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Gupta S, Varanakkottu SN, Mani E, Satapathy DK. Contact Angle Modulation: In Situ Polymer Deposition during Sessile Drop Evaporation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:12594-12601. [PMID: 38837177 DOI: 10.1021/acs.langmuir.4c01039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
The drying kinetics of a sessile drop on a solid surface are a widely studied phenomenon because of their relevance to various fields such as coating, printing, medical diagnostics, sensing, and microfluidic technology. Typically, the drop undergoes drying either at a constant contact radius (R) with a decrease in the three-phase contact angle or at a constant contact angle (θ) with a reduction in the radius with time. These two drying modes are referred to as CCR and CCA, respectively. It is not uncommon where both R and θ may decrease during drying, especially in the penultimate stage of drying. In this work, we report a scenario wherein the θ increases while R decreases during the drying process of an aqueous polymer solution on a high surface energy substrate. This behavior is observed across different polymer systems (such as poly(ethylene oxide) and polyvinyl pyrrolidine), varying molecular weights, and polymer concentrations. As the drop dries, the polymer gets deposited at the three-phase contact line, thus reducing the surface energy of the substrate and leading to an increase in the contact angle. The drop responds by attempting to reach a new equilibrium contact angle through slipping. The temporal increase in contact angle follows a power law scaling behavior. This study demonstrates an in situ modulation of contact angle facilitated by evaporation and polymer deposition, showcasing unconventional drying dynamics.
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Affiliation(s)
- Shakshi Gupta
- Soft Material Laboratory, Department of Physics, IIT Madras, Chennai 600036, India
- Centre for Soft and Biological Matter, IIT Madras, Chennai 600036, India
| | | | - Ethayaraja Mani
- Department of Chemical Engineering, IIT Madras, Chennai 600036, India
- Centre for Soft and Biological Matter, IIT Madras, Chennai 600036, India
| | - Dillip K Satapathy
- Soft Material Laboratory, Department of Physics, IIT Madras, Chennai 600036, India
- Centre for Soft and Biological Matter, IIT Madras, Chennai 600036, India
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Tiwari A, Lee SJ, Garg DK, Shin S, Thokchom AK. Characterizing the Microparticles Deposition Structure and its Photonic Nature in Surfactant-Laden Evaporating Colloidal Sessile Droplets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:8711-8720. [PMID: 38608175 DOI: 10.1021/acs.langmuir.4c00596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/14/2024]
Abstract
This work presents a simple method to create photonic microstructures via the natural evaporation of surfactant-laden colloidal sessile droplets on a flat substrate. In the absence of dissolved surfactant, the evaporating colloidal droplet forms a well-known coffee ring deposition. In contrast, the presence of surfactant leads to the formation of multiple ring structures due to the repetitive pinning-depinning behavior of the droplet contact line (CL). It is found that the multiring structure shows vibrant iridescent structural colors while the coffee ring lacks a photonic nature. This difference in the structural color for the presence and absence of the surfactant is found to be dependent on the arrangement of the particles in the deposition structure. The particle arrangement in the multirings is monolayered and well-ordered. The ordering of the particles is strongly influenced by the particle dynamics, contact angle (CA), and CL dynamics of the evaporating colloidal solution droplet. Furthermore, the iridescent nature of the multiring deposition is demonstrated and explained. The dependence of the multiring deposition structure on the concentration of the dissolved surfactant and the suspended particles is also studied. The findings demonstrate that an intermediate surfactant concentration is desirable for the formation of a multiring structure. Further, the pinning-depinning CL dynamics that causes the formation of the multiring deposition structure is discussed. Finally, we demonstrate the applicability of the approach to smaller droplet volumes.
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Affiliation(s)
- Appurva Tiwari
- Soft Matter Lab, Department of Chemical Engineering, Shiv Nadar Institution of Eminence Deemed to be University, Greater Noida 201314, India
| | - Seong Jae Lee
- Department of Polymer Engineering, The University of Suwon, Hwaseong, Gyeonggi 18323, South Korea
| | - Dhiraj Kumar Garg
- Intencity Lab, Department of Chemical Engineering, Shiv Nadar Institution of Eminence Deemed to be University, Greater Noida 201314, India
| | - Sehyun Shin
- Department of Mechanical Engineering, Korea University, Anam Dong, Seoul 02841, South Korea
| | - Ashish Kumar Thokchom
- Soft Matter Lab, Department of Chemical Engineering, Shiv Nadar Institution of Eminence Deemed to be University, Greater Noida 201314, India
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3
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Song T, Jiang Z, Man X, Shi W. Joint Experimental and Theoretical Study on Deposition Morphologies in Polymer Sessile Droplets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:860-870. [PMID: 38109327 DOI: 10.1021/acs.langmuir.3c03038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
Although past experimental and theoretical research has made substantial progress in understanding evaporation behaviors in various suspensions, the fundamental mechanism for polymer sessile droplets is still lacking. One critical effect is the molecular weight on the evaporation behaviors. Here, systematic experiments are carried out to investigate the evaporation behavior of polymer droplets under the effects of polymer concentration, evaporation rate, and especially molecular weight. We obtain polymer films with various morphologies with molecular weights ranging from 2 orders of magnitude to 4 orders of magnitude and polymer concentration across 4 orders of magnitude. We further develop a theoretical model based on the Onsager principle to explain the evaporation mechanism from a dynamic perspective. Analysis indicates that increasing molecular weight or polymer concentration enhances the contact angle hysteresis and slows down the evaporation, resulting in the transition from multiring to coffee ring and eventually to uniform films. The findings offer a guideline for achieving the desired deposition patterns via droplet processing techniques.
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Affiliation(s)
- Tiantian Song
- Key Laboratory of Functional Polymer Materials of Ministry of Education, Tianjin Key Laboratory of Functional Polymer Materials, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Zechao Jiang
- School of Physics, Beihang University, Beijing 100191, China
| | - Xingkun Man
- School of Physics, Beihang University, Beijing 100191, China
- Peng Huanwu Collaborative Center for Research and Education, Beihang University, Beijing 100191, China
| | - Weichao Shi
- Key Laboratory of Functional Polymer Materials of Ministry of Education, Tianjin Key Laboratory of Functional Polymer Materials, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
- Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300071, China
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4
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Needles to Spheres: Evaluation of inkjet printing as a particle shape enhancement tool. Eur J Pharm Biopharm 2023; 184:92-102. [PMID: 36707008 DOI: 10.1016/j.ejpb.2023.01.016] [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: 12/07/2022] [Revised: 01/20/2023] [Accepted: 01/21/2023] [Indexed: 01/26/2023]
Abstract
Active pharmaceutical ingredients (APIs) often reveal shapes challenging to process, e.g. acicular structures, and exhibit reduced bioavailability induced by slow dissolution rate. Leveraging the API particles' surface and bulk properties offers an attractive pathway to circumvent these challenges. Inkjet printing is an attractive processing technique able to tackle these limitations already in initial stages when little material is available, while particle properties are maintained over the entire production scale. Additionally, it is applicable to a wide range of formulations and offers the possibility of co-processing with a variety of excipients to improve the API's bioavailability. This study addresses the optimization of particle shapes for processability enhancement and demonstrates the successful application of inkjet printing to engineer spherical lacosamide particles, which are usually highly acicular. By optimizing the ink formulation, adapting the substrate-liquid interface and tailoring the heat transfer to the particle, spherical particles in the vicinity of 100 µm, with improved flow properties compared to the bulk material, were produced. Furthermore, the particle size was tailored reproducibly by adjusting the deposited ink volume per cycle and the number of printing cycles. Therefore, the present study shows a novel, reliable, scalable and economical strategy to overcome challenging particle morphologies by co-processing an API with suitable excipients.
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Issakhani S, Jadidi O, Farhadi J, Bazargan V. Geometrically-controlled evaporation-driven deposition of conductive carbon nanotube patterns on inclined surfaces. SOFT MATTER 2023; 19:1393-1406. [PMID: 36723256 DOI: 10.1039/d2sm01431a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Controllable accumulation of carbon nanotubes in self-assembly techniques is of critical importance in smart patterning and printed electronics. This study investigates how inclining the substrate and inhibiting the droplet spreading by sharp solid edges can affect the droplet contact angle and pinning time to improve the electrical conductivity and uniformity of the deposited patterns. Rectangular and circular pedestals were employed to investigate the effect of geometry on the deposition characteristics and to incorporate the gravitational effect by varying the substrate inclination angle. The results indicate that confining the droplet contact line to remain pinned to the pedestal edge can significantly alter the width, uniformity, and precision of the deposited patterns. These improvements correspond to the enhancement of the droplet pinning time (due to the edge effect) and to the further increase of the local evaporation rate near the contact line (due to the droplet elevation). By conducting experiments on different rectangular pedestals with varying solid-liquid interfacial areas and comparing their deposition characteristics, a rectangular pedestal with specific dimensions is selected in terms of pattern consistency and material usage efficiency. It is also shown that higher inclination angles further increase the deposited line accumulation density. Combining confinement and inclination techniques yields promising deposited patterns with high consistency and low resistivity, ranging from 8.75 kΩ mm-1 to a minimum of 0.63 kΩ mm-1 for a 3 × 6 mm2 rectangular pedestal.
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Affiliation(s)
- Shervin Issakhani
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran.
| | - Omid Jadidi
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran.
| | - Jafar Farhadi
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran.
| | - Vahid Bazargan
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran.
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Ye L, Li S, Huang X. Effect of Nanoparticle Addition on Evaporation of Jet Fuel Liquid Films and Nanoparticle Deposition Patterns during Evaporation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:15973-15983. [PMID: 36521023 DOI: 10.1021/acs.langmuir.2c02306] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Jet fuel-based nanofluid fuel has been proposed for improving the energy density and utilization efficiency of jet fuel that is widely applied in aircraft powered by aviation turbine engines. To recognize the evaporation behavior of the formed liquid film as a jet fuel-based nanofluid sprayed onto the engine wall or blades, this paper presents the evaporation and deposition characteristics of the jet fuel-based nanofluid liquid film adhering on the hydrophilic substrate. The changes in contact line, contact angle, volume, and deposition pattern during liquid film evaporation under different substrate temperatures, different nanoparticle concentrations, and different kinds of nanoparticle additions were investigated. The effect of nano-Al addition on the evaporation kinetics and deposition pattern of the nano-Al/jet fuel (nAl/JF) nanofluid fuel liquid film was explored. Repeated pinning and de-pinning of contact lines during evaporation occurred, resulting in the formation of concentric multi-ring deposition patterns. The addition of nano-Al increased the evaporation rate and shortened the evaporation lifetime, demonstrating a promotion effect on jet fuel liquid film evaporation. The existence of an energy barrier shows that the movement of three-phase contact lines on the hydrophilic solid surface presented not a continuous sliding behavior but a "stick-slip" behavior, and there were multiple jumps in contact lines and contact angles. Finally, a comparison was made with the deposition pattern of jet fuel liquid films with different graphite and Fe nanoparticle additions during evaporation. The mechanism of deposition phenomena was deeply revealed by the analysis of capillary flow and Marangoni recirculation.
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Affiliation(s)
- Linhui Ye
- Institute of Energy, Department of Physics, Hangzhou Dianzi University, Hangzhou310018, China
| | - Shengji Li
- College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou310018, China
| | - Xuefeng Huang
- Institute of Energy, Department of Physics, Hangzhou Dianzi University, Hangzhou310018, China
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Formation and development of distinct deposit patterns by drying Polyelectrolyte-stabilized colloidal droplets at different surfactant concentrations. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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8
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Chai Z, Childress A, Busnaina AA. Directed Assembly of Nanomaterials for Making Nanoscale Devices and Structures: Mechanisms and Applications. ACS NANO 2022; 16:17641-17686. [PMID: 36269234 PMCID: PMC9706815 DOI: 10.1021/acsnano.2c07910] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 10/06/2022] [Indexed: 05/19/2023]
Abstract
Nanofabrication has been utilized to manufacture one-, two-, and three-dimensional functional nanostructures for applications such as electronics, sensors, and photonic devices. Although conventional silicon-based nanofabrication (top-down approach) has developed into a technique with extremely high precision and integration density, nanofabrication based on directed assembly (bottom-up approach) is attracting more interest recently owing to its low cost and the advantages of additive manufacturing. Directed assembly is a process that utilizes external fields to directly interact with nanoelements (nanoparticles, 2D nanomaterials, nanotubes, nanowires, etc.) and drive the nanoelements to site-selectively assemble in patterned areas on substrates to form functional structures. Directed assembly processes can be divided into four different categories depending on the external fields: electric field-directed assembly, fluidic flow-directed assembly, magnetic field-directed assembly, and optical field-directed assembly. In this review, we summarize recent progress utilizing these four processes and address how these directed assembly processes harness the external fields, the underlying mechanism of how the external fields interact with the nanoelements, and the advantages and drawbacks of utilizing each method. Finally, we discuss applications made using directed assembly and provide a perspective on the future developments and challenges.
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Affiliation(s)
- Zhimin Chai
- State
Key Laboratory of Tribology in Advanced Equipment, Tsinghua University, Beijing100084, China
- NSF
Nanoscale Science and Engineering Center for High-Rate Nanomanufacturing
(CHN), Northeastern University, Boston, Massachusetts02115, United States
| | - Anthony Childress
- NSF
Nanoscale Science and Engineering Center for High-Rate Nanomanufacturing
(CHN), Northeastern University, Boston, Massachusetts02115, United States
| | - Ahmed A. Busnaina
- NSF
Nanoscale Science and Engineering Center for High-Rate Nanomanufacturing
(CHN), Northeastern University, Boston, Massachusetts02115, United States
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Inanlu MJ, Farhadi J, Ansari E, Charkas S, Bazargan V. Effect of surfactant concentration on the evaporation-driven deposition of carbon nanotubes: from coffee-ring effect to strain sensing. RSC Adv 2022; 12:31688-31698. [PMID: 36380929 PMCID: PMC9638968 DOI: 10.1039/d2ra03833a] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 10/31/2022] [Indexed: 10/31/2023] Open
Abstract
Carbon nanotubes (CNTs) as electrically conductive materials are of great importance in the fabrication of flexible electronic devices and wearable sensors. In this regard, the evaporation-driven self-assembly of CNTs has attracted increasing attention. CNT-based applications are mostly concerned with the alignment of CNTs and the density of CNT films. In the present work, we focus on the latter by trying to achieve an optimal evaporation-driven deposition with the densest CNT ring. Although surfactants are used for effective dispersion and colloidal stabilization of CNTs in the aqueous phase, their excessive usage induces Marangoni eddies in the evaporating sessile droplets, leading to poor ring depositions. Thus, there is an optimum surfactant concentration that contributes to CNTs deagglomeration and results in the densest ring-like deposition with relatively high thickness. We report that this optimum concentration for sodium dodecyl sulfate (SDS) as a surfactant can be approximately considered as much as the concentration of multi-walled carbon nanotubes (MWCNTs) as the colloidal nanoparticles. Optimal depositions show the lowest electrical resistances for each CNT concentration, making them suitable for electronic applications. We also propose the multiple depositions method in which a new droplet is printed after the complete evaporation of the previous droplet. This method can lead to denser rings with a higher conductivity using lower concentrations of CNTs. Lastly, we fabricate strain sensors based on the optimal evaporation-driven deposition of CNTs which show higher gauge factors than the commercial strain gauges, corroborating the applicability of our method.
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Affiliation(s)
- Mohammad Jalal Inanlu
- School of Mechanical Engineering, College of Engineering, University of Tehran Tehran Iran
| | - Jafar Farhadi
- School of Mechanical Engineering, College of Engineering, University of Tehran Tehran Iran
| | - Ehsan Ansari
- School of Electrical and Computer Engineering, College of Engineering, University of Tehran Tehran Iran
| | - Saina Charkas
- School of Mechanical Engineering, College of Engineering, University of Tehran Tehran Iran
| | - Vahid Bazargan
- School of Mechanical Engineering, College of Engineering, University of Tehran Tehran Iran
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10
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Yang XY, Li GH, Huang X, Yu YS. Evaporative Deposition of Surfactant-Laden Nanofluid Droplets over a Silicon Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:11666-11674. [PMID: 36097700 DOI: 10.1021/acs.langmuir.2c01564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Morphologies of evaporative deposition, which has been widely applied in potential fields, were induced by the competition between internal flows inside evaporating droplets. Controlling the pattern of deposition and suppressing the coffee-ring effect are essential issues of intense interest in the aspects of industrial technologies and scientific applications. Here, evaporative deposition of surfactant-laden nanofluid droplets over silicon was experimentally investigated. A ring-like deposition was formed after complete evaporation of sodium dodecyl sulfate (SDS)-laden nanofluid droplets with an initial SDS concentration ranging from 0 to 1.5 CMC. In the case of initial SDS concentrations above 1.3 CMC, no cracks were observed in the ring-like deposition, indicating that the deposition patterns of nanofluid droplets could be completely changed and cracks could be eliminated by sufficient addition of SDS. With the increase of the initial concentration of hexadecyl trimethylammonium bromide (CTAB), the width of the deposition ring gradually decreased until no ring-like structure was formed. On the contrary, with the increase of the initial Triton X-100 (TX-100) concentration, the width of the deposition ring gradually increased until a uniform deposition was generated. Moreover, when the initial TX-100 concentration was high, a "tree-ring-like" pattern was discovered. Besides, morphologies of evaporative pattern due to the addition of surfacants were qualitatively analyzed.
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Affiliation(s)
- Xiao-Ye Yang
- Department of Mechanics, School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan 430068, P. R. China
| | - Guo-Hao Li
- Department of Mechanics, School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan 430068, P. R. China
| | - Xianfu Huang
- State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, P. R. China
- School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Ying-Song Yu
- Department of Mechanics, School of Civil Engineering, Architecture and Environment, Hubei University of Technology, Wuhan 430068, P. R. China
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11
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Zaibudeen A, Bandyopadhyay R. Correlating the drying kinetics and dried morphologies of aqueous colloidal gold droplets of different particle concentrations. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.128982] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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12
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Control of the Drying Patterns for Complex Colloidal Solutions and Their Applications. NANOMATERIALS 2022; 12:nano12152600. [PMID: 35957030 PMCID: PMC9370329 DOI: 10.3390/nano12152600] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 07/24/2022] [Accepted: 07/25/2022] [Indexed: 12/02/2022]
Abstract
The uneven deposition at the edges of an evaporating droplet, termed the coffee-ring effect, has been extensively studied during the past few decades to better understand the underlying cause, namely the flow dynamics, and the subsequent patterns formed after drying. The non-uniform evaporation rate across the colloidal droplet hampers the formation of a uniform and homogeneous film in printed electronics, rechargeable batteries, etc., and often causes device failures. This review aims to highlight the diverse range of techniques used to alleviate the coffee-ring effect, from classic methods such as adding chemical additives, applying external sources, and manipulating geometrical configurations to recently developed advancements, specifically using bubbles, humidity, confined systems, etc., which do not involve modification of surface, particle or liquid properties. Each of these methodologies mitigates the edge deposition via multi-body interactions, for example, particle–liquid, particle-particle, particle–solid interfaces and particle–flow interactions. The mechanisms behind each of these approaches help to find methods to inhibit the non-uniform film formation, and the corresponding applications have been discussed together with a critical comparison in detail. This review could pave the way for developing inks and processes to apply in functional coatings and printed electronic devices with improved efficiency and device yield.
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Watanabe C, Yanagisawa M. Evaporation Patterns of Dextran-Poly(Ethylene Glycol) Droplets with Changes in Wettability and Compatibility. Life (Basel) 2022; 12:life12030373. [PMID: 35330124 PMCID: PMC8954583 DOI: 10.3390/life12030373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/23/2022] [Accepted: 03/01/2022] [Indexed: 11/16/2022] Open
Abstract
The dextran−PEG system is one of the most famous systems exhibiting phase separation. Various phase behaviors, including the evaporation process of the dextran−PEG system, have been studied in order to understand the physicochemical mechanism of intracellular phase separation and the effect of condensation on the origin of life. However, there have been few studies in dilute regime. In this study, we focused on such regimes and analyzed the pattern formation by evaporation. The specificity of this regime is the slow onset of phase separation due to low initial concentration, and the separated phases can have contrasting wettability to the substrate as evaporation progresses. When the polymer concentration is rather low (<5 wt%), the dextran−PEG droplets form a phase-separated pattern, consisting of PEG at the center and dextran ring of multiple strings pulling from the ring. This pattern formation is explained from the difference in wettability and compatibility between dextran and PEG upon condensation. At the initial dilute stage, the dextran-rich phase with higher wettability accumulates at the contact line of the droplet to form a ring pattern, and then forms multiple domains due to density fluctuation. The less wettable PEG phase recedes and pulls the dextran domains, causing them to deform into strings. Further condensation leads to phase separation, and the condensed PEG with improved wettability stops receding and prevents a formed circular pattern. These findings suggest that evaporation patterns of polymer blend droplets can be manipulated through changes in wettability and compatibility between polymers due to condensation, thus providing the basis to explore origins of life that are unique to the process of condensate formation from dilute systems.
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Affiliation(s)
- Chiho Watanabe
- School of Integrated Arts and Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, Kagamiyama 1-7-1, Higashi-Hiroshima 739-8521, Japan
- Correspondence:
| | - Miho Yanagisawa
- Komaba Institute for Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Tokyo 153-8902, Japan;
- Universal Biology Institute, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Tokyo 153-8902, Japan
- Department of Physics, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Tokyo 113-0033, Japan
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