Hydrophobicity effect in the self assembly of particles in an evaporating droplet

Shao, Fen Fen; Neild, Adrian; Ng, Tuck Wah

doi:10.1063/1.3455845

Cited by 20 publications

(15 citation statements)

References 25 publications

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“…Lama et al [18] studied crack formation in the ring using silica nanoparticles and polystyrene particles (0.1 μm diameter) of different concentration of [0.1-2.0] % wt and observed larger crack density and ordered cracks on the ring at a larger substrate temperature due to lesser ring height. The particle hydrophobicity can also influence the morphology, as reported by Shao et al [36]. They showed that the hydrophobic particles result in a spoke-like deposit as compared to a typical ring-like deposit due to stronger capillary forces among them [36].…”

Section: Introductionmentioning

confidence: 87%

“…The particle hydrophobicity can also influence the morphology, as reported by Shao et al [36]. They showed that the hydrophobic particles result in a spoke-like deposit as compared to a typical ring-like deposit due to stronger capillary forces among them [36]. Here, too though, there has been little work on examining the occurrence of cracks in a single system over a wide range of concentrations and particle sizes, or quantitative studies of the rings formed.…”

Section: Introductionmentioning

confidence: 96%

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Analysis of profile and morphology of colloidal deposits obtained from evaporating sessile droplets

Malla

Bhardwaj

Neild

2019

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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We experimentally investigate the profile and morphology of the ring-like deposits obtained after evaporation of a sessile water droplet containing polystyrene colloidal particles on a hydrophilic glass substrate. In particular, the coupled effect of particle size and concentration are studied. The deposits were qualitatively visualized under an optical microscope and profile of the ring was measured by an optical profilometer. The profile of the ring resembles a partial torus-like shape for all cases of particles size and concentration. The cracks on the surface of the ring were found to occur only at smaller particle size and larger concentration. We plot a regime map to classify three deposit types -discontinuous monolayer ring, continuous monolayer ring, and multiple layers ring -on particles concentration -particle size plane. Our data shows a possible existence of a critical concentration (particle size) for a given particle size (concentration) at which the monolayer ring forms. For the larger particle sizes, the immersion capillary forces between the particles dominate, aiding the formation of a monolayer ring of the particles. The relative mass of the particles accumulated in the ring is lesser in cases of the monolayer ring. We measure the width and height of the ring and show that they scale with particle concentration by a power law for the multiple layers ring. This scaling corroborates with an existing continuum based theoretical model.We briefly discuss the effect of the interaction of growing deposit with shrinking free surface on the ring dimensions and profile. The present results aid understanding of the ring formation process and will be useful in guiding the design of self-assemblies of the colloidal particles formed by the evaporating droplets.

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Section: Introductionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 96%

Analysis of profile and morphology of colloidal deposits obtained from evaporating sessile droplets

Malla

Bhardwaj

Neild

2019

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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“…7b). Multiple ring deposition patterns have been observed before (Shao et al 2010;Deegan 2000), based on sequential pinning and movement of the contact line. We monitored the drying process on both of the surfaces under the contact angle goniometer, but were unable to observe any re-pinning of the contact line.…”

Section: Deposition Patterns On Surfaces With Intermediate Wettabilitmentioning

confidence: 96%

“…It is not currently clear what kind of mechanism(s) can lead to different deposition patterns for different solutes, as the basic phenomenon can be theoretically described without taking into account the properties of the solute (Deegan et al 1997). Very recently, Shao et al (2010) provided theoretical modeling and experimental data of drying patterns of hydrophilic versus hydrophobic microspheres (&1 lm, investigated separately). In their study, the main reason for the different drying patterns was related to the interaction of the particles with each other and the fluid at the receding contact line.…”

Section: Deposition Patterns Of Analyte Mixturesmentioning

confidence: 98%

Engineered droplets for dried droplet solute deposition by mass spectrometric imaging

Jokinen

Franssila

Baumann

2011

Microfluid Nanofluid

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Solute deposition patterns of peptides are studied on dried droplet deposits from engineered droplet shapes using surface assisted laser desorption ionization mass spectrometric imaging. The engineered droplet shapes are achieved through superhydrophilic/hydrophobic patterned surfaces. Strong pinning of the contact line to the edges of the hydrophilic area causes the solutes to deposit mostly to the perimeter of the hydrophilic area on simple circular and square shaped spots. More complex geometries resulted in unique deposition patterns, showing potential for spotting and chemical analysis. In particular, a geometry where the analyte was split and concentrated onto eight discrete target sites is described. The deposition patterns of analyte mixtures are also studied, and spatial separation is observed between various analytes, enabling the possibility for analyte separation.

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“…For instance, in inkjet printing, a uniform deposit is desired than the ring-like deposit. In addition to the Marangoni convection, other effects which were found important in controlling the shape of the deposit are pH of the colloidal suspension 12 , particles hydrophobicity 13 , shape of the particles 14,15 , surfactant concentration 16 , substrate elasticity 17 , ambient pressure 18 , particles size 19 and bio-molecular interaction between the particles and substrate 20 . The present study investigates the influence of substrate temperature, substrate wettability and particle concentration on the mechanism of the particles deposition and associated evaporation dynamics.…”

Section: Introductionmentioning

confidence: 99%

Effects of Substrate Heating and Wettability on Evaporation Dynamics and Deposition Patterns for a Sessile Water Droplet Containing Colloidal Particles

et al. 2016

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Effects of substrate temperature, substrate wettability and particles concentration are experimentally investigated for evaporation of a sessile water droplet containing colloidal particles. Time-varying droplet shapes and temperature of the liquid-gas interface are measured using high-speed visualization and infrared thermography, respectively. The motion of the particles inside the evaporating droplet is qualitatively visualized by an optical microscope and profile of final particle deposit is measured by an optical profilometer. On a non-heated hydrophilic substrate, a ring-like deposit forms after the evaporation, as reported extensively in the literature; while on a heated hydrophilic substrate, a thinner ring with an inner deposit is reported in the present work. The latter is attributed to Marangoni convection and recorded motion of the particles as well as measured temperature gradient across the liquid-gas interface confirms this hypothesis.The thinning of the ring scales with the substrate temperature and is reasoned to stronger Marangoni convection at larger substrate temperature. In case of a non-heated hydrophobic substrate, an inner deposit forms due to very early depinning of the contact line. On the other hand, in case of a heated hydrophobic substrate, the substrate heating as well as larger particle concentration helps in the pinning of the contact line, which results in a thin ring with an inner deposit. We propose a regime map for predicting three types of deposits namely, ring, thin ring with inner deposit and inner deposit -for varying substrate temperature, substrate wettability and particles concentration. A first-order model corroborates the liquid-gas interface temperature measurements and variation in the measured ring profile with the substrate temperature.3

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Hydrophobicity effect in the self assembly of particles in an evaporating droplet

Cited by 20 publications

References 25 publications

Analysis of profile and morphology of colloidal deposits obtained from evaporating sessile droplets

Analysis of profile and morphology of colloidal deposits obtained from evaporating sessile droplets

Engineered droplets for dried droplet solute deposition by mass spectrometric imaging

Effects of Substrate Heating and Wettability on Evaporation Dynamics and Deposition Patterns for a Sessile Water Droplet Containing Colloidal Particles

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