1
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Klockars KW, Greca LG, Majoinen J, Mihhels K, Rojas OJ, Tardy BL. Drying stresses in cellulose nanocrystal coatings: Impact of molecular and macromolecular additives. Carbohydr Polym 2023; 303:120465. [PMID: 36657848 DOI: 10.1016/j.carbpol.2022.120465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 12/07/2022] [Accepted: 12/10/2022] [Indexed: 12/23/2022]
Abstract
The industrial implementation of cellulose nanocrystals (CNCs) in films and coatings requires thorough evaluation of the internal stresses post-consolidation, as they cause fracturing and peeling. Characterizing the impact of plasticizing additives on stress is therefore critical. Herein, we use the deflection of thin glass substrates to measure drying stresses in consolidating CNC films, and benchmark the impact of five additives (glucose, glycerol, poly(ethylene glycol) (PEG), poly(vinyl alcohol) (PVA) and bovine serum albumin). Glycerol and PEG reduced drying stresses effectively, while PEG of increased molecular weight (from 0.2 to 10 kDa), PVA, and BSA were less effective. We analyzed the temporal aspects of the process, where stress relaxation of up to 30 % was observed 2 years after coating formation. Finally, we provide a framework to evaluate the impact of CNC morphology on residual stresses. The introduced approach is expected to fast-track the optimization and implementation of coatings based on biocolloids.
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Affiliation(s)
- Konrad W Klockars
- Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, FI-00076 Aalto, Finland
| | - Luiz G Greca
- Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, FI-00076 Aalto, Finland
| | - Johanna Majoinen
- Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, FI-00076 Aalto, Finland
| | - Karl Mihhels
- Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, FI-00076 Aalto, Finland
| | - Orlando J Rojas
- Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, FI-00076 Aalto, Finland; Bioproducts Institute, Department of Chemical and Biological Engineering, Department of Chemistry and Department of Wood Science, University of British Columbia, 2360 East Mall, Vancouver, BC V6T 1Z4, Canada.
| | - Blaise L Tardy
- Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, FI-00076 Aalto, Finland; Department of Chemical Engineering, Khalifa University, Abu Dhabi, United Arab Emirates.
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2
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Halahlah A, Piironen V, Mikkonen KS, Ho TM. Polysaccharides as wall materials in spray-dried microencapsulation of bioactive compounds: Physicochemical properties and characterization. Crit Rev Food Sci Nutr 2022; 63:6983-7015. [PMID: 35213281 DOI: 10.1080/10408398.2022.2038080] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Natural bioactive compounds (BCs) are types of chemicals found in plants and certain foods that promote good health, however they are sensitive to processing and environmental conditions. Microencapsulation by spray drying is a widely used and cost-effective approach to create a coating layer to surround and protect BCs and control their release, enabling the production of high functional products/ingredients with extended shelf life. In this process, wall materials determine protection efficiency, and physical properties, bioavailability, and storage stability of microencapsulated products. Therefore, an understanding of physicochemical properties of wall materials is essential for the successful and effective spray-dried microencapsulation process. Typically, polysaccharide-based wall materials are generated from more sustainable sources and have a wider range of physicochemical properties and applications compared to their protein-based counterparts. In this review, we highlight the essential physicochemical properties of polysaccharide-based wall materials for spray-dried microencapsulation of BCs including solubility, thermal stability, and emulsifying properties, rheological and film forming properties. We provide further insight into possibilities for the chemical structure modification of native wall materials and their controlled release behaviors. Finally, we summarize the most recent studies involving polysaccharide biopolymers as wall materials and/or emulsifiers in spray-dried microencapsulation of BCs.
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Affiliation(s)
| | - Vieno Piironen
- Department of Food and Nutrition, University of Helsinki, Finland
| | - Kirsi S Mikkonen
- Department of Food and Nutrition, University of Helsinki, Finland
- Helsinki Institute of Sustainability Science (HELSUS), University of Helsinki, Finland
| | - Thao M Ho
- Department of Food and Nutrition, University of Helsinki, Finland
- Helsinki Institute of Sustainability Science (HELSUS), University of Helsinki, Finland
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3
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Tardy BL, Mattos BD, Otoni CG, Beaumont M, Majoinen J, Kämäräinen T, Rojas OJ. Deconstruction and Reassembly of Renewable Polymers and Biocolloids into Next Generation Structured Materials. Chem Rev 2021; 121:14088-14188. [PMID: 34415732 PMCID: PMC8630709 DOI: 10.1021/acs.chemrev.0c01333] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Indexed: 12/12/2022]
Abstract
This review considers the most recent developments in supramolecular and supraparticle structures obtained from natural, renewable biopolymers as well as their disassembly and reassembly into engineered materials. We introduce the main interactions that control bottom-up synthesis and top-down design at different length scales, highlighting the promise of natural biopolymers and associated building blocks. The latter have become main actors in the recent surge of the scientific and patent literature related to the subject. Such developments make prominent use of multicomponent and hierarchical polymeric assemblies and structures that contain polysaccharides (cellulose, chitin, and others), polyphenols (lignins, tannins), and proteins (soy, whey, silk, and other proteins). We offer a comprehensive discussion about the interactions that exist in their native architectures (including multicomponent and composite forms), the chemical modification of polysaccharides and their deconstruction into high axial aspect nanofibers and nanorods. We reflect on the availability and suitability of the latter types of building blocks to enable superstructures and colloidal associations. As far as processing, we describe the most relevant transitions, from the solution to the gel state and the routes that can be used to arrive to consolidated materials with prescribed properties. We highlight the implementation of supramolecular and superstructures in different technological fields that exploit the synergies exhibited by renewable polymers and biocolloids integrated in structured materials.
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Affiliation(s)
- Blaise L. Tardy
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, P.O. Box 16300, FI-00076 Aalto, Finland
| | - Bruno D. Mattos
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, P.O. Box 16300, FI-00076 Aalto, Finland
| | - Caio G. Otoni
- Department
of Physical Chemistry, Institute of Chemistry, University of Campinas, P.O. Box 6154, Campinas, São Paulo 13083-970, Brazil
- Department
of Materials Engineering, Federal University
of São Carlos, Rod. Washington Luís, km 235, São
Carlos, São Paulo 13565-905, Brazil
| | - Marco Beaumont
- School
of Chemistry and Physics, Queensland University
of Technology, 2 George
Street, Brisbane, Queensland 4001, Australia
- Department
of Chemistry, Institute of Chemistry of Renewable Resources, University of Natural Resources and Life Sciences, Vienna, A-3430 Tulln, Austria
| | - Johanna Majoinen
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, P.O. Box 16300, FI-00076 Aalto, Finland
| | - Tero Kämäräinen
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, P.O. Box 16300, FI-00076 Aalto, Finland
| | - Orlando J. Rojas
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, P.O. Box 16300, FI-00076 Aalto, Finland
- Bioproducts
Institute, Department of Chemical and Biological Engineering, Department
of Chemistry and Department of Wood Science, University of British Columbia, 2360 East Mall, Vancouver, British Columbia V6T 1Z4, Canada
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4
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Fischer SB, Koos E. Using an added liquid to suppress drying defects in hard particle coatings. J Colloid Interface Sci 2021; 582:1231-1242. [PMID: 32950839 DOI: 10.1016/j.jcis.2020.08.055] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 08/13/2020] [Accepted: 08/14/2020] [Indexed: 10/23/2022]
Abstract
HYPOTHESIS Lateral accumulation and film defects during drying of hard particle coatings is a common problem, typically solved using polymeric additives and surface active ingredients, which require further processing of the dried film. Capillary suspensions with their tunable physical properties, devoid of polymers, offer new pathways in producing uniform and defect free particulate coatings. EXPERIMENTS We investigated the effect of small amounts of secondary liquid on the coating's drying behavior. Stress build-up and weight loss in a temperature and humidity controlled drying chamber were simultaneously measured. Changes in the coating's reflectance and height profile over time were related with the weight loss and stress curve. FINDINGS Capillary suspensions dry uniformly without defects. Lateral drying is inhibited by the high yield stress, causing the coating to shrink to an even height. The bridges between particles prevent air invasion and extend the constant drying period. The liquid in the lower layers is transported to the interface via corner flow within surface pores, leading to a partially dry layer near the substrate while the pores above are still saturated. Using capillary suspensions for hard particle coatings results in more uniform, defect free films with better printing characteristics, rendering high additive content obsolete.
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Affiliation(s)
- Steffen B Fischer
- KU Leuven, Soft Matter, Rheology and Technology, Department of Chemical Engineering, Celestijnenlaan 200f, 3001 Leuven, Belgium; Karlsruhe Institute of Technology, Institute for Mechanical Process Engineering and Mechanics, Karlsruhe, Germany
| | - Erin Koos
- KU Leuven, Soft Matter, Rheology and Technology, Department of Chemical Engineering, Celestijnenlaan 200f, 3001 Leuven, Belgium.
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5
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Franks GV, Sesso ML, Lam M, Lu Y, Xu L. Elastic plastic fracture mechanics investigation of toughness of wet colloidal particulate materials: Influence of saturation. J Colloid Interface Sci 2021; 581:627-634. [PMID: 32810728 DOI: 10.1016/j.jcis.2020.07.142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 07/16/2020] [Accepted: 07/29/2020] [Indexed: 10/23/2022]
Abstract
HYPOTHESIS Previous use of linear elastic fracture mechanics to estimate toughness of wet particulate materials underestimates the toughness because it does not account for plastic deformation as a dissipation mechanism. Plastic deformation is responsible for the majority of energy dissipated during the fracture of wet colloidal particulate materials. Plastic deformation around the crack tip increases with saturation of the particulate body. The toughness of the body increases with increasing saturation. EXPERIMENTS Elastic plastic fracture mechanics using the J-integral approach was used for the first time to measure the fracture toughness (JIC) of wet micron sized alumina powder bodies as a function of saturation. The samples were prepared by slip casting. The saturation was controlled by treatment in a humidity chamber. The elastic modulus (E) and the energy dissipated by plastic flow (Apl) were measured in uniaxial compression. The critical stress intensity factor (KIC) was measured using a diametral compression sample with a flaw of known size. The fracture toughness (JIC) was calculated from these measured quantities and the geometry of the specimen. FINDINGS Elastic plastic fracture mechanics was used for the first time to quantitively account for plastic deformation of wet particulate materials. The linear elastic fracture mechanics approach previously used accounted for less than 1% of the total energy dissipated in fracture. Toughness (JIC) was found to increase with increasing saturation due to plastic deformation that increased with saturation level. The improved understanding of toughness as a function of saturation will aid in providing quantitative analysis of cracking in drying colloidal films and bodies.
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Affiliation(s)
- George V Franks
- Department of Chemical Engineering, University of Melbourne, Parkville, Vic 3010, Australia.
| | - Mitchell L Sesso
- Department of Engineering, School of Engineering and Mathematical Sciences, College of Science, Health and Engineering, La Trobe University, Vic 3086, Australia
| | - Matthew Lam
- Department of Chemical Engineering, University of Melbourne, Parkville, Vic 3010, Australia
| | - Yi Lu
- Department of Chemical Engineering, University of Melbourne, Parkville, Vic 3010, Australia
| | - Liqing Xu
- Department of Chemical Engineering, University of Melbourne, Parkville, Vic 3010, Australia
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6
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Fischer SB, Koos E. Apparatus for simultaneous stress and weight measurement during film drying in an environmentally controlled chamber. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:123904. [PMID: 33380003 DOI: 10.1063/5.0030739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 11/23/2020] [Indexed: 06/12/2023]
Abstract
The drying behavior of coatings is essential for the development of formulations in order to obtain reliable and defect free finishes. There are two major measures of interest: the development of the stress responsible for cracking and the drying rate that gives insight into the morphological structure. The cantilever deflection method is the predominant way of determining stresses under defined drying conditions such as temperature and humidity. However, both measures of interest are currently obtained using two different coatings when dried in a chamber or a single coating with simultaneous measurements that can only be dried under ambient conditions. In this paper, we present an apparatus design based on the cantilever deflection method that allows simultaneous measurement of the stress and drying rate in an environmentally controlled chamber.
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Affiliation(s)
- Steffen B Fischer
- KU Leuven, Soft Matter, Rheology and Technology, Department of Chemical Engineering, Celestijnenlaan 200f, 3001 Leuven, Belgium
| | - Erin Koos
- KU Leuven, Soft Matter, Rheology and Technology, Department of Chemical Engineering, Celestijnenlaan 200f, 3001 Leuven, Belgium
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7
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Oh K, Abhari AR, Im W, Lee HL. Stress Development in a Cellulose-Nanofibril-Containing Pigment Coating Layer during Drying. Ind Eng Chem Res 2019. [DOI: 10.1021/acs.iecr.9b02906] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kyudeok Oh
- Department of Forest Sciences, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea
- Research Institute of Agriculture and Life Sciences, Seoul 08826, Korea
| | - Araz Rajabi Abhari
- Department of Forest Sciences, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea
| | - Wanhee Im
- Department of Forest Sciences, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea
| | - Hak Lae Lee
- Department of Forest Sciences, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea
- Research Institute of Agriculture and Life Sciences, Seoul 08826, Korea
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8
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Yoshihara H, Yamamura M. Formation mechanism of asymmetric porous polymer films by photoinduced phase separation in the presence of solvent. J Appl Polym Sci 2019. [DOI: 10.1002/app.47867] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Hirokazu Yoshihara
- Dai Nippon Printing Co., Ltd. Tukuba Ibaraki Japan
- Department of Applied ChemistryKyushu Institute of Technology Kitakyushu, Fukuoka Japan
| | - Masato Yamamura
- Department of Applied ChemistryKyushu Institute of Technology Kitakyushu, Fukuoka Japan
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9
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Doumenc F, Salmon JB, Guerrier B. Modeling Flow Coating of Colloidal Dispersions in the Evaporative Regime: Prediction of Deposit Thickness. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:13657-13668. [PMID: 27966979 DOI: 10.1021/acs.langmuir.6b02282] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We investigate flow coating processes, i.e., the formation of dry coatings starting from dilute complex fluids confined between a static blade and a moving substrate. In particular, we focus on the evaporative regime encountered at low substrate velocity, at which the coating flow is driven mainly by solvent evaporation in the liquid meniscus. In this regime, general arguments based on mass conservation show that the thickness of the dry film decreases as the substrate velocity increases, unlike the behavior in the well-known Landau-Levich regime. This work focuses on colloidal dispersions, which deserve special attention. Indeed, flow coating is expected to draw first a solvent-saturated film of densely packed colloids, which further dries fully when air invades the pores of the solid film. We first develop a model based on the transport equations for binary mixtures, which can describe this phenomenon continuously, using appropriate boundary conditions and a criterion to take into account pore-emptying in the colloidal film. Extensive numerical simulations of the model then demonstrate two regimes for the deposit thickness as a function of the process parameters (substrate velocity, evaporation rate, bulk concentration, and particle size). We finally derive an analytical model based on simplified transport equations that can reproduce the output of our numerical simulations very well. This model can predict analytically the two observed asymptotic regimes and therefore unifies the models recently reported in the literature.
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Affiliation(s)
- Frédéric Doumenc
- Laboratoire FAST, Université Paris-Sud, CNRS, Université Paris-Saclay , F-91405 Orsay, France
- Sorbonne Universités , UPMC Université Paris 06, UFR 919, 75005 Paris, France
| | | | - Béatrice Guerrier
- Laboratoire FAST, Université Paris-Sud, CNRS, Université Paris-Saclay , F-91405 Orsay, France
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10
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Lim S, Kim S, Ahn KH, Lee SJ. Stress Development of Li-Ion Battery Anode Slurries during the Drying Process. Ind Eng Chem Res 2015. [DOI: 10.1021/acs.iecr.5b00878] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sanghyuk Lim
- School
of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul 151-744, Korea
| | - Sunhyung Kim
- Institute
for Mechanical Process Engineering and Mechanics, Karlsruhe Institute Technology, Gotthard-Franz-Straße 3, Building 50.31, 76131 Karlsruhe, Germany
| | - Kyung Hyun Ahn
- School
of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul 151-744, Korea
| | - Seung Jong Lee
- School
of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul 151-744, Korea
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11
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Kim S, Sung JH, Chun S, Ahn KH, Lee SJ. Adsorption–stress relationship in drying of silica/PVA suspensions. J Colloid Interface Sci 2011; 361:497-502. [DOI: 10.1016/j.jcis.2011.05.052] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2011] [Revised: 05/12/2011] [Accepted: 05/13/2011] [Indexed: 11/26/2022]
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12
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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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13
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Yow HN, Goikoetxea M, Goehring L, Routh AF. Effect of film thickness and particle size on cracking stresses in drying latex films. J Colloid Interface Sci 2010; 352:542-8. [DOI: 10.1016/j.jcis.2010.08.074] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Revised: 07/21/2010] [Accepted: 08/27/2010] [Indexed: 10/19/2022]
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14
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Imaging in-plane and normal stresses near an interface crack using traction force microscopy. Proc Natl Acad Sci U S A 2010; 107:14964-7. [PMID: 20696929 DOI: 10.1073/pnas.1005537107] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Colloidal coatings, such as paint, are all around us. However, we know little about the mechanics of the film-forming process because the composition and properties of drying coatings vary dramatically in space and time. To surmount this challenge, we extend traction force microscopy to quantify the spatial distribution of all three components of the stress at the interface of two materials. We apply this approach to image stress near the tip of a propagating interface crack in a drying colloidal coating and extract the stress intensity factor.
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15
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Abstract
During the drying of colloidal suspensions, the desiccation process causes the suspension near the air interface to consolidate into a connected porous matrix or crust. Fluid transport in the porous medium is governed by Darcy’s law and the equations of poroelasticity, while the equations of colloid physics govern processes in the suspension. We derive new equations describing this process, including unique boundary conditions coupling the two regions, yielding a moving-boundary model of the concentration and stress profiles during drying. A solution is found for the steady-state growth of a one-dimensional crust during constant evaporation rate from the surface. The solution is used to demonstrate the importance of the system boundary conditions on stress profiles and diffusivity in a drying crust.
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Affiliation(s)
- Robert W. Style
- Oxford Centre for Collaborative Applied Mathematics, University of Oxford, Mathematical Institute, 24-29 St Giles’, Oxford OX1 3LB, UK
| | - Stephen S. L. Peppin
- Oxford Centre for Collaborative Applied Mathematics, University of Oxford, Mathematical Institute, 24-29 St Giles’, Oxford OX1 3LB, UK
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16
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Yow HN, Beristain I, Goikoetxea M, Barandiaran MJ, Routh AF. Evolving stresses in latex films as a function of temperature. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:6335-6342. [PMID: 20387802 DOI: 10.1021/la1007439] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Latex films were dried on a flexible substrate, and the substrate deflection was monitored over time to give an averaged film stress-evolution profile. Films were dried at various temperatures below and above the minimum film-formation temperature of the latex dispersion. The effect of polymer rheology, which is a temperature-dependent parameter, on film formation, was investigated. The reliability of the Stoney model in predicting film stress from substrate curvature was also examined and compared to the Euler-Bernoulli model. It was shown that the linearized Stoney model was unsuitable for the larger measured stresses.
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Affiliation(s)
- Huai Nyin Yow
- Department of Chemical Engineering and Biotechnology, BP Institute, University of Cambridge, Madingley Road, Cambridge CB3 0EZ, UK
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17
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Kim S, Sung JH, Ahn KH, Lee SJ. Drying of the silica/PVA suspension: effect of suspension microstructure. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:6155-6161. [PMID: 19466778 DOI: 10.1021/la804112b] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The particle/polymer/solvent suspension system shows complicated microstructure. When the suspension system experiences an industrial process such as coating and drying, the system experiences microstructural change. In this study, we investigated the microstructural change during the drying of a silica/polyvinyl alcohol (PVA) suspension, with an emphasis on suspension stability. We controlled the amount of PVA adsorption on the silica surface by adjusting the pH (1.5, 3.6, and 9) of the silica/PVA suspension. The amount of adsorption was measured to increase with decreasing pH, and the degree of flocculation in the silica/PVA suspension became stronger with decreasing pH. However, through the measurement of stress development during drying and the observation of film microstructure after drying, we found that the more strongly flocculated suspension became a more disperse, close-packed film after drying. By evaluating the potential energy, we could suggest the role of adsorbed polymers in structural change during the drying of the silica/PVA suspension. As pH decreases, the adsorbed polymers could bridge the particles and lead to a flocculated suspension before drying. As the solvent evaporates during drying, the adsorbed polymers introduce steric repulsion between approaching particles, leading to a change from flocculated to dispersed microstructure. This implies that the required silica/PVA film performance and the microstructure of the silica/PVA suspension can be tailored through controlling the polymer adsorption in suspension.
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Affiliation(s)
- Sunhyung Kim
- School of Chemical and Biological Engineering, Seoul National University, San 56-1 Shillim-dong, Gwanak-gu, Seoul 151-744, Korea
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18
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Yamamura M, Ono H, Uchinomiya T, Mawatari Y, Kage H. Multiple crack nucleation in drying nanoparticle-polymer coatings. Colloids Surf A Physicochem Eng Asp 2009. [DOI: 10.1016/j.colsurfa.2009.04.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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19
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Chen J, Ettelaie R, Yang H, Yao L. A novel technique for in situ measurements of stress development within a drying film. J FOOD ENG 2009. [DOI: 10.1016/j.jfoodeng.2008.12.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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20
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Immediate consolidation behaviour of aqueous pigment coatings applied to porous substrates. Chem Eng Sci 2008. [DOI: 10.1016/j.ces.2008.03.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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21
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Russel WB, Wu N, Man W. Generalized Hertzian model for the deformation and cracking of colloidal packings saturated with liquid. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:1721-1730. [PMID: 18197713 DOI: 10.1021/la702633t] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The process of drying colloidal dispersions generally produces particulate solids under stress as a result of capillary or interparticle forces. The derivation of a constitutive relation on the basis of Hertzian contact mechanics between spheres provides a model for quantitatively predicting the conditions under which close-packed colloidal layers form continuous void-free films or homogeneous porous films or crack under tensile stresses.
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Affiliation(s)
- William B Russel
- Department of Chemical Engineering, Princeton University, Princeton, New Jersey 08544, USA.
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22
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Santanach Carreras E, Chabert F, Dunstan DE, Franks GV. Avoiding “mud” cracks during drying of thin films from aqueous colloidal suspensions. J Colloid Interface Sci 2007; 313:160-8. [PMID: 17521665 DOI: 10.1016/j.jcis.2007.03.076] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2006] [Revised: 02/18/2007] [Accepted: 03/26/2007] [Indexed: 10/23/2022]
Abstract
The critical cracking thickness of films obtained by drying aqueous alumina suspensions has been investigated. The effects of solution chemistry, binder and binder crosslinking were studied. Films formed from flocculated and dispersed suspensions are compared. The influence of the addition of the polymeric binder, poly(vinyl alcohol) (PVA) was also investigated. In addition, in some of the dispersed suspensions the PVA was covalently crosslinked. The critical cracking thickness is found to be 3 times greater for the films obtained from dispersed suspensions than for the films obtained from flocculated suspensions. The superior mechanical properties are primarily due to the higher final solids concentration in the films obtained from dispersed suspensions. Addition of PVA leads to an increase of the critical cracking thickness by a factor of two for both dispersed and flocculated systems. When the PVA is crosslinked, the mechanical properties of the gel during drying are improved and the critical cracking thickness is increased 10 fold with respect to the suspensions with uncrosslinked PVA.
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Affiliation(s)
- E Santanach Carreras
- Department of Chemical & Biomolecular Engineering, The University of Melbourne, Vic 3010, Australia
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23
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Kameyama K, Komoda Y, Suzuki H, Usui H. Optimization of Preparation and Drying Conditions of Titanium Dioxide Slurry for Coating on a Plastic Substrate. JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 2007. [DOI: 10.1252/jcej.07we026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | - Hiroshi Suzuki
- Department of Chemical Science and Engineering, Kobe University
| | - Hiromoto Usui
- Department of Chemical Science and Engineering, Kobe University
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24
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Laudone GM, Matthews GP, Gane PAC. Modelling the shrinkage in pigmented coatings during drying: A stick–slip mechanism. J Colloid Interface Sci 2006; 304:180-90. [PMID: 16996533 DOI: 10.1016/j.jcis.2006.08.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2006] [Revised: 07/06/2006] [Accepted: 08/12/2006] [Indexed: 11/22/2022]
Abstract
Pigmented coatings, used to improve optical and printing properties, are applied to fibrous paper substrates as slurry, which then dries. We have elucidated the mechanism of the shrinkage which occurs during drying. The void space of the dry coating layers and their effective solid skeletal elements were modelled using the porous network simulation software Pore-Cor. The water-filled porous structures at the beginning of the shrinking process were modelled by creating simulated structures with the same effective skeletal element size distribution as the dry ones, but with higher given porosity to account for the water present. The capillary forces acting on the surface of the drying coating were calculated for the model structures and found to be orders of magnitude larger than the experimentally measured shrinkage forces. The shrinkage process was therefore postulated as resulting from the effect of capillary forces resisted by a discrete stick-slip process. The differences in the visco-elastic properties of the slurries also supported this postulate, as did further experimental evidence.
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Affiliation(s)
- G M Laudone
- Environmental and Fluid Modelling Group, University of Plymouth, Plymouth PL4 8AA, UK
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25
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Evans DR, Craig VSJ. The Origin of Surface Stress Induced by Adsorption of Iodine on Gold. J Phys Chem B 2006; 110:19507-14. [PMID: 17004812 DOI: 10.1021/jp063232e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The cantilever technique for the measurement of film stress on both macroscopic and microscopic cantilevers is validated, then applied to the experimental determination of film stress induced by the adsorption of a monolayer of iodine onto a gold substrate. A model is proposed that relates the change in the interatom potential upon chemisorption of iodine onto gold to the measured film stress. Excellent agreement is found with the experimentally determined value. This result gives insight into the origins of film stress that is observed in all thin film and coating applications.
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Affiliation(s)
- Drew R Evans
- Department of Applied Mathematics, RSPhysSE, Australian National University, Canberra 0200 A.C.T., Australia
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26
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Evans DR, Craig VSJ. Sensing Cantilever Beam Bending by the Optical Lever Technique and Its Application to Surface Stress. J Phys Chem B 2006; 110:5450-61. [PMID: 16539483 DOI: 10.1021/jp0536807] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cantilever beams, both microscopic and macroscopic, are used as sensors in a great variety of applications. An optical lever system is commonly employed to determine the deflection and thereby the profile of the cantilever under load. The sensitivity of the optical lever must be calibrated, and this is usually achieved by application of a known load or deflection to the free end of the cantilever. When the sensing operation involves a different type of load or a combination of types of loadings, the calibration and the deflection values derived from it become invalid. Here we develop a master equation that permits the true deflection of the cantilever to be obtained simply from the measurement of the apparent deflection for uniformly distributed loadings and end-moment loadings. These loadings are relevant to the uniform adsorption or application of material to the cantilever or the application of a surface stress to the cantilever and should assist experimentalists using the optical lever, such as in the atomic force microscope, to measure cantilever deflections in a great variety of sensing applications. We then apply this treatment to the experimental evaluation of surface stress. Three forms of Stoney's equation that relate the apparent deflection to the surface stress, which is valid for both macroscopic and microscopic experiments, are derived. Analysis of the errors arising from incorrect modeling of the loading conditions of the cantilever currently applied in experiments is also presented. It is shown that the reported literature values for surface stress in microscopic experiments are typically 9% smaller than their true value. For macroscopic experiments, we demonstrate that the added mass of the film or coating generally dominates the measured deflection and must be accounted for accurately if surface stress measurements are to be made. Further, the reported measurements generally use a form of Stoney's equation that is in error, resulting in an overestimation of surface stress by a factor >5.
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Affiliation(s)
- Drew R Evans
- Department of Applied Mathematics, RSPhysSE, Australian National University, Canberra 0200, A.C.T., Australia
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27
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Wedin P, Lewis JA, Bergström L. Soluble organic additive effects on stress development during drying of calcium carbonate suspensions. J Colloid Interface Sci 2005; 290:134-44. [PMID: 16122547 DOI: 10.1016/j.jcis.2005.04.020] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2004] [Revised: 03/26/2005] [Accepted: 04/03/2005] [Indexed: 11/19/2022]
Abstract
The effect of polymer, plasticizer, and surfactant additives on stress development during drying of calcium carbonate particulate coatings was studied using a controlled-environment apparatus that simultaneously monitors drying stress, weight loss, and relative humidity. We found that the calcium carbonate coatings display a drying stress evolution typical of granular films, which is characterized by a sharp capillary-induced stress rise followed by a rapid stress relaxation. The addition of a soluble polymer to the CaCO3 suspension resulted in a two-stage stress evolution process. The initial stress rise stems from capillary-pressure-induced stresses within the film, while the second, larger stress rise occurs due to solidification and shrinkage of the polymeric species. Measurements on the corresponding pure polymer solutions established a clear correlation between the magnitude of residual stress in both the polymer and CaCO3-polymer films to the physical properties of the polymer phase, i.e. its glass transition temperature, T(g), and Young's modulus. The addition of small organic molecules can reduce the residual stress observed in the CaCO3-polymer films; e.g., glycerol, which acts as a plasticizer, reduces the drying stress by lowering T(g), while surfactant additions reduce the surface tension of the liquid phase, and, hence, the magnitude of the capillary pressure within the film.
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Affiliation(s)
- Pär Wedin
- YKI, Institute for Surface Chemistry, P.O. Box 5607, SE-11486 Stockholm, Sweden
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28
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Wedin P, Bergström L. Migration and precipitation of soluble species during drying of colloidal films. J Colloid Interface Sci 2005; 281:146-54. [PMID: 15567390 DOI: 10.1016/j.jcis.2004.08.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2004] [Accepted: 08/06/2004] [Indexed: 11/26/2022]
Abstract
The evaporation-induced convection resulted in a transport of dissolved species, a water-soluble polymer (carboxymethylcellulose) and dissolved CaCO(3), to the drying front of silica and CaCO(3) dispersions where the material eventually precipitates. Scanning electron microscopy and chemical analysis showed that the concentration of carboxymethylcellulose, CMC, is highest in the centre of the dried silica film and decreases towards the perifery. The colloidal films of the monodisperse silica particles displayed a high degree of structural order even at high concentrations of the non-adsorbed polymer CMC, which suggests that any depletion induced interparticle attraction is insufficient to affect the assembly of the colloidal crystal. The CaCO(3) particles are slightly soluble and we found that rod-like crystals reprecipitated in the centre of the particle films on top of the polyacrylate-coated particles. Addition of CMC disturbs the formation of distinct crystal shapes which was attributed to a complexation of Ca(2+) in solution.
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Affiliation(s)
- Pär Wedin
- YKI, Institute for Surface Chemistry, P.O. Box 5607, SE-114 86 Stockholm, Sweden
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