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Zou H, Zhang D, Fu Q, Yang L, Zheng K, Dong RY. Scaling variation in the pinch-off of colloid-polymer mixtures. J Colloid Interface Sci 2024; 675:848-856. [PMID: 39002235 DOI: 10.1016/j.jcis.2024.07.054] [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: 02/05/2024] [Revised: 06/13/2024] [Accepted: 07/06/2024] [Indexed: 07/15/2024]
Abstract
HYPOTHESIS The scaling laws of drop pinch-off are known to be affected by drop compositions including dissolved polymers and non-Brownian particles. When the size of the particles is comparable to the characteristic length scale of the polymer network, these particles may interact strongly with the polymer environment, leading to new types of scaling behaviors not reported before. EXPERIMENTS Using high-speed imaging, we experimentally studied the time evolution of the neck diameter hmin of drops composed of silica nanoparticles dispersed in PEO solution when extruded from a nozzle. FINDINGS After initial Newtonian necking with hmin ∼ t2/3, the subsequent stage may exhibit scaling variation, characterized by either exponential or power-law decay, depending on the nanoparticle volume fraction ϕ. The exponential decay hmin ∼ e-t/τ signifies the coil-stretch transition in typical viscoelastic suspensions. We conducted an analysis of the power-law scenario hmin ∼ tα at high ϕ, categorizing the entire process into three distinct regimes based on the exponents α. The dependences of critical thicknesses at transition points and exponents on polymer concentration offer initial insights into the potential transition from heterogeneous to homogeneous thinning in the mixture. This novel scaling variation bears implications for accurately predicting and controlling droplet fragmentation in industrial applications.
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Affiliation(s)
- Hongyi Zou
- School of Astronautics, Beihang University, Beijing 100191, China
| | - Dingwei Zhang
- School of Astronautics, Beihang University, Beijing 100191, China
| | - Qingfei Fu
- School of Astronautics, Beihang University, Beijing 100191, China; Aircraft and Propulsion Laboratory, Ningbo Institute of Technology, Beihang University, Ningbo 315100, China
| | - Lijun Yang
- School of Astronautics, Beihang University, Beijing 100191, China; Aircraft and Propulsion Laboratory, Ningbo Institute of Technology, Beihang University, Ningbo 315100, China
| | - Kaikai Zheng
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA 01003, USA; Center for Soft and Living Matter, Institute for Basic Science (IBS), Ulsan, South Korea.
| | - Ruo-Yu Dong
- School of Astronautics, Beihang University, Beijing 100191, China; Aircraft and Propulsion Laboratory, Ningbo Institute of Technology, Beihang University, Ningbo 315100, China.
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Fiscina JE, Darras A, Attinger D, Wagner C. Impact of anti-coagulant choice on blood elongational behavior. SOFT MATTER 2024; 20:4561-4566. [PMID: 38775063 DOI: 10.1039/d4sm00178h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2024]
Abstract
Blood is a highly complex fluid with rheological properties that have a significant impact on various flow phenomena. In particular, it exhibits a non-Newtonian elongational viscosity that is comparable to polymer solutions. In this study, we investigate the effect of three different anticoagulants, namely EDTA (ethylene diamine tetraacetic acid), heparin, and citrate, on the elongational properties of both human and swine blood. We observe a unique two stage thinning process and a strong dependency of the characteristic relaxation time on the chosen anticoagulant, with the longest relaxation time and thus the highest elongational viscosity being found for the case of citrate. Our findings for the latter are consistent with the physiological values obtained from a dripping droplet of human blood without any anticoagulant. Furthermore, our study resolves the discrepancy found in the literature regarding the reported range of characteristic relaxation times, confirming that the elongational viscosity must be taken into account for a full rheological characterization of blood. These results have important implications for understanding blood flow in various physiological, pathological and technological conditions.
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Affiliation(s)
| | - Alexis Darras
- Saarland University, Physics Department, 66123 Saarbruecken, Germany
| | | | - Christian Wagner
- Saarland University, Physics Department, 66123 Saarbruecken, Germany
- University of Luxemburg, Physics and Materials Science Research Unit, 1511 Luxembourg, Luxembourg
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3
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Wu T, Chen Y, Yang Z. 3D pore-scale characterization of colloid aggregation and retention by confocal microscopy: Effects of fluid structure and ionic strength. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 917:170349. [PMID: 38280576 DOI: 10.1016/j.scitotenv.2024.170349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 01/03/2024] [Accepted: 01/19/2024] [Indexed: 01/29/2024]
Abstract
Understanding the mechanisms of colloid transport and retention as well as the spatial distribution of colloids in porous media is an important topic for contamination transport and remediation in subsurface environments. Utilizing advanced three-dimensional visualization experiments, we effectively capture the intricate distribution characteristics of colloids in the 3D pore space and quantify the size of colloid clusters that aggregate at fluid-fluid interfaces and solid surfaces during two-phase flow. Our experimental results reveal the influence of pore-scale events, such as Haines jumps and pinch-off, on colloid retention. Our results also indicate that large drainage rates can facilitate colloid retention on solid surfaces, especially under the condition of high ionic strength. This can be attributed to the migration of colloids from the fluid-fluid interface to the solid surface, propelled by transients in the local fluid structure. The findings reveal a synergistic effect of the ionic strength and hydrodynamic conditions on colloid transport and retention during two-phase flow and provide important insights for predicting the fate and transport of contaminants in soil and groundwater environments involving multiple fluid phases.
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Affiliation(s)
- Ting Wu
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering of the Ministry of Education, Wuhan University, Wuhan 430072, China
| | - Yurun Chen
- Wuhan Britain-China School, Wuhan 430033, China
| | - Zhibing Yang
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China; Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering of the Ministry of Education, Wuhan University, Wuhan 430072, China.
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Chen H, Tian Y, Zhang S, Wang X, Qu H. Image processing-based online analysis and feedback control system for droplet dripping process. Int J Pharm 2024; 651:123736. [PMID: 38142872 DOI: 10.1016/j.ijpharm.2023.123736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 12/01/2023] [Accepted: 12/21/2023] [Indexed: 12/26/2023]
Abstract
Droplets find wide application across diverse industries, where maintaining their quality is paramount. Precise control over the substance content within droplets demands non-destructive and online analysis techniques, such as Process Analytical Technology (PAT), often integrated with control strategies. In this context, the present study focuses on the example of controlling droplet quality during the dripping process of pills. Leveraging the dripping and image acquisition systems established in previous research, a novel feedback control system centered on image processing was devised for the quality control of dripping pills. The system was developed and its efficacy was assessed, yielding satisfactory outcomes. The proposed system facilitates real-time monitoring of pill weight through the analysis of droplet images during the dripping process, thereby offering real-time feedback control of pill weight. Importantly, this system holds potential for broader applications beyond the scope of this study.
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Affiliation(s)
- Hang Chen
- Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Ying Tian
- Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Sheng Zhang
- Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Xiaoping Wang
- Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Haibin Qu
- Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
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Nikolova NN, Martínez Narváez CDV, Hassan L, Nicholson RA, Boehm MW, Baier SK, Sharma V. Rheology and dispensing of real and vegan mayo: the chickpea or egg problem. SOFT MATTER 2023; 19:9413-9427. [PMID: 38014426 DOI: 10.1039/d3sm00946g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
The rheology, stability, texture, and taste of mayonnaise, a dense oil-in-water (O/W) emulsion, are determined by interfacially active egg lipids and proteins. Often mayonnaise is presented as a challenging example of an egg-based food material that is hard to emulate using plant-based or vegan ingredients. In this contribution, we characterize the flow behavior of animal-based and plant-based mayo emulsions, seeking to decipher the signatures that make the real mayonnaise into such an appetizing complex fluid. We find that commercially available vegan mayos can emulate the apparent yield stress and shear thinning of yolk-based mayonnaise by the combined influence of plant-based proteins (like those extracted from chickpeas) and polysaccharide thickeners. However, we show that the dispensing and dipping behavior of egg-based and vegan mayos display striking differences in neck shape, sharpness, and length. The ratio of apparent extensional to shear yield stress value is found to be larger than the theoretically predicted square root of three for all mayo emulsions. The analysis of neck radius evolution of these extension thinning yield stress fluids reveals that even when the power law exponent governing the intermediate pinching dynamics is similar to the exponent obtained from the shear flow curve, the terminal pinching dynamics show strong local effects, possibly influenced by interstitial fluid properties, finite drop size and deformations, and capillarity.
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Affiliation(s)
- Nadia N Nikolova
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, IL 60607, USA.
| | | | - Lena Hassan
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, IL 60607, USA.
| | | | | | - Stefan K Baier
- Motif FoodWorks Inc., Boston, MA 02210, USA
- School of Chemical Engineering, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Vivek Sharma
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, IL 60607, USA.
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Jeong DH, Xing L, Lee MKH, Vani N, Sauret A. Deposition and alignment of fiber suspensions by dip coating. J Colloid Interface Sci 2023; 650:407-415. [PMID: 37418891 DOI: 10.1016/j.jcis.2023.06.180] [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: 03/20/2023] [Revised: 06/21/2023] [Accepted: 06/26/2023] [Indexed: 07/09/2023]
Abstract
HYPOTHESIS The dip coating of suspensions made of monodisperse non-Brownian spherical particles dispersed in a Newtonian fluid leads to different coating regimes depending on the ratio of the particle diameter to the thickness of the film entrained on the substrate. In particular, dilute particles dispersed in the liquid are entrained only above a threshold value of film thickness. In the case of anisotropic particles, in particular fibers, the smallest characteristic dimension will control the entrainment of the particle. Furthermore, it is possible to control the orientation of the anisotropic particles depending on the substrate geometry. In the thick film regime, the Landau-Levich-Derjaguin model remains valid if one account for the change in viscosity. EXPERIMENT To test the hypotheses, we performed dip-coating experiments with dilute suspensions of non-Brownian fibers with different length-to-diameter aspect ratios. We characterize the number of fibers entrained on the surface of the substrate as a function of the withdrawal velocity, allowing us to estimate a threshold capillary number below which all the particles remain in the liquid bath. Besides, we measure the angular distribution of the entrained fibers for two different substrate geometries: flat plates and cylindrical rods. We then measure the film thickness for more concentrated fiber suspensions. FINDINGS The entrainment of the fibers on a flat plate and a cylindrical rod is primarily controlled by the smaller characteristic length of the fibers: their diameter. At first order, the entrainment threshold scales similarly to that of spherical particles. The length of the fibers only appears to have a minor influence on the entrainment threshold. No preferential alignment is observed for non-Brownian fibers on a flat plate, except for very thin films, whereas the fibers tend to align themselves along the axis of a cylindrical rod for a large enough ratio of the fiber length to the radius of the cylindrical rod. The Landau-Levich-Derjaguin law is recovered for more concentrated suspension by introducing an effective capillary number accounting for the change in viscosity.
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Affiliation(s)
- Deok-Hoon Jeong
- Department of Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.
| | - Langqi Xing
- Department of Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.
| | - Michael Ka Ho Lee
- Department of Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.
| | - Nathan Vani
- Department of Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA; PMMH, ESPCI Paris, Université PSL, Sorbonne Université, Université de Paris, Paris, F-75005, France.
| | - Alban Sauret
- Department of Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.
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7
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Priyadarshani J, Awasthi P, Das S, Chakraborty S. Thermally-modulated shape transition at the interface of soft gel filament and hydrophobic substrate. J Colloid Interface Sci 2023; 640:246-260. [PMID: 36863181 DOI: 10.1016/j.jcis.2023.02.089] [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: 12/13/2022] [Revised: 02/08/2023] [Accepted: 02/15/2023] [Indexed: 02/21/2023]
Abstract
A liquid filament may pinch off into different shapes on interacting with a soft surface, as modulated by the interplay of inertial, capillary, and viscous forces. While similar shape transitions may intuitively be realized for more complex materials such as soft gel filaments as well, their intricate controllability towards deriving precise and stable morphological features remains challenging, as attributed to the complexities stemming from the underlying interfacial interactions over the relevant length and time scales during the sol-gel transition process. Circumventing these deficits in the reported literature, here we report a new means of precisely-controlled fabrication of gel microbeads via exploiting thermally-modulated instabilities of a soft filament atop a hydrophobic substrate. Our experiments reveal that abrupt morphological transitions of the gel material set in at a threshold temperature, resulting in spontaneous capillary thinning and filament breakup. We show that this phenomenon may be precisely modulated by an alteration in the hydration state of the gel material that may be preferentially dictated by its intrinsic glycerol content. Our results demonstrate that the consequent morphological transitions give rise to topologically-selective microbeads as an exclusive signature of the interfacial interactions of the gel material with the deformable hydrophobic interface underneath. Thus, intricate control may be imposed on the spatio-temporal evolution of the deforming gel, facilitating the inception of highly ordered structures of specific shapes and dimensionalities on demand. This is likely to advance the strategies of long shelf-life analytical biomaterial encapsulations via realizing one-step physical immobilization of bio-analytes on the bead surfaces as a new route to controlled materials processing, without demanding any resourced microfabrication facility or delicate consumable materials.
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Affiliation(s)
- Jyotsana Priyadarshani
- School of Medical Science & Technology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India; Department of Mechanical Engineering, KU Leuven, Leuven 3001, Belgium
| | - Prasoon Awasthi
- School of Medical Science & Technology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Soumen Das
- School of Medical Science & Technology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Suman Chakraborty
- Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
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8
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Jeong DH, Xing L, Boutin JB, Sauret A. Particulate suspension coating of capillary tubes. SOFT MATTER 2022; 18:8124-8133. [PMID: 36239275 DOI: 10.1039/d2sm01211a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The displacement of a suspension of particles by an immiscible fluid in a capillary tube or in porous media is a canonical configuration that finds application in a large number of natural and industrial applications, including water purification, dispersion of colloids and microplastics, coating and functionalization of tubings. The influence of particles dispersed in the fluid on the interfacial dynamics and on the properties of the liquid film left behind remain poorly understood. Here, we study the deposition of a coating film on the walls of a capillary tube induced by the translation of a suspension plug pushed by air. We identify the different deposition regimes as a function of the translation speed of the plug, the particle size, and the volume fraction of the suspension. The thickness of the coating film is characterized, and we show that similarly to dip coating, three coating regimes are observed, liquid only, heterogeneous, and thick films. We also show that, at first order, the thickness of films thicker than the particle diameter can be predicted using the effective viscosity of the suspension. Nevertheless, we also report that for large particles and concentrated suspensions, a shear-induced migration mechanism leads to local variations in volume fraction and modifies the deposited film thickness and composition.
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Affiliation(s)
- D-H Jeong
- Department of Mechanical Engineering, University of California, Santa Barbara, CA 93106, USA.
| | - L Xing
- Department of Mechanical Engineering, University of California, Santa Barbara, CA 93106, USA.
| | - J-B Boutin
- Department of Mechanical Engineering, University of California, Santa Barbara, CA 93106, USA.
| | - A Sauret
- Department of Mechanical Engineering, University of California, Santa Barbara, CA 93106, USA.
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9
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Rajesh S, Thiévenaz V, Sauret A. Transition to the viscoelastic regime in the thinning of polymer solutions. SOFT MATTER 2022; 18:3147-3156. [PMID: 35363237 DOI: 10.1039/d2sm00202g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In this study, we investigate the transition between the Newtonian and the viscoelastic regimes during the pinch-off of droplets of dilute polymer solutions and discuss its link to the coil-stretch transition. The detachment of a drop from a nozzle is associated with the formation of a liquid neck that causes the divergence of the local stress in a vanishingly small region. If the liquid is a polymer solution, this increasing stress progressively unwinds the polymer chains, up to a point where the resulting increase in the viscosity slows down drastically the thinning. This threshold to a viscoelastic behavior corresponds to a macroscopic strain rate. In the present study, we characterize the variations of with respect to the polymer concentration and molar weight, to the solvent viscosity, and to the nozzle size, i.e., the weight of the drop. We provide empirical scaling laws for these variations. We also analyze the thinning dynamics at the transition and show that it follows a self-similar dynamics controlled by the time scale c-1. This characteristic time is different and always shorter than the relaxation time of the polymer.
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Affiliation(s)
- Sreeram Rajesh
- Department of Mechanical Engineering, University of California, Santa Barbara, California 93106, USA.
| | - Virgile Thiévenaz
- Department of Mechanical Engineering, University of California, Santa Barbara, California 93106, USA.
| | - Alban Sauret
- Department of Mechanical Engineering, University of California, Santa Barbara, California 93106, USA.
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