Evaporation of Sessile Drops Containing Colloidal Rods: Coffee-Ring and Order–Disorder Transition

Dugyala, Venkateshwar Rao; Basavaraj, Madivala G.

doi:10.1021/jp511611v

Cited by 63 publications

(66 citation statements)

References 34 publications

(80 reference statements)

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“…2D, the particles are oriented and aligned in one direction. 31 Similar observation have been reported in the deposits formed from sessile drops of anisotropic rod like particles and evaporation of suspensions of nano-rods under electric eld. The FFTs show further evidence for the random and aligned nature of ellipsoids as conrmed by the isotropic and anisotropic nature of the FFT patterns.…”

Section: Resultssupporting

confidence: 78%

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Self-assembly of nano-ellipsoids into ordered structures via vertical deposition

Dugyala

Basavaraj

2015

RSC Adv.

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The self-assembly of anisotropic particles into two or three dimensional ordered arrays has diverse applications in several areas of science and engineering. In this article, we report the formation of a multi-layer film of nano-sized ellipsoids with long-range orientation and positional order through an evaporation driven vertical deposition technique. Using nano-sized ellipsoids of tunable surface charge, we show that electrostatic interactions can be exploited to control the arrangement of ellipsoids in the film. The pH of the aqueous suspensions used for vertical deposition is adjusted such that the surface charge and hence the electro-static interactions can be controlled. We show that the interplay between various Derjaguin and Landau, Verwey and Overbeek (DLVO) interactions can be effectively controlled to fabricate films with a random arrangement of particles as well as to create particulate films with threedimensional ordering of ellipsoids. When the particles are weakly charged, the nano-ellipsoids in the film are randomly oriented giving an amorphous particulate film. However, when the particles are highly charged, the nano-ellipsoids in the film are oriented with major axis parallel to each other and ordered in three dimensions. These particulate film are observed to have parallel cracks across the entire width of the film. The major axis of the particle is found to be parallel to the crack direction and therefore, the direction of crack formation can be exploited to indicate the nature of particle ordering. † Electronic supplementary information (ESI) available: Document contains measurement of zeta potential of hematite particle as a function pH, results of peeling experiment that demonstrate self-assembly of particles across the cross section of the lm and DLVO potential calculations. See

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Section: Resultssupporting

confidence: 78%

“…The Fast Fourier Transform (FFT) images of the SEM images are shown in corresponding image as inset. 31,32 Role of DLVO interactions on the particle arrangement From the zeta-potential measurements (Fig. The assembly of hematite nanoellipsoids at pH 2 at the surface and interior of the lm deposit is shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Self-assembly of nano-ellipsoids into ordered structures via vertical deposition

Dugyala

Basavaraj

2015

RSC Adv.

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“…In order to understand the shape effect on crack patterns, a similar type of sessile drop evaporation experiment with dispersion of hematite ellipsoids (3.0 wt% and with an aspect ratio of 3.73 ± 0.37) is conducted under the favorable conditions where they form coffee-ring like deposits 7 27 . The coffee-ring like formation with hematite ellipsoids has been studied in more detail by Dugyala et al .…”

Section: Resultsmentioning

confidence: 99%

Role of particle shape anisotropy on crack formation in drying of colloidal suspension

Dugyala

Lama

Satapathy

2016

Sci Rep

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Cracks in a colloidal film formed by evaporation induced drying can be controlled by changing drying conditions. We show, for the first time that the crack morphologies in colloidal films are dependent on shape of constituting particles apart from the microstructure and particle assembly. In order to investigate the particle shape effect on crack patterns, monodispered spherical and ellipsoidal particles are used in sessile drop experiments. On observing the dried sessile drop we found cracks along the radial direction for spherical particle dispersions and circular crack patterns for ellipsoidal particle dispersions. The change in crack pattern is a result of self assembly of shape anisotropic particles and their ordering. The ordering of particles dictate the crack direction and the cracks follow the path of least resistance to release the excess stress stored in the particle film. Ellipsoids having different aspect ratio (~3 to 7) are used and circular crack patterns are repeatedly observed in all experiments.

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“…For weakly charged particles, a disordered structure was obtained. Studies of the drying of colloidal suspensions containing model rod-like silica particles (with aspect ratios ranging from 4 to 15) have revealed parallel orientation of the silica rods in several layers close to the contact line [15]. Special interest has been paid to the behaviors of thin films obtained by drying colloidal suspensions of carbon nanotubes (CNTs) in experimental investigations (for a review, see [16]).…”

Section: Introductionmentioning

confidence: 99%

Monte Carlo simulation of evaporation-driven self-assembly in suspensions of colloidal rods

et al. 2016

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The vertical drying of a colloidal film containing rodlike particles was studied by means of kinetic Monte Carlo (MC) simulation. The problem was approached using a two-dimensional square lattice, and the rods were represented as linear k-mers (i.e., particles occupying k adjacent sites). The initial state before drying was produced using a model of random sequential adsorption (RSA) with isotropic orientations of the k-mers (orientation of the k-mers along horizontal x and vertical y directions are equiprobable). In the RSA model, overlapping of the k-mers is forbidden. During the evaporation, an upper interface falls with a linear velocity of u in the vertical direction and the k-mers undergo translation Brownian motion. The MC simulations were run at different initial concentrations, p_{i}, (p_{i}∈[0,p_{j}], where p_{j} is the jamming concentration), lengths of k-mers (k∈[1,12]), and solvent evaporation rates, u. For completely dried films, the spatial distributions of k-mers and their electrical conductivities in both x and y directions were examined. Significant evaporation-driven self-assembly and orientation stratification of the k-mers oriented along the x and y directions were observed. The extent of stratification increased with increasing value of k. The anisotropy of the electrical conductivity of the film can be finely regulated by changes in the values of p_{i}, k, and u.

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Evaporation of Sessile Drops Containing Colloidal Rods: Coffee-Ring and Order–Disorder Transition

Cited by 63 publications

References 34 publications

Self-assembly of nano-ellipsoids into ordered structures via vertical deposition

Self-assembly of nano-ellipsoids into ordered structures via vertical deposition

Role of particle shape anisotropy on crack formation in drying of colloidal suspension

Monte Carlo simulation of evaporation-driven self-assembly in suspensions of colloidal rods

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