1
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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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2
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Murdoch T, Quienne B, Argaiz M, Tomovska R, Espinosa E, D’Agosto F, Lansalot M, Pinaud J, Caillol S, Martín-Fabiani I. One Step Closer to Coatings Applications Utilizing Self-Stratification: Effect of Rheology Modifiers. ACS APPLIED POLYMER MATERIALS 2023; 5:6672-6684. [PMID: 37588086 PMCID: PMC10425952 DOI: 10.1021/acsapm.3c01288] [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: 06/15/2023] [Accepted: 07/18/2023] [Indexed: 08/18/2023]
Abstract
Self-stratification of model blends of colloidal spheres has recently been demonstrated as a method to form multifunctional coatings in a single pass. However, practical coating formulations are complex fluids with upward of 15 components. Here, we investigate the influence of three different rheology modifiers (RMs) on the stratification of a 10 wt % 7:3 w:w blend of 270 and 96 nm anionic latex particles that do not stratify without RM. However, addition of a high molar mass polysaccharide thickener, xanthan gum, raises the viscosity and corresponding Péclet number enough to achieve small-on-top stratification as demonstrated by atomic force microscopy (AFM) measurements. Importantly, this was possible due to minimal particle-rheology modifier interactions, as demonstrated by the bulk rheology. In contrast, Carbopol 940, a microgel-based RM, was unable to achieve small-on-top stratification despite a comparable increase in viscosity. Instead, pH-dependent interactions with latex particles lead to either laterally segregated structures at pH 3 or a surface enrichment of large particles at pH 8. Strong RM-particle interactions are also observed when the triblock associative RM HEUR10kC12 is used. Here, small-on-top, large-enhanced, and randomly mixed structures were observed at respectively 0.01, 0.1, and 1 wt % HEUR10kC12. Combining rheology, dynamic light scattering, and AFM results allows the mechanisms behind the nonmonotonic stratification in the presence of associative RMs to be elucidated. Our results highlight that stratification can be predicted and controlled for RMs with weak particle interactions, while a strong RM-particle interaction may afford a wider range of stratified structures. This takes a step toward successfully harnessing stratification in coatings formulations.
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Affiliation(s)
- Timothy
J. Murdoch
- Department
of Materials, Loughborough University, LE11 1RJ Loughborough, United Kingdom
| | - Baptiste Quienne
- CNRS,
ENSCM, ICGM, Univ Montpellier, 34293 Cedex 5 Montpellier, France
| | - Maialen Argaiz
- POLYMAT
and Departmento de Química Aplicada, Facultad de Ciencias Químicas, University of the Basque Country, UPV/EHU, Joxe Mari
Korta Zentroa, Tolosa
Hiribidea 72, Donostia-San Sebastian 20018, Spain
| | - Radmila Tomovska
- POLYMAT
and Departmento de Química Aplicada, Facultad de Ciencias Químicas, University of the Basque Country, UPV/EHU, Joxe Mari
Korta Zentroa, Tolosa
Hiribidea 72, Donostia-San Sebastian 20018, Spain
| | - Edgar Espinosa
- CPE
Lyon, CNRS, UMR 5128, Catalysis, Polymerization, Processes and Materials
(CP2M), Univ Lyon, Université Claude
Bernard Lyon 1, 43 Bd du 11 novembre 1918, 69616 Villeurbanne, France
| | - Franck D’Agosto
- CPE
Lyon, CNRS, UMR 5128, Catalysis, Polymerization, Processes and Materials
(CP2M), Univ Lyon, Université Claude
Bernard Lyon 1, 43 Bd du 11 novembre 1918, 69616 Villeurbanne, France
| | - Muriel Lansalot
- CPE
Lyon, CNRS, UMR 5128, Catalysis, Polymerization, Processes and Materials
(CP2M), Univ Lyon, Université Claude
Bernard Lyon 1, 43 Bd du 11 novembre 1918, 69616 Villeurbanne, France
| | - Julien Pinaud
- CNRS,
ENSCM, ICGM, Univ Montpellier, 34293 Cedex 5 Montpellier, France
| | - Sylvain Caillol
- CNRS,
ENSCM, ICGM, Univ Montpellier, 34293 Cedex 5 Montpellier, France
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3
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Argaiz M, Aguirre M, Tomovska R. Towards improved performance of waterborne polymer dispersions through creation of dense ionic interparticle network within their films. POLYMER 2023. [DOI: 10.1016/j.polymer.2022.125571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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4
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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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5
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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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6
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Singh PK, Pacholski ML, Gu J, Go YK, Singhal G, Leal C, Braun PV, Patankar KA, Drumright R, Rogers SA, Schroeder CM. Designing Multicomponent Polymer Colloids for Self-Stratifying Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:11160-11170. [PMID: 36053575 DOI: 10.1021/acs.langmuir.2c00855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Aqueous polymer colloids known as latexes are widely used in coating applications. Multicomponent latexes comprised of two incompatible polymeric species organized into a core-shell particle morphology are a promising system for self-stratifying coatings that spontaneously partition into multiple layers, thereby yielding complex structured coatings requiring only a single application step. Developing new materials for self-stratifying coatings requires a clear understanding of the thermodynamic and kinetic properties governing phase separation and polymeric species transport. In this work, we study phase separation and self-stratification in polymer films based on multicomponent acrylic (shell) and acrylic-silicone (core) latex particles. Our results show that the molecular weight of the shell polymer and heat aging conditions of the film critically determine the underlying transport phenomena, which ultimately controls phase separation in the film. Unentangled shell polymers result in efficient phase separation within hours with heat aging at reasonable temperatures, whereas entangled shell polymers effectively inhibit phase separation even under extensive heat aging conditions over a period of months due to kinetic limitations. Transmission electron microscopy is used to track morphological changes as a function of thermal aging. Interestingly, our results show that the rheological properties of the latex films are highly sensitive to morphology, and linear shear rheology is used to understand morphological changes. Overall, these results highlight the importance of bulk rheology as a simple and effective tool for understanding changes in morphology in multicomponent latex films.
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Affiliation(s)
| | | | - Junsi Gu
- The Dow Chemical Company, Collegeville, Pennsylvania 19426-2914, United States
| | | | | | | | | | | | - Ray Drumright
- The Dow Chemical Company, Midland, Michigan 48667, United States
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7
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Tinkler JD, Scacchi A, Argaiz M, Tomovska R, Archer AJ, Willcock H, Martín-Fabiani I. Effect of Particle Interactions on the Assembly of Drying Colloidal Mixtures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:5361-5371. [PMID: 35439018 PMCID: PMC9097527 DOI: 10.1021/acs.langmuir.1c03144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 03/17/2022] [Indexed: 06/14/2023]
Abstract
The effects of particle interactions on the size segregation and assembly of colloidal mixtures during drying were investigated. A cationic surfactant was added to a binary latex/silica colloidal dispersion that has been shown to self-stratify upon drying at room temperature. Atomic force microscopy was used to show that the change in particle interactions due to the presence of surfactants reduced the degree of stratification and, in some cases, suppressed the effect altogether. Colloidal dispersions containing higher surfactant concentrations can undergo a complete morphology change, resulting instead in the formation of armored particles consisting of latex particles coated with smaller silica nanoparticles. To further prove that armored particles are produced and that stratification is suppressed, cross-sectional images were produced with energy-dispersive X-ray spectroscopy and confocal fluorescence microscopy. The growth of armored particles was also measured using dynamic light scattering. To complement this research, Brownian dynamics simulations were used to model the drying. By tuning the particle interactions to make them more attractive, the simulations showed the presence of armored particles, and the size segregation process was hindered. The prevention of segregation also results in enhanced transparency of the colloidal films. Overall, this research proves that there is a link between particle interactions and size segregation in drying colloidal blends and provides a valuable tool to control the assembly of different film architectures using an extremely simple method.
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Affiliation(s)
- James D. Tinkler
- Department
of Materials, Loughborough University, Loughborough LE11 3TU, U.K.
| | - Alberto Scacchi
- Department
of Chemistry and Materials Science, Aalto
University, P.O. Box 16100, FI-00076 Aalto, Finland
- Department
of Applied Physics, Aalto University, P.O. Box 11000, FI-00076 Aalto, Finland
| | - Maialen Argaiz
- POLYMAT
and Departmento de Química Aplicada, Facultad de Ciencias Químicas, University of the Basque Country, UPV/EHU, Joxe Mari
Korta Zentroa, Tolosa Hiribidea 72, Donostia-San Sebastian 20018, Spain
| | - Radmila Tomovska
- POLYMAT
and Departmento de Química Aplicada, Facultad de Ciencias Químicas, University of the Basque Country, UPV/EHU, Joxe Mari
Korta Zentroa, Tolosa Hiribidea 72, Donostia-San Sebastian 20018, Spain
- Ikerbasque,
Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao, Spain
| | - Andrew J. Archer
- Department
of Mathematical Sciences and Interdisciplinary Centre for Mathematical
Modelling, Loughborough University, Loughborough LE11 3TU, U.K.
| | - Helen Willcock
- Department
of Materials, Loughborough University, Loughborough LE11 3TU, U.K.
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8
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The effect of pigment volume concentration on self-stratification and physico-mechanical properties of solvent-free silicone/epoxy coating systems. Polym Bull (Berl) 2022. [DOI: 10.1007/s00289-022-04138-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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9
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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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10
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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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11
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Chun B, Yoo T, Jung HW. Temporal evolution of concentration and microstructure of colloidal films during vertical drying: a lattice Boltzmann simulation study. SOFT MATTER 2020; 16:523-533. [PMID: 31807739 DOI: 10.1039/c9sm01925a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We study the temporal and structural development of colloid films during vertical drying using the lattice Boltzmann (LB) simulation. The dispersed particles moving in Brownian motion have excluded volume and hydrodynamic interactions in the film. The concentrated colloidal film formed by solvent evaporation is modeled as an uniaxial compression of colloids with a planar moving interface. The simulation studies are carried out over a wide range of Péclet number (Pe), the relative ratio between the evaporation rate and the diffusion rate of colloids. The results clearly demonstrate a temporal variation of colloid concentration as the evaporation rate increases. In the case of high Pe, the increase of colloid concentration in the top layer creates structural features that can be distinguished along the height of the film, and eventually can induce a large tensile stress in the layer. However, surprisingly, the colloids are maximally crystallized in the case of moderate Pe. The LB simulation results are further compared with those from previous studies of the Brownian Dynamics (BD) simulation and the continuum model for the evaporation film. The LB and BD results match well both at low and high Pe limits. The qualitatively significant differences between LB and BD simulations at a moderate Pe indicate that hydrodynamic interactions (HIs) play an important role in this Pe. The presence of HIs induces a greater reduction of diffusion than under geometrical restriction alone, and the effect is conspicuous when particles are driven both by diffusion and by advection.
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Affiliation(s)
- Byoungjin Chun
- Department of Chemical and Biological Engineering, Korea University, Seoul 02841, Republic of Korea.
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12
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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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13
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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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14
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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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15
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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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16
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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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17
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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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18
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Nassar M, Gromer A, Favier D, Thalmann F, Hébraud P, Holl Y. Horizontal drying fronts in films of colloidal dispersions: influence of hydrostatic pressure and collective diffusion. SOFT MATTER 2017; 13:9162-9173. [PMID: 29177309 DOI: 10.1039/c7sm01334e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The origin and time evolution of heterogeneities in drying colloidal films is still a matter of debate. In this work, we studied the behaviour of horizontal drying fronts in a 1D configuration. The effects of hydrostatic pressure and collective diffusion of charged particles, neglected so far, were introduced. We made use of the new simulation tool based on cellular automata we recently presented (Langmuir 2015 & 2017). To check the simulation results, measurements of film profiles in the wet state and drying front velocities were performed with silica colloids. It was shown that taking hydrostatic pressure into account much improves agreement between theory and experiment. On the other hand, the simulation showed that collective diffusion slows down the drying fronts, even more when the Debye length is increased. This latter effect remains to be checked experimentally. This work opens the way to further improvements of theory and simulation, notably 2D and 3D simulations.
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Affiliation(s)
- M Nassar
- CNRS-ICS & Université de Strasbourg 23, rue du Loess BP 84047 67034, Strasbourg Cedex 2, France.
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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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20
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Makepeace DK, Fortini A, Markov A, Locatelli P, Lindsay C, Moorhouse S, Lind R, Sear RP, Keddie JL. Stratification in binary colloidal polymer films: experiment and simulations. SOFT MATTER 2017; 13:6969-6980. [PMID: 28920986 DOI: 10.1039/c7sm01267e] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
UNLABELLED When films are deposited from mixtures of colloidal particles of two different sizes, a diverse range of functional structures can result. One structure of particular interest is a stratified film in which the top surface layer has a composition different than in the interior. Here, we explore the conditions under which a stratified layer of small particles develops spontaneously in a colloidal film that is cast from a binary mixture of small and large polymer particles that are suspended in water. A recent model, which considers the cross-interaction between the large and small particles (Zhou et al., Phys. Rev. Lett., 2017, 118, 108002), predicts that stratification will develop from dilute binary mixtures when the particle size ratio (α), initial volume fraction of small particles (ϕS), and Péclet number are high. In experiments and Langevin dynamics simulations, we systematically vary α and ϕS in both dilute and concentrated suspensions. We find that stratified films develop when ϕS is increased, which is in agreement with the model. In dilute suspensions, there is reasonable agreement between the experiments and the Zhou et al. MODEL In concentrated suspensions, stratification occurs in experiments only for the higher size ratio α = 7. Simulations using a high Péclet number, additionally find stratification with α = 2, when ϕS is high enough. Our results provide a quantitative understanding of the conditions under which stratified colloidal films assemble. Our research has relevance for the design of coatings with targeted optical and mechanical properties at their surface.
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Affiliation(s)
- D K Makepeace
- Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH, UK.
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21
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Schaefer C, Michels JJ, van der Schoot P. Dynamic Surface Enrichment in Drying Thin-Film Binary Polymer Solutions. Macromolecules 2017; 50:5914-5919. [PMID: 29056760 PMCID: PMC5645757 DOI: 10.1021/acs.macromol.7b01224] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Indexed: 01/27/2023]
Abstract
![]()
Solution-cast, thin-film
polymer composites find a wide range of
applications, such as in the photoactive layer of organic solar cells.
The performance of this layer crucially relies on its phase-separated
morphology. Efficient charge-carrier extraction requires each of the
components to preferentially wet one of the two electrodes. It is
often presumed that the experimentally observed surface enrichment
required for this is caused by specific interactions of the active
ingredients with each surface. By applying a generalized diffusion
model, we find the dynamics to also play an important role in determining
which component accumulates at which surface. We show that for sufficiently
fast evaporation the component with the smallest cooperative diffusivity
accumulates at the free interface. Counterintuitively, depending on
the interactions between the various components, this may be the smaller
solute. Our comprehensive numerical and analytical study provides
a tool to predict and control phase-separated morphologies in thin-film
polymer composites.
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Affiliation(s)
- C Schaefer
- Dutch Polymer Institute, P.O. Box 902, 5600 AX Eindhoven, The Netherlands.,Theory of Polymers and Soft Matter, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.,Simbeyond B.V., Groene Loper 19, 5612 AE Eindhoven, The Netherlands
| | - J J Michels
- Max Planck Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany
| | - P van der Schoot
- Theory of Polymers and Soft Matter, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.,Institute for Theoretical Physics, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
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22
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Fortini A, Sear RP. Stratification and Size Segregation of Ternary and Polydisperse Colloidal Suspensions during Drying. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:4796-4805. [PMID: 28423894 DOI: 10.1021/acs.langmuir.7b00946] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We investigate the drying process of three-component and polydisperse colloidal suspensions using Brownian dynamics simulations. We have previously reported (Phys. Rev. Lett. 2016, 116, 118301) on the drying of binary mixtures. For binary mixtures, we found that a gradient of colloidal osmotic pressure develops during drying and that this leads to the final film being stratified with a layer of smaller particles on top of a layer of larger particles. Here, we find that stratification by size is very general and also occurs in ternary and polydisperse mixtures. We name the segregation effect colloidal diffusiophoresis. In particular, we show that by changing the composition of a ternary mixture, different stratification morphologies can be achieved and hence the film properties can be tuned. In polydisperse spheres, colloidal diffusiophoresis leads to enrichment in the large particles at the bottom part of the film, whereas the top part is enriched with smaller particles. This segregation means that in the final film, the particle size distribution depends on height. Thus, the properties of the film will then depend on height. We propose a model that predicts a power-law dependence of the phoretic velocity on particle size. Results from the model and simulation show a good agreement.
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Affiliation(s)
- Andrea Fortini
- Department of Physics, University of Surrey , Guildford GU2 7XH, United Kingdom
| | - Richard P Sear
- Department of Physics, University of Surrey , Guildford GU2 7XH, United Kingdom
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23
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Howard MP, Nikoubashman A, Panagiotopoulos AZ. Stratification Dynamics in Drying Colloidal Mixtures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:3685-3693. [PMID: 28349690 DOI: 10.1021/acs.langmuir.7b00543] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Stratification in binary colloidal mixtures was investigated using implicit-solvent molecular dynamics simulations. For large particle size ratios and film Péclet numbers greater than unity, smaller colloids migrated to the top of the film, while big colloids were pushed to the bottom, creating an "inverted" stratification. This peculiar behavior was observed in recent simulations and experiments conducted by Fortini et al. [ Phys. Rev. Lett. 2016 , 116 , 118301 ]. To rationalize this behavior, particle size ratios and drying rates spanning qualitatively different Péclet number regimes were systematically studied, and the dynamics of the inverted stratification were quantified in detail. The stratified layer of small colloids was found to grow faster and to larger thicknesses for larger size ratios. Interestingly, inverted stratification was observed even at moderate drying rates where the film Péclet numbers were comparable to unity, but the thickness of the stratified layer decreased. A model based on dynamical density functional theory is proposed to explain the observed phenomena.
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Affiliation(s)
- Michael P Howard
- Department of Chemical and Biological Engineering, Princeton University , Princeton, New Jersey 08544, United States
| | - Arash Nikoubashman
- Institute of Physics, Johannes Gutenberg University Mainz , Staudingerweg 7, 55128 Mainz, Germany
| | - Athanassios Z Panagiotopoulos
- Department of Chemical and Biological Engineering, Princeton University , Princeton, New Jersey 08544, United States
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24
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Martín-Fabiani I, Fortini A, Lesage de la Haye J, Koh ML, Taylor SE, Bourgeat-Lami E, Lansalot M, D'Agosto F, Sear RP, Keddie JL. pH-Switchable Stratification of Colloidal Coatings: Surfaces "On Demand". ACS APPLIED MATERIALS & INTERFACES 2016; 8:34755-34761. [PMID: 27936562 DOI: 10.1021/acsami.6b12015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Stratified coatings are used to provide properties at a surface, such as hardness or refractive index, which are different from underlying layers. Although time-savings are offered by self-assembly approaches, there have been no methods yet reported to offer stratification on demand. Here, we demonstrate a strategy to create self-assembled stratified coatings, which can be switched to homogeneous structures when required. We use blends of large and small colloidal polymer particle dispersions in water that self-assemble during drying because of an osmotic pressure gradient that leads to a downward velocity of larger particles. Our confocal fluorescent microscopy images reveal a distinct surface layer created by the small particles. When the pH of the initial dispersion is raised, the hydrophilic shells of the small particles swell substantially, and the stratification is switched off. Brownian dynamics simulations explain the suppression of stratification when the small particles are swollen as a result of reduced particle mobility, a drop in the pressure gradient, and less time available before particle jamming. Our strategy paves the way for applications in antireflection films and protective coatings in which the required surface composition can be achieved on demand, simply by adjusting the pH prior to deposition.
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Affiliation(s)
- Ignacio Martín-Fabiani
- Department of Physics, University of Surrey , Guildford, Surrey GU2 7XH, United Kingdom
- Department of Materials, Loughborough University , Loughborough, Leicestershire, LE11 3TU, United Kingdom
| | - Andrea Fortini
- Department of Physics, University of Surrey , Guildford, Surrey GU2 7XH, United Kingdom
| | - Jennifer Lesage de la Haye
- Univ Lyon, Université Claude Bernard Lyon 1 , CPE Lyon, CNRS, UMR 5265, Chemistry, Catalysis, Polymers and Processes (C2P2), 43 Bd du 11 Novembre 1918, 69616 Villeurbanne, France
| | - Ming Liang Koh
- Univ Lyon, Université Claude Bernard Lyon 1 , CPE Lyon, CNRS, UMR 5265, Chemistry, Catalysis, Polymers and Processes (C2P2), 43 Bd du 11 Novembre 1918, 69616 Villeurbanne, France
| | - Spencer E Taylor
- Centre for Petroleum and Surface Chemistry, Department of Chemistry, University of Surrey , Guildford, Surrey GU2 7XH, United Kingdom
| | - Elodie Bourgeat-Lami
- Univ Lyon, Université Claude Bernard Lyon 1 , CPE Lyon, CNRS, UMR 5265, Chemistry, Catalysis, Polymers and Processes (C2P2), 43 Bd du 11 Novembre 1918, 69616 Villeurbanne, France
| | - Muriel Lansalot
- Univ Lyon, Université Claude Bernard Lyon 1 , CPE Lyon, CNRS, UMR 5265, Chemistry, Catalysis, Polymers and Processes (C2P2), 43 Bd du 11 Novembre 1918, 69616 Villeurbanne, France
| | - Franck D'Agosto
- Univ Lyon, Université Claude Bernard Lyon 1 , CPE Lyon, CNRS, UMR 5265, Chemistry, Catalysis, Polymers and Processes (C2P2), 43 Bd du 11 Novembre 1918, 69616 Villeurbanne, France
| | - 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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25
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Remarkable red-shift in absorption and emission of linear BODIPY oligomers containing thiophene linkers. Tetrahedron Lett 2016. [DOI: 10.1016/j.tetlet.2016.03.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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26
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Fortini A, Martín-Fabiani I, De La Haye JL, Dugas PY, Lansalot M, D'Agosto F, Bourgeat-Lami E, Keddie JL, Sear RP. Dynamic Stratification in Drying Films of Colloidal Mixtures. PHYSICAL REVIEW LETTERS 2016; 116:118301. [PMID: 27035324 DOI: 10.1103/physrevlett.116.118301] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Indexed: 05/27/2023]
Abstract
In simulations and experiments, we study the drying of films containing mixtures of large and small colloidal particles in water. During drying, the mixture stratifies into a layer of the larger particles at the bottom with a layer of the smaller particles on top. We developed a model to show that a gradient in osmotic pressure, which develops dynamically during drying, is responsible for the segregation mechanism behind stratification.
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Affiliation(s)
- Andrea Fortini
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, Universitätsstraße 30, D-95447 Bayreuth, Germany
| | | | - Jennifer Lesage De La Haye
- Laboratoire de Chimie, Catalyse, Polymères et Procédés, Université Claude Bernard Lyon 1, 69616 Villeurbanne cedex, France
| | - Pierre-Yves Dugas
- Laboratoire de Chimie, Catalyse, Polymères et Procédés, Université Claude Bernard Lyon 1, 69616 Villeurbanne cedex, France
| | - Muriel Lansalot
- Laboratoire de Chimie, Catalyse, Polymères et Procédés, Université Claude Bernard Lyon 1, 69616 Villeurbanne cedex, France
| | - Franck D'Agosto
- Laboratoire de Chimie, Catalyse, Polymères et Procédés, Université Claude Bernard Lyon 1, 69616 Villeurbanne cedex, France
| | - Elodie Bourgeat-Lami
- Laboratoire de Chimie, Catalyse, Polymères et Procédés, Université Claude Bernard Lyon 1, 69616 Villeurbanne cedex, France
| | - Joseph L Keddie
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
| | - Richard P Sear
- Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
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27
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Noguera-Marín D, Moraila-Martínez CL, Cabrerizo-Vílchez M, Rodríguez-Valverde MA. Impact of the collective diffusion of charged nanoparticles in the convective/capillary deposition directed by receding contact lines. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2016; 39:20. [PMID: 26920523 DOI: 10.1140/epje/i2016-16020-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 01/14/2016] [Indexed: 06/05/2023]
Abstract
The motion of electrically charged particles under crowding conditions and subjected to evaporation-driven capillary flow might be ruled by collective diffusion. The concentration gradient developed inside an evaporating drop of colloidal suspension may reduce by diffusion the number of particles transported toward the contact line by convection. Unlike self-diffusion coefficient, the cooperative diffusion coefficient of interacting particles becomes more pronounced in crowded environments. In this work, we examined experimentally the role of the collective diffusion of charge-stabilized nanoparticles in colloidal patterning. To decouple the sustained evaporation from the contact line motion, we conducted evaporating menisci experiments with driven receding contact lines at low capillary number. This allowed us to explore convective assembly at fixed and low bulk concentration, which enabled to develop high concentration gradients. At fixed velocity of receding contact line, we explored a variety of substrate-particle systems where the particle-particle electrostatic interaction was changed (via p H) as well as the substrate receding contact angle and the relative humidity. We found that the particle deposition directed by receding contact lines may be controlled by the interplay between evaporative convection and collective diffusion, particularly at low particle concentration.
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Affiliation(s)
- Diego Noguera-Marín
- Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, E-18071, Granada, Spain
| | | | - Miguel Cabrerizo-Vílchez
- Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, E-18071, Granada, Spain
| | - Miguel Angel Rodríguez-Valverde
- Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, E-18071, Granada, Spain.
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28
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Beer V, Koynov K, Steffen W, Landfester K, Musyanovych A. Polylactide-Based Nanoparticles with Tailor-Made Functionalization. MACROMOL CHEM PHYS 2015. [DOI: 10.1002/macp.201500153] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Veronika Beer
- Max Planck Institute for Polymer Research; Ackermannweg 10 55128 Mainz Germany
| | - Kaloian Koynov
- Max Planck Institute for Polymer Research; Ackermannweg 10 55128 Mainz Germany
| | - Werner Steffen
- Max Planck Institute for Polymer Research; Ackermannweg 10 55128 Mainz Germany
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29
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Noguera-Marín D, Moraila-Martínez CL, Cabrerizo-Vílchez MA, Rodríguez-Valverde MA. Particle Segregation at Contact Lines of Evaporating Colloidal Drops: Influence of the Substrate Wettability and Particle Charge-Mass Ratio. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:6632-6638. [PMID: 26000909 DOI: 10.1021/acs.langmuir.5b01062] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Segregation of particles during capillary/convective self-assembly is interesting for self-stratification in colloidal deposits. In evaporating drops containing colloidal particles, the wettability properties of substrate and the sedimentation of particles can affect their accumulation at contact lines. In this work we studied the size segregation and discrimination of charged particles with different densities. We performed in-plane particle counting at evaporating triple lines by using fluorescence confocal microscopy. We studied separately substrates with very different wettability properties and particles with different charge-mass ratios at low ionic strength. We used binary colloidal suspensions to compare simultaneously the deposition of two different particles. The particle deposition rate strongly depends on the receding contact angle of the substrate. We further observed a singular behavior of charged polystyrene particles in binary mixtures under "salt-free" conditions explained by the "colloidal Brazil nut" effect.
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Affiliation(s)
- Diego Noguera-Marín
- Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, E-18071 Granada, Spain
| | - Carmen L Moraila-Martínez
- Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, E-18071 Granada, Spain
| | - Miguel A Cabrerizo-Vílchez
- Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, E-18071 Granada, Spain
| | - Miguel A Rodríguez-Valverde
- Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, E-18071 Granada, Spain
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30
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Ghosh UU, Chakraborty M, Bhandari AB, Chakraborty S, DasGupta S. Effect of Surface Wettability on Crack Dynamics and Morphology of Colloidal Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:6001-6010. [PMID: 25973978 DOI: 10.1021/acs.langmuir.5b00690] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The effect of surface wettability on the dynamics of crack formation and their characteristics are examined during the drying of aqueous colloidal droplets (1 μL volume) containing nanoparticles (53 nm mean particle diameter, 1 w/w %). Thin colloidal films, formed during drying, rupture as a result of the evaporation-induced capillary pressure and exhibit microscopic cracks. The crack initiation and propagation velocity as well as the number of cracks are experimentally evaluated for substrates of varying wettability and correlated to their wetting nature. Atomic force and scanning electron microscopy are used to examine the region in the proximity of the crack including the particle arrangements near the fracture zone. The altered substrate-particle Derjaguin-Landau-Verwey-Overbeek (DLVO) interactions, as a consequence of the changed wettability, are theoretically evaluated and found to be consistent with the experimental observations. The resistance of the film to cracking is found to depend significantly on the substrate surface energy and quantified by the critical stress intensity factor, evaluated by analyzing images obtained from confocal microscopy. The results indicate the possibility of controlling crack dynamics and morphology by tuning the substrate wettability.
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Affiliation(s)
- Udita Uday Ghosh
- †Department of Chemical Engineering and ‡Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur 721302, India
| | - Monojit Chakraborty
- †Department of Chemical Engineering and ‡Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur 721302, India
| | - Aditya Bikram Bhandari
- †Department of Chemical Engineering and ‡Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur 721302, India
| | - Suman Chakraborty
- †Department of Chemical Engineering and ‡Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur 721302, India
| | - Sunando DasGupta
- †Department of Chemical Engineering and ‡Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur 721302, India
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31
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Noguera-Marín D, Moraila-Martínez CL, Cabrerizo-Vílchez MA, Rodríguez-Valverde MA. In-plane particle counting at contact lines of evaporating colloidal drops: effect of the particle electric charge. SOFT MATTER 2015; 11:987-993. [PMID: 25520154 DOI: 10.1039/c4sm02693d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Complete understanding of colloidal assembly is still a goal to be reached. In convective assembly deposition, the concentration gradients developed in evaporating drops or reservoirs are usually significant. However, collective diffusion of charge-stabilized particles has been barely explored. The balance between convective and diffusive flows may dictate the particle dynamics inside evaporating colloidal drops. In this work we performed in situ counting of fluorescent particles in the vicinity of the triple line of evaporating sessile drops by using confocal laser scanning microscopy. We used particles of different sizes, with different charge response over the pH scale and we focused on charged and nearly uncharged particles. Two substrates with different receding contact angles were used. Binary colloidal mixtures were used to illustrate simultaneously the accumulation of particles with two different charge states at the triple line. The deposition rate close to the triple line was different depending on the electric state of the particle, regardless of the substrate used.
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Affiliation(s)
- Diego Noguera-Marín
- Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, E-18071 Granada, Spain.
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32
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Hofmann D, Tenzer S, Bannwarth MB, Messerschmidt C, Glaser SF, Schild H, Landfester K, Mailänder V. Mass spectrometry and imaging analysis of nanoparticle-containing vesicles provide a mechanistic insight into cellular trafficking. ACS NANO 2014; 8:10077-10088. [PMID: 25244389 DOI: 10.1021/nn502754c] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Rational design of nanocarriers for drug delivery approaches requires an unbiased knowledge of uptake mechanisms and intracellular trafficking pathways. Here we dissected these processes using a quantitative proteomics approach. We isolated intracellular vesicles containing superparamagnetic iron oxide polystyrene nanoparticles and analyzed their protein composition by label-free quantitative mass spectrometry. The proteomic snapshot of organelle marker proteins revealed that an atypical macropinocytic-like mechanism mediated the entry of nanoparticles. We show that the entry mechanism is controlled by actin reorganization, atypical macropinocytic signaling, and ADP-ribosylation factor 1. Additionally, our proteomics data demonstrated a central role for multivesicular bodies and multilamellar lysosomes in trafficking and final nanoparticle storage. This was confirmed by confocal microscopy and cryo-TEM measurements. By quantitatively analyzing the protein composition of nanoparticle-containing vesicles, our study clearly defines the routes of nanoparticle entry, intracellular trafficking, and the proteomic milieu of a nanoparticle-containing vesicle.
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Affiliation(s)
- Daniel Hofmann
- Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany
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33
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Staff RH, Schaeffel D, Turshatov A, Donadio D, Butt HJ, Landfester K, Koynov K, Crespy D. Particle formation in the emulsion-solvent evaporation process. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2013; 9:3514-3522. [PMID: 23606602 DOI: 10.1002/smll.201300372] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2013] [Revised: 03/06/2013] [Indexed: 06/02/2023]
Abstract
The mechanism of particle formation from submicrometer emulsion droplets by solvent evaporation is revisited. A combination of dynamic light scattering, fluorescence resonance energy transfer, zeta potential measurements, and fluorescence cross-correlation spectroscopy is used to analyze the colloids during the evaporation process. It is shown that a combination of different methods yields reliable and quantitative data for describing the fate of the droplets during the process. The results indicate that coalescence plays a minor role during the process; the relatively large size distribution of the obtained polymer colloids can be explained by the droplet distribution after their formation.
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Affiliation(s)
- Roland H Staff
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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Lim S, Ahn KH, Yamamura M. Latex migration in battery slurries during drying. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:8233-8244. [PMID: 23745604 DOI: 10.1021/la4013685] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We used real-time fluorescence microscopy to investigate the migration of latex particles in drying battery slurries. The time evolution of the fluorescence signals revealed that the migration of the latex particles was suppressed above the entanglement concentration of carboxymethyl cellulose (CMC), while it was significantly enhanced when CMC fully covered the surfaces of the graphite particles. In particular, a two-step migration was observed when the graphite particles flocculated by depletion attraction at high CMC/graphite mass ratios. The transient states of the nonadsorbing CMC and graphite particles in a medium were discussed, and the uses of this novel measurement technique to monitor the complex drying processes of films were demonstrated.
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Affiliation(s)
- Sanghyuk Lim
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul 151-744, Korea
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35
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Routh AF. Drying of thin colloidal films. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2013; 76:046603. [PMID: 23502077 DOI: 10.1088/0034-4885/76/4/046603] [Citation(s) in RCA: 223] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
When thin films of colloidal fluids are dried, a range of transitions are observed and the final film profile is found to depend on the processes that occur during the drying step. This article describes the drying process, initially concentrating on the various transitions. Particles are seen to initially consolidate at the edge of a drying droplet, the so-called coffee-ring effect. Flow is seen to be from the centre of the drop towards the edge and a front of close-packed particles passes horizontally across the film. Just behind the particle front the now solid film often displays cracks and finally the film is observed to de-wet. These various transitions are explained, with particular reference to the capillary pressure which forms in the solidified region of the film. The reasons for cracking in thin films is explored as well as various methods to minimize its effect. Methods to obtain stratified coatings through a single application are considered for a one-dimensional drying problem and this is then extended to two-dimensional films. Different evaporative models are described, including the physical reason for enhanced evaporation at the edge of droplets. The various scenarios when evaporation is found to be uniform across a drying film are then explained. Finally different experimental techniques for examining the drying step are mentioned and the article ends with suggested areas that warrant further study.
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Affiliation(s)
- Alexander F Routh
- BP Institute and Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, UK.
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36
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Gurney RS, Dupin D, Nunes JS, Ouzineb K, Siband E, Asua JM, Armes SP, Keddie JL. Switching off the tackiness of a nanocomposite adhesive in 30 s via infrared sintering. ACS APPLIED MATERIALS & INTERFACES 2012; 4:5442-5452. [PMID: 22974179 DOI: 10.1021/am3013642] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Soft adhesives require an optimum balance of viscous and elastic properties. Adhesion is poor when the material is either too solidlike or too liquidlike. The ability to switch tack adhesion off at a desired time has many applications, such as in recycling, disassembly of electronics, and painless removal of wound dressings. Here, we describe a new strategy to switch off the tack adhesion in a model nanocomposite adhesive in which temperature is the trigger. The nanocomposite comprises hard methacrylic nanoparticles blended with a colloidal dispersion of soft copolymer particles. At relatively low volume fractions, the nanoparticles (50 nm diameter) accumulate near the film surface, where they pack around the larger soft particles (270 nm). The viscoelasticity of the nanocomposite is adjusted via the nanoparticle concentration. When the nanocomposite is heated above the glass transition temperature of the nanoparticles (T(g) = 130 °C), they sinter together to create a rigid network that raises the elastic modulus at room temperature. The tackiness is switched off. Intense infrared radiation is used to heat the nanocomposites, leading to a fast temperature rise. Tack adhesion is switched off within 30 s in optimized compositions. These one-way switchable adhesives have the potential to be patterned through localized heating.
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Affiliation(s)
- Robert S Gurney
- Department of Physics, University of Surrey, Guildford, Surrey, GU2 7XH, United Kingdom
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37
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Florez L, Herrmann C, Cramer JM, Hauser CP, Koynov K, Landfester K, Crespy D, Mailänder V. How shape influences uptake: interactions of anisotropic polymer nanoparticles and human mesenchymal stem cells. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:2222-30. [PMID: 22528663 DOI: 10.1002/smll.201102002] [Citation(s) in RCA: 156] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 01/09/2012] [Indexed: 05/21/2023]
Abstract
Among several nanoparticle properties, shape is important for their interaction with cells and, therefore, relevant for uptake studies and applications. In order to further investigate such characteristics, fluorescently labeled spherical polymer nanoparticles are synthesized by free-radical polymerization via the miniemulsion process. The spherical nanoparticles are subsequently submitted to controlled mechanical deformation to yield quasi-ellipsoidal polymeric nanoparticles with different aspect ratios. The uptake behaviors of spherical and non-spherical particles with equal volume are investigated qualitatively and quantitatively by electron microscopy, confocal laser scanning microscopy, and flow cytometry measurements. Non-spherical particles show fewer uptake by cells than their spherical counterparts with a negative correlation between aspect ratio and uptake rate. This is attributed to the larger average curvature radius of adsorbed non-spherical particles experienced by the cells.
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Affiliation(s)
- Laura Florez
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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38
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Trueman R, Lago Domingues E, Emmett S, Murray M, Routh A. Auto-stratification in drying colloidal dispersions: A diffusive model. J Colloid Interface Sci 2012; 377:207-12. [DOI: 10.1016/j.jcis.2012.03.045] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 03/14/2012] [Accepted: 03/15/2012] [Indexed: 10/28/2022]
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39
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Sauer R, Turshatov A, Baluschev S, Landfester K. One-Pot Production of Fluorescent Surface-Labeled Polymeric Nanoparticles via Miniemulsion Polymerization with Bodipy Surfmers. Macromolecules 2012. [DOI: 10.1021/ma300090a] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rüdiger Sauer
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz,
Germany
| | - Andrey Turshatov
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz,
Germany
| | - Stanislav Baluschev
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz,
Germany
- Optics and Spectroscopy
Department,
Faculty of Physics, Sofia University “St. Kliment Ochridski”, 5 James Bourchier, 1164 Sofia, Bulgaria
| | - Katharina Landfester
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz,
Germany
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40
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41
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Trueman RE, Lago Domingues E, Emmett SN, Murray MW, Keddie JL, Routh AF. Autostratification in drying colloidal dispersions: experimental investigations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:3420-3428. [PMID: 22257386 DOI: 10.1021/la203975b] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In films cast from a colloidal dispersion comprising two particle sizes, we experimentally examine the distribution of particles normal to the substrate. The particle concentrations at various positions in the film are determined through atomic force microscopy and NMR profiling. The results are compared to a previously derived diffusional model. Evidence for diffusional driven stratification is found, but the importance of other flows is also highlighted. The conditions that enhance particle stratification are found to be a colloidally stable dispersion, low initial volume fractions, a low concentration of the stratifying particle, and for the Peclet numbers of the two components to straddle unity.
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Affiliation(s)
- R E Trueman
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, United Kingdom
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42
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Atmuri AK, Bhatia SR, Routh AF. Autostratification in drying colloidal dispersions: effect of particle interactions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:2652-2658. [PMID: 22204277 DOI: 10.1021/la2039762] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
When particles differing in size or charge are mixed and cast, vertical segregation is an inevitable phenomenon in the produced films. Apart from the Peclet number, which is the ratio of evaporation to diffusion rates, particle interactions play a crucial role in determining the distribution of particles in the dried films. Trueman et al. (1) developed a model for vertical segregation of particles during drying. Their numerical solution assumed that the chemical potentials were determined entirely by entropy. We report the effect of particle interactions in various systems: (i) charged particles with different Peclet numbers and (ii) charged particles with the same Peclet numbers. An experimental study has also been carried out for particles with Peclet numbers straddling unity; the experimental results conform with the behavior predicted theoretically.
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Affiliation(s)
- Anand K Atmuri
- Department of Chemical Engineering & Biotechnology and BP Institute, University of Cambridge, Madingley Rise, Cambridge CB3 0EZ, United Kingdom
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43
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Hu L, Zhang C, Hu Y, Chen Y, Chen W. Effect of annealing on self-organized gradient film obtained from poly(3-[tris(trimethylsilyloxy)silyl] propyl methacrylate-co-methyl methacrylate)/poly(methyl methacrylate-co-n-butyl acrylate) blend latexes. Colloid Polym Sci 2012. [DOI: 10.1007/s00396-011-2582-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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44
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Liu Z, Zhao Y, Zhou J, Yuan X. Synthesis and characterization of core–shell polyacrylate latex containing fluorine/silicone in the shell and the self-stratification film. Colloid Polym Sci 2011. [DOI: 10.1007/s00396-011-2537-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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45
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Friedemann K, Turshatov A, Landfester K, Crespy D. Characterization via two-color STED microscopy of nanostructured materials synthesized by colloid electrospinning. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:7132-7139. [PMID: 21561104 DOI: 10.1021/la104817r] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A model system for multicompartment nanofibers was fabricated by colloid electrospinning. The obtained nanostructured material consisted of fluorescent polymer nanoparticles that were synthesized in a miniemulsion and then embedded in fluorescently labeled polymer nanofibers. Because of the absence of contrast between both polymers, the immobilized nanoparticles cannot be reliably identified in the nanofibers via electron microscopy or other techniques. Here, we describe investigations on the hybrid material with two-color STED microscopy to localize the nanoparticles and to quantify their distribution along nanofibers with particle and fiber radii down to 50 nm.
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Affiliation(s)
- Kathrin Friedemann
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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46
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Russel WB. Mechanics of drying colloidal dispersions: Fluid/solid transitions, skinning, crystallization, cracking, and peeling. AIChE J 2011. [DOI: 10.1002/aic.12651] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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