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Kuk K, Ringling J, Gräff K, Hänsch S, Carrasco-Fadanelli V, Rudov AA, Potemkin II, von Klitzing R, Buttinoni I, Karg M. Drying of Soft Colloidal Films. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2406977. [PMID: 39498779 DOI: 10.1002/advs.202406977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2024] [Revised: 10/25/2024] [Indexed: 11/07/2024]
Abstract
Thin films made of deformable micro- and nano-units, such as biological membranes, polymer interfaces, and particle-laden liquid surfaces, exhibit a complex behavior during drying, with consequences for various applications like wound healing, coating technologies, and additive manufacturing. Studying the drying dynamics and structural changes of soft colloidal films thus holds the potential to yield valuable insights to achieve improvements for applications. In this study, interfacial monolayers of core-shell (CS) microgels with varying degrees of softness are employed as model systems and to investigate their drying behavior on differently modified solid substrates (hydrophobic vs hydrophilic). By leveraging video microscopy, particle tracking, and thin film interference, this study shed light on the interplay between microgel adhesion to solid surfaces and the immersion capillary forces that arise in the thin liquid film. It is discovered that a dried replica of the interfacial microstructure can be more accurately achieved on a hydrophobic substrate relative to a hydrophilic one, particularly when employing softer colloids as opposed to harder counterparts. These observations are qualitatively supported by experiments with a thin film pressure balance which allows mimicking and controlling the drying process and by computer simulations with coarse-grained models.
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Affiliation(s)
- Keumkyung Kuk
- Institut für Physikalische Chemie I: Kolloide und Nanooptik, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225, Düsseldorf, Germany
| | - Julian Ringling
- Institut für Physikalische Chemie I: Kolloide und Nanooptik, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225, Düsseldorf, Germany
| | - Kevin Gräff
- Institute for Condensed Matter Physics, Soft Matter at Interfaces, Technische Universität Darmstadt, Hochschulstr. 8, 64289, Darmstadt, Germany
| | - Sebastian Hänsch
- Center for Advanced Imaging, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225, Düsseldorf, Germany
| | - Virginia Carrasco-Fadanelli
- Institut für Experimentelle Physik der kondensierten Materie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, 40225, Düsseldorf, Germany
| | - Andrey A Rudov
- DWI-Leibniz Institute for Interactive Materials, 52056, Aachen, Germany
- Physics Department, Lomonosov Moscow State University, 119991, Moscow, Russian Federation
| | - Igor I Potemkin
- DWI-Leibniz Institute for Interactive Materials, 52056, Aachen, Germany
- Physics Department, Lomonosov Moscow State University, 119991, Moscow, Russian Federation
| | - Regine von Klitzing
- Institute for Condensed Matter Physics, Soft Matter at Interfaces, Technische Universität Darmstadt, Hochschulstr. 8, 64289, Darmstadt, Germany
| | - Ivo Buttinoni
- Institut für Experimentelle Physik der kondensierten Materie, 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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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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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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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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