry and liquid phase properties. Food Hydrocoll 2022. [DOI: 10.1016/j.foodhyd.2022.108435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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11
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Gu Y, Zhou M, Tu H. Effect of linking groups and hydrophobic groups on properties of sulfate Gemini surfactants. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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12
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Design of shear-based microfluidic channels for production and stability assessment of food emulsions. Curr Opin Food Sci 2022. [DOI: 10.1016/j.cofs.2022.100957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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13
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Lee WH, Park CY, Diaz D, Rodriguez KL, Chung J, Church J, Willner MR, Lundin JG, Paynter DM. Predicting bilgewater emulsion stability by oil separation using image processing and machine learning. WATER RESEARCH 2022; 223:118977. [PMID: 35988334 DOI: 10.1016/j.watres.2022.118977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 07/18/2022] [Accepted: 08/12/2022] [Indexed: 06/15/2023]
Abstract
Bilgewater is a shipboard multi-component oily wastewater, combining numerous wastewater sources. A better understanding of bilgewater emulsions is required for proper wastewater management to meet discharge regulations. In this study, we developed 360 emulsion samples based on commonly used Navy cleaner data and previous bilgewater composition studies. Oil value (OV) was obtained from image analysis of oil/creaming layer and validated by oil separation (OS) which was experimentally determined using a gravimetric method. OV (%) showed good agreement with OS (%), indicating that a simple image-based parameter can be used for emulsion stability prediction model development. An ANOVA analysis was conducted of the five variables (Cleaner, Salinity, Suspended Solids [SS], pH, and Temperature) that significantly impacted estimates of OV, finding that the Cleaner, Salinity, and SS variables were statistically significant (p < 0.05), while pH and Temperature were not. In general, most cleaners showed improved oil separation with salt additions. Novel machine learning (ML)-based predictive models of both classification and regression for bilgewater emulsion stability were then developed using OV. For classification, the random forest (RF) classifiers achieved the most accurate prediction with F1-score of 0.8224, while in regression-based models the decision tree (DT) regressor showed the highest prediction of emulsion stability with the average mean absolute error (MAE) of 0.1611. Turbidity also showed a good emulsion prediction with RF regressor (MAE of 0.0559) and RF classifier (F1-score of 0.9338). One predictor variable removal test showed that Salinity, SS, and Temperature are the most impactful variables in the developed models. This is the first study to use image processing and machine learning for the prediction of oil separation for the application of bilgewater assessment within the marine sector.
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Affiliation(s)
- Woo Hyoung Lee
- Department of Civil, Environmental and Construction Engineering, University of Central Florida, Orlando, FL, United States.
| | - Cheol Young Park
- Department of Civil, Environmental and Construction Engineering, University of Central Florida, Orlando, FL, United States
| | - Daniela Diaz
- Department of Civil, Environmental and Construction Engineering, University of Central Florida, Orlando, FL, United States
| | - Kelsey L Rodriguez
- Department of Civil, Environmental and Construction Engineering, University of Central Florida, Orlando, FL, United States
| | - Jongik Chung
- Department of Statistics and Data Science, University of Central Florida, Orlando, FL 32816-2370, United States
| | - Jared Church
- Environmental Engineering, Science, and Technology Branch, Naval Surface Warfare Center, Carderock Division, West Bethesda, MD, United States
| | - Marjorie R Willner
- Environmental Engineering, Science, and Technology Branch, Naval Surface Warfare Center, Carderock Division, West Bethesda, MD, United States
| | - Jeffrey G Lundin
- Chemistry Division, United States Naval Research Laboratory, Washington, D.C., United States
| | - Danielle M Paynter
- Environmental Engineering, Science, and Technology Branch, Naval Surface Warfare Center, Carderock Division, West Bethesda, MD, United States
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14
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Ho TM, Razzaghi A, Ramachandran A, Mikkonen KS. Emulsion characterization via microfluidic devices: A review on interfacial tension and stability to coalescence. Adv Colloid Interface Sci 2022; 299:102541. [PMID: 34920366 DOI: 10.1016/j.cis.2021.102541] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 09/22/2021] [Accepted: 10/03/2021] [Indexed: 01/29/2023]
Abstract
Emulsions have gained significant importance in many industries including foods, pharmaceuticals, cosmetics, health care formulations, paints, polymer blends and oils. During emulsion generation, collisions can occur between newly-generated droplets, which may lead to coalescence between the droplets. The extent of coalescence is driven by the properties of the dispersed and continuous phases (e.g. density, viscosity, ion strength and pH), and system conditions (e.g. temperature, pressure or any external applied forces). In addition, the diffusion and adsorption behaviors of emulsifiers which govern the dynamic interfacial tension of the forming droplets, the surface potential, and the duration and frequency of the droplet collisions, contribute to the overall rate of coalescence. An understanding of these complex behaviors, particularly those of interfacial tension and droplet coalescence during emulsion generation, is critical for the design of an emulsion with desirable properties, and for the optimization of the processing conditions. However, in many cases, the time scales over which these phenomena occur are extremely short, typically a fraction of a second, which makes their accurate determination by conventional analytical methods extremely challenging. In the past few years, with advances in microfluidic technology, many attempts have demonstrated that microfluidic systems, characterized by micrometer-size channels, can be successfully employed to precisely characterize these properties of emulsions. In this review, current applications of microfluidic devices to determine the equilibrium and dynamic interfacial tension during droplet formation, and to investigate the coalescence stability of dispersed droplets applicable to the processing and storage of emulsions, are discussed.
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15
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Deng B, Schroën K, de Ruiter J. Effects of dynamic adsorption on bubble formation and coalescence in partitioned-EDGE devices. J Colloid Interface Sci 2021; 602:316-324. [PMID: 34130178 DOI: 10.1016/j.jcis.2021.06.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 10/21/2022]
Abstract
HYPOTHESIS Dynamic adsorption effects can play a crucial role in bubble formation and stabilization. We hypothesize that microfluidic tools provide direct insights to these effects, and that the final bubble size depends on the intersection of time scales for bubble formation versus adsorption of proteins. EXPERIMENTS We use a microfluidic device to study Laplace pressure-driven formation of bubbles that are stabilized by whey proteins. Bubble behavior is studied as a function of the pressure difference imposed across the pores (Pd∗), and thus the bubble formation time (τ, ranging from μs to s), using highspeed recordings, quasi-static pressure arguments and a semi-empirical coalescence model. FINDINGS We observe two distinct bubble formation regimes, delimited by the pressure difference required to initiate bubble formation in pure water, Pd∗= 1400 mbar. When Pd∗<1400 mbar, protein adsorption is a requisite to lower the surface tension and initialize bubble formation. Individual bubbles (fixed d0~ 25 μm) are formed slowly with τ≫1 ms. When Pd∗ exceeds 1400 mbar, bubbles (fixed d0~ 16 μm) experience no adsorption lag and thus are formed at steeply increasing frequency, with τ < 1 ms. Interaction between these bubbles causes finite coalescence to a diameter dcoal that increases for lower τ. A minimum time of 0.4 ms is needed to immediately stabilize individual bubbles. Our study provides a promising microfluidic tool to study bubble formation and coalescence dynamics simultaneously.
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Affiliation(s)
- Boxin Deng
- Wageningen University, Food Process Engineering Group, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - Karin Schroën
- Wageningen University, Food Process Engineering Group, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - Jolet de Ruiter
- Wageningen University, Food Process Engineering Group, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands.
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16
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Deng B, Neef T, Schroën K, de Ruiter J. Mapping Bubble Formation and Coalescence in a Tubular Cross-Flow Membrane Foaming System. MEMBRANES 2021; 11:membranes11090710. [PMID: 34564527 PMCID: PMC8468550 DOI: 10.3390/membranes11090710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 09/01/2021] [Accepted: 09/12/2021] [Indexed: 11/16/2022]
Abstract
Membrane foaming is a promising alternative to conventional foaming methods to produce uniform bubbles. In this study, we provide a fundamental study of a cross-flow membrane foaming (CFMF) system to understand and control bubble formation for various process conditions and fluid properties. Observations with high spatial and temporal resolution allowed us to study bubble formation and bubble coalescence processes simultaneously. Bubble formation time and the snap-off bubble size (D0) were primarily controlled by the continuous phase flow rate (Qc); they decreased as Qc increased, from 1.64 to 0.13 ms and from 125 to 49 µm. Coalescence resulted in an increase in bubble size (Dcoal>D0), which can be strongly reduced by increasing either continuous phase viscosity or protein concentration-factors that only slightly influence D0. Particularly, in a 2.5 wt % whey protein system, coalescence could be suppressed with a coefficient of variation below 20%. The stabilizing effect is ascribed to the convective transport of proteins and the intersection of timescales (i.e., μs to ms) of bubble formation and protein adsorption. Our study provides insights into the membrane foaming process at relevant (micro-) length and time scales and paves the way for its further development and application.
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Chou PM, Khiew PS, Brown PD, Hu B. Development of Thermally Responsive PolyNIPAm Microcarrier for Application of Cell Culturing-Part I: A Feasibility Study. Polymers (Basel) 2021; 13:polym13162629. [PMID: 34451170 PMCID: PMC8400069 DOI: 10.3390/polym13162629] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 07/29/2021] [Accepted: 08/02/2021] [Indexed: 11/16/2022] Open
Abstract
Poly(N-isopropylacrylamide) (polyNIPAm) microspheres were synthesized via the suspension polymerization technique. Thermal and redox initiators were compared for the polymerization, in order to study the effect of initiator type on the surface charge and particle size of polyNIPAm microspheres. The successful polymerization of NIPAm was confirmed by FTIR analysis. Microspheres of diameter >50 µm were synthesized when a pair of ammonium persulfate (APS) and N,N,N',N'-tetramethylene-diamine (TEMED) redox initiators was used, whilst relatively small microspheres of ~1 µm diameter were produced using an Azobis-isobutyronitrile (AIBN) thermal initiator. Hence, suspension polymerization using a redox initiator pair was found to be more appropriate for the synthesis of polyNIPAm microspheres of a size suitable for human embryonic kidney (HEK) cell culturing. However, the zeta potential of polyNIPAm microspheres prepared using an APS/TEMED redox initiator was significantly more negative than AIBN thermal initiator prepared microspheres and acted to inhibit cell attachment. Conversely, strong cell attachment was observed in the case of polyNIPAm microspheres of diameter ~90 µm, prepared using an APS/TEMED redox initiator in the presence of a cetyl trimethyl ammonium bromide (CTAB) cationic surfactant; demonstrating that surface charge modified polyNIPAm microspheres have great potential for use in cell culturing.
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Affiliation(s)
- Pui May Chou
- School of Computer Science and Engineering, Faculty of Innovation and Technology, Taylor’s University Lakeside Campus, No. 1, Jalan Taylor’s, Subang Jaya 47500, Selangor, Malaysia
- Correspondence: (P.M.C.); (B.H.)
| | - Poi Sim Khiew
- Center of Nanotechnology and Advanced Materials, Faculty of Science and Engineering, University of Nottingham Malaysia Campus, Jalan Broga, Semenyih 43500, Selangor, Malaysia;
| | - Paul D Brown
- Department of Mechanical, Materials & Manufacturing Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK;
| | - Binjie Hu
- Department of Chemical and Environmental Engineering, University of Nottingham China, 199 Taikang East Road, Ningbo 315100, China
- Correspondence: (P.M.C.); (B.H.)
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18
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Handschuh-Wang S, Gan T, Wang T, Stadler FJ, Zhou X. Surface Tension of the Oxide Skin of Gallium-Based Liquid Metals. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:9017-9025. [PMID: 34281345 DOI: 10.1021/acs.langmuir.1c00966] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Gallium-based alloys have garnered considerable attention in the scientific community, particularly as they are in an atypical liquid state at and near room temperature. Though physical parameters, such as thermal conductivity, electrical conductivity, viscosity, yield stress, and surface tension, of these alloys are broadly known, the surface tension (surface free energy) of the oxide skin remains intangible due to the high yield stress of the oxide skin. In this article, we propose to employ gradually attenuated vibrations to obtain equilibrium shapes, which are analyzed along the lines of the puddle height method. The surface tension of the oxide skin was determined on quartz glass and liquid metal-phobic diamond coating to be around 350-365 mN/m, thus independent of the substrate surface or employed liquid metal (i.e., eutectic Ga-In (EGaIn) and galinstan). The similarity of the surface tension for different alloys was ascribed to the composition of the oxide skin, which predominantly comprises gallium oxides due to thermodynamic constraints. We envision that this method can also be applied to other liquid metal alloys and liquid metal marble systems facilitating modeling, simulation, and optimization processes.
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Affiliation(s)
- Stephan Handschuh-Wang
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, People's Republic of China
| | - Tiansheng Gan
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, People's Republic of China
| | - Tao Wang
- Functional Thin Films Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China
| | - Florian J Stadler
- College of Materials Science and Engineering, Shenzhen University, Shenzhen 518055, People's Republic of China
| | - Xuechang Zhou
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, People's Republic of China
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19
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Sun X, Yang D, Zhang H, Zeng H, Tang T. Unraveling the Interaction of Water-in-Oil Emulsion Droplets via Molecular Simulations and Surface Force Measurements. J Phys Chem B 2021; 125:7556-7567. [PMID: 34229441 DOI: 10.1021/acs.jpcb.1c04227] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Water-in-oil emulsions widely exist in various chemical and petroleum engineering processes, and their stabilization and destabilization behaviors have attracted much attention. In this work, molecular dynamic (MD) simulations were conducted on the water-in-oil emulsion droplets with the presence of surface-active components, including a polycyclic aromatic compound (VO-79) and two nonionic surfactants: the PEO5PPO10PEO5 triblock copolymer and Brij-93. At the surface of water droplets, films were formed by the adsorbate molecules that redistributed during the approaching of the droplets. The redistribution of PEO5PPO10PEO5 was more pronounced than that of Brij-93 and VO-79, which contributed to lower repulsion during coalescence. The interaction forces during droplet coalescence were also measured using atomic force microscopy. Jump-in phenomenon and coalescence were observed for systems with VO-79, Brij-93, and a low concentration of Pluronic P123. The critical force before jump-in was lowest for the low concentration of Pluronic P123, consistent with the MD results. Adhesion was measured when separating water droplets with a high concentration of Pluronic P123. By correlating theoretical simulations and experimental force measurements, this work improves the fundamental understanding on the interaction behaviors of water droplets in an oil medium in the presence of interface-active species and provides atomic-level insights into the stabilization and destabilization mechanisms of water-in-oil emulsion.
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Affiliation(s)
- Xiaoyu Sun
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Diling Yang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Hao Zhang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Hongbo Zeng
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Tian Tang
- Department of Mechanical Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
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20
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Thin liquid films: Where hydrodynamics, capillarity, surface stresses and intermolecular forces meet. Curr Opin Colloid Interface Sci 2021. [DOI: 10.1016/j.cocis.2021.101441] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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21
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Design, Preparation, and Characterization of Effective Dermal and Transdermal Lipid Nanoparticles: A Review. COSMETICS 2021. [DOI: 10.3390/cosmetics8020039] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Limited permeability through the stratum corneum (SC) is a major obstacle for numerous skin care products. One promising approach is to use lipid nanoparticles as they not only facilitate penetration across skin but also avoid the drawbacks of conventional skin formulations. This review focuses on solid lipid nanoparticles (SLNs), nanostructured lipid nanocarriers (NLCs), and nanoemulsions (NEs) developed for topical and transdermal delivery of active compounds. A special emphasis in this review is placed on composition, preparation, modifications, structure and characterization, mechanism of penetration, and recent application of these nanoparticles. The presented data demonstrate the potential of these nanoparticles for dermal and transdermal delivery.
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22
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Narayan S, Barman S, Moravec DB, Hauser BG, Dallas AJ, Zasadzinski JA, Dutcher CS. Dilatational rheology of water-in-diesel fuel interfaces: effect of surfactant concentration and bulk-to-interface exchange. SOFT MATTER 2021; 17:4751-4765. [PMID: 33861293 PMCID: PMC8140520 DOI: 10.1039/d1sm00064k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Micrometer-sized water droplets dispersed in diesel fuel are stabilized by the fuel's surface-active additives, such as mono-olein and poly(isobutylene)succinimide (PIBSI), making the droplets challenging for coalescing filters to separate. Dynamic material properties found from interfacial rheology are known to influence the behavior of microscale droplets in coalescing filters. In this work, we study the interfacial dilatational properties of water-in-fuel interfaces laden with mono-olein and PIBSI, with a fuel phase of clay-treated ultra-low sulphur diesel (CT ULSD). First, the dynamic interfacial tension (IFT) is measured using pendant drop tensiometry, and a curvature-dependent form of the Ward and Tordai diffusion equation is applied for extracting the diffusivity of the surfactants. Additionally, Langmuir kinetics are applied to the dynamic IFT results to obtain the maximum surface concentration (Γ∞) and ratio of adsorption to desorption rate constants (κ). We then use a capillary pressure microtensiometer to measure the interfacial dilatational modulus, and further extract the characteristic frequency of surfactant exchange (ω0) by fitting a model assuming diffusive exchange between the interface and bulk. In this measurement, 50-100 μm diameter water droplets are pinned at the tip of a glass capillary in contact with the surfactant-containing fuel phase, and small amplitude capillary pressure oscillations over a range of frequencies from 0.45-20 rad s-1 are applied to the interface, inducing changes in interfacial tension and area to yield the dilatational modulus, E*(ω). Over the range of concentrations studied, the dilatational modulus of CT ULSD with either mono-olein or PIBSI increases with a decrease in bulk concentration and plateaus at the lowest concentrations of mono-olein. Characteristic frequency (ω0) values extracted from the fit are compared with those calculated using equilibrium surfactant parameters (κ and Γ∞) derived from pendant drop tensiometry, and good agreement is found between these values. Importantly, the results imply that diffusive exchange models based on the equilibrium relationships between surfactant concentration and interfacial tension can be used to infer the dynamic dilatational behavior of complex surfactant systems, such as the water-in-diesel fuel interfaces in this study.
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Affiliation(s)
- Shweta Narayan
- Department of Mechanical Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, USA.
| | - Sourav Barman
- Department of Chemical Engineering and Materials Science, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | | | | | | | - Joseph A Zasadzinski
- Department of Chemical Engineering and Materials Science, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Cari S Dutcher
- Department of Mechanical Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, USA. and Department of Chemical Engineering and Materials Science, University of Minnesota - Twin Cities, Minneapolis, MN, USA
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Lee D, Shen AQ. Interfacial Tension Measurements in Microfluidic Quasi-Static Extensional Flows. MICROMACHINES 2021; 12:272. [PMID: 33800831 PMCID: PMC8000871 DOI: 10.3390/mi12030272] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 03/03/2021] [Accepted: 03/03/2021] [Indexed: 12/04/2022]
Abstract
Droplet microfluidics provides a versatile tool for measuring interfacial tensions between two immiscible fluids owing to its abilities of fast response, enhanced throughput, portability and easy manipulations of fluid compositions, comparing to conventional techniques. Purely homogeneous extension in the microfluidic device is desirable to measure the interfacial tension because the flow field enables symmetric droplet deformation along the outflow direction. To do so, we designed a microfluidic device consisting of a droplet production region to first generate emulsion droplets at a flow-focusing area. The droplets are then trapped at a stagnation point in the cross junction area, subsequently being stretched along the outflow direction under the extensional flow. These droplets in the device are either confined or unconfined in the channel walls depending on the channel height, which yields different droplet deformations. To calculate the interfacial tension for confined and unconfined droplet cases, quasi-static 2D Darcy approximation model and quasi-static 3D small deformation model are used. For the confined droplet case under the extensional flow, an effective viscosity of the two immiscible fluids, accounting for the viscosity ratio of continuous and dispersed phases, captures the droplet deformation well. However, the 2D model is limited to the case where the droplet is confined in the channel walls and deforms two-dimensionally. For the unconfined droplet case, the 3D model provides more robust estimates than the 2D model. We demonstrate that both 2D and 3D models provide good interfacial tension measurements under quasi-static extensional flows in comparison with the conventional pendant drop method.
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Affiliation(s)
- Doojin Lee
- Department of Polymer Science and Engineering, Chonnam National University, Gwangju 61186, Korea
| | - Amy Q. Shen
- Micro/Bio/Nanofluidics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
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