1
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Noce E, Zobayed I, Fontenot RJ, Jumet B, Rasheed RM, Turrubiantes J, Preston DJ. Attaining Tailored Wicking Behavior with Additive Manufacturing. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024. [PMID: 39152911 DOI: 10.1021/acs.langmuir.4c01464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/19/2024]
Abstract
Additive manufacturing (AM) has opened a new pathway to create customized wicking materials. With lower manufacturing costs and a larger design space than many alternatives for wicking, AM is of particular value in fields such as thermal management and microfluidics. Fluid propagation during wicking in porous media, however, has largely remained limited to Washburnian (t ) behavior, and optimizing these materials for wicking in a variety of use cases presents a challenge. In this work, we present a method of tailoring wicking behavior to an arbitrary target function of propagation distance versus time, achieved through the use of AM to create nonuniform porous materials. Layers of parallel lines, each successive layer rotated 90° from the last, form a gridded structure with a spatially varying unit cell size for which analytical models for the capillary pressure and solid fraction and a semianalytical model for permeability were found. These models were validated with capillary rise experiments for spatially uniform porous materials over a range of solid fractions from 0.4 to 0.9. Leveraging these models and representing a nonuniform porous material as a series of Ohmic fluidic resistors, we created an inverse design algorithm that generates a wicking material with spatially varying parameters to achieve a specified target function for fluid propagation as a function of time. These materials can exhibit atypical wicking behavior, including fluid propagation displaying simple linear and piecewise linear relationships with time rather than the conventional Washburn relationship.
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Affiliation(s)
- Evan Noce
- Department of Mechanical Engineering, Rice University, Houston, Texas 77005, United States
| | - Irfan Zobayed
- Department of Mechanical Engineering, Rice University, Houston, Texas 77005, United States
| | - Richard J Fontenot
- Department of Mechanical Engineering, Rice University, Houston, Texas 77005, United States
| | - Barclay Jumet
- Department of Mechanical Engineering, Rice University, Houston, Texas 77005, United States
| | - Rawand M Rasheed
- Department of Mechanical Engineering, Rice University, Houston, Texas 77005, United States
| | - Jennifer Turrubiantes
- Department of Mechanical Engineering, Rice University, Houston, Texas 77005, United States
| | - Daniel J Preston
- Department of Mechanical Engineering, Rice University, Houston, Texas 77005, United States
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2
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Zhang J, Wang G, Chai Z, Li Z, Yuan S, Wang Y, Ding Y, Sun T, Wang T, Zhao D, Busnaina AA, Ren TL, Lu X. All-Solution-Processed Electronics with Sub-Microscale Resolution and Nanoscale Fidelity Fabricated Via a Humidity-Controlled, Surface Energy-Directed Assembly Process. ACS NANO 2024. [PMID: 39001855 DOI: 10.1021/acsnano.4c04936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/15/2024]
Abstract
Solution-based processes have received considerable attention in the fabrication of electronics and sensors owing to their merits of being low-cost, vacuum-free, and simple in equipment. However, the current solution-based processes either lack patterning capability or have low resolution (tens of micrometers) and low pattern fidelity in terms of line edge roughness (LER, several micrometers). Here, we present a surface energy-directed assembly (SEDA) process to fabricate metal oxide patterns with up to 2 orders of magnitude improvement in resolution (800 nm) and LER (16 nm). Experiment results show that high pattern fidelity can be achieved only at low relative humidities of below 30%. The reason for this phenomenon lies in negligible water condensation on the solution droplet. Employing the SEDA process, all-solution-processed metal oxide thin film transistors (TFTs) are fabricated by using indium oxide as channel layers, indium tin oxide as source/drain electrodes and gate electrodes, and aluminum oxide as gate dielectrics. TFT-based logic gate circuits, including NOT, NOR, NAND, and AND are fabricated as well, demonstrating the applicability of the SEDA process in fabricating large area functional electronics.
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Affiliation(s)
- Jingwei Zhang
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Tribology in Advanced Equipment, Tsinghua University, Beijing 100084, China
| | - Guangji Wang
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Tribology in Advanced Equipment, Tsinghua University, Beijing 100084, China
| | - Zhimin Chai
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Tribology in Advanced Equipment, Tsinghua University, Beijing 100084, China
| | - Zetong Li
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Tribology in Advanced Equipment, Tsinghua University, Beijing 100084, China
| | - Siqing Yuan
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Tribology in Advanced Equipment, Tsinghua University, Beijing 100084, China
| | - Yihuan Wang
- Weiyang College, Tsinghua University, Beijing 100084, China
| | - Yi Ding
- Weiyang College, Tsinghua University, Beijing 100084, China
| | - Taohan Sun
- Weiyang College, Tsinghua University, Beijing 100084, China
| | - Tongqing Wang
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Tribology in Advanced Equipment, Tsinghua University, Beijing 100084, China
| | - Dewen Zhao
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Tribology in Advanced Equipment, Tsinghua University, Beijing 100084, China
| | - Ahmed A Busnaina
- NSF Nanoscale Science and Engineering Center for High-Rate Nanomanufacturing (CHN), Northeastern University, Boston, Massachusetts 02115, United States
| | - Tian-Ling Ren
- School of Integrated Circuits and Beijing National Research on Information Science and Technology (BNRist), Tsinghua University, Beijing 100084, China
| | - Xinchun Lu
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Tribology in Advanced Equipment, Tsinghua University, Beijing 100084, China
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3
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Choi C, Choi J, Jo JS, Jeon GW, Lee KW, Park DH, Jang JW. Photoluminescence variations in organic fluorescent crystals by changing the surface energy of the substrate. J Colloid Interface Sci 2024; 663:379-386. [PMID: 38412723 DOI: 10.1016/j.jcis.2024.02.131] [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: 12/07/2023] [Revised: 01/29/2024] [Accepted: 02/16/2024] [Indexed: 02/29/2024]
Abstract
Organic fluorescent crystals were obtained using single-benzene-based diethyl 2,5-dihydroxyterephthalate (DDT) molecules through crystallization from a droplet of the DDT solution on an Au substrate. To control the size of the DDT crystals, the surface energy of the Au substrate was modified with air plasma treatment, producing a hydrophilic surface and a hydrophobic self-assembled monolayer (SAM) coating. The size of DDT crystals increased as the surface energy of the substrate decreased. The averaged cross-section area of the DDT crystals on the Au substrates increased in the order of the air-plasma-treated substrate (∼23.43 μm2) < pristine substrate (∼225.6 μm2) < hydrophobic SAM-coated substrate (∼2240 μm2). On the other hand, the main emission of the DDT crystals redshifted from blue to green as the crystal size increased, which is related to the aggregation of the DDT crystals. Moreover, the coffee-ring effect during the DDT crystallization was hindered by controlling the solvent evaporation conditions. As examples of the application of the proposed technique, patterned DDT crystals were obtained using selectively patterned hydrophobic and hydrophilic substrates.
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Affiliation(s)
- Chiwon Choi
- Division of Physics and Semiconductor Science, Dongguk University, Seoul 04620, Republic of Korea
| | - Jinho Choi
- Department of Chemical Engineering, Program in Biomedical Science and Engineering, Inha University, Incheon 22212, Republic of Korea
| | - Jeong-Sik Jo
- Division of Physics and Semiconductor Science, Dongguk University, Seoul 04620, Republic of Korea
| | - Gi Wan Jeon
- Division of Physics and Semiconductor Science, Dongguk University, Seoul 04620, Republic of Korea
| | - Kyu Won Lee
- Department of Physics, Korea University, Seoul 02841, Republic of Korea
| | - Dong Hyuk Park
- Department of Chemical Engineering, Program in Biomedical Science and Engineering, Inha University, Incheon 22212, Republic of Korea.
| | - Jae-Won Jang
- Division of Physics and Semiconductor Science, Dongguk University, Seoul 04620, Republic of Korea.
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4
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Ye X, Yang Y, Liao D, Tang K, Qiu H. Interfacial Effects of Nanostructured Doubly Reentrant Surfaces on the Evolution of Local Concentration and Fluid Flow in an Evaporating Droplet. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:9785-9796. [PMID: 38680055 DOI: 10.1021/acs.langmuir.4c00893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/01/2024]
Abstract
Surface modification, such as bioinspired nanostructured doubly reentrant surfaces that have presented superhydrophobic wettability even under low-surface-tension liquid, is a very promising technology for controlling droplet dynamics, heat transfer, and evaporation. In this article, we investigate the interfacial effects of nanostructured doubly reentrant surfaces on the flow behaviors and local concentration evolution during the evaporation of an ethanol/water multicomponent droplet. Using particle image velocimetry (PIV) and novel aggregate-induced emission-based (AIE) techniques, the flow patterns and local concentration distributions on both hydrophobic and nanostructured doubly reentrant surfaces were probed and compared. It is found that in addition to the established Marangoni flow-dominated stage, transition stage, and buoyancy-induced flow-dominated stage, a new transition stage and a rolling stage for the nanostructured doubly reentrant surface are detected in the late evaporation period. Differences in the local concentration distribution evolution occur depending on the hydrophobicity of the surface on which the droplet is placed. For the hydrophobic surface, a nonuniform local concentration distribution exists consistently, with a high water fraction in a shell-shaped region near the liquid-air interface and a secondary concentration gradient within this shell-shaped region. The concentration distribution on the nanostructured doubly reentrant surface evolves in a more complex manner, with a strip-shaped region of high water fraction forming in the intermediate stage and then reorganized by rolling flow in the late stage. Finally, theoretical analysis combining PIV and AIE visualization results reveals that the variations in droplet concentration distributions on surfaces with different hydrophobicities exert a significant impact on evaporative behaviors. These behaviors, in turn, affect the evolution of the local concentration distribution.
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Affiliation(s)
- Xin Ye
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong SAR, China
- Sustainable Energy and Environment Thrust, Function Hub, The Hong Kong University of Science and Technology (Guangzhou), Nansha, Guangzhou 511453, Guangdong, China
| | - Yinchuang Yang
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong SAR, China
| | - Dong Liao
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong SAR, China
| | - Kai Tang
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong SAR, China
- Smart Manufacturing Thrust, Systems Hub, The Hong Kong University of Science and Technology (Guangzhou), Nansha, Guangzhou 511453, Guangdong, China
| | - Huihe Qiu
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong SAR, China
- Sustainable Energy and Environment Thrust, Function Hub, The Hong Kong University of Science and Technology (Guangzhou), Nansha, Guangzhou 511453, Guangdong, China
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5
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Gibouin F, Nalatamby D, Lidon P, Medina-Gonzalez Y. Molecular Rotors for In Situ Viscosity Mapping during Evaporation of Confined Fluid Mixtures. ACS APPLIED MATERIALS & INTERFACES 2024; 16:8066-8076. [PMID: 38316660 DOI: 10.1021/acsami.3c16808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
Numerous formulation processes of materials involve a drying step, during which evaporation of a solvent from a multicomponent liquid mixture, often confined in a thin film or in a droplet, leads to concentration and assembly of nonvolatile compounds. While the basic phenomena ruling evaporation dynamics are known, precise modeling of practical situations is hindered by the lack of tools for local and time-resolved mapping of concentration fields in such confined systems. In this article, the use of fluorescence lifetime imaging microscopy and of fluorescent molecular rotors is introduced as a versatile, in situ, and quantitative method to map viscosity and concentration fields in confined, evaporating liquids. More precisely, the cases of drying of a suspended liquid film and of a sessile droplet of mixtures of fructose and water are investigated. Measured viscosity and concentration fields allow characterization of drying dynamics, in agreement with simple modeling of the evaporation process.
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Affiliation(s)
- Florence Gibouin
- Laboratoire du Futur, (LOF)─Solvay─CNRS─Université de Bordeaux, UMR 5258, Bordeaux, Pessac 33600, France
| | - Dharshana Nalatamby
- Laboratoire du Futur, (LOF)─Solvay─CNRS─Université de Bordeaux, UMR 5258, Bordeaux, Pessac 33600, France
| | - Pierre Lidon
- Laboratoire du Futur, (LOF)─Solvay─CNRS─Université de Bordeaux, UMR 5258, Bordeaux, Pessac 33600, France
| | - Yaocihuatl Medina-Gonzalez
- Laboratoire du Futur, (LOF)─Solvay─CNRS─Université de Bordeaux, UMR 5258, Bordeaux, Pessac 33600, France
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6
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Yamada Y, Isobe K, Horibe A. Analysis of Evaporation of Droplet Pairs by a Quasi-Steady-State Diffusion Model Coupled with the Evaporative Cooling Effect. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:15587-15596. [PMID: 37867300 DOI: 10.1021/acs.langmuir.3c01893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Abstract
Multidroplet evaporation is a common phase-change phenomenon not only in nature but also in many industrial applications, including inkjet printing and spray cooling. The evaporation behavior of these droplets is strongly affected by the distance between neighboring droplets, and in particular, evaporation suppression occurs as the distance decreases. However, further quantitative information, such as the temperature and local evaporation flux, is limited because the analytical models of multidroplet evaporation only treat vapor diffusion, and the effect of the latent heat transfer through the liquid-vapor phase change is ignored. Here, we perform a numerical analysis of evaporating droplet pairs that linked vapor diffusion from the droplet surface and evaporative cooling. Heat transfer through the liquid and gas phases is also considered because the saturation pressure depends on the temperature. The results show an increase in the vapor concentration in the region between the two droplets. Consequently, the local evaporation flux in the proximate region significantly decreases with decreasing separation distance. This means that the latent heat transfer through the phase change is diminished, and an asymmetrical temperature distribution occurs in the liquid and gas phases. These numerical results provide quantitative information about the temperature and local evaporation flux of evaporating droplet pairs, and they will guide further investigation of multiple droplet evaporation.
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Affiliation(s)
- Yutaka Yamada
- Faculty of Environmental, Life, Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Kazuma Isobe
- Faculty of Environmental, Life, Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Akihiko Horibe
- Faculty of Environmental, Life, Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
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7
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Junisu BA, Sun YS. Hierarchical Surface Instability in Polymer Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:15249-15259. [PMID: 37862459 DOI: 10.1021/acs.langmuir.3c01936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2023]
Abstract
This study demonstrates hierarchical instabilities in thin films. The hierarchical instabilities display three morphological characteristics: (1) windmill-like patterns at the macroscale, (2) Bénard cells and striations at the microscale, and (3) holes at the mesoscale. Such hierarchical instabilities occurred when spin coating was performed on high-volatile solutions under a high relative humidity (RH) but were suppressed when spin coating was performed on low-volatile solutions regardless of the RH. The high-volatile solutions comprise poly(4-vinylpyridine) (P4VP) in methanol or ethanol. The low-volatility solutions comprise P4VP in propanol or butanol. P4VP molecular weights, P4VP concentrations, spin rates, and film thicknesses are not vital factors in forming hierarchical instability in spin-coated P4VP films. Instead, the formation of hierarchical instabilities depends on the RH and solvent types. Namely, the hierarchical instabilities are driven by Bénard-Marangoni convection, water vapor condensation, and disturbance of spin-up and spin-off stages during spin coating of highly volatile solutions under high RH. Mechanisms of hierarchical instabilities are interpreted in detail.
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Affiliation(s)
- Belda Amelia Junisu
- Department of Chemical and Materials Engineering, National Central University, Taoyuan 32001, Taiwan
| | - Ya-Sen Sun
- Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan
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8
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Othman AM, Poulos AS, Torres O, Routh AF. Liquid-Liquid Phase Separation Induced by Vapor Transfer in Evaporative Binary Sessile Droplets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:13242-13257. [PMID: 37677134 PMCID: PMC10515642 DOI: 10.1021/acs.langmuir.3c01686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 08/21/2023] [Indexed: 09/09/2023]
Abstract
Drying of binary sessile droplets consisting of ethanol and octamethyltrisiloxane on a high-energy surface is investigated. During the process of evaporation, the droplets undergo liquid-liquid phase separation, resulting in the appearance of microdroplets at the liquid-air interface, which subsequently violently burst. This phase separation is attributed to water vapor transfer into the droplet, which modifies the solubility and leads to the formation of a ternary mixture. The newly formed ternary mixture may undergo nucleation and growth or spinodal decomposition, depending on the droplet composition path. By control of the relative humidity of air, phase separation can be mitigated or even eliminated. The droplets also display high mobility and complex wetting behavior due to phase separation, with two contracting and two spreading stages. The mass loss experiments reveal that the droplets undergo three distinct drying stages with an enhanced evaporation rate observed during the phase separation stage. A modified diffusion-limited model was employed to predict the evaporation rate, accounting for the physiochemical changes during evaporation and proved to be consistent with experimental observations. The findings of this work enhance our understanding of a coupled fundamental process involving the evaporation of multicomponent mixtures, wetting, and phase separation.
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Affiliation(s)
- Ahmed M. Othman
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Dr, Cambridge CB3 0AS, U.K.
| | | | - Ophelie Torres
- Unilever
R & D Port Sunlight, Quarry Road East, Wirral CH63 3JW, U.K.
| | - Alexander. F. Routh
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Dr, Cambridge CB3 0AS, U.K.
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9
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Yang L, Pahlavan AA, Stone HA, Bain CD. Evaporation of alcohol droplets on surfaces in moist air. Proc Natl Acad Sci U S A 2023; 120:e2302653120. [PMID: 37695912 PMCID: PMC10515150 DOI: 10.1073/pnas.2302653120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 08/01/2023] [Indexed: 09/13/2023] Open
Abstract
Droplets of alcohol-based formulations are common in applications from sanitizing sprays to printing inks. However, our understanding of the drying dynamics of these droplets on surfaces and the influence of ambient humidity is still very limited. Here, we report the drying dynamics of picoliter droplets of isopropyl alcohol deposited on a surface under controlled humidity. Condensation of water vapor in the ambient environment onto alcohol droplets leads to unexpectedly complex drying behavior. As relative humidity (RH) increases, we observed a variety of phenomena including enhanced spreading, nonmonotonic changes in the drying time, the formation of pancake-like shapes that suppress the coffee-ring effect, and the formation of water-rich films around an alcohol-rich drop. We developed a lubrication model that accounts for the coupling between the flow field within the drop, the shape of the drop, and the vapor concentration field. The model reproduces many of the experimentally observed morphological and dynamic features, revealing the presence of unusually large spatial compositional gradients within the evaporating droplet and surface-tension-gradient-driven flows arising from water condensation/evaporation at the surface of the droplet. One unexpected feature from the simulation is that water can evaporate and condense concurrently in different parts of the drop, providing fundamental insights that simpler models based on average fluxes lack. We further observed rim instabilities at higher RH that are well-described by a model based on the Rayleigh-Plateau instability. Our findings have implications for the testing and use of alcohol-based disinfectant sprays and printing inks.
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Affiliation(s)
- Lisong Yang
- Department of Chemistry, Durham University, DurhamDH1 3LE, UK
| | - Amir A. Pahlavan
- Department of Mechanical Engineering & Materials Science, Yale University, New Haven, CT06511
| | - Howard A. Stone
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ08544
| | - Colin D. Bain
- Department of Chemistry, Durham University, DurhamDH1 3LE, UK
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10
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Schubotz S, Besford QA, Nazari S, Uhlmann P, Bittrich E, Sommer JU, Auernhammer GK. Influence of the Atmosphere on the Wettability of Polymer Brushes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:4872-4880. [PMID: 36995334 DOI: 10.1021/acs.langmuir.2c03009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Polymer brushes, i.e., end-tethered polymer chains on substrates, are sensitive to adaptation, e.g., swelling, adsorption, and reorientation of the surface molecules. This adaptation can originate from a contacting liquid or atmosphere for partially wetted substrates. The macroscopic contact angle of the aqueous drop can depend on both adaptation mechanisms. We analyze how the atmosphere around an aqueous droplet determines the resulting contact angle of the wetting droplet on polymer brush surfaces. Poly(N-isopropylacrylamide) (PNiPAAm)-based brushes are used due to their exceptional sensitivity to solvation and liquid mixture composition. We develop a method that reliably measures wetting properties when the drop and the surrounding atmosphere are not in equilibrium, e.g., when evaporation and condensation tend to contaminate the liquid of the drop and the atmosphere. For this purpose, we use a coaxial needle in the droplet, which continuously exchanges the wetting liquid, and in addition, we constantly exchange the almost saturated atmosphere. Depending on the wetting history, PNiPAAm can be prepared in two states, state A with a large water contact angle (∼65°) and state B with a small water contact angle (∼25°). With the coaxial needle, we can demonstrate that the water contact angle of a sample in state B significantly increases by ∼30° when a water-free atmosphere is almost saturated with ethanol, compared to an ethanol-free atmosphere at 50% relative humidity. For a sample in state A, the relative humidity has little influence on the water contact angle.
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Affiliation(s)
- Simon Schubotz
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden 01069, Germany
- Technische Universität Dresden, Helmholtztraße 10, Dresden 01062, Germany
| | - Quinn A Besford
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden 01069, Germany
| | - Saghar Nazari
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden 01069, Germany
- Technische Universität Dresden, Helmholtztraße 10, Dresden 01062, Germany
| | - Petra Uhlmann
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden 01069, Germany
| | - Eva Bittrich
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden 01069, Germany
| | - Jens-Uwe Sommer
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden 01069, Germany
- Institute for Theoretical Physics, Technische Universität Dresden, Dresden 01069, Germany
| | - Günter K Auernhammer
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden 01069, Germany
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11
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Pereira D, Bierlich J, Kobelke J, Pereira V, Ferreira MS. Optical Fiber Sensor for Monitoring the Evaporation of Ethanol-Water Mixtures. SENSORS (BASEL, SWITZERLAND) 2022; 22:5498. [PMID: 35898002 PMCID: PMC9331179 DOI: 10.3390/s22155498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/16/2022] [Accepted: 07/21/2022] [Indexed: 02/04/2023]
Abstract
An inline optical fiber sensor is proposed to monitor in real time the evaporation process of ethanol-water binary mixtures. The sensor presents two interferometers, a cladding modal interferometer (CMI) and a Mach-Zehnder interferometer (MZI). The CMI is used to acquire the variations in the external medium refractive index, presenting a maximum sensitivity of 387 nm/RIU, and to attain the variation in the sample concentration profile, while the MZI monitors temperature fluctuations. For comparison purposes, an image analysis is also conducted to obtain the droplet profile. The sensor proposed in this work is a promising alternative in applications where a rigorous measurement of volatile organic compound concentrations is required, and in the study of chemical and physical properties related to the evaporation process.
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Affiliation(s)
- Diana Pereira
- i3N & Department of Physics, University of Aveiro, Campus Universitario de Santiago, 3810-193 Aveiro, Portugal; (D.P.); (V.P.)
| | - Jörg Bierlich
- Leibniz Institute of Photonic Technology IPHT, Albert-Einstein-Str. 9, 07745 Jena, Germany; (J.B.); (J.K.)
| | - Jens Kobelke
- Leibniz Institute of Photonic Technology IPHT, Albert-Einstein-Str. 9, 07745 Jena, Germany; (J.B.); (J.K.)
| | - Vanda Pereira
- i3N & Department of Physics, University of Aveiro, Campus Universitario de Santiago, 3810-193 Aveiro, Portugal; (D.P.); (V.P.)
- ISOPlexis—Sustainable Agriculture and Food Technology Center, University of Madeira, Campus da Penteada, 9020-105 Funchal, Portugal
| | - Marta S. Ferreira
- i3N & Department of Physics, University of Aveiro, Campus Universitario de Santiago, 3810-193 Aveiro, Portugal; (D.P.); (V.P.)
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12
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Al Balushi KM, Sefiane K, Orejon D. Binary mixture droplet wetting on micro-structure decorated surfaces. J Colloid Interface Sci 2022; 612:792-805. [PMID: 35065463 DOI: 10.1016/j.jcis.2021.12.171] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 12/17/2021] [Accepted: 12/26/2021] [Indexed: 10/19/2022]
Abstract
Liquid surface tension as well as solid structure play a paramount role on the intimate wetting and non-wetting regimes and interactions between liquids droplets and solid substrates. We hypothesise that the coupling of these two variables, independently addressed in the past, eventually offer a wider range of understanding to the surface science and interfacial communities. In this work, intrinsically hydrophobic micro-pillared surfaces varying in the spacing between structures, and pure ethanol, pure water and their binary mixtures (as well as acetone-water and ethylene glycol-water mixtures) are utilised, accessing a wide range of substrate solid fractions and liquid surface tensions experimentally. Wettability measurements are carried out at different azimuthal directions to exemplify the wetting/non-wetting behaviour as well as the droplet asymmetry function of both liquid composition and structure spacing. Our findings reveal that high water concentration droplets, i.e., high surface tension fluids, sit in the Cassie-Baxter regime while partial non-wetting Wenzel or mixed-mode regimes with enhanced droplet asymmetry ensuing for medium and high ethanol concentrations, i.e., low surface tension fluids, below certain micropillar spacing. Beyond micropillar spacing s ≥ 40 µm, the impact of the surface structure on the droplet shape is negligible, and droplets adopt a similar contact angle and circular shape as on a flat smooth hydrophobic surface. Wetting and non-wetting regimes are then supported by classical wetting theories and equations. A wetting regime map for a wide range of surface tension fluids and/or their mixtures on a wide domain of solid fractions is then proposed.
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Affiliation(s)
- Khaloud Moosa Al Balushi
- Institute for Multiscale Thermofluids, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FD, Scotland, UK; Department of Engineering, The University of Technology and Applied Sciences, Suhar 311, Oman
| | - Khellil Sefiane
- Institute for Multiscale Thermofluids, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FD, Scotland, UK
| | - Daniel Orejon
- Institute for Multiscale Thermofluids, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FD, Scotland, UK; International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
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13
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Dong A, Su Q, Ma N, Xu P, Zhou L, Wu F, Wang L, Wan Y, Qian W. Effect of Relative Humidity on the Thickness of Assembled Silica Colloidal Crystal Films. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2021; 21:5215-5221. [PMID: 33875109 DOI: 10.1166/jnn.2021.19441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
In order for the colloidal crystal films to be better applied, the influence of relative humidity on the preparation of silica colloidal crystal (SCC) films was systematically studied to solve the problem of different thicknesses of SCC films prepared by different batches under the conditions with the same temperature, concentration of suspension and diameter of the particles. SCC films with 190 nm particles were prepared by static vertical deposition method under different humidity regulated by saturated salt solutions, and the thickness of the films was obtained by an interferometric method. The results showed that the increase in humidity would reduce the thickness of the prepared films, which was believed to be caused by the decrease in evaporation rate after the wetting film absorbs water vapor. A new formula for calculating film thickness was proposed and verified from a series of experiments. With the control of humidity, high-quality SCC films with controlled thickness can be repeatedly prepared.
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Affiliation(s)
- Ao Dong
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Qianqian Su
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Ning Ma
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Pengfei Xu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Lele Zhou
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Feng Wu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Lu Wang
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Yizhen Wan
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Weiping Qian
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
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14
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Park SM, Kim WG, Kim J, Choi EJ, Kim H, Oh JW, Yoon DK. Fabrication of Chiral M13 Bacteriophage Film by Evaporation-Induced Self-Assembly. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2008097. [PMID: 34081393 DOI: 10.1002/smll.202008097] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Revised: 03/25/2021] [Indexed: 06/12/2023]
Abstract
Biomacromolecules are likely to undergo self-assembly and show specific collective behavior concentrated in the medium. Although the assembly procedures have been studied for unraveling their mysteries, there are few cases to directly demonstrate the collective behavior and phase transition process in dynamic systems. In the contribution, the drying process of M13 droplet is investigated, and can be successfully simulated by a doctor blade coating method. The morphologies in the deposited film are measured by atomic force microscopy and the liquid crystal phase development is captured in real time using polarized optical microscope. Collective behaviors near the contact line are characterized by the shape of meniscus curve and particle movement velocity. With considering rheological properties and flow, the resultant chiral film is used to align gold nanorods, and this approach can suggest a way to use M13 bacteriophage as a scaffold for the multi-functional chiral structures.
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Affiliation(s)
- Soon Mo Park
- Graduate School of Nanoscience and Technology, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Won-Geun Kim
- BIT Fusion Technology Center, Pusan National University, Busan, 46241, Republic of Korea
| | - Junkyu Kim
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Eun-Jung Choi
- BIT Fusion Technology Center, Pusan National University, Busan, 46241, Republic of Korea
| | - Hyoungsoo Kim
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Jin-Woo Oh
- BIT Fusion Technology Center, Pusan National University, Busan, 46241, Republic of Korea
- Department of Nano Fusion Technology, Pusan National University, Busan, 46241, Republic of Korea
- Department of Nano Energy Engineering, Pusan National University, Busan, 46241, Republic of Korea
| | - Dong Ki Yoon
- Graduate School of Nanoscience and Technology, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
- KAIST Institute for NanoCentury, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
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15
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Andalib S, Taira K, Kavehpour HP. Data-driven time-dependent state estimation for interfacial fluid mechanics in evaporating droplets. Sci Rep 2021; 11:13579. [PMID: 34193897 PMCID: PMC8245485 DOI: 10.1038/s41598-021-92965-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 05/28/2021] [Indexed: 11/09/2022] Open
Abstract
Droplet evaporation plays crucial roles in biodiagnostics, microfabrication, and inkjet printing. Experimentally studying the evolution of a sessile droplet consisting of two or more components needs sophisticated equipment to control the vast parameter space affecting the physical process. On the other hand, the non-axisymmetric nature of the problem, attributed to compositional perturbations, introduces challenges to numerical methods. In this work, droplet evaporation problem is studied from a new perspective. We analyze a sessile methanol droplet evolution through data-driven classification and regression techniques. The models are trained using experimental data of methanol droplet evolution under various environmental humidity levels and substrate temperatures. At higher humidity levels, the interfacial tension and subsequently contact angle increase due to higher water uptake into droplet. Therefore, different regimes of evolution are observed due to adsorption-absorption and possible condensation of water which turns the droplet from a single component into a binary system. In this work, machine learning and data-driven techniques are utilized to estimate the regime of droplet evaporation, the time evolution of droplet base diameter and contact angle, and level of surrounding humidity. Droplet regime is estimated by classification algorithms through point-by-point analysis of droplet profile. Decision tree demonstrates a better performance compared to Naïve Bayes (NB) classifier. Additionally, the level of surrounding humidity, as well as the time evolution of droplet base diameter and contact angle, are estimated by regression algorithms. The estimation results show promising performance for four cases of methanol droplet evolution under conditions unseen by the model, demonstrating the model's capability to capture the complex physics underlying binary droplet evolution.
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Affiliation(s)
- Sahar Andalib
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA, 90095, USA.
| | - Kunihiko Taira
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA, 90095, USA
| | - H Pirouz Kavehpour
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA, 90095, USA
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16
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Li W, Chen R, Zhu X, Liao Q, Ye D, Yang Y, Li D. Photothermally Caused Propylene Glycol–Water Binary Droplet Evaporation on a Hydrophobic Surface. Ind Eng Chem Res 2021. [DOI: 10.1021/acs.iecr.0c05873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Wei Li
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030, China
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400030, China
| | - Rong Chen
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030, China
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400030, China
| | - Xun Zhu
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030, China
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400030, China
| | - Qiang Liao
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030, China
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400030, China
| | - Dingding Ye
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030, China
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400030, China
| | - Yang Yang
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030, China
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400030, China
| | - Dongliang Li
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030, China
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400030, China
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17
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Günay AA, Gnadt M, Sett S, Vahabi H, Kota AK, Miljkovic N. Droplet Evaporation Dynamics of Low Surface Tension Fluids Using the Steady Method. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:13860-13871. [PMID: 33167611 DOI: 10.1021/acs.langmuir.0c02272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Droplet evaporation governs many heat- and mass-transfer processes germane in nature and industry. In the past 3 centuries, transient techniques have been developed to characterize the evaporation of sessile droplets. These methods have difficulty in reconciling transient effects induced by the droplet shape and size changes during evaporation. Furthermore, investigation of evaporation of microdroplets residing on wetting substrates, or fluids having low surface tensions (<30 mN/m), is difficult to perform using established approaches. Here, we use the steady method to study the microdroplet evaporation dynamics of low surface tension liquids. We start by employing the steady method to benchmark with water droplets having base radii (20 ≤ Rb ≤ 260 μm), apparent advancing contact angle (45° ≤ θa,app ≤ 162°), surface temperature (30 < Ts < 60 °C), and relative humidity (40% < ϕ < 60%). Following validation, evaporation of ethanol (≈22 mN/m), hexane (≈18 mN/m), and dodecane (≈25 mN/m) were studied for 90 ≤ Rb ≤ 400 μm and 10 < Ts < 25 °C. We elucidate the mechanisms governing the observed behavior using heat and mass transport scaling analysis during evaporation, demonstrating our steady technique to be particularly advantageous for microdroplets, where Marangoni and buoyant forces are negligible. Our work not only elucidates the droplet evaporation mechanisms of low surface tension liquids but also demonstrates the steady method as a means to study phase change processes.
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Affiliation(s)
- A Alperen Günay
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 W Green Street, Urbana, Illinois 61801, United States
| | - Marisa Gnadt
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 W Green Street, Urbana, Illinois 61801, United States
| | - Soumyadip Sett
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 W Green Street, Urbana, Illinois 61801, United States
| | - Hamed Vahabi
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
| | - Arun K Kota
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Nenad Miljkovic
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 W Green Street, Urbana, Illinois 61801, United States
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 1206 W Green Street, Urbana, Illinois 61801, United States
- Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, United States
- International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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18
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Self-assembly of supported lipid multi-bilayers investigated by time-resolved X-ray diffraction. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183437. [PMID: 32783887 DOI: 10.1016/j.bbamem.2020.183437] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 07/30/2020] [Accepted: 07/30/2020] [Indexed: 11/23/2022]
Abstract
Supported lipid multi-bilayers or bilayer stacks are an important model membrane system, particularly suitable for surface-sensitive characterization methods like X-ray and neutron diffraction. Spreading organic solution (sOS) is one of the most widely used protocols for the preparation of lipid multi-bilayers. Despite its great popularity, the self-assembly mechanism of the bilayers is not yet fully elucidated, limiting further improvements of this protocol. In order to solve this problem, we investigated the formation process of lipid bilayers in the sOS protocol, using in-situ time-resolved X-ray diffraction, complemented by X-ray reflectivity and molecular dynamics simulation. Results reveal a simultaneous self-assembly scheme for both cholesterol-free and cholesterol-containing bilayers, with one bilayer phase forming at the surface and the other forming in the solution. The solution phase gradually transforms into the surface phase, yielding clean single phase in the end.
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19
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Shukla P, Jagdhari T, Fugaro AP, Boreyko JB. Characterizing Hygroscopic Materials via Droplet Evaporation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:1871-1877. [PMID: 32068407 DOI: 10.1021/acs.langmuir.9b02840] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Hygroscopic materials are widely used as desiccants for applications including food production, packaging, anti-icing, and gas storage. Current techniques for quantifying the hygroscopicity of materials, such as the use of a tandem differential mobility analyzer or a gravimetric vapor sorption analyzer, require complex and expensive setups. Here, we show that the hygroscopicity of any bulk material can be simply characterized by suspending it above a deposited droplet and measuring the droplet's evaporation rate. By controlling the temperature of the droplet to correspond to the dew point, we ensured that any evaporation was directly correlated with diffusive transport into the low-pressure hygroscopic material. Using Fick's law, the effective water vapor concentration of each material was extracted and nondimensionalized by the saturation concentration to obtain a hygroscopic index. This nondimensional index ranges from 0 (no hygroscopicity) to 1 (null vapor pressure) and can also be conceptualized as 1 - aw, where aw is the material's water activity.
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Affiliation(s)
- Pranav Shukla
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Tejas Jagdhari
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Andrew P Fugaro
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Jonathan B Boreyko
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia 24061, United States
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
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20
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Ozturk T, Erbil HY. Simple Model for Diffusion-Limited Drop Evaporation of Binary Liquids from Physical Properties of the Components: Ethanol-Water Example. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:1357-1371. [PMID: 31909624 DOI: 10.1021/acs.langmuir.9b03590] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The understanding of the evaporation process of drops consisting of binary mixtures, in particular ethanol-water drops, is important in many industries such as ink-jet printing, cooling of microelectronics, and alcohol-added pesticide spray applications. The theory of the diffusion-limited drop evaporation process for pure liquids has been investigated thoroughly, and linear (dV(2/3)/dt) slopes were obtained for most of the cases. However, the evaporation of binary liquid drops was found to be much more complicated than that of the pure liquids due to the change of the composition of the drop by time and there is a need for the development of a new model. The experimental results on the diffusion-limited drop evaporation behavior of ethanol-water binary drops initially containing 25 and 50% ethanol by wt and having a volume of 7 μL were reported on a flat hydrophobic Teflon-FEP substrate under the constant relative humidity of 54% and 25 °C temperature conditions, together with pure liquids. The change of contact angles, heights, and contact radius of the drops by time were monitored with a camera. In a parallel study, the concentration changes in the bulk composition of ethanol-water binary drops of 7 μL (25 and 50% ethanol by wt) by time in the same evaporation conditions were monitored using a refractive index-ethanol concentration calibration curve. Then, the parameters affecting the drop evaporation process, such as total vapor pressures, average diffusion coefficient of binary vapors, average molecular weights, and densities of the liquid drops, were calculated using well-known physical chemistry approaches from the previously published data. These parameters were used to estimate the rate of binary ethanol-water drop evaporation, and it was determined that the proposed model fitted the (dV(2/3)/dt) slopes obtained from experimental data points with lower than 5% error when the surface cooling of the drops was considered.
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Affiliation(s)
- Tugba Ozturk
- Department of Chemical Engineering , Gebze Technical University , Gebze 41400 , Kocaeli , Turkey
| | - H Yildirim Erbil
- Department of Chemical Engineering , Gebze Technical University , Gebze 41400 , Kocaeli , Turkey
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21
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Hegde O, Kabi P, Agarwal S, Basu S. Controlling self-assembly and buckling in nano fluid droplets through vapour mediated interaction of adjacent droplets. J Colloid Interface Sci 2019; 541:348-355. [PMID: 30708250 DOI: 10.1016/j.jcis.2019.01.106] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Revised: 01/24/2019] [Accepted: 01/24/2019] [Indexed: 11/15/2022]
Abstract
HYPOTHESIS Sessile droplets of contrasting volatilities can communicate via long range (∼O (1) mm) vapour-mediated interactions which allow the remote control of the flow driven self-assembly of nanoparticles in the drop of lower volatility. This allows morphological control of the buckling instability observed in evaporating nanofluid droplets. EXPERIMENTS A nanofluid droplet is dispensed adjacent to an ethanol droplet. Asymmetrical adsorption induced Marangoni flow (∼O (1) mm/s) internally segregates the particle population. Particle aggregation occurs preferentially on one side of the droplet leaving the other side to develop a relatively weaker shell which buckles under the effect of evaporation driven capillary pressure. FINDINGS The inter-droplet distance is varied to demonstrate the effect on the precipitate shape (flatter to dome shaped) and the location of the buckling (top to side). In addition to being a simple template for hierarchical self-assembly, the presented exposition also promises to enhance mixing rates (∼1000 times) in droplet-based bioassays with minimal contamination.
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Affiliation(s)
- Omkar Hegde
- Department of Mechanical Engineering, Indian Institute of Science, Bangalore 560012, India
| | - Prasenjit Kabi
- Interdisciplinary Centre for Energy Research, Indian Institute of Science, Bangalore 560012, India
| | - Shashwat Agarwal
- Department of Mechanical Engineering, Indian Institute of Science, Bangalore 560012, India
| | - Saptarshi Basu
- Department of Mechanical Engineering, Indian Institute of Science, Bangalore 560012, India.
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22
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Wang Z, Orejon D, Sefiane K, Takata Y. Water vapor uptake into hygroscopic lithium bromide desiccant droplets: mechanisms of droplet growth and spreading. Phys Chem Chem Phys 2019; 21:1046-1058. [PMID: 30320327 DOI: 10.1039/c8cp04504f] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The study of vapor absorption into liquid desiccant droplets is of general relevance to a better understanding and description of vapor absorption phenomena occurring at the macroscale as well as for practical optimization of dehumidification and refrigeration processes. Hence, in the present work, we provide the first systematic experimental study on the fundamentals of vapor absorption into liquid desiccant at the droplet scale, which initiates a novel avenue for the research of hygroscopic droplet growth. More specifically we address the behavior of lithium bromide-water droplets on hydrophobic PTFE and hydrophilic glass substrates under controlled ambient conditions. Driven by the vapor pressure difference between the ambient air and the droplet interface, desiccant droplets absorb water vapor and increase in volume. To provide further insights on the vapor absorption process, the evolution of the droplet profile is recorded using optical imaging and relevant profile characteristics are extracted. Results show that, even though the final expansion ratio of droplet volume is only a function of relative humidity, the dynamics of contact line and the absorption rate are found to differ greatly when comparing data with varying substrate wettability. Droplets on hydrophilic substrates show higher absorption kinetics and reach equilibrium with the ambient much faster than those on hydrophobic substrates. This is attributed to the absorption process being controlled by solute diffusion on the droplet side and to the shorter characteristic length for the solute diffusion on hydrophilic substrates. Moreover, the apparent droplet spreading process on hydrophilic substrates when compared to hydrophobic ones is explained based on a force balance analysis near the triple contact line, by the change of liquid-vapor surface tension due to the increase in water concentration, and assuming a development of a precursor film.
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Affiliation(s)
- Zhenying Wang
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
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23
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Gregson FKA, Ordoubadi M, Miles REH, Haddrell AE, Barona D, Lewis D, Church T, Vehring R, Reid JP. Studies of competing evaporation rates of multiple volatile components from a single binary-component aerosol droplet. Phys Chem Chem Phys 2019; 21:9709-9719. [PMID: 31025989 DOI: 10.1039/c9cp01158g] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The simultaneous evaporation and condensation of multiple volatile components from multicomponent aerosol droplets leads to changes in droplet size, composition and temperature. Measurements and models that capture and predict these dynamic aerosol processes are key to understanding aerosol microphysics in a broad range of contexts. We report measurements of the evaporation kinetics of droplets (initially ∼25 μm radius) formed from mixtures of ethanol and water levitated within a electrodynamic balance over timescales spanning 500 ms to 6 s. Measurements of evaporation into a gas phase of varied relative humidity and temperature are shown to compare well with predictions from a numerical model. We show that water condensation from the gas phase can occur concurrently with ethanol evaporation from aqueous-ethanol droplets. Indeed, water can condense so rapidly during the evaporation of a pure ethanol droplet in a humid environment, driven by the evaporative cooling the droplet experiences, that the droplet becomes pure water within 0.4 s.
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Affiliation(s)
- F K A Gregson
- School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK.
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