Direct observation of nanoparticle multiple-ring pattern formation during droplet evaporation with dark-field microscopy

Li, Hui; Zhang, Zhen; Li, Yongjun; Xiong, Bin; Qiao, Chen; Cao, Xuan; Wang, Tie; He, Yan; Jing, Guangyin

doi:10.1039/c6cp00593d

Cited by 20 publications

(17 citation statements)

References 50 publications

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“…It has been reported that the multi-ring pattern is usually made of a solid circle in the center surrounded by many concentric rings, as schematically shown in Figure 1. This phenomenon has indeed been observed experimentally in drying of droplets containing a wide type of solutes, including colloid [1,10,24], polymer [11], DNA [2] and nanoparticles [25].…”

Section: Introductionsupporting

confidence: 57%

Multi-ring Deposition Pattern of Drying Droplets

Man

Doi

2018

Langmuir

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We propose a theory for the multi-ring pattern of the deposits that are formed when droplets of the suspension are dried on a substrate. Assuming a standard model for the stick-slip motion of the contact line, we show that as droplets evaporate many concentric rings of deposits are formed but are taken over by a solid-circle pattern in the final stage of drying. An analytical expression is given to indicate when the ring pattern changes to a solid-circle pattern during the evaporation process. The results are in qualitative agreement with existing experiments, and the other predictions on how the evaporation rate, droplet radius, and receding contact angle affect the pattern are all subject to an experimental test.

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Section: Introductionsupporting

confidence: 57%

Multi-ring Deposition Pattern of Drying Droplets

Man

Doi

2018

Langmuir

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“…At low concentrations, we observed an unusual combination of dotlike and multi-ring patterns. In their review, Li et al underlined that dotlike patterns were typically observed on hydrophobic substrates, resulting from an evaporation process at constant contact angle with an important contribution of the Marangoni flow that should be oriented radially inward along the substrate and radially outward along the air/liquid interface . Nevertheless, similar patterns, by other names (i.e., “dome”, “coffee eyes”, and “central bump”) were observed on hydrophilic substrates with nanoparticles showing a hydrophobic character (and only at high particle concentration) and with hydrophilic particles deposited on hot substrates or mixed with micrometric particles .…”

Section: Resultsmentioning

confidence: 95%

Self-Assembly of Nanoparticles from Evaporating Sessile Droplets: Fresh Look into the Role of Particle/Substrate Interaction

et al. 2020

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We studied the dependence of solid deposit shape obtained by free drying of sessile drops on the particles concentration and Derjaguin-Landau-Verwey-Overbeek (DLVO) particle/substrate interaction. In contrast to previous contributions using pH as a control parameter of interactions, we investigated an unprecedentedly wide range of concentrations and particle/substrate DLVO forces by modifying the nature of the substrate and particles as well as their size and surface chemistry whereas long-distance repulsive interactions between particles were maintained for most of the drying time. Our main result is that the different shapes of deposits obtained by modifying the particle concentration are the same in the different regimes of concentration regardless of particle/substrate interaction in the studied range of DLVO forces and particle concentrations. The second result is that, contrary to expectations, the dominant morphology of dry patterns at low particle concentration always shows a dot-like pattern for all the studied systems.

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“…The contact line may even become pinned multiple times, with different pinning strengths, onto the different components that fall out of the solution. This is in addition to the mechanisms for multiple pinning events reported in the literature [34][35][36][37][38] , which mainly consist of multiple deposition events of a single compound or colloidal particle type. The resulting footprint and its topology will in our case consist of several edges of the different deposited materials, effectively being a superposition of several profiles as presented in Fig.…”

Section: Deposit Vs Droplet Propertiesmentioning

confidence: 67%

Compound redistribution due to droplet evaporation on a thin polymeric film: Theory

Heijden

Darhuber

Schoot

2019

Journal of Applied Physics

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A thin polymeric film in contact with a fluid body may leach low-molecular-weight compounds into the fluid. If this fluid is a small droplet, the compound concentration within the liquid increases due to ongoing leaching in combination with the evaporation of the droplet. This may eventually lead to an inversion of the transport process and a redistribution of the compounds within the thin film. In order to gain an understanding of the compound redistribution, we apply a macroscopic model for the evaporation of a droplet and combine that with a diffusion model for the compound transport. In the model, material deposition and the resulting contact line pinning are associated with the precipitation of a fraction of the dissolved material. We find three power law regimes for the size of the deposit area as a function of the initial droplet size, dictated by the competition between evaporation, diffusion and the initial compound concentrations in the droplet and the thin film. The strength of the contact line pinning determines the deposition profile of the precipitate, characterised by a pronounced edge and a linearly decaying profile towards the centre of the stain. Our predictions for the concentration profile within the solid substrate resemble patterns found experimentally.The following article will be submitted to Journal of Applied Physics. After it is published, it will be found at https://aip.scitation.org/journal/jap.

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Direct observation of nanoparticle multiple-ring pattern formation during droplet evaporation with dark-field microscopy

Cited by 20 publications

References 50 publications

Multi-ring Deposition Pattern of Drying Droplets

Multi-ring Deposition Pattern of Drying Droplets

Self-Assembly of Nanoparticles from Evaporating Sessile Droplets: Fresh Look into the Role of Particle/Substrate Interaction

Compound redistribution due to droplet evaporation on a thin polymeric film: Theory

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