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Palmer TR, van der Kooij HM, Abu Bakar R, Duewel M, Greiner K, McAleese CD, Couture P, Sharpe MK, Smith RW, Keddie JL. How Particle Deformability Influences the Surfactant Distribution in Colloidal Polymer Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:12689-12701. [PMID: 36194469 PMCID: PMC9583616 DOI: 10.1021/acs.langmuir.2c02170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 09/19/2022] [Indexed: 06/16/2023]
Abstract
The distribution of surfactants in waterborne colloidal polymer films is of significant interest for scientific understanding and defining surface properties in applications including pressure-sensitive adhesives and coatings. Because of negative effects on appearance, wetting, and adhesion, it is desirable to prevent surfactant accumulation at film surfaces. The effect of particle deformation on surfactant migration during film formation was previously investigated by Gromer et al. through simulations, but experimental investigations are lacking. Here, we study deuterium-labeled sodium dodecyl sulfate surfactant in a poly(butyl acrylate) latex model system. The particle deformability was varied via cross-linking of the intraparticle polymer chains by differing extents. The cross-linker concentration varied from 0 to 35 mol % in the copolymer, leading to a transition from viscoelastic to elastic. Ion beam analysis was used to probe the dry films and provide information on the near-surface depth distribution of surfactant. Films of nondeformable particles, containing the highest concentration of cross-linker, show no surfactant accumulation at the top surface. Films from particles partially deformed by capillary action show a distinct surfactant surface layer (ca. 150 nm thick). Films of coalesced particles, containing little or no cross-linker, show a very small amount of surfactant on the surface (ca. 20 nm thick). The observed results are explained by considering the effect of cross-linking on rubber elasticity and applying the viscous particle deformation model by Gromer et al. to elastically deformed particles. We find that partially deformed particles allow surfactant transport to the surface during film formation, whereas there is far less transport when skin formation acts as a barrier. With elastic particles, the surfactant is carried in the water phase as it falls beneath the surface of packed particles. The ability to exert control over surfactant distribution in waterborne colloidal films will aid in the design of new high-performance adhesives and coatings.
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Affiliation(s)
- Toby R. Palmer
- Department
of Physics, University of Surrey, Guildford, SurreyGU2 7XH, United Kingdom
| | - Hanne M. van der Kooij
- Physical
Chemistry and Soft Matter, Wageningen University
& Research, 6708 WEWageningen, The Netherlands
| | - Rohani Abu Bakar
- Department
of Physics, University of Surrey, Guildford, SurreyGU2 7XH, United Kingdom
| | - Mathis Duewel
- Synthomer
Germany GmbH, Werrastraße
10, 45768Marl, Germany
| | - Katja Greiner
- Synthomer
Germany GmbH, Werrastraße
10, 45768Marl, Germany
| | - Callum D. McAleese
- Surrey
Ion Beam Centre, University of Surrey, Guildford, SurreyGU2 7XH, United Kingdom
| | - Pierre Couture
- Surrey
Ion Beam Centre, University of Surrey, Guildford, SurreyGU2 7XH, United Kingdom
| | - Matthew K. Sharpe
- Surrey
Ion Beam Centre, University of Surrey, Guildford, SurreyGU2 7XH, United Kingdom
| | - Richard W. Smith
- Surrey
Ion Beam Centre, University of Surrey, Guildford, SurreyGU2 7XH, United Kingdom
| | - Joseph L. Keddie
- Department
of Physics, University of Surrey, Guildford, SurreyGU2 7XH, United Kingdom
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2
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Tanaka H, Komoda Y, Horie T, Imakoma H, Ohmura N. Drying rate of latex coating affected by the deformability of resin particles in convection drying. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2022; 45:2. [PMID: 35006390 DOI: 10.1140/epje/s10189-021-00155-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 12/14/2021] [Indexed: 06/14/2023]
Abstract
Latex paints are widely used, and many researchers pointed out that the film formation process depends on the deformability of dispersed polymer particles. However, the relationship between the film formation process and drying rate has not been totally understood due to the lack of accurate data on drying rate throughout the drying process. In the present study, we measured the drying rate of latex coating by the temperature change method proposed by Imakoma in convective drying. We revealed that the drying process significantly depends on particle deformability, especially in the former stage of the falling drying rate period. At a low drying temperature, the close-packed structure of polymer particles is formed throughout the film at the end of the constant drying rate period. On the other hand, partially deformed soft particles due to wet sintering inhibit the drying rate even under high moisture content at high drying temperatures. In either case, after forming the closest-packed structure, the shrinkage of the gap space between particles due to capillary deformation decreases the drying rate, proportional to the moisture content.
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Affiliation(s)
- Hiroaki Tanaka
- Department of Chemical Science and Engineering, Kobe University, 1-1, Rokkodai-cho, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Yoshiyuki Komoda
- Department of Chemical Science and Engineering, Kobe University, 1-1, Rokkodai-cho, Nada-ku, Kobe, Hyogo, 657-8501, Japan.
| | - Takafumi Horie
- Department of Chemical Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8531, Japan
| | - Hironobu Imakoma
- Graduate School of Engineering, Osaka City University, 3 Sugimoto Sumiyoshi-ku, Osaka, 558-8585, Japan
| | - Naoto Ohmura
- Department of Chemical Science and Engineering, Kobe University, 1-1, Rokkodai-cho, Nada-ku, Kobe, Hyogo, 657-8501, Japan
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3
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Batishcheva K, Kuznetsov G, Orlova E, Vympina Y. Evaporation of colloidal droplets from aluminum–magnesium alloy surfaces after laser-texturing and mechanical processing. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.127301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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4
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Dong Y, Busatto N, Roth PJ, Martin-Fabiani I. Colloidal assembly of polydisperse particle blends during drying. SOFT MATTER 2020; 16:8453-8461. [PMID: 32812973 DOI: 10.1039/d0sm00785d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In this work, we synthesize a polydisperse aqueous colloidal system composed of small and large zwitterionic particles, as well as medium sized standard acrylic particles. By assembling these dispersions into films by drying, we show using atomic force microscopy (AFM) how their top surfaces can be mostly covered by zwitterionic groups for a wide range of evaporation rates. We probe underneath the top film surface using Fourier-transform infrared (FTIR) spectroscopy - attenuated total reflection (ATR), observing that the content in zwitterionic particles of the film upper layer increases for faster evaporation rates. We show how polydisperse systems hold great potential to overcome the evaporation rate dependence of size segregation processes in drying colloidal blends, and we provide further insights into the assembly mechanisms involved. Polydisperse blends enhance the robustness of such processes for application in coatings and other soft products where evaporation rate can not be tuned.
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Affiliation(s)
- Yichen Dong
- Department of Materials, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK.
| | - Nicolas Busatto
- Department of Chemistry, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | - Peter J Roth
- Department of Chemistry, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | - Ignacio Martin-Fabiani
- Department of Materials, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK.
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5
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Voogt B, Venema P, Sagis L, Huinink H, Erich B, Scheerder J, Adan O. Surface characterization of drying acrylic latex dispersions with variable methacrylic acid content using surface dilatational rheology. J Colloid Interface Sci 2019; 556:584-591. [PMID: 31491680 DOI: 10.1016/j.jcis.2019.08.074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 08/19/2019] [Accepted: 08/20/2019] [Indexed: 10/26/2022]
Abstract
HYPOTHESIS Drying of latex dispersions often results in particle gradients at the latex-air interface. We expect that, by increasing the carboxylic acid content of latex particles, inter-particle interactions at the interface change. With dilatational rheology one could detect particle-particle interactions in an early stage of the drying process and elucidate the nature of these interactions. EXPERIMENTS Acrylic latex dispersions were prepared with different amounts of methacrylic acid (MAA), ranging from 2 to 10 wt% on dry mass. Dilatational rheology studies during drying at different relative humidities RH were performed using profile analysis tensiometry. Visco-elastic properties of latex surfaces were used to identify inter-particle interactions at the surfaces depending on the drying rate and particle composition. FINDINGS Drying at 85% RH did not show significant changes of the mechanical properties of the latex surfaces. Drying at 65 and 53% RH resulted in a change of the mechanical properties, ultimately showing non-linear visco-elastic behavior. This indicates that capillary and/or Van der Waals forces were operating between particles at the surface. With increasing MAA content the viscous contribution decreased, possibly due to the formation of more gel-like structures at the particle surface due to higher solubility of polymer segments near to the surface.
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Affiliation(s)
- Benjamin Voogt
- Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, Eindhoven, Netherlands
| | - Paul Venema
- Laboratory of Physics and Physical Chemistry of Foods, Wageningen University, Wageningen, Netherlands
| | - Leonard Sagis
- Laboratory of Physics and Physical Chemistry of Foods, Wageningen University, Wageningen, Netherlands
| | - Henk Huinink
- Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, Eindhoven, Netherlands.
| | - Bart Erich
- Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, Eindhoven, Netherlands; TNO (The Netherlands Organization for Applied Scientific Research), P.O. Box 49, Delft, Netherlands
| | | | - Olaf Adan
- Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, Eindhoven, Netherlands; TNO (The Netherlands Organization for Applied Scientific Research), P.O. Box 49, Delft, Netherlands
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6
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The Properties of Solvent-Based and Water-Borne Butyl Acrylate/Styrene Copolymer Films. ADVANCES IN POLYMER TECHNOLOGY 2019. [DOI: 10.1155/2019/4261691] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
With the increasing demands of environmental protection, the properties of water-borne coatings film must meet or exceed current solvent-based coatings. It is an important part of coating science for characterizing the film properties of polymers which was used in the water-borne and the solvent-based coating. In this study, UV-visible spectroscopy, gravimetric analysis, scanning electron microscopy, and electrochemical impedance spectroscopy were used to characterize the properties of the water-borne and the solvent-based poly(butyl acrylate/styrene) (P(BA/St)) copolymer films. The water-borne and the solvent-based P(BA/St) copolymer was synthesized by two methods. The copolymer had a Tg of approximately 14.4°C, which was close to room temperature. The water-borne copolymers were prepared via a three-step film formation process, while the solvent-based copolymer films were prepared in two steps. Comparing the properties of the water-borne and the solvent-based films, the water absorption capacities decreased with increasing film formation times, and the film barrier properties and electrochemical properties of both films improved as the film formation time increased.
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7
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Schulz M, Keddie JL. A critical and quantitative review of the stratification of particles during the drying of colloidal films. SOFT MATTER 2018; 14:6181-6197. [PMID: 30024010 DOI: 10.1039/c8sm01025k] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
For a wide range of applications, films are deposited from colloidal particles suspended in a volatile liquid. There is burgeoning interest in stratifying colloidal particles into separate layers within the final dry film to impart properties at the surface different to the interior. Here, we outline the mechanisms by which colloidal mixtures can stratify during the drying process. The problem is considered here as a three-way competition between evaporation of the continuous liquid, sedimentation of particles, and their Brownian diffusion. In particle mixtures, the sedimentation of larger or denser particles offers one means of stratification. When the rate of evaporation is fast relative to diffusion, binary mixtures of large and small particles can stratify with small particles on the top, according to physical models and computer simulations. We compare experimental results found in the scientific literature to the predictions of several recent models in a quantitative way. Although there is not perfect agreement between them, some general trends emerge in the experiments, simulations and models. The stratification of small particles on the top of a film is favoured when the colloidal suspension is dilute but when both the concentration of the small particles and the solvent evaporation rate are sufficiently high. A higher particle size ratio also favours stratification by size. This review points to ways that microstructures can be designed and controlled in colloidal materials to achieve desired properties.
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Affiliation(s)
- M Schulz
- Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH, England, UK.
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8
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Cheng S, Stevens MJ, Grest GS. Ordering nanoparticles with polymer brushes. J Chem Phys 2017; 147:224901. [DOI: 10.1063/1.5006048] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Affiliation(s)
- Shengfeng Cheng
- Department of Physics, Center for Soft Matter and Biological Physics, and Macromolecules Innovation Institute, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Mark J. Stevens
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - Gary S. Grest
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
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9
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Gromer A, Thalmann F, Hébraud P, Holl Y. Simulation of Vertical Surfactant Distributions in Drying Latex Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:561-572. [PMID: 28001076 DOI: 10.1021/acs.langmuir.6b03913] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Following our previous contribution ( Gromer, A. et al. Langmuir 2015 , 31 , 10983 - 10994 ) presenting a new simulation tool devoted to particle distributions in drying latex films, this Article describes the prediction of surfactant concentration profiles in the vertical direction during the complete film formation process. The simulation is inspired by cellular automata and equations by Routh and co-workers. It includes effects that were not considered before: surfactant convection by water and surfactant desorption upon particle deformation. It is based on five parameters describing the nature of the polymer/surfactant system and on film formation conditions. In particular, the viscoelastic properties of the polymer were taken into account through the λ̅ parameter introduced by Routh and Russel. Results show the importance of convection by water and the influence of the particular deformation mechanism on the final surfactant distribution. Excesses or depletions can be predicted either on the surface or on the substrate sides, in qualitative agreement with the numerous existing experimental studies. The complex interplay between parameters governing surfactant distributions makes the results unpredictable without the help of such a simulation tool. Therefore, it should be of interest to both industrial and academic scientists.
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Affiliation(s)
- A Gromer
- CNRS-ICS and Université de Strasbourg, 23, rue du Loess, BP 84047, 67034 Cedex 2 Strasbourg, France
| | - F Thalmann
- CNRS-ICS and Université de Strasbourg, 23, rue du Loess, BP 84047, 67034 Cedex 2 Strasbourg, France
| | - P Hébraud
- IPCMS , 23 rue du Loess, BP 43, 67034 Cedex 2 Strasbourg, France
| | - Y Holl
- CNRS-ICS and Université de Strasbourg, 23, rue du Loess, BP 84047, 67034 Cedex 2 Strasbourg, France
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10
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Use of acoustic levitation to examine the drying behavior of microdroplets of polymer latex dispersions. Colloid Polym Sci 2016. [DOI: 10.1007/s00396-016-3954-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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11
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Divry V, Gromer A, Nassar M, Lambour C, Collin D, Holl Y. Drying Mechanisms in Plasticized Latex Films: Role of Horizontal Drying Fronts. J Phys Chem B 2016; 120:6791-802. [PMID: 27244562 DOI: 10.1021/acs.jpcb.6b03009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This article presents studies on the drying kinetics of latexes with particles made progressively softer by adding increasing amounts of a plasticizer, in relation to speeds of horizontal drying fronts and particle deformation mechanisms. Global drying rates were measured by gravimetry, and speeds of the horizontal fronts were recorded using a video camera and image processing. Particle deformation mechanisms were inferred using the deformation map established by Routh and Russel (RR). This required precise measurements of the rheological properties of the polymers using a piezorheometer. The results show that latexes with softer particles dry slowly, but in our systems, this is not due to skin formation. A correlation between global drying rates and speeds of horizontal fronts could be established and interpreted in terms of the evolution of mass transfer coefficients of water in different areas of the drying system. The speeds of the horizontal drying fronts were compared with the RR model. A remarkable qualitative agreement of the curve shapes was observed; however, the fit could not be considered good. These results call for further research efforts in modeling and simulation.
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Affiliation(s)
- V Divry
- CNRS-ICS & Université de Strasbourg , 23, rue du Loess, BP 84047, 67034 Strasbourg Cedex 2, France
| | - A Gromer
- CNRS-ICS & Université de Strasbourg , 23, rue du Loess, BP 84047, 67034 Strasbourg Cedex 2, France
| | - M Nassar
- CNRS-ICS & Université de Strasbourg , 23, rue du Loess, BP 84047, 67034 Strasbourg Cedex 2, France
| | - C Lambour
- CNRS-ICS & Université de Strasbourg , 23, rue du Loess, BP 84047, 67034 Strasbourg Cedex 2, France
| | - D Collin
- CNRS-ICS & Université de Strasbourg , 23, rue du Loess, BP 84047, 67034 Strasbourg Cedex 2, France
| | - Y Holl
- CNRS-ICS & Université de Strasbourg , 23, rue du Loess, BP 84047, 67034 Strasbourg Cedex 2, France
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12
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Abstract
Large-scale molecular dynamics simulations are used to study the dispersion of nanoparticles (NPs) in a polymer film during solvent evaporation. As the solvent evaporates, a dense polymer-rich skin layer forms at the liquid/vapor interface, which is either NP rich or poor depending on the strength of the NP/polymer interaction. When the NPs are strongly wet by the polymer, the NPs accumulate at the interface and form layers. However, when the NPs are only partially wet by the polymer, most NPs are uniformly distributed in the bulk of the polymer film, with the dense skin layer serving as a barrier to prevent the NPs from moving to the interface. Our results point to a possible route to employ less favorable NP/polymer interactions and fast solvent evaporation to uniformly disperse NPs in a polymer film, contrary to the common belief that strong NP/polymer attractions are needed to make NPs well dispersed in polymer nanocomposites.
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Affiliation(s)
- Shengfeng Cheng
- Department
of Physics, Center for Soft Matter and Biological Physics, and Macromolecules
Innovation Institute, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States
| | - Gary S. Grest
- Sandia National
Laboratories, Albuquerque, New Mexico 87185, United States
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13
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Baesch S, Siebel D, Schmidt-Hansberg B, Eichholz C, Gerst M, Scharfer P, Schabel W. Comparison of Surfactant Distributions in Pressure-Sensitive Adhesive Films Dried from Dispersion under Lab-Scale and Industrial Drying Conditions. ACS APPLIED MATERIALS & INTERFACES 2016; 8:8118-8128. [PMID: 26953641 DOI: 10.1021/acsami.6b00830] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Film-forming latex dispersions are an important class of material systems for a variety of applications, for example, pressure-sensitive adhesives, which are used for the manufacturing of adhesive tapes and labels. The mechanisms occurring during drying have been under intense investigations in a number of literature works. Of special interest is the distribution of surfactants during the film formation. However, most of the studies are performed at experimental conditions very different from those usually encountered in industrial processes. This leaves the impact of the drying conditions and the resulting influence on the film properties unclear. In this work, two different 2-ethylhexyl-acrylate (EHA)-based adhesives with varying characteristics regarding glass transition temperature, surfactants, and particle size distribution were investigated on two different substrates. The drying conditions, defined by film temperature and mass transfer in the gas phase, were varied to emulate typical conditions encountered in the laboratory and industrial processes. Extreme conditions equivalent to air temperatures up to 250 °C in a belt dryer and drying rates of 12 g/(m(2)·s) were realized. The surfactant distributions were measured by means of 3D confocal Raman spectroscopy in the dry film. The surfactant distributions were found to differ significantly with drying conditions at moderate film temperatures. At elevated film temperatures the surfactant distributions are independent of the investigated gas side transport coefficients: the heat and mass transfer coefficient. Coating on substrates with significantly different surface energies has a large impact on surfactant concentration gradients, as the equilibrium between surface and bulk concentration changes. Dispersions with higher colloidal stability showed more homogeneous lateral surfactant distributions. These results indicate that the choice of the drying conditions, colloidal stability, and substrates is crucial to control the surfactant distribution. Results obtained under lab-scale drying conditions cannot be transferred directly to the industrial application. The results were similar for both tested adhesive material systems, despite their different properties. This indicates that other properties, such as the particle size distribution and glass transition temperature, have surprisingly little effect on the development of the surfactant distribution.
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Affiliation(s)
- S Baesch
- Institute of Thermal Process Engineering, Karlsruhe Institute of Technology , Kaiserstr. 12, 76131 Karlsruhe, Germany
| | - D Siebel
- Institute of Thermal Process Engineering, Karlsruhe Institute of Technology , Kaiserstr. 12, 76131 Karlsruhe, Germany
| | | | | | | | - P Scharfer
- Institute of Thermal Process Engineering, Karlsruhe Institute of Technology , Kaiserstr. 12, 76131 Karlsruhe, Germany
| | - W Schabel
- Institute of Thermal Process Engineering, Karlsruhe Institute of Technology , Kaiserstr. 12, 76131 Karlsruhe, Germany
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14
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Control of stain geometry by drop evaporation of surfactant containing dispersions. Adv Colloid Interface Sci 2015; 222:275-90. [PMID: 25217332 DOI: 10.1016/j.cis.2014.08.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Revised: 08/16/2014] [Accepted: 08/18/2014] [Indexed: 11/22/2022]
Abstract
Control of stain geometry by drop evaporation of surfactant containing dispersions is an important topic of interest because it plays a crucial role in many applications such as forming templates on solid surfaces, in ink-jet printing, spraying of pesticides, micro/nano material fabrication, thin film coatings, biochemical assays, deposition of DNA/RNA micro-arrays, and manufacture of novel optical and electronic materials. This paper presents a review of the published articles on the diffusive drop evaporation of pure liquids (water), the surfactant stains obtained from evaporating drops that do not contain dispersed particles and deposits obtained from drops containing polymer colloids and carbon based particles such as carbon nanotubes, graphite and fullerenes. Experimental results of specific systems and modeling attempts are discussed. This review also has some special subtopics such as suppression of coffee-rings by surfactant addition and "stick-slip" behavior of evaporating nanosuspension drops. In general, the drop evaporation process of a surfactant/particle/substrate system is very complex since dissolved surfactants adsorb on both the insoluble organic/inorganic micro/nanoparticles in the drop, on the air/solution interface and on the substrate surface in different extends. Meanwhile, surfactant adsorbed particles interact with the substrate giving a specific contact angle, and free surfactants create a solutal Marangoni flow in the drop which controls the location of the particle deposition together with the rate of evaporation. In some cases, the presence of a surfactant monolayer at the air/solution interface alters the rate of evaporation. At present, the magnitude of each effect cannot be predicted adequately in advance and consequently they should be carefully studied for any system in order to control the shape and size of the final deposit.
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15
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Komoda Y, Niga K, Suzuki H. Effect of Shear Strain Applied in Coating and Colloidal Stability on the Drying Process of Latex Dispersions. JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 2015. [DOI: 10.1252/jcej.14we128] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Yoshiyuki Komoda
- Department of Chemical Science and Engineering, Kobe University, 1-1 Rokkoudai-cho, Nada-ku, Kobe 657-8501, Japan
| | | | - Hiroshi Suzuki
- Department of Chemical Science and Engineering, Kobe University, 1-1 Rokkoudai-cho, Nada-ku, Kobe 657-8501, Japan
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16
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Kimber JA, Gerst M, Kazarian SG. Fast drying and film formation of latex dispersions studied with FTIR spectroscopic imaging. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:13588-13595. [PMID: 25343527 DOI: 10.1021/la5035257] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Drying of thin latex films (∼20 μm) at high drying speeds (of the order of seconds) has been studied by fast chemical imaging. ATR-FTIR spectroscopic imaging combined with a fast "kinetic" mode was used to acquire spectral images without coaddition, enabling the amount of water and homogeneity of the drying film to be studied over time. Drying profiles, constructed from analyzing the water content in each image, show two stages of drying, a fast and a slow region. The formulation of latex dispersions affects the onset of slow drying and the volume fraction of water remaining at the onset of slow drying. In this work, the effect of physical properties, film thickness and glass transition temperature (Tg), were investigated, as well as the effect of monomer composition where two monomoers, 2-ethylhexyl acrylate and n-butyl acrylate, and the amount of hydrophilic comonomer, methyl methacrylate (MMA), were varied. It was found that thicker films produced slower overall drying and that the formulation with a Tg above the minimum film formation temperature did not dry evenly, exhibiting cracking. However, the drying kinetics of high and low Tg films were similar, highlighting the advantage of using a spatially-resolved spectroscopic approach. Formulations containing more MMA dried faster than those with less. This was due to the hydrophilicity of MMA and the increase in Tg of the dispersion from the addition of MMA. Overall, FTIR spectroscopic imaging was shown to be a suitable approach in measuring film drying at high speeds as both chemical changes and chemical distribution could be analyzed over time.
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Affiliation(s)
- James A Kimber
- Department of Chemical Engineering, Imperial College London , London SW7 2AZ, United Kingdom
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17
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Pohl K, König R, Römermann H, Schulz M, Johannsmann D. Coarsening of the pore network in drying latex films upon interparticle aggregation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:9384-9389. [PMID: 25033245 DOI: 10.1021/la501354k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The lateral drying front observed during film formation from latex dispersions with a Tg of the polymer around room temperature is composed of three three distinct lines. The lines are characterized by a decrease in turbidity, a renewed sharp increase in turbidity, and a more gradual decrease in turbidity at the end of what can be called a "halo". Microcracks with herringbone morphology develop at the first line, where the turbidity decreases. If macrocracks are present, these nucleate close to the end of the halo. At the line, where the turbidity sharply increases, one also observes an increase in stress birefringence. The substructure of the drying front is characteristically different from the structures described previously for films drying from hard particles. In particular, the renewed increase in turbidity cannot be explained as pore-opening, but rather is the consequence of a coarsening of the pore network after the particles jump into contact. A capillary instability sets in, by which the small pores collapse under the polymer/water interfacial energy, while the larger pores expand correspondingly. The instability (related to the Rayleigh instability of liquid jets) makes the films appear turbid. Also, the induced mechanical heterogeneity prevents straight macrocracks from penetrating into the halo because crack deflection and crack branching would result, which is energetically unfavorable.
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Affiliation(s)
- Katja Pohl
- Institute of Physical Chemistry, Clausthal University of Technology , 38678 Clausthal-Zellerfeld, Germany
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Gonzalez E, Paulis M, Barandiaran MJ, Keddie JL. Use of a Routh-Russel deformation map to achieve film formation of a latex with a high glass transition temperature. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:2044-2053. [PMID: 23327465 DOI: 10.1021/la3049967] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In the film formation of latex, particle deformation can occur by processes of wet sintering, dry sintering, or capillary action. When latex films dry nonuniformly and when particles deform and coalesce while the film is still wet, a detrimental skin layer will develop at the film surface. In their process model, Routh and Russel proposed that the operative particle deformation mechanism can be determined by the values of control parameters on a deformation map. Here, the film formation processes of three methyl methacrylate/butyl acrylate copolymer latexes with high glass transition temperatures (T(g)), ranging from 45 to 64 °C, have been studied when heated by infrared radiation. Adjusting the infrared (IR) power density enables the film temperature, polymer viscosity, and evaporation rate during latex film formation to be controlled precisely. Different polymer particle deformation mechanisms have been demonstrated for the same latex under a variety of film formation process conditions. When the temperature is too high, a skin layer develops. On the other hand, when the temperature is too low, particles deform by dry sintering, and the process requires extended time periods. The deduced mechanisms can be interpreted and explained by the Routh-Russel deformation maps. Film formation of hard (high T(g)) coatings is achieved without using coalescing aids that emit volatile organic compounds (VOCs), which is a significant technical achievement.
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Affiliation(s)
- Edurne Gonzalez
- POLYMAT, University of the Basque Country UPV/EHU, Joxe Mari Korta zentroa, Avda. Tolosa 72, 20018 Donostia-San Sebastián, Spain
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Chen X, Fischer S, Men Y. Temperature and relative humidity dependency of film formation of polymeric latex dispersions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:12807-12814. [PMID: 21942473 DOI: 10.1021/la202300p] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Thermogravimetric analysis and a synchrotron small-angle X-ray scattering technique were employed to characterize the structural evolution of a polymeric latex dispersion during the first three stages of film formation at different temperatures and relative humidities. Three intermediate stages were identified: (1) stage I*, (2) stage I**, and (3) stage II*. Stage I* is intermediate to the conventionally defined stages I and II, where latex particles began to crystallization. The change of drying temperature affects the location of the onset of ordering, whereas relative humidity does not. Stage I** is where the latex particles with their diffuse shell of counterions in the fcc structure are in contact with each other. The overlapping of these layers results in an acceleration of the lattice shrinkage due to a decrease of effective charges. Stage II* is where the latex particles, dried well above their T(g), are deformed and packed only partially during film formation due to incomplete evaporation of water in the latex film. This is because of a rapid deformation of the soft latex particles at the liquid/air interface so that a certain amount of water is unable to evaporate from the latex film effectively. For a latex dispersion dried at a temperature close to its minimum film formation temperature, the transition between stages II and III can be continuous because the latex particles deform at a much slower rate, providing sufficient surface area for water evaporation.
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Affiliation(s)
- Xuelian Chen
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Graduate School of Chinese Academy of Sciences, Renmin Street 5625, 130022 Changchun, PR China
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König AM, Johannsmann D. Stress fluctuations in drying polymer dispersions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:9437-9441. [PMID: 20297831 DOI: 10.1021/la100454z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Drying polymer dispersions usually experience tensile stress, induced by the reduction in volume and by the rigid substrate. Due to edge-in drying, the stress is usually heterogeneous over the film. Stress peaks play a decisive role in the formation of cracks. This work relies on membrane bending, a technique that provides spatially resolved stress maps. In the experiments reported here, stress fluctuations on the order of 10% on the time scale of a few seconds were found. The stress fluctuations occur coherently over the entire drying front. Fluctuations go back to slight fluctuations in humidity of the environment (as opposed to local stress relaxations due to reorganizations of the particle network). The stress fluctuations disappear when covering the sample with a lid. They can be enhanced by blowing humid or dry air across the sample surface. Modeling builds on the assumption that all stresses go back to capillary pressure created at the menisci in between different spheres at the film-air interface. The local radius of curvature changes in response to slight variations in ambient humidity according to the Kelvin equation. The fluctuations are observed under a wide variety of drying conditions and should be included in film formation models.
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Affiliation(s)
- Alexander M König
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany
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König AM, Bourgeat-Lami E, Mellon V, von der Ehe K, Routh AF, Johannsmann D. Dilational lateral stress in drying latex films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:3815-3820. [PMID: 20146486 DOI: 10.1021/la9041937] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Drying latex films usually experience tensile stress due to the reduction in volume. While an unconstrained film would shrink affinely in all three dimensions, a coating can only shrink along the vertical and therefore exerts tensile stress onto the substrate. Using an instrument capable of producing maps of the stress distribution, we found that dilational stress sometimes develops as well. The in-plane stress was monitored by spreading the latex dispersion on a flexible membrane. Usually, the membrane bends upward under the tensile stress exerted by the film, but it may also bend downward. Dilational stress was only found with samples showing a strong coffee stain effect, that is, samples in which there is a significant lateral flow from the center to the edge while the film dries. During drying, particles consolidate first at the edge because of the lower height in this region. Continued evaporation from the consolidated region results in a water flow toward the edge, exerting a force onto the latex particles. At the time, when the network is formed, any single sphere must be in a force-balance condition: the network must exert an elastic force onto the sphere which just compensates the viscous drag. Pictorially speaking, a spring (an elastic network) is created while an external force acts onto it. Once the flow stops, the drag force vanishes and the internal stress, which previously compensated the drag, expands the film laterally. This phenomenon can lead to buckling. Given that lateral flow of liquid while films dry is a rather common occurrence, this mode of structure formation should be widespread. It requires lateral flow in conjunction with elastic recovery of the particle network.
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Affiliation(s)
- Alexander M König
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany
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An improved method to validate the relative humidity generation in sorption balances. Eur J Pharm Biopharm 2009; 72:99-104. [DOI: 10.1016/j.ejpb.2008.10.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2007] [Revised: 09/17/2008] [Accepted: 10/27/2008] [Indexed: 11/22/2022]
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Singh KB, Bhosale LR, Tirumkudulu MS. Cracking in drying colloidal films of flocculated dispersions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:4284-4287. [PMID: 19323451 DOI: 10.1021/la804331c] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Understanding the mechanism of cracking during the drying of aqueous colloidal dispersions is important to preventing film failure. While most of the reported work has dealt with stable aqueous dispersions, a few studies have focused on flocculated systems. The latter especially assumes importance because the role of particle packing in the mechanism of cracking is not completely understood. In this work, we study the cracking of colloidal films cast from flocculated aqueous dispersions of alpha-alumina. Here, the extent of flocculation is controlled by varying the pH of the dispersion and characterized in terms of the final packing volume fraction of the dried film. The influence of varying the close-packed volume fraction on the critical cracking thickness and critical cracking stress is measured. The measurements are compared with the model predictions based on Griffith's energy balance, and good agreement is found between theory and experiments, suggesting that the model is universal and applies equally well to stable as well as flocculated systems.
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Affiliation(s)
- Karnail B Singh
- Department of Chemical Engineering, IIT-Bombay, Powai, Mumbai-400076, India
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Rodríguez R, de las Heras Alarcón C, Ekanayake P, McDonald PJ, Keddie JL, Barandiaran MJ, Asua JM. Correlation of Silicone Incorporation into Hybrid Acrylic Coatings with the Resulting Hydrophobic and Thermal Properties. Macromolecules 2008. [DOI: 10.1021/ma8006015] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Raquel Rodríguez
- Institute for Polymer Materials POLYMAT and Grupo de Ingeniería Química, Departamento de Química Aplicada, Facultad de Ciencias Químicas, The University of the Basque Country, Centro Joxe Mari Korta, Avda Tolosa 72, 20018 Donostia-San Sebastián, Spain, and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH, U.K
| | - Carolina de las Heras Alarcón
- Institute for Polymer Materials POLYMAT and Grupo de Ingeniería Química, Departamento de Química Aplicada, Facultad de Ciencias Químicas, The University of the Basque Country, Centro Joxe Mari Korta, Avda Tolosa 72, 20018 Donostia-San Sebastián, Spain, and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH, U.K
| | - Piyasiri Ekanayake
- Institute for Polymer Materials POLYMAT and Grupo de Ingeniería Química, Departamento de Química Aplicada, Facultad de Ciencias Químicas, The University of the Basque Country, Centro Joxe Mari Korta, Avda Tolosa 72, 20018 Donostia-San Sebastián, Spain, and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH, U.K
| | - Peter J. McDonald
- Institute for Polymer Materials POLYMAT and Grupo de Ingeniería Química, Departamento de Química Aplicada, Facultad de Ciencias Químicas, The University of the Basque Country, Centro Joxe Mari Korta, Avda Tolosa 72, 20018 Donostia-San Sebastián, Spain, and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH, U.K
| | - Joseph L. Keddie
- Institute for Polymer Materials POLYMAT and Grupo de Ingeniería Química, Departamento de Química Aplicada, Facultad de Ciencias Químicas, The University of the Basque Country, Centro Joxe Mari Korta, Avda Tolosa 72, 20018 Donostia-San Sebastián, Spain, and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH, U.K
| | - María J. Barandiaran
- Institute for Polymer Materials POLYMAT and Grupo de Ingeniería Química, Departamento de Química Aplicada, Facultad de Ciencias Químicas, The University of the Basque Country, Centro Joxe Mari Korta, Avda Tolosa 72, 20018 Donostia-San Sebastián, Spain, and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH, U.K
| | - José M. Asua
- Institute for Polymer Materials POLYMAT and Grupo de Ingeniería Química, Departamento de Química Aplicada, Facultad de Ciencias Químicas, The University of the Basque Country, Centro Joxe Mari Korta, Avda Tolosa 72, 20018 Donostia-San Sebastián, Spain, and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH, U.K
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König AM, Weerakkody TG, Keddie JL, Johannsmann D. Heterogeneous drying of colloidal polymer films: dependence on added salt. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:7580-7589. [PMID: 18563885 DOI: 10.1021/la800525n] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Using magnetic resonance profiling coupled with dynamic light scattering, we have investigated the mechanisms leading to the formation of a partly coalesced surface layer, or "open skin", during film formation from waterborne polymer dispersions. We present the first use of the skewness of the distribution of free water as a model-free indicator of the spatial nonuniformity of drying. The skewness reaches a maximum at the same time at which a strong, static component, presumably originating from a skin at the film/air interface, appears in the light scattering data. Addition of salt to the dispersion increases both the skewness of the distribution of free water and the propensity for skin formation. Surprisingly, the drying is influenced not only by the concentration and valency of the ions in the salt but also by the particular ion. At intermediate particle densities, added salt strongly lowers the cooperative diffusion coefficient, Dcoop. When the particles reach close packing, Dcoop sharply increases. If the particles readily coalesce, the effects of the increased diffusivity will be counteracted, thereby inducing the formation of a skin. A modified Peclet number, Pe, using Dcoop, is proposed, so that the presence of salt is explicitly considered. This modified Pe is able to predict the nonuniformity in drying that leads to skin formation.
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Affiliation(s)
- Alexander M König
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany
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