Buckling-induced structural transition during the drying of a polymeric latex droplet on a solid surface

Chen, Xuelian; Boyko, Volodymyr; Rieger, Jens; Reinhold, Frank; Reck, Bernd; Perlich, Jan; Gehrke, Rainer; Men, Yongfeng

doi:10.1039/c2sm26580j

Cited by 13 publications

(7 citation statements)

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“…The substrate provided a contact angle of around 106° for a water droplet and around 103° for a WPI concentrate droplet. A pendant configuration of the droplet was adopted in order to maintain a spherical shape as much as possible and avoid an inversion of the curvature of the particle . In the sessile configuration, it is well known that the shell collapses under a gravity and pressure gradient when water evaporates through the porous shell. , Therefore, with a suspended system, the impact of drying kinetics and matter might be more noticeable.…”

Section: Experimental Methodsmentioning

confidence: 99%

Shape, Shell, and Vacuole Formation during the Drying of a Single Concentrated Whey Protein Droplet

et al. 2013

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The drying of milk concentrate droplets usually leads to specific particle morphology influencing their properties and their functionality. Understanding how the final shape of the particle is formed therefore represents a key issue for industrial applications. In this study, a new approach to the investigation of droplet-particle conversion is proposed. A single droplet of concentrated globular proteins extracted from milk was deposited onto a hydrophobic substrate and placed in a dry environment. Complementary methods (high-speed camera, confocal microscopy, and microbalance) were used to record the drying behavior of the concentrated protein droplets. Our results showed that whatever the initial concentration, particle formation included three dynamic stages clearly defined by the loss of mass and the evolution of the internal and external shapes of the droplet. A new and reproducible particle shape was related in this study. It was observed after drying a smooth, hemispherical cap-shaped particle, including a uniform protein shell and the nucleation of an internal vacuole. The particle morphology was strongly influenced by the drying environment, the contact angle, and the initial protein concentration, all of which governed the duration of the droplet shrinkage, the degree of buckling, and the shell thickness. These results are discussed in terms of specific protein behaviors in forming a predictable and a characteristic particle shape. The way the shell is formed may be the starting point in shaping particle distortion and thus represents a potential means of tuning the particle morphology.

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Section: Experimental Methodsmentioning

confidence: 99%

Shape, Shell, and Vacuole Formation during the Drying of a Single Concentrated Whey Protein Droplet

et al. 2013

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“…Colloidal nanoparticle ordering at the contact line of an evaporating droplet on a wetting surface can be probed by GISAXS (Roth et al, 2007(Roth et al, , 2010. Ordering effects during collapse of the shell formed on top of a drying latex droplet have been revealed by ultrasmall-angle X-ray scattering (Chen et al, 2012). Similar processes presumably occur in the final stage of evaporation of low solute concentration droplets on a pillared SHS.…”

Section: Droplet Deposition and Residue Formationmentioning

confidence: 99%

Probing droplets on superhydrophobic surfaces by synchrotron radiation scattering techniques

Accardo

Fabrizio

Limongi

et al. 2014

J Synchrotron Radiat

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Droplets on artificially structured superhydrophobic surfaces represent quasi contact-free sample environments which can be probed by X-ray microbeams and nanobeams in the absence of obstructing walls. This review will discuss basic surface wettability concepts and introduce the technology of structuring surfaces. Quasi contact-free droplets are compared with contact-free droplets; processes related to deposition and evaporation on solid surfaces are discussed. Droplet coalescence based on the electrowetting effect allows the probing of short-time mixing and reaction processes. The review will show for several materials of biological interest that structural processes related to conformational changes, nucleation and assembly during droplet evaporation can be spatially and temporally resolved by raster-scan diffraction techniques. Orientational ordering of anisotropic materials deposited during solidification at pinning sites facilitates the interpretation of structural data.

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“…Film formation in drying dispersion droplets involves the intricate interplay of many processes, including fluid flow, particle deformation, coalescence, and cracking. Each of these processes has been individually investigated in some detail, − yet crucial connections between them are lacking. Particle deformation is effectively described in the Routh–Russel model, which identifies distinct deformation regimes depending on the relative time scales of particle deformation and evaporation. , However, the Routh–Russel model makes several simplifying assumptions regarding fluid flow and does not take into account particle coalescence and cracking, while especially these phenomena, governed not only by the properties of single particles but also by collective effects spanning much larger length scales, determine the properties of the dried film.…”

Section: Introductionmentioning

confidence: 99%

Coalescence, Cracking, and Crack Healing in Drying Dispersion Droplets

et al. 2015

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The formation of a uniform film from a polymer dispersion is a complex phenomenon involving the interplay of many processes: evaporation and resulting fluid flows through confined geometries, particle packing and deformation, coalescence, and cracking. Understanding this multidimensional problem has proven challenging, precluding a clear understanding of film formation to date. This is especially true for drying dispersion droplets, where the particular geometry introduces additional complexity such as lateral flow toward the droplet periphery. We study the drying of these droplets using a simplified approach in which we systematically vary a single parameter: the glass transition temperature (Tg) of the polymer. We combine optical with scanning electron microscopy to elucidate these processes from the macroscopic down to the single-particle level, both qualitatively and quantitatively, over times ranging from seconds to days. Our results indicate that the polymer Tg has a marked influence on the time evolution of particle deformation and coalescence, giving rise to a distinct and sudden cracking transition. Moreover, in cracked droplets it affects the frequently overlooked time scale of crack healing, giving rise to a second transition from self-healing to permanently cracked droplets. These findings are in line with the classical Routh-Russel model for film formation yet extend its scope from particle-level dynamics to long-range polymer flow.

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Buckling-induced structural transition during the drying of a polymeric latex droplet on a solid surface

Cited by 13 publications

References 50 publications

Shape, Shell, and Vacuole Formation during the Drying of a Single Concentrated Whey Protein Droplet

Shape, Shell, and Vacuole Formation during the Drying of a Single Concentrated Whey Protein Droplet

Probing droplets on superhydrophobic surfaces by synchrotron radiation scattering techniques

Coalescence, Cracking, and Crack Healing in Drying Dispersion Droplets

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