Blooming flowers from drying drops

Lilin, Paul; Bourrianne, Philippe; Sintès, Guillaume; Bischofberger, Irmgard

doi:10.1103/physrevfluids.5.110511

Cited by 6 publications

(4 citation statements)

References 3 publications

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“…1b (Movie S2). The cracks reach the center of the deposit when the liquid cap has fully evaporated, and the petals that are formed bend to create a flower-like shape 12,14,23,24 ; at high volume fraction, the coffee ring observed in the dilute regime "blooms". How does such a spectacular transition of the pattern occur upon a change in particle volume fraction?…”

Section: Resultsmentioning

confidence: 99%

Crack morphologies in drying suspension drops

et al. 2021

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Section: Resultsmentioning

confidence: 99%

Crack morphologies in drying suspension drops

et al. 2021

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“…The first event is the appearance of a first crack in the deposit, ,, which occurs at a deposit width of w crack (Figure a). This crack is quickly followed by a series of regular radial cracks that form with avalanche-like dynamics mediated by the delamination of the deposit from the substrate. ,, As the deposit grows, the cracks propagate inward with a stop-and-go motion while maintaining a thin crack-free ring of deposit close to the liquid cap. ,, The second event is the invasion of the deposit by air, ,, which occurs at a deposit width of w air . As air progressively replaces the water inside the deposit, the deposit becomes opaque, as seen in Figure a.…”

Section: Resultsmentioning

confidence: 99%

“…Cracked paint on building facades, fractured mud in dry regions, and desiccation cracks in drops of blood illustrate the fragility of films composed of colloidal suspensions. − As the solvent evaporates from a suspension placed on a substrate, a solid deposit of close-packed particles is left behind. − This deposit fractures into a variety of patterns depending on its thickness and the solvent, particle, substrate, and air properties. − Controlling or preventing this thin film failure requires a thorough understanding of the microscale mechanics and flows, from the initial deposition to the evaporation of the last water molecule.…”

Section: Introductionmentioning

confidence: 99%

Criteria for Crack Formation and Air Invasion in Drying Colloidal Suspensions

Lilin

Bischofberger

2022

Langmuir

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The drying of sessile drops of aqueous colloidal suspensions leads to the formation of a close-packed particle deposit. As water evaporates, a solidification front propagates from the edge of the drop toward the center, leaving behind a thin disk-shaped deposit. For drops with sufficiently large particle volume fractions, the deposit eventually covers the entire wetted area. In this regime, the dynamics of the deposit growth is governed by volume conservation across a large range of particle volume fractions and drying times. During drying, water flows radially through the deposit to compensate for evaporation over the solid's surface, creating a negative pore pressure in the deposit which we rationalize with a hydrodynamic model. We show that the pressure inside the deposit controls both the onset of crack formation and the onset of air invasion. Two distinct regimes of air invasion occur, which we can account for using the same model that further provides a quantitative criterion for the crossover between the two regimes. ■ EXPERIMENTAL METHODSDrop drying experiments are performed using charge-stabilized suspensions of colloidal silica particles (Ludox AS-40, Sigma-Aldrich)

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“…When an aqueous drop with silica nanoparticles dries, fractures typically nucleate at the contact line and travel radially inwards, following the gelation front. These fractures divide the deposit into an array of "petals" that simultaneously delaminate from the substrate, resulting in the entire solid "blooming" into a structure that resembles a lotus flower [13,14]. In the case of dried blood drops, the solid deposit often has an orthoradial fracture at the contact line, an annular region with several radial fractures, and a central zone with smaller-scale fractures with no preferred orientation [15].…”

Section: Introductionmentioning

confidence: 99%

Drying-induced stresses in poroelastic drops on rigid substrates

Hennessy

Matar

2022

Phys. Rev. E

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We develop a theory for drying-induced stresses in sessile, poroelastic drops undergoing evaporation on rigid surfaces. Using a lubrication-like approximation, the governing equations of three-dimensional nonlinear poroelasticity are reduced to a single thin-film equation for the drop thickness. We find that thin drops experience compressive elastic stresses but the total in-plane stresses are tensile. The mechanical response of the drop is dictated by the initial profile of the solid skeleton, which controls the in-plane deformation, the dominant components of elastic stress, and sets a limit on the depth of delamination that can potentially occur. Our theory suggests that the alignment of desiccation fractures in colloidal drops is selected by the shape of the drop at the point of gelation. We propose that the emergence of three distinct fracture patterns in dried blood drops is a consequence of a nonmonotonic drop profile at gelation. We also show that depletion fronts, which separate wet and dry solid, can invade the drop from the contact line and localize the generation of mechanical stress during drying. Finally, the finite element method is used to explore the stress profiles in drops with large contact angles.

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Blooming flowers from drying drops

Cited by 6 publications

References 3 publications

Crack morphologies in drying suspension drops

Crack morphologies in drying suspension drops

Criteria for Crack Formation and Air Invasion in Drying Colloidal Suspensions

Drying-induced stresses in poroelastic drops on rigid substrates

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