1
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Kim BQ, Kim JQ, Yoon H, Lee E, Choi SQ, Kim K. Active Stratification of Colloidal Mixtures for Asymmetric Multilayers. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2404348. [PMID: 39150055 DOI: 10.1002/smll.202404348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Revised: 08/05/2024] [Indexed: 08/17/2024]
Abstract
Stratified films offer high performance and multifunctionality, yet achieving fully stratified films remains a challenge. The layer-by-layer method, involving the sequential deposition of each layer, has been commonly utilized for stratified film fabrication. However, this approach is time-consuming, labor-intensive, and prone to leaving defects within the film. Alternatively, the self-stratification process exploiting a drying binary colloidal mixture is intensively developed recently, but it relies on strict operating conditions, typically yielding a heterogeneous interlayer. In this study, an active interfacial stratification process for creating completely stratified nanoparticle (NP) films is introduced. The technique leverages NPs with varying interfacial activity at the air-water interface. With the help of depletion pressure, the lateral compression of NP mixtures at the interface induces individual desorption of less interfacial active NPs into the subphase, while more interfacial active NPs remain at the interface. This simple compression leads to nearly perfect stratified NP films with controllability, universality, and scalability. Combined with a solvent annealing process, the active stratification process enables the fabrication of stratified films comprising a polymeric layer atop a NP layer. This work provides insightful implications for designing drug encapsulation and controlled release, as well as manufacturing transparent and flexible electrodes.
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Affiliation(s)
- Baekmin Q Kim
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Jongmin Q Kim
- Interface Materials and Chemical Engineering Research Center, Korea Research Institute of Chemical Technology (KRICT), Daejeon, 34114, Republic of Korea
| | - Hojoon Yoon
- Department of Chemical and Biomolecular Engineering, Seoul National University of Science and Technology (SeoulTech), Seoul, 01811, Republic of Korea
| | - EunSuk Lee
- Department of Chemical and Biomolecular Engineering, Seoul National University of Science and Technology (SeoulTech), Seoul, 01811, Republic of Korea
| | - Siyoung Q Choi
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
- KAIST Institute for the Nanocentury, KAIST, Daejeon, 34141, Republic of Korea
| | - KyuHan Kim
- Department of Chemical and Biomolecular Engineering, Seoul National University of Science and Technology (SeoulTech), Seoul, 01811, Republic of Korea
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2
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Yetkin M, Wani YM, Kritika K, Howard MP, Kappl M, Butt HJ, Nikoubashman A. Structure Formation in Supraparticles Composed of Spherical and Elongated Particles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:1096-1108. [PMID: 38153401 DOI: 10.1021/acs.langmuir.3c03410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
We studied the evaporation-induced formation of supraparticles from dispersions of elongated colloidal particles using experiments and computer simulations. Aqueous droplets containing a dispersion of ellipsoidal and spherical polystyrene particles were dried on superamphiphobic surfaces at different humidity values that led to varying evaporation rates. Supraparticles made from only ellipsoidal particles showed short-range lateral ordering at the supraparticle surface and random orientations in the interior regardless of the evaporation rate. Particle-based simulations corroborated the experimental observations in the evaporation-limited regime and showed an increase in the local nematic ordering as the diffusion-limited regime was reached. A thin shell of ellipsoids was observed at the surface when supraparticles were made from binary mixtures of ellipsoids and spheres. Image analysis revealed that the supraparticle porosity increased with an increasing aspect ratio of the ellipsoids.
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Affiliation(s)
- Melis Yetkin
- Department of Physics at Interfaces, Max-Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Yashraj M Wani
- Institute of Physics, Johannes Gutenberg University of Mainz, Staudingerweg 7, Mainz 55128, Germany
| | - Kritika Kritika
- Institute of Physics, Johannes Gutenberg University of Mainz, Staudingerweg 7, Mainz 55128, Germany
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden 01069, Germany
- Institut für Theoretische Physik, Technische Universität Dresden, Dresden 01069, Germany
| | - Michael P Howard
- Department of Chemical Engineering, Auburn University, Auburn, Alabama 36849, United States
| | - Michael Kappl
- Department of Physics at Interfaces, Max-Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Hans-Jürgen Butt
- Department of Physics at Interfaces, Max-Planck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
| | - Arash Nikoubashman
- Institute of Physics, Johannes Gutenberg University of Mainz, Staudingerweg 7, Mainz 55128, Germany
- Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden 01069, Germany
- Institut für Theoretische Physik, Technische Universität Dresden, Dresden 01069, Germany
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3
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Liu B, Grest GS, Cheng S. Inducing stratification of colloidal mixtures with a mixed binary solvent. SOFT MATTER 2023; 19:9195-9205. [PMID: 37997155 DOI: 10.1039/d3sm01192e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
Molecular dynamics simulations are used to demonstrate that a binary solvent can be used to stratify colloidal mixtures when the suspension is rapidly dried. The solvent consists of two components, one more volatile than the other. When evaporated at high rates, the more volatile component becomes depleted near the evaporation front and develops a negative concentration gradient from the bulk of the mixture to the liquid-vapor interface while the less volatile solvent is enriched in the same region and exhibit a positive concentration gradient. Such gradients can be used to drive a binary mixture of colloidal particles to stratify if one is preferentially attracted to the more volatile solvent and the other to the less volatile solvent. During solvent evaporation, the fraction of colloidal particles preferentially attracted to the less volatile solvent is enhanced at the evaporation front, whereas the colloidal particles having stronger attractions with the more volatile solvent are driven away from the interfacial region. As a result, the colloidal particles show a stratified distribution after drying, even if the two colloids have the same size.
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Affiliation(s)
- Binghan Liu
- Department of Physics, Center for Soft Matter and Biological Physics, and Macromolecules Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, USA.
| | - Gary S Grest
- Sandia National Laboratories, Albuquerque, NM 87185, USA
| | - Shengfeng Cheng
- Department of Physics, Center for Soft Matter and Biological Physics, and Macromolecules Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, USA.
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia 24061, USA
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4
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Hooiveld E, Dols M, van der Gucht J, Sprakel J, van der Kooij HM. Quantitative imaging methods for heterogeneous multi-component films. SOFT MATTER 2023; 19:8871-8881. [PMID: 37955195 PMCID: PMC10663990 DOI: 10.1039/d3sm01212c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 11/02/2023] [Indexed: 11/14/2023]
Abstract
The drying of multi-component dispersions is a common phenomenon in a variety of everyday applications, including coatings, inks, processed foods, and cosmetics. As the solvent evaporates, the different components may spontaneously segregate laterally and/or in depth, which can significantly impact the macroscopic properties of the dried film. To obtain a quantitative understanding of these processes, high-resolution analysis of segregation patterns is crucial. Yet, current state-of-the-art methods are limited to transparent, non-deformable labeled colloids, limiting their applicability. In this study, we employ three techniques that do not require customized samples, as their imaging contrast relies on intrinsic variations in the chemical nature of the constituent species: confocal Raman microscopy, cross-sectional Raman microscopy, and a combination of scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDX). For broad accessibility, we offer a thorough guide to our experimental steps and data analysis methods. We benchmark the capabilities on a film that dries homogeneously at room temperature but exhibits distinct segregation features at elevated temperature, notably self-stratification, i.e., autonomous layer formation, due to a colloidal size mismatch. Confocal Raman microscopy offers a direct means to visualize structures in three dimensions without pre-treatment, its accuracy diminishes deeper within the film, making cross-sectional Raman imaging and SEM-EDX better options. The latter is the most elaborate method, yet we show that it can reveal the most subtle and small-scale microseparation of the two components in the lateral direction. This comparative study assists researchers in choosing and applying the most suitable technique to quantify structure formation in dried multi-component films.
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Affiliation(s)
- Ellard Hooiveld
- Physical Chemistry and Soft Matter, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
| | - Maarten Dols
- Physical Chemistry and Soft Matter, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
| | - Jasper van der Gucht
- Physical Chemistry and Soft Matter, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
| | - Joris Sprakel
- Laboratory of Biochemistry, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Hanne M van der Kooij
- Physical Chemistry and Soft Matter, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
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5
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Palmer TR, van der Kooij HM, Abu Bakar R, McAleese CD, Duewel M, Greiner K, Couture P, Sharpe MK, Keddie JL. Diffusiophoresis-Driven Stratification in Pressure-Sensitive Adhesive Films from Bimodal Waterborne Colloids. ACS APPLIED POLYMER MATERIALS 2023; 5:1565-1576. [PMID: 36817335 PMCID: PMC9926484 DOI: 10.1021/acsapm.2c02044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 01/11/2023] [Indexed: 06/18/2023]
Abstract
The uses of pressure-sensitive adhesives (PSAs) are wide ranging, with applications including labels, tapes, and graphics. To achieve good adhesion, a PSA must exhibit a balance of viscous and elastic properties. Previous research has found that a thin, elastic surface layer on top of a softer, dissipative layer resulted in greater tack adhesion compared with the single layers. Superior properties were achieved through a bilayer obtained via successive depositions, which consume energy and time. To achieve a multilayered structure via a single deposition process, we have stratified mixtures of waterborne colloidal polymer particles with two different sizes: large poly(acrylate) adhesive particles (ca. 660 nm in diameter) and small poly(butyl acrylate) (pBA) particles (ca. 100 nm). We used two types of pBA within the particles: either viscoelastic pBA without an added cross-linker or elastic pBA with a fully cross-linked network. Stratified surface layers of deuterium-labeled pBA particles with thicknesses of at least 1 μm were found via elastic recoil detection and qualitatively verified via the analysis of surface topography. The extent of stratification increased with the evaporation rate; films that were dried slowest exhibited no stratification. This result is consistent with a model of diffusiophoresis. When the elastic, cross-linked pBA particles were stratified at the surface, the tack adhesion properties made a transition from brittle failure to tacky. For pBA without an added cross-linker, all adhesives showed fibrillation during debonding, but the extent of fibrillation increased when the films were stratified. These results demonstrate that the PSA structure can be controlled through the processing conditions to achieve enhanced properties. This research will aid the future development of layered or graded single-deposition PSAs with designed adhesive properties.
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Affiliation(s)
- Toby R. Palmer
- Department
of Physics, University of Surrey, Guildford, SurreyGU2 7XH, U.K.
| | - Hanne M. van der Kooij
- Physical
Chemistry and Soft Matter, Wageningen University
and Research, 6708 WEWageningen, The Netherlands
| | - Rohani Abu Bakar
- Department
of Physics, University of Surrey, Guildford, SurreyGU2 7XH, U.K.
| | - Callum D. McAleese
- Surrey
Ion Beam Centre, University of Surrey, Guildford, SurreyGU2 7XH, U.K.
| | - Mathis Duewel
- Synthomer
Germany GmbH, Werrastraße 10, 45768Marl, Germany
| | - Katja Greiner
- Synthomer
Germany GmbH, Werrastraße 10, 45768Marl, Germany
| | - Pierre Couture
- Surrey
Ion Beam Centre, University of Surrey, Guildford, SurreyGU2 7XH, U.K.
| | - Matthew K. Sharpe
- Surrey
Ion Beam Centre, University of Surrey, Guildford, SurreyGU2 7XH, U.K.
| | - Joseph L. Keddie
- Department
of Physics, University of Surrey, Guildford, SurreyGU2 7XH, U.K.
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6
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In-situ and quantitative imaging of evaporation-induced stratification in binary suspensions. J Colloid Interface Sci 2023; 630:666-675. [DOI: 10.1016/j.jcis.2022.10.103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 10/05/2022] [Accepted: 10/20/2022] [Indexed: 11/06/2022]
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7
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Stratified and gradient films by evaporation-induced stratification of bimodal latexes. Potential of confocal and scanning electron microscopy for compositional depth profiling. POLYMER 2023. [DOI: 10.1016/j.polymer.2023.125752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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8
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Perez A, Kynaston E, Lindsay C, Ballard N. Semi‐crystalline/amorphous latex blends for coatings with improved mechanical performance. J Appl Polym Sci 2022. [DOI: 10.1002/app.53517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Adrián Perez
- POLYMAT and Departamento de Química Aplicada, Facultad de Ciencias Químicas University of the Basque Country UPV/EHU Donostia‐San Sebastián Spain
| | - Emily Kynaston
- Syngenta, Jealott's Hill International Research Centre Bracknell UK
| | | | - Nicholas Ballard
- POLYMAT and Departamento de Química Aplicada, Facultad de Ciencias Químicas University of the Basque Country UPV/EHU Donostia‐San Sebastián Spain
- IKERBASQUE Basque Foundation for Science Bilbao Spain
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9
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Kundu M, Howard MP. Dynamic density functional theory for drying colloidal suspensions: Comparison of hard-sphere free-energy functionals. J Chem Phys 2022; 157:184904. [DOI: 10.1063/5.0118695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Dynamic density functional theory (DDFT) is a promising approach for predicting the structural evolution of a drying suspension containing one or more types of colloidal particles. The assumed free-energy functional is a key component of DDFT that dictates the thermodynamics of the model and, in turn, the density flux due to a concentration gradient. In this work, we compare several commonly used free-energy functionals for drying hard-sphere suspensions, including local-density approximations based on the ideal-gas, virial, and Boublík–Mansoori–Carnahan–Starling–Leland (BMCSL) equations of state as well as a weighted-density approximation based on fundamental measure theory (FMT). To determine the accuracy of each functional, we model one- and two-component hard-sphere suspensions in a drying film with varied initial heights and compositions, and we compare the DDFT-predicted volume fraction profiles to particle-based Brownian dynamics (BD) simulations. FMT accurately predicts the structure of the one-component suspensions even at high concentrations and when significant density gradients develop, but the virial and BMCSL equations of state provide reasonable approximations for smaller concentrations at a reduced computational cost. In the two-component suspensions, FMT and BMCSL are similar to each other but modestly overpredict the extent of stratification by size compared to BD simulations. This work provides helpful guidance for selecting thermodynamic models for soft materials in nonequilibrium processes, such as solvent drying, solvent freezing, and sedimentation.
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Affiliation(s)
- Mayukh Kundu
- Department of Chemical Engineering, Auburn University, Auburn, Alabama 36849, USA
| | - Michael P. Howard
- Department of Chemical Engineering, Auburn University, Auburn, Alabama 36849, USA
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10
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Lee D, Charpota N, Mei H, Terlier T, Pietrzak D, Stein GE, Verduzco R. Impact of Processing Effects on Surface Segregation of Bottlebrush Polymer Additives. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c01418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Dongjoo Lee
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, United States
| | - Nilesh Charpota
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Hao Mei
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, United States
| | - Tanguy Terlier
- SIMS Lab, Shared Equipment Authority, Rice University, Houston, Texas 77005, United States
| | - Danica Pietrzak
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, United States
| | - Gila E. Stein
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Rafael Verduzco
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, United States
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
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11
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Tang Y, McLaughlan JE, Grest GS, Cheng S. Modeling Solution Drying by Moving a Liquid-Vapor Interface: Method and Applications. Polymers (Basel) 2022; 14:polym14193996. [PMID: 36235944 PMCID: PMC9573352 DOI: 10.3390/polym14193996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/16/2022] [Accepted: 09/19/2022] [Indexed: 11/22/2022] Open
Abstract
A method of simulating the drying process of a soft matter solution with an implicit solvent model by moving the liquid-vapor interface is applied to various solution films and droplets. For a solution of a polymer and nanoparticles, we observe “polymer-on-top” stratification, similar to that found previously with an explicit solvent model. Furthermore, “polymer-on-top” is found even when the nanoparticle size is smaller than the radius of gyration of the polymer chains. For a suspension droplet of a bidisperse mixture of nanoparticles, we show that core-shell clusters of nanoparticles can be obtained via the “small-on-outside” stratification mechanism at fast evaporation rates. “Large-on-outside” stratification and uniform particle distribution are also observed when the evaporation rate is reduced. Polymeric particles with various morphologies, including Janus spheres, core-shell particles, and patchy particles, are produced from drying droplets of polymer solutions by combining fast evaporation with a controlled interaction between the polymers and the liquid-vapor interface. Our results validate the applicability of the moving interface method to a wide range of drying systems. The limitations of the method are pointed out and cautions are provided to potential practitioners on cases where the method might fail.
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Affiliation(s)
- Yanfei Tang
- Department of Physics, Center for Soft Matter and Biological Physics, Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA 24061, USA
| | - John E. McLaughlan
- Department of Physics, Center for Soft Matter and Biological Physics, Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA 24061, USA
| | - Gary S. Grest
- Sandia National Laboratories, Albuquerque, NM 87185, USA
| | - Shengfeng Cheng
- Department of Physics, Center for Soft Matter and Biological Physics, Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA 24061, USA
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, USA
- Correspondence: ; Tel.: +1-540-231-5767
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12
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Park JS, Yun J, Chun B, Jung HW. Mild stratification in drying films of colloidal mixtures. SOFT MATTER 2022; 18:3487-3497. [PMID: 35438125 DOI: 10.1039/d2sm00205a] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Size stratification of bidisperse colloidal mixtures during vertical drying was investigated using the implicit solvent Langevin dynamics (LD) simulation and the explicit solvent lattice Boltzmann (LB) method. Simulations were performed for the Péclet number (Pe) over a wide range of 1-1000. In the case of a low size ratio of 2, mild stratification was observed in both simulation methods, in contrast to distinct stratification with thick "small-on-top" or "large-on-top" layers. The LD simulations exhibited a "small-on-top" stratification or mixed state. In contrast, the LB simulations exhibited a "large-on-top" or mixed state, according to the variation in Pe. The results demonstrated that the explicit solvent reduced the collective diffusion under moderate Pe conditions. This suppressed the steep concentration gradient of small particles in the packed region of particles near the air-solvent interface. Thus, distinguishable stratification patterns were obtained for the implicit and explicit solvent models.
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Affiliation(s)
- Jin Seok Park
- Department of Chemical and Biological Engineering, Korea University, Seoul 02841, Republic of Korea.
| | - Jinseong Yun
- Department of Chemical and Biological Engineering, Korea University, Seoul 02841, Republic of Korea.
| | - Byoungjin Chun
- Department of Chemical and Biological Engineering, Korea University, Seoul 02841, Republic of Korea.
| | - Hyun Wook Jung
- Department of Chemical and Biological Engineering, Korea University, Seoul 02841, Republic of Korea.
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13
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Schulz M, Brinkhuis R, Crean C, Sear RP, Keddie JL. Suppression of self-stratification in colloidal mixtures with high Péclet numbers. SOFT MATTER 2022; 18:2512-2516. [PMID: 35297936 DOI: 10.1039/d2sm00194b] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The non-equilibrium assembly of bimodal colloids during evaporative processes is an attractive means to achieve gradient or stratified layers in thick films. Here, we show that the stratification of small colloids on top of large is prevented when the viscosity of the continuous aqueous phase is too high. We propose a model where a too narrow width of the gradient in concentration of small colloids suppresses the stratification.
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Affiliation(s)
- M Schulz
- Department of Physics, University of Surrey, Guildford, Surrey, GU2 7XH, UK.
| | - R Brinkhuis
- Allnex, Nieuwe Kanaal 7N, 6709 PA Wageningen, The Netherlands
| | - C Crean
- Department of Chemistry, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | - R P Sear
- Department of Physics, University of Surrey, Guildford, Surrey, GU2 7XH, UK.
| | - J L Keddie
- Department of Physics, University of Surrey, Guildford, Surrey, GU2 7XH, UK.
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14
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Jeong JH, Lee YK, Ahn KH. Stratification Mechanism in the Bidisperse Colloidal Film Drying Process: Evolution and Decomposition of Normal Stress Correlated with Microstructure. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:13712-13728. [PMID: 34751580 DOI: 10.1021/acs.langmuir.1c02455] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The evolution of the normal stress and microstructure in the drying process of bidisperse colloidal films is studied using the Brownian dynamics simulation. Here, we show that the formation process of small-on-top stratification can be explained by normal stress development. At high PeL's, a stratified layer with small particles is formed near the interface. The accumulated particles near the interface induce the localization of normal stress so that the normal stress at the interface increases from the beginning of drying. We analyze this stress development from two points of view, on the global length scale and particle length scale. On the global length scale, the localization of normal stress is quantified by the scaled normal stress difference between the interface and substrate. For all PeL's tested in this study, the scaled normal stress difference increases until the accumulation region reaches the substrate. After the maximum, the stress difference remains at the maximum at lower PeL's, while it decreases at higher PeL's. The microstructural analysis shows that this stress development is explained through the evolution of the particle contact number distribution at the interface and substrate. On the particle length scale, we derive the scaled local force applied to each type of particle by decomposing the local normal stress. At high PeL's, the scaled local force for the large particle is large compared to that for the small particle near the interface, indicating that the large particles are strongly pushed away from the interface. Associating the volume fraction profile with the local force field, we suggest that the strong scaled force for the large particle is attributed to the significant increase in the average number of small particles in contact with large ones. This study has significance in probing the drying mechanism of bidisperse colloidal films and the stratification mechanism.
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Affiliation(s)
- Jae Hwan Jeong
- School of Chemical and Biological Engineering, and Institute of Chemical Processes, Seoul National University, Seoul 08826, Korea
| | - Young Ki Lee
- School of Food Biotechnology and Chemical Engineering, Hankyong National University, Anseong 17579, Korea
| | - Kyung Hyun Ahn
- School of Chemical and Biological Engineering, and Institute of Chemical Processes, Seoul National University, Seoul 08826, Korea
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15
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Abstract
A framework for performant Brownian Dynamics (BD) many-body simulations with adaptive timestepping is presented. Contrary to the Euler-Maruyama scheme in common non-adaptive BD, we employ an embedded Heun-Euler integrator for the propagation of the overdamped coupled Langevin equations of motion. This enables the derivation of a local error estimate and the formulation of criteria for the acceptance or rejection of trial steps and for the control of optimal stepsize. Introducing erroneous bias in the random forces is avoided by rejection sampling with memory due to Rackauckas and Nie, which makes use of the Brownian bridge theorem and guarantees the correct generation of a specified random process even when rejecting trial steps. For test cases of Lennard-Jones fluids in bulk and in confinement, it is shown that adaptive BD solves performance and stability issues of conventional BD, already outperforming the latter even in standard situations. We expect this novel computational approach to BD to be especially helpful in long-time simulations of complex systems, e.g., in non-equilibrium, where concurrent slow and fast processes occur.
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Affiliation(s)
- Florian Sammüller
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany
| | - Matthias Schmidt
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany
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16
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Yu M, Le Floch-Fouéré C, Pauchard L, Boissel F, Fu N, Chen XD, Saint-Jalmes A, Jeantet R, Lanotte L. Skin layer stratification in drying droplets of dairy colloids. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.126560] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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17
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Baba H, Yoshioka R, Takatori S, Oe Y, Yoshikawa K. Transitions among Cracking, Peeling and Homogenization on Drying of an Aqueous Solution Containing Glucose and Starch. CHEM LETT 2021. [DOI: 10.1246/cl.210009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Hikari Baba
- Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan
| | - Risa Yoshioka
- Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan
| | - Satoshi Takatori
- Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan
| | - Yohei Oe
- Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan
| | - Kenichi Yoshikawa
- Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan
- Center for Integrative Medicine and Physics, Institute for Advanced Study, Kyoto University, Kyoto 606-8501, Japan
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18
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Liu W, Shen J, Bhatia SR. An in-situ SAXS approach to probe stratification during drying of inorganic nanoparticle films. Inorganica Chim Acta 2021. [DOI: 10.1016/j.ica.2020.120213] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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He B, Martin-Fabiani I, Roth R, Tóth GI, Archer AJ. Dynamical Density Functional Theory for the Drying and Stratification of Binary Colloidal Dispersions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:1399-1409. [PMID: 33471532 DOI: 10.1021/acs.langmuir.0c02825] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We develop a dynamical density functional theory based model for the drying of colloidal films on planar surfaces. We consider mixtures of two different sizes of hard-sphere colloids. Depending on the solvent evaporation rate and the initial concentrations of the two species, we observe varying degrees of stratification in the final dried films. Our model predicts the various structures described in the literature previously from experiments and computer simulations, in particular the small-on-top stratified films. Our model also includes the influence of adsorption of particles to the interfaces.
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Affiliation(s)
- Boshen He
- Department of Materials, Loughborough University, Loughborough LE11 3TU, United Kingdom
| | | | - Roland Roth
- Institut für Theoretische Physik, Universität Tübingen, Tübingen, Germany
| | - Gyula I Tóth
- Department of Mathematical Sciences, Loughborough University, Loughborough LE11 3TU, United Kingdom
- Interdisciplinary Centre for Mathematical Modelling, Loughborough University, Loughborough LE11 3TU, United Kingdom
| | - Andrew J Archer
- Department of Mathematical Sciences, Loughborough University, Loughborough LE11 3TU, United Kingdom
- Interdisciplinary Centre for Mathematical Modelling, Loughborough University, Loughborough LE11 3TU, United Kingdom
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20
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Tinkler JD, Scacchi A, Kothari HR, Tulliver H, Argaiz M, Archer AJ, Martín-Fabiani I. Evaporation-driven self-assembly of binary and ternary colloidal polymer nanocomposites for abrasion resistant applications. J Colloid Interface Sci 2021; 581:729-740. [PMID: 32818678 DOI: 10.1016/j.jcis.2020.08.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/10/2020] [Accepted: 08/01/2020] [Indexed: 10/23/2022]
Abstract
We harness the self-assembly of aqueous binary latex/silica particle blends during drying to fabricate films segregated by size in the vertical direction. We report for the first time the experimental drying of ternary colloidal dispersions and demonstrate how a ternary film containing additional small latex particles results in improved surface stability and abrasion resistance compared with a binary film. Through atomic force microscopy (AFM) and energy-dispersive X-ray spectroscopy (EDX), we show that the vertical distribution of filler particles and the surface morphologies of the films can be controlled by altering the evaporation rate and silica volume fraction. We report the formation of various silica superstructures at the film surface, which we attribute to a combination of diffusiophoresis and electrostatic interactions between particles. Brownian dynamics simulations of the final stages of solvent evaporation provide further evidence for this formation mechanism. We show how an additional small latex particle population results in an increased abrasion resistance of the film without altering its morphology or hardness. Our work provides a method to produce water-based coatings with enhanced abrasion resistance as well as valuable insights into the mechanisms behind the formation of colloidal superstructures.
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Affiliation(s)
- James D Tinkler
- Department of Materials, Loughborough University, Loughborough, UK.
| | - Alberto Scacchi
- Department of Mathematical Sciences, Loughborough University, Loughborough, UK
| | - Harsh R Kothari
- Department of Materials, Loughborough University, Loughborough, UK
| | - Hanna Tulliver
- Department of Materials, Loughborough University, Loughborough, UK
| | - Maialen Argaiz
- POLYMAT and Departmento de Química Aplicada, Facultad de Ciencias Químicas, University of the Basque Country, UPV/EHU, Donostia-San Sebastian, Spain
| | - Andrew J Archer
- Department of Mathematical Sciences, Loughborough University, Loughborough, UK
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21
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Tatsumi R, Koike O, Yamaguchi Y, Tsuji Y. Classification of drying segregation states by a generalized diffusion model. J Chem Phys 2020; 153:164902. [PMID: 33138397 DOI: 10.1063/5.0021872] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
During drying of binary colloidal mixtures, one colloidal particle component can segregate to the top surface. We investigate conditions where the segregation occurs through the analysis of a linearized diffusion model with Fick's law generalized for binary colloidal mixtures. The present model is the simplest representation that includes cross-diffusion between different particle components to describe the segregation. Using the analytical solutions of this model, we classify states in terms of which the particle component segregates for the following variables: the mixture ratio of particle components, diffusion coefficients, and drying rates. The obtained state diagrams suggest how to control the segregation by designing material and operation conditions.
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Affiliation(s)
- Rei Tatsumi
- Environmental Science Center, The University of Tokyo, Tokyo 113-8656, Japan
| | - Osamu Koike
- Products Innovation Association, Tokyo 113-8656, Japan
| | | | - Yoshiko Tsuji
- Environmental Science Center, The University of Tokyo, Tokyo 113-8656, Japan
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22
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Schulz M, Smith RW, Sear RP, Brinkhuis R, Keddie JL. Diffusiophoresis-Driven Stratification of Polymers in Colloidal Films. ACS Macro Lett 2020; 9:1286-1291. [PMID: 35638630 DOI: 10.1021/acsmacrolett.0c00363] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The molecular composition of polymer blend surfaces defines properties such as adhesion, wetting, gloss, and biocompatibility. The surface composition often differs from the bulk because of thermodynamic effects or modification. Mixtures of colloids and linear polymers in a common solvent are often used to deposit films for use in encapsulants, inks, coatings, and adhesives. However, means to control the nonequilibrium surface composition are lacking for these systems. Here we show how the surface composition and hydrophilicity of a film deposited from a bimodal mixture of linear polymers and colloids in water can be adjusted simply by varying the evaporation rate. Ion beam analysis was used to quantify the extent of stratification of the linear polymers near the surface, and the results are in agreement with a recent diffusiophoretic model. Because our approach to stratification relies solely on diffusiophoresis, it is widely applicable to any system deposited from colloids and nonadsorbing polymers in solution as a means to tailor surface properties.
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Affiliation(s)
- Malin Schulz
- Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom
| | - Richard W Smith
- Surrey Ion Beam Centre, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom
| | - Richard P Sear
- Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom
| | | | - Joseph L Keddie
- Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom
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23
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Howard MP, Nikoubashman A. Stratification of polymer mixtures in drying droplets: Hydrodynamics and diffusion. J Chem Phys 2020; 153:054901. [PMID: 32770900 DOI: 10.1063/5.0014429] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
We study the evaporation-induced stratification of a mixture of short and long polymer chains in a drying droplet using molecular simulations. We systematically investigate the effects of hydrodynamic interactions (HI) on this process by comparing hybrid simulations accounting for HI between polymers through the multiparticle collision dynamics technique with free-draining Langevin dynamics simulations neglecting the same. We find that the dried supraparticle morphologies are homogeneous when HI are included but are stratified in core-shell structures (with the short polymers forming the shell) when HI are neglected. The simulation methodology unambiguously attributes this difference to the treatment of the solvent in the two models. We rationalize the presence (or absence) of stratification by measuring phenomenological multicomponent diffusion coefficients for the polymer mixtures. The diffusion coefficients show the importance of not only solvent backflow but also HI between polymers in controlling the dried supraparticle morphology.
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Affiliation(s)
- Michael P Howard
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA
| | - Arash Nikoubashman
- Institute of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany
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24
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Samanta A, Bordes R. On the effect of particle surface chemistry in film stratification and morphology regulation. SOFT MATTER 2020; 16:6371-6378. [PMID: 32568354 DOI: 10.1039/d0sm00317d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Combinations of colloids and binders are often used to formulate functional coatings. In these mixtures, competition between particle migration, polymer chain diffusion, evaporation and sedimentation affects their respective spatial location and therefore can govern the surface features. In addition to this, the surface chemistry of the nanoparticles (NPs) and the resulting interparticle interactions can play a significant role in dictating the morphology and the properties of resultant films. Hence it would be possible to tune the surface and bulk topology of the films by controlling these parameters. A combination of various acrylic binders with two types of silica sols, bare (BSiO2) and modified silica (MSiO2), differing in their ability to gel, were formulated and dried under controlled conditions. Factors influencing the mobility and migration of binder and silica particles were evaluated with respect to particle concentration and drying rate. MSiO2 films showed prominent pores with gradual increase in Si% across the cross-section of the films, whereas, BSiO2 films had no pores and showed a uniform Si content across the cross-section of the films. This difference is explained by the variation in gelation between BSiO2 compared to MSiO2, that hindered the NPs migration and affects the infiltration and stratification process. This study paves a path forward to achieve desired surface and bulk porosity from colloidal silica coatings by effective control of chemistry of particles along with process parameters.
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Affiliation(s)
- Archana Samanta
- Department of Chemistry and Chemical Engineering, Applied Chemistry, Chalmers University of Technology, Sweden.
| | - Romain Bordes
- Department of Chemistry and Chemical Engineering, Applied Chemistry, Chalmers University of Technology, Sweden.
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25
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Kaewpetch T, Gilchrist JF. Chemical vs. mechanical microstructure evolution in drying colloid and polymer coatings. Sci Rep 2020; 10:10264. [PMID: 32581230 PMCID: PMC7314827 DOI: 10.1038/s41598-020-66875-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 05/28/2020] [Indexed: 12/04/2022] Open
Abstract
Colloidal based films have been widely developed for a wide range of applications including chemical and electrical barrier coatings, photonic materials, biomaterials, and pharmaceutical oral drug delivery. Many previous studies investigate methods to generate uniformity or desired stratification of the final components with a desired microstructure. Few studies have been able to investigate this microstructure in-situ during drying. This experimental study directly tracks fluorescent colloids that are either stable in suspension or have attractive interactions during the drying process using high speed laser scanning confocal microscopy to obtain details of microstructural evolution during drying. The colloidal microstructure in stable suspensions evolves continuously during drying. Microstructures in these systems have a signature Voronoi polyhedra distribution that is defined by lognormal curve having a constant standard deviation that only depends on its chemical composition. Those formulations having strongly attractive constituents have microstructure that is heterogeneous and non-monotonic due to the mechanics associated with internal convection and capillary forces. Toward the end of drying, the influence of the mode of microstructure rearrangements remains evident.
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Affiliation(s)
- Thitiporn Kaewpetch
- Polymer Science and Engineering, Department of Materials Science and Engineering, Lehigh University, Bethlehem, PA, USA
| | - James F Gilchrist
- Polymer Science and Engineering, Department of Materials Science and Engineering, Lehigh University, Bethlehem, PA, USA.
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA, USA.
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26
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Inoue K, Inasawa S. Drying-induced back flow of colloidal suspensions confined in thin unidirectional drying cells. RSC Adv 2020; 10:15763-15768. [PMID: 35493636 PMCID: PMC9052441 DOI: 10.1039/d0ra02837a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Accepted: 04/14/2020] [Indexed: 12/31/2022] Open
Abstract
A clear back flow was observed in the thin unidirectional drying cell of a colloidal suspension. Flow around the colloidal-particle packing front was more complex than expected, even though a colloidal suspension was confined in a narrow space with a submillimeter-scale or shorter gap height. We propose that an increase in particle concentration around the packing front induces downward flow, which is the origin for back flow inside the cell. A mathematical model, which considered both a drying induced horizontal flow and a circulation flow caused by a concentration gradient of particles, showed a reasonable agreement with experimental data for the width of the back-flow region. The concentration gradient of particles was not negligible and it generated a rather complicated flow even in a thin drying liquid film.
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Affiliation(s)
- Kai Inoue
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology 2-24-16 Nakacho, Koganei Tokyo 184-8588 Japan +81-42-388-7798 +81-42-388-7105
| | - Susumu Inasawa
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology 2-24-16 Nakacho, Koganei Tokyo 184-8588 Japan +81-42-388-7798 +81-42-388-7105
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology 2-24-16 Nakacho, Koganei Tokyo 184-8588 Japan
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27
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Inoue K, Inasawa S. Positive and negative birefringence in packed films of binary spherical colloidal particles. RSC Adv 2020; 10:2566-2574. [PMID: 35496111 PMCID: PMC9048605 DOI: 10.1039/c9ra09704j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 01/06/2020] [Indexed: 12/20/2022] Open
Abstract
We have investigated the birefringence in packed films of binary spherical colloidal particles. Particulate films were obtained by drying a mixed suspension of colloidal particles with two different diameters. We observed positive and negative birefringence depending on the diameters and volume ratios of the large and small particles. When the diameters of the large and small particles were similar, the films showed positive birefringence. However, negative birefringence or weakening of positive birefringence was observed in films with a large diameter ratio and an optimal volume fraction of large particles. The large particles were embedded in packed small particles in the negative and weakened positive birefringent films. We propose a packing structure in which a single shell layer of small particles formed around a large particle. Using this model, we estimated the required volume ratio of large particles, and it was in good agreement with the optimal volume fraction. The relation between the packing structure of the binary colloidal particles and the birefringence is discussed. We have investigated the birefringence in packed films of binary spherical colloidal particles.![]()
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Affiliation(s)
- Kai Inoue
- Graduate School of Bio-Applications and Systems Engineering
- Tokyo University of Agriculture and Technology
- Koganei
- Japan
| | - Susumu Inasawa
- Graduate School of Bio-Applications and Systems Engineering
- Tokyo University of Agriculture and Technology
- Koganei
- Japan
- Department of Chemical Engineering
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28
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Xiao M, Hu Z, Gartner TE, Yang X, Li W, Jayaraman A, Gianneschi NC, Shawkey MD, Dhinojwala A. Experimental and theoretical evidence for molecular forces driving surface segregation in photonic colloidal assemblies. SCIENCE ADVANCES 2019; 5:eaax1254. [PMID: 31555734 PMCID: PMC6754227 DOI: 10.1126/sciadv.aax1254] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Accepted: 08/20/2019] [Indexed: 05/05/2023]
Abstract
Surface segregation in binary colloidal mixtures offers a simple way to control both surface and bulk properties without affecting their bulk composition. Here, we combine experiments and coarse-grained molecular dynamics (CG-MD) simulations to delineate the effects of particle chemistry and size on surface segregation in photonic colloidal assemblies from binary mixtures of melanin and silica particles of size ratio (D large /D small) ranging from 1.0 to ~2.2. We find that melanin and/or smaller particles segregate at the surface of micrometer-sized colloidal assemblies (supraballs) prepared by an emulsion process. Conversely, no such surface segregation occurs in films prepared by evaporative assembly. CG-MD simulations explain the experimental observations by showing that particles with the larger contact angle (melanin) are enriched at the supraball surface regardless of the relative strength of particle-interface interactions, a result with implications for the broad understanding and design of colloidal particle assemblies.
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Affiliation(s)
- Ming Xiao
- Department of Polymer Science, The University of Akron, Akron, OH 44325, USA
| | - Ziying Hu
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | - Thomas E. Gartner
- Department of Chemical & Biomolecular Engineering, University of Delaware, Newark, DE 19716, USA
| | - Xiaozhou Yang
- Department of Polymer Science, The University of Akron, Akron, OH 44325, USA
| | - Weiyao Li
- Department of Polymer Science, The University of Akron, Akron, OH 44325, USA
| | - Arthi Jayaraman
- Department of Chemical & Biomolecular Engineering, University of Delaware, Newark, DE 19716, USA
- Department of Materials Science & Engineering, University of Delaware, Newark, DE 19716, USA
| | | | - Matthew D. Shawkey
- Evolution & Optics of Nanostructures Group, Department of Biology, Ghent University, Ghent 9000, Belgium
| | - Ali Dhinojwala
- Department of Polymer Science, The University of Akron, Akron, OH 44325, USA
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29
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Grest GS. Stratification of drying particle suspensions: Comparison of implicit and explicit solvent simulations. J Chem Phys 2019; 150:224901. [DOI: 10.1063/1.5066035] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Affiliation(s)
- Gary S. Grest
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
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30
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Tang Y, Grest GS, Cheng S. Control of Stratification in Drying Particle Suspensions via Temperature Gradients. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:4296-4304. [PMID: 30807180 DOI: 10.1021/acs.langmuir.8b03659] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A potential strategy for controlling stratification in a drying suspension of bidisperse particles is studied using molecular dynamics simulations. When the suspension is maintained at a constant temperature during fast drying, it can exhibit "small-on-top" stratification with an accumulation (depletion) of smaller (larger) particles in the top region of the drying film, consistent with the prediction of current theories based on diffusiophoresis. However, when only the region near the substrate is thermalized at a constant temperature, a negative temperature gradient develops in the suspension because of evaporative cooling at the liquid-vapor interface. Since the associated thermophoresis is stronger for larger nanoparticles, a higher fraction of larger nanoparticles migrate to the top of the drying film at fast evaporation rates. As a result, stratification is converted to "large-on-top". Very strong small-on-top stratification can be produced with a positive thermal gradient in the drying suspension. Here, we explore a way to produce a positive thermal gradient by thermalizing the vapor at a temperature higher than that of the solvent. Possible experimental approaches to realize various thermal gradients in a suspension undergoing solvent evaporation and thus to produce different stratification states in the drying film are suggested.
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Affiliation(s)
- Yanfei Tang
- 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
| | - 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
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31
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Liu W, Carr AJ, Yager KG, Routh AF, Bhatia SR. Sandwich layering in binary nanoparticle films and effect of size ratio on stratification behavior. J Colloid Interface Sci 2019; 538:209-217. [PMID: 30508741 DOI: 10.1016/j.jcis.2018.11.084] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 11/21/2018] [Accepted: 11/22/2018] [Indexed: 10/27/2022]
Abstract
HYPOTHESIS Stratification or self-segregation of multicomponent particle mixtures during drying is an important phenomenon to understand for the development of single-step deposition processes for complex coatings. We hypothesize that varying the ratio of particle Peclet numbers will lead to different types of stratification behavior. EXPERIMENTS Binary colloidal films of polystyrene and silica were prepared by evaporative film formation, and stratification of nanoparticles of different size ratio (7.7-1.2) was studied using microbeam small-angle X-ray scattering (SAXS). FINDINGS SAXS spectra showed noticeable variations at different film depths, consistent with stratification. These results are quantified to obtain vertical composition profiles. We observe "sandwich"-type layered structures at different nanoparticle size ratios, which to our knowledge have not been previously observed experimentally or predicted by theory. For example, for films of larger particle size ratios (7.7-4.8), large particles are enriched at the film top and bottom, leading to a large-small-large or "LSL" behavior; while within films of smaller particle size ratio (2.2-1.2), small particles are enriched at the top and bottom of the film (small-large-small or "SLS" structures). The enrichment of particles at the top persists over several hundred particle layers and is not just a single monolayer pinned to the upper surface.
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Affiliation(s)
- Weiping Liu
- Department of Chemistry, Stony Brook University, Stony Brook, NY, USA
| | - Amanda J Carr
- Department of Chemistry, Stony Brook University, Stony Brook, NY, USA
| | - Kevin G Yager
- Center for Functionalized Nanomaterials, Brookhaven National Laboratory, Upton, NY, USA
| | - Alexander F Routh
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, United Kingdom
| | - Surita R Bhatia
- Department of Chemistry, Stony Brook University, Stony Brook, NY, USA.
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32
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Limousin E, Ballard N, Asua JM. Soft core-hard shell latex particles for mechanically strong VOC-free polymer films. J Appl Polym Sci 2019. [DOI: 10.1002/app.47608] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Elodie Limousin
- POLYMAT and Departamento de Química Aplicada, Facultad de Ciencias Químicas; University of the Basque Country UPV/EHU, Joxe Mari Korta Zentroa; Tolosa Hiribidea 72, Donostia-San Sebastián 20018 Spain
| | - Nicholas Ballard
- POLYMAT and Departamento de Química Aplicada, Facultad de Ciencias Químicas; University of the Basque Country UPV/EHU, Joxe Mari Korta Zentroa; Tolosa Hiribidea 72, Donostia-San Sebastián 20018 Spain
| | - José M. Asua
- POLYMAT and Departamento de Química Aplicada, Facultad de Ciencias Químicas; University of the Basque Country UPV/EHU, Joxe Mari Korta Zentroa; Tolosa Hiribidea 72, Donostia-San Sebastián 20018 Spain
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33
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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: 51] [Impact Index Per Article: 8.5] [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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34
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Statt A, Howard MP, Panagiotopoulos AZ. Influence of hydrodynamic interactions on stratification in drying mixtures. J Chem Phys 2018; 149:024902. [DOI: 10.1063/1.5031789] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Affiliation(s)
- Antonia Statt
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Michael P. Howard
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
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35
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Tang Y, Grest GS, Cheng S. Stratification in Drying Films Containing Bidisperse Mixtures of Nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:7161-7170. [PMID: 29792029 DOI: 10.1021/acs.langmuir.8b01334] [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
Large scale molecular dynamics simulations for bidisperse nanoparticle suspensions with an explicit solvent are used to investigate the effects of evaporation rates and volume fractions on the nanoparticle distribution during drying. Our results show that "small-on-top" stratification can occur when Pe sϕ s ≳ c with c ∼ 1, where Pe s is the Péclet number and ϕ s is the volume fraction of the smaller particles. This threshold of Pe sϕ s for "small-on-top" is larger by a factor of ∼α2 than the prediction of the model treating solvent as an implicit viscous background, where α is the size ratio between the large and small particles. Our simulations further show that when the evaporation rate of the solvent is reduced, the "small-on-top" stratification can be enhanced, which is not predicted by existing theories. This unexpected behavior is explained with thermophoresis associated with a positive gradient of solvent density caused by evaporative cooling at the liquid/vapor interface. For ultrafast evaporation the gradient is large and drives the nanoparticles toward the liquid/vapor interface. This phoretic effect is stronger for larger nanoparticles, and consequently the "small-on-top" stratification becomes more distinct when the evaporation rate is slower (but not too slow such that a uniform distribution of nanoparticles in the drying film is produced), as thermophoresis that favors larger particles on the top is mitigated. A similar effect can lead to "large-on-top" stratification for Pe sϕ s above the threshold when Pe s is large but ϕ s is small. Our results reveal the importance of including the solvent explicitly when modeling evaporation-induced particle separation and organization and point to the important role of density gradients brought about by ultrafast evaporation.
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Affiliation(s)
- Yanfei Tang
- 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
| | - 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
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Cusola O, Kivistö S, Vierros S, Batys P, Ago M, Tardy BL, Greca LG, Roncero MB, Sammalkorpi M, Rojas OJ. Particulate Coatings via Evaporation-Induced Self-Assembly of Polydisperse Colloidal Lignin on Solid Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:5759-5771. [PMID: 29718673 PMCID: PMC6150720 DOI: 10.1021/acs.langmuir.8b00650] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 04/04/2018] [Indexed: 05/19/2023]
Abstract
Polydisperse smooth and spherical biocolloidal particles were suspended in aqueous media and allowed to consolidate via evaporation-induced self-assembly. The stratification of the particles at the solid-air interface was markedly influenced, but not monotonically, by the drying rate. Cross-sectional imaging via electron microscopy indicated a structured coating morphology that was distinctive from that obtained by using particles with a mono- or bimodal distribution. Segregation patterns were found to derive from the interplay of particle diffusion, interparticle forces, and settling dynamics. Supporting our experimental findings, computer simulations showed an optimal drying rate for achieving maximum segregation. Overall, stratified coatings comprising nano- and microparticles derived from lignin are expected to open opportunities for multifunctional structures that can be designed and predicted on the basis of experimental Péclet numbers and computational order.
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Affiliation(s)
- Oriol Cusola
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Department of Chemistry
and Materials Science, School of Chemical Engineering, and Department of
Applied Physics, School of Science, Aalto
University, FI-00076 Aalto, Finland
- CELBIOTECH
Research Group, Escola Superior d’Enginyeries
Industrial, Aeroespacial i Audiovisual de Terrassa, 08222 Terrassa, Spain
- E-mail: (O.C.)
| | - Samu Kivistö
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Department of Chemistry
and Materials Science, School of Chemical Engineering, and Department of
Applied Physics, School of Science, Aalto
University, FI-00076 Aalto, Finland
| | - Sampsa Vierros
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Department of Chemistry
and Materials Science, School of Chemical Engineering, and Department of
Applied Physics, School of Science, Aalto
University, FI-00076 Aalto, Finland
| | - Piotr Batys
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Department of Chemistry
and Materials Science, School of Chemical Engineering, and Department of
Applied Physics, School of Science, Aalto
University, FI-00076 Aalto, Finland
- Jerzy
Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland
| | - Mariko Ago
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Department of Chemistry
and Materials Science, School of Chemical Engineering, and Department of
Applied Physics, School of Science, Aalto
University, FI-00076 Aalto, Finland
| | - Blaise L. Tardy
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Department of Chemistry
and Materials Science, School of Chemical Engineering, and Department of
Applied Physics, School of Science, Aalto
University, FI-00076 Aalto, Finland
| | - Luiz G. Greca
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Department of Chemistry
and Materials Science, School of Chemical Engineering, and Department of
Applied Physics, School of Science, Aalto
University, FI-00076 Aalto, Finland
| | - M. Blanca Roncero
- CELBIOTECH
Research Group, Escola Superior d’Enginyeries
Industrial, Aeroespacial i Audiovisual de Terrassa, 08222 Terrassa, Spain
| | - Maria Sammalkorpi
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Department of Chemistry
and Materials Science, School of Chemical Engineering, and Department of
Applied Physics, School of Science, Aalto
University, FI-00076 Aalto, Finland
| | - Orlando J. Rojas
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Department of Chemistry
and Materials Science, School of Chemical Engineering, and Department of
Applied Physics, School of Science, Aalto
University, FI-00076 Aalto, Finland
- E-mail: (O.J.R.)
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Sear RP. Stratification of mixtures in evaporating liquid films occurs only for a range of volume fractions of the smaller component. J Chem Phys 2018; 148:134909. [DOI: 10.1063/1.5022243] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
- Richard P. Sear
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
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38
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Liu X, Liu W, Carr AJ, Santiago Vazquez D, Nykypanchuk D, Majewski PW, Routh AF, Bhatia SR. Stratification during evaporative assembly of multicomponent nanoparticle films. J Colloid Interface Sci 2018; 515:70-77. [DOI: 10.1016/j.jcis.2018.01.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 12/31/2017] [Accepted: 01/02/2018] [Indexed: 11/30/2022]
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39
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Sear RP, Warren PB. Diffusiophoresis in nonadsorbing polymer solutions: The Asakura-Oosawa model and stratification in drying films. Phys Rev E 2017; 96:062602. [PMID: 29347396 DOI: 10.1103/physreve.96.062602] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Indexed: 05/01/2023]
Abstract
A colloidal particle placed in an inhomogeneous solution of smaller nonadsorbing polymers will move towards regions of lower polymer concentration in order to reduce the free energy of the interface between the surface of the particle and the solution. This phenomenon is known as diffusiophoresis. Treating the polymer as penetrable hard spheres, as in the Asakura-Oosawa model, a simple analytic expression for the diffusiophoretic drift velocity can be obtained. In the context of drying films we show that diffusiophoresis by this mechanism can lead to stratification under easily accessible experimental conditions. By stratification we mean spontaneous formation of a layer of polymer on top of a layer of the colloid. Transposed to the case of binary colloidal mixtures, this offers an explanation for the stratification observed recently in these systems [A. Fortini et al., Phys. Rev. Lett. 116, 118301 (2016)PRLTAO0031-900710.1103/PhysRevLett.116.118301]. Our results emphasize the importance of treating solvent dynamics explicitly in these problems and caution against the neglect of hydrodynamic interactions or the use of implicit solvent models in which the absence of solvent backflow results in an unbalanced osmotic force that gives rise to large but unphysical effects.
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Affiliation(s)
- Richard P Sear
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - Patrick B Warren
- Unilever R&D Port Sunlight, Quarry Road East, Bebington, Wirral CH63 3JW, United Kingdom
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