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Li W, Zhang C, Wang Y. Evaporative self-assembly in colloidal droplets: Emergence of ordered structures from complex fluids. Adv Colloid Interface Sci 2024; 333:103286. [PMID: 39232473 DOI: 10.1016/j.cis.2024.103286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Revised: 07/14/2024] [Accepted: 08/26/2024] [Indexed: 09/06/2024]
Abstract
Colloidal droplet evaporation is an intriguing and intricate phenomenon that has captured the interest of scientists across diverse disciplines, including physical chemistry, fluid dynamics, and soft matter science, over the past two decades. Despite being a non-equilibrium system with inherent challenges posed by coffee ring formation and Marangoni effects, which hinder the precise control of deposition patterns, evaporative self-assembly presents a convenient and cost-effective approach for generating arrays of well-ordered structures and functional patterns with wide-ranging applications in inkjet printing, photonic crystals, and biochemical assays. In the realm of printed electronics and photonics, effectively mitigating coffee rings while achieving uniformity and orderliness has emerged as a critical factor in realising the next generation of large-area, low-cost, flexible devices that are exceptionally sensitive and high-performance. This review highlights the evaporative self-assembly process in colloidal droplets with a focus on the intricate mechanical environment, self-assembly at diverse interfaces, and potential applications of these assembling ordered structures.
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Affiliation(s)
- Weibin Li
- National Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences, 100190 Beijing, China; School of Engineering Science, University of Chinese Academy of Sciences, 100049 Beijing, China.
| | - Chen Zhang
- National Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences, 100190 Beijing, China; School of Engineering Science, University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Yuren Wang
- National Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences, 100190 Beijing, China; School of Engineering Science, University of Chinese Academy of Sciences, 100049 Beijing, China
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Majumder S, Basavaraj MG, Satapathy DK. Soft colloidal monolayers with reflection symmetry through confined drying. NANOSCALE ADVANCES 2024:d4na00542b. [PMID: 39139712 PMCID: PMC11317906 DOI: 10.1039/d4na00542b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2024] [Accepted: 07/17/2024] [Indexed: 08/15/2024]
Abstract
Colloidal monolayers serve as fundamental building blocks in fabricating diverse functional materials, pivotal for surface modifications, chemical reactivity, and controlled assembly of nanoparticles. In this article, we report the formation of colloidal monolayers generated by drying an aqueous droplet containing soft colloids confined between two hydrophilic parallel plates. The analysis of the kinetics of evaporation in this confined mode showed that: (i) for a significant portion of the drying time, the drops adopt a catenoid configuration; (ii) in the penultimate stage of drying, the catenoid structure undergoes division into two daughter droplets; (iii) the three-phase contact line remains pinned at a specific location while it continuously slips at all other locations. The interplay between interface-assisted particle deposition onto the solid substrate and the time evolution of particle concentration within the droplet during evaporation results in unique microstructural features in the deposited patterns. Notably, these deposit patterns exhibit reflection symmetry. The microstructural features of the dried deposits are further quantified by calculating the particle number density, inter-particle separation, areal disorder parameter, and bond orientational order parameter. The variation of these parameters for deposits formed under different conditions, such as by altering the spacing between parallel plates and the concentration of microgel particles in the droplet, is discussed.
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Affiliation(s)
- Sanjib Majumder
- Soft Material Laboratory, Department of Physics, IIT Madras Chennai-600036 India
- Centre for Soft and Biological Matter, IIT Madras Chennai-600036 India
| | - Madivala G Basavaraj
- PECS Lab, 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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Hariharan S, Thampi SP, Basavaraj MG. Quantifying the Microstructure of Dried Deposits Using Height-Height Correlation Function. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:11650-11660. [PMID: 38773679 DOI: 10.1021/acs.langmuir.4c00957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2024]
Abstract
Colloidal self-assembly has garnered significant attention in recent research, owing to applications in medical and engineering domains. Understanding the arrangement of particles in self-assembled systems is crucial for comprehending the underlying physics and synthesizing complex nano- and microscale structures. In this study, we introduce a novel methodology for analyzing the spatial distribution of particles in colloidal assemblies, focusing specifically on quantifying the microstructure of deposits formed by the evaporation of colloidal particle-laden drops. Utilizing a height-height correlation-function-based approach, we quantify variations in the height profile of deposits in radial and azimuthal directions. This approach enables the classification of the patterns into typical examples encountered in an evaporation-driven assembly. The method is demonstrated to be robust for quantifying synthetic and experimentally obtained deposit patterns, exhibiting excellent agreement in the estimated parameters. The mapping developed between pattern morphology and the quantitative measures introduced in this work may be used in a variety of applications including disease diagnosis as well as in developing pattern recognition tools.
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Affiliation(s)
- Sankar Hariharan
- Polymer Engineering and Colloid Science Lab, Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai, Tamil Nadu 600036, India
| | - Sumesh P Thampi
- Polymer Engineering and Colloid Science Lab, Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai, Tamil Nadu 600036, India
| | - Madivala G Basavaraj
- Polymer Engineering and Colloid Science Lab, Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai, Tamil Nadu 600036, India
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Jose M, Singh R, Satapathy DK. Depletion zone in two-dimensional deposits of soft microgel particles. J Colloid Interface Sci 2023; 642:364-372. [PMID: 37018961 DOI: 10.1016/j.jcis.2023.03.076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 03/06/2023] [Accepted: 03/10/2023] [Indexed: 04/05/2023]
Abstract
HYPOTHESIS Microgels are a class of model soft colloids that act like surfactants due to their amphiphilicity and are spontaneously adsorbed to the fluid-air interface. Here, we exploit the surfactant-like characteristics of microgels to generate Marangoni stress-induced fluid flow at the surface of a drop containing soft colloids. This Marangoni flow combined with the well-known capillary flow that arises during the evaporation of a drop placed on a solid surface, leads to the formation of a novel two-dimensional deposit of particles with distinct depletion zones at its edge. EXPERIMENTS The evaporation experiments using sessile and pendant drops containing microgel particles were carried out, and the microstructure of the final particulate deposits were recorded. The kinetics of the formation of the depletion zone and its width is studied by tracking the time evolution of the microgel particle monolayer adsorbed to the interface using in situ video microscopy. FINDINGS The experiments reveal that the depletion zone width linearly increases with droplet volume. Interestingly, the depletion zone width is larger for drops evaporated in pendant configuration than the sessile drops, which is corroborated by considering the gravitational forces exerted on the microgel assembly on the fluid-air interface. The fluid flows arising from Marangoni stresses and the effect of gravity provide novel ways to manipulate the self-assembly of two-dimensional layers of soft colloids.
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Affiliation(s)
- Merin Jose
- Department of Physics, IIT Madras, Chennai 600036, India
| | - Rajesh Singh
- Department of Physics, IIT Madras, Chennai 600036, India
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Feller D, Karg M. Fluid interface-assisted assembly of soft microgels: recent developments for structures beyond hexagonal packing. SOFT MATTER 2022; 18:6301-6312. [PMID: 35993260 DOI: 10.1039/d2sm00872f] [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
Microgels adsorb to air/water and oil/water interfaces - a process driven by a significant reduction in interfacial tension. Depending on the available interface area per microgel, strong lateral deformation can be observed. Typically, hexagonally ordered structures appear spontaneously upon contact of the microgel shells. Transfer from the interface to solid substrates gives access to macroscopically sized microgel monolayers that are interesting for photonic and plasmonic studies as well as colloid-based lithography, for example. Significant efforts have been made to understand the phase behavior of microgels at different interfaces and to explore the available parameter space for achieving complex tessellations. In this review, we will discuss the most recent developments in the realization of microgel monolayers with structures beyond hexagonal packing.
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Affiliation(s)
- Déborah Feller
- Institut für Physikalische Chemie I: Kolloide und Nanooptik, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany.
| | - Matthias Karg
- Institut für Physikalische Chemie I: Kolloide und Nanooptik, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany.
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Chatterjee S, Murallidharan JS, Bhardwaj R. Size-Dependent Dried Colloidal Deposit and Particle Sorting via Saturated Alcohol Vapor-Mediated Sessile Droplet Spreading. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:6128-6147. [PMID: 35507639 DOI: 10.1021/acs.langmuir.2c00492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We experimentally and theoretically investigate a distinct problem of spreading, evaporation, and the associated dried deposits of a colloidal particle-laden aqueous sessile droplet on a surface in a saturated alcohol vapor environment. In particular, the effect of particle size on monodispersed suspensions and efficient self-sorting of bidispersed particles have been investigated. The alcohol vapor diffuses toward the droplet's curved liquid-vapor interface from the far field. The incoming vapor mass flux profile assumes a nonuniform pattern across the interface. The alcohol vapor molecules are adsorbed at the liquid-vapor interface, which eventually leads to absorption into the droplet's liquid phase due to the miscibility. This phenomenon triggers a liquid-vapor interfacial tension gradient and causes a reduction in the global surface tension of the droplet. This results in a solutal Marangoni flow recirculation and spontaneous droplet spreading. The interplay between these phenomena gives rise to a complex internal fluid flow within the droplet, resulting in a significantly modified and strongly particle-size-dependent dried colloidal deposit. While the smaller particles form a multiple ring pattern, larger particles form a single ring, and additional "patchwise" deposits emerge. High-speed visualization of the internal liquid-flow revealed that initially, a ring forms at the first location of the contact line. Concurrently, the Marangoni flow recirculation drives a collection of particles at the liquid-vapor interface to form clusters. Thereafter, as the droplet spreads, the smaller particles in the cluster exhibit a "jetlike" outward flow, forming multiple ring patterns. In contrast, the larger particles tend to coalesce together in the cluster, forming the "patchwise" deposits. The widely different response of the different-sized particles to the internal fluid flow enables an efficient sorting of the smaller particles at the contact line from bidispersed suspensions. We corroborate the measurements with theoretical and numerical models wherever possible.
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Affiliation(s)
- Sanghamitro Chatterjee
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | | | - Rajneesh Bhardwaj
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
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Jose M, Lokesh M, Vaippully R, Satapathy DK, Roy B. Temporal evolution of viscoelasticity of soft colloid laden air-water interface: a multiple mode microrheology study. RSC Adv 2022; 12:12988-12996. [PMID: 35497011 PMCID: PMC9049755 DOI: 10.1039/d2ra00765g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Accepted: 04/19/2022] [Indexed: 12/17/2022] Open
Abstract
Mechanical properties of particle laden interfaces is crucial for various applications. For water droplets containing soft microgel particles, passive microrheology studies have revealed that the dynamically varying surface area of the evaporating drop results in a viscous to viscoelastic transition along the plane of the interface. However, the behaviour of the medium orthogonal to the interface has been elusive to study using passive microrheology techniques. In this work, we employ optical tweezers and birefringent probe particles to extract the direction-resolved viscoelastic properties of the particle-laden interface. By using special types of birefringent tracer particles, we detect not only the in-plane translational mode but also the out-of-plane translational (perpendicular to the interface) and rotational modes. We first compare different passive methods of probing the viscoelasticity of the microgel laden interface of sessile drop and then study the modes perpendicular to the interface and the out-of-plane rotational mode using optical tweezers based passive microrheology. The viscoelasticity of the interface using two different methods, i.e., multiple-particle tracking passive microrheology using video microscopy and by trapping birefringent tracer particles in optical tweezers, relying on different models are studied and found to exhibit comparable trends. Interestingly, the mode orthogonal to the interface and the rotational mode also show the viscous to viscoelastic transition as the droplet evaporates, but with lesser viscoelasticity during the same evaporation time than the in-plane mode.
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Affiliation(s)
- Merin Jose
- Department of Physics, Indian Institute of Technology Madras Chennai Tamil Nadu India 600036
| | - Muruga Lokesh
- Department of Physics, Indian Institute of Technology Madras Chennai Tamil Nadu India 600036
| | - Rahul Vaippully
- Department of Physics, Indian Institute of Technology Madras Chennai Tamil Nadu India 600036
| | - Dillip K Satapathy
- Department of Physics, Indian Institute of Technology Madras Chennai Tamil Nadu India 600036
| | - Basudev Roy
- Department of Physics, Indian Institute of Technology Madras Chennai Tamil Nadu India 600036
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