Auto-stratification in drying colloidal dispersions: A diffusive model

Trueman, R.E.; Domingues, Éric; Emmett, S.N.; Murray, Martin; Routh, Alexander F.

doi:10.1016/j.jcis.2012.03.045

Cited by 87 publications

(135 citation statements)

References 23 publications

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“…1-3 together, it appears that BSA and lactose do not separate within a film during drying, except in the immediate vicinity of the surface (within a few nanometers). One possible explanation for the observed separation of BSA and lactose at the surface is the mechanism of capture of large solutes by the receding evaporative surface while small solutes diffuse away [7,8]. According to Trueman et al [8], two solutes with Peclet numbers on either side of unity will separate at the surface by this mechanism.…”

Section: Resultsmentioning

confidence: 99%

“…One possible explanation for the observed separation of BSA and lactose at the surface is the mechanism of capture of large solutes by the receding evaporative surface while small solutes diffuse away [7,8]. According to Trueman et al [8], two solutes with Peclet numbers on either side of unity will separate at the surface by this mechanism. Assuming Stoke-Einstein diffusion, the Peclet number is defined by the equation…”

Section: Resultsmentioning

confidence: 99%

“…Thus, the receding surface captures these solutes like a net, but smaller more mobile solutes such as simple carbohydrates can diffuse away towards the interior. Trueman et al [8] provide a mathematical model of this mechanism, using it to show that an increase in the size ratio of two solutes from 1 to 5 leads to more segregation due to increased differences in diffusion rates of the two solutes. Considering these mechanisms, it is expected that proteins should be concentrated at the surface of a spraydried particle and decrease in concentration towards the interior, while simple carbohydrates should be concentrated in the interior, reducing in concentration towards the surface.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Coat formation of surface-active proteins on aqueous surfaces during drying

Nijdam

Trouillet

Kachel

et al. 2014

Colloids and Surfaces B: Biointerfaces

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Coat formation of surface-active proteins on aqueous surfaces during drying

Nijdam

Trouillet

Kachel

et al. 2014

Colloids and Surfaces B: Biointerfaces

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“…If P e ≪ 1, the particle diffusion will be more significant; this will lead to a homogeneous distribution of the suspended particles within the sessile drop. If P e ≫ 1, the diffusion will be too weak to prevent the increase in the particle concentration at the interface, thus producing a dense skin on the surface of the colloidal droplet [32,33].…”

Section: Advances In Colloid Sciencementioning

confidence: 99%

Wetting and Drying of Colloidal Droplets: Physics and Pattern Formation

Chen¹,

Zhang²,

Zang³

et al. 2016

Advances in Colloid Science

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When a colloidal droplet is deposited on a solid substrate at ambient condition, it will experience the processes of wetting and drying spontaneously. These ostensibly simple and ubiquitous processes involve numerous physics: droplet spreading and wetting, three-phase contact line motion, flow fields inside droplets, and mass transportation within droplets during drying. Meanwhile, the continuous evaporation of liquid produces inter-and/or intra-molecular interactions among suspended materials and builds up the internal stress within droplets. After drying, interesting and complex desiccation patterns form in the dried droplets. These desiccation patterns are believed to have wide applications, e.g., medical diagnosis. However, many potential applications are limited by the current understanding of wetting and drying of colloidal droplets. This chapter focuses on the complex physics associated with these processes and the pattern formation in the dried colloidal droplets. Moreover, potential applications of these desiccation patterns and prospective works of wetting and drying of the colloidal droplets are outlined in this chapter.

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“…They conjectured that this is due to the interaction between particles. [38] On the other hand, Fortini et al [40] conducted a computer simulation and reported that the small-on-top structure appears for hard sphere systems when both Peclet numbers are large (Pe 1 > 1, Pe 2 > 1) and the size ratio is large (larger than 7). Howard et al [41] performed a thorough examination of the parameter space on a similar system.…”

Section: Drying Of Two-component Solutionsmentioning

confidence: 99%

Structure Formation in Soft‐Matter Solutions Induced by Solvent Evaporation

et al. 2017

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etc., and the interplay between different processes determines the final structure of the dried materials.Here, we report recent advances of selfassembled structures induced by uniform evaporation, examples including drying in a thin-film geometry or evaporating a spherical droplet on a superhydrophobic surface. [4] In these situations, the structure formation takes place in the direction of the evaporation. This excludes the case where lateral flow is induced by nonuniform drying. The lateral flow is important in explaining the coffee-ring effect, where excellent reviews exist in literature. [5,6] After introducing the general procedure in experiments, we explain the physical mechanisms responsible for the structure formation in solvent evaporation. We then discuss recent advances based on single-and binarycomponent solutions, with a special emphasis on the theoretical approaches. Drying of Single-Component SolutionsA general experiment starts with spin-coating a thin-film solution on a substrate, then the sample is left to dry. In the first step, it is important that the spin-cast film is uniform. [7,8] In the second step, the evaporation flux, i.e., the mass removed from the liquid phase to the vapor phase in unit time from unit surface area needs to be controlled precisely. Even for the pure solvent evaporation, the process is complex and involves the diffusion of solvent molecules in both the liquid and vapor phases, and external flow in the vapor phase to prevent saturation. The evaporation flux can be computed using the Hertz-Knudsen equation that is based on the thermodynamics variables [9][10][11] or solving the diffusion equation in the vapor phase using suitable boundary conditions. [12][13][14] The solvent evaporation drives the free surface to recede toward the substrate, resulting in an accumulation of the solutes at the surface. Two competing processes determine the spatial distribution of the solutes. One is the Brownian motion, which is characterized by the diffusion constant D of the solutes. The other is the evaporation, characterized by the rate v ev at which the free surface recedes. Two timescales are related to these two processes: the diffusion time τ D =  2 /D, where  is a characteristic length and the evaporation time τ ev = /v ev . To quantify the relative importance between the diffusion and the evaporation, one can define a dimensionless number called film formation Peclet number: [15]

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Auto-stratification in drying colloidal dispersions: A diffusive model

Cited by 87 publications

References 23 publications

Coat formation of surface-active proteins on aqueous surfaces during drying

Coat formation of surface-active proteins on aqueous surfaces during drying

Wetting and Drying of Colloidal Droplets: Physics and Pattern Formation

Structure Formation in Soft‐Matter Solutions Induced by Solvent Evaporation

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