Influence of anisotropic nanoparticles on the deposition pattern of an evaporating droplet

. The suppression or enhancement of the “coffee ring” effect depends on whether nanoparticles easily adhere to the gas-liquid interface and particle shape. To obtain deposition patterns of suspensions of nanoparticles strongly deviating from spheres, which is less studied in the literature, prolate...

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Bibliographic Details
Published in:The European physical journal. E, Soft matter and biological physics Soft matter and biological physics, 2019-02, Vol.42 (2), p.17-14, Article 17
Main Authors: Ye, Xuemin, Fei, Long, Lu, Lifang, Li, Chunxi
Format: Article
Language:English
Subjects:
Aspect ratio
Biological and Medical Physics
Biophysics
Coffee
Complex Fluids and Microfluidics
Complex Systems
Condensed matter physics
Deposition
Droplets
Film thickness
Nanoparticles
Nanotechnology
Particle shape
Physics
Physics and Astronomy
Polymer Sciences
Recession
Regular Article
Shape effects
Shrinkage
Soft and Granular Matter
Surfaces and Interfaces
Thin Films
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Summary:. The suppression or enhancement of the “coffee ring” effect depends on whether nanoparticles easily adhere to the gas-liquid interface and particle shape. To obtain deposition patterns of suspensions of nanoparticles strongly deviating from spheres, which is less studied in the literature, prolate ellipsoidal and cylindrical rod-shaped particles with a minimum aspect ratio of 4 are selected. Dynamic viscosity, which is a function of particle shape and volume fraction, is introduced into the evolution equations for film thickness and particle concentration. The nanoparticle deposition features and the contact line dynamics are examined numerically, and the effect of particle shape on the drying process is analysed. The results show that the contact line is in the depinning state during the droplet shrinkage, while the concentration and effective layer thickness of nanoparticles in the ring-formation region decrease with time, and the deposition band widens. The deposition ring height increases, and the recession of the contact line slows down with increasing aspect ratio. This means that for nanoparticles deviating strongly from spheres and not easily adhering to the gas-liquid interface, the “coffee ring” effect is enhanced when the suspension dries. A larger aspect ratio leads to a more obvious “coffee ring” feature. Graphical abstract
ISSN:1292-8941
1292-895X
DOI:10.1140/epje/i2019-11779-9