Dynamical Density Functional Theory for the Drying and Stratification of Binary Colloidal Dispersions

He, Boshen; Martín-Fabiani, Ignacio; Roth, Roland; Tóth, Gyula I.; Archer, Andrew J.

doi:10.1021/acs.langmuir.0c02825

Cited by 20 publications

(25 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, the ability to isolate and determine the depth-resolved properties is a unique feature, which can be critical when attempting to track the stratification dynamics of colloidal mixtures and to test the dynamical density functional theories in different practical situations. 27 , 36 …”

Section: Discussionmentioning

confidence: 99%

Simultaneous Spatiotemporal Measurement of Structural Evolution in Dynamic Complex Media

Dogariu

2022

ACS Omega

View full text Add to dashboard Cite

When the properties of soft materials evolve in time, the simultaneous measurement of different characteristics is critical. Here, we demonstrate an experimental system that permits monitoring both the spatial and temporal evolution of the optical and mechanical properties. An integrated fiber-optic-based system allows determining the mechanical vibrations of structural elements over 5 orders of magnitude and over a broad frequency range. At the same time, the optical properties can be obtained within seconds from high-resolution measurements of the path-length distribution of reflected light. With proper cyclical scanning, the temporal evolution of the mesoscopic light scattering properties can be obtained in a depth-resolved manner. The performance of this integrated measurement is validated in the particular case of drying paint films. For these typical nonstationary media, we show how our approach provides unique access to the spatiotemporal material properties and how this information permits identifying the specific stages of structural evolution.

show abstract

Section: Discussionmentioning

confidence: 99%

Simultaneous Spatiotemporal Measurement of Structural Evolution in Dynamic Complex Media

Dogariu

2022

ACS Omega

View full text Add to dashboard Cite

show abstract

“…This process is used for modeling solvent water evaporation. 10 , 12 , 31 The interaction between particles of the same species is modeled via a truncated 12-6 Lennard-Jones (LJ) potential of the form where ε ii defines the attraction strength between particles, and σ ii = 2 R i . Note, the cutoff means that ϕ ii ( r ) are purely repulsive.…”

Section: Simulation Sectionmentioning

confidence: 99%

Effect of Particle Interactions on the Assembly of Drying Colloidal Mixtures

et al. 2022

Self Cite

View full text Add to dashboard Cite

The effects of particle interactions on the size segregation and assembly of colloidal mixtures during drying were investigated. A cationic surfactant was added to a binary latex/silica colloidal dispersion that has been shown to self-stratify upon drying at room temperature. Atomic force microscopy was used to show that the change in particle interactions due to the presence of surfactants reduced the degree of stratification and, in some cases, suppressed the effect altogether. Colloidal dispersions containing higher surfactant concentrations can undergo a complete morphology change, resulting instead in the formation of armored particles consisting of latex particles coated with smaller silica nanoparticles. To further prove that armored particles are produced and that stratification is suppressed, cross-sectional images were produced with energy-dispersive X-ray spectroscopy and confocal fluorescence microscopy. The growth of armored particles was also measured using dynamic light scattering. To complement this research, Brownian dynamics simulations were used to model the drying. By tuning the particle interactions to make them more attractive, the simulations showed the presence of armored particles, and the size segregation process was hindered. The prevention of segregation also results in enhanced transparency of the colloidal films. Overall, this research proves that there is a link between particle interactions and size segregation in drying colloidal blends and provides a valuable tool to control the assembly of different film architectures using an extremely simple method.

show abstract

“…As a result, they found that there is a Pe L where small-on-top stratification is the most enhanced. Most of the previous simulation studies have focused on observing the small-on-top stratification according to the Péclet number. ,− There were limitations in the analysis of the stress and microstructure during the drying process and of the origin for the stratification from a microscopic point of view.…”

Section: Introductionmentioning

confidence: 99%

Stratification Mechanism in the Bidisperse Colloidal Film Drying Process: Evolution and Decomposition of Normal Stress Correlated with Microstructure

2021

View full text Add to dashboard Cite

The evolution of the normal stress and microstructure in the drying process of bidisperse colloidal films is studied using the Brownian dynamics simulation. Here, we show that the formation process of small-on-top stratification can be explained by normal stress development. At high Pe L’s, a stratified layer with small particles is formed near the interface. The accumulated particles near the interface induce the localization of normal stress so that the normal stress at the interface increases from the beginning of drying. We analyze this stress development from two points of view, on the global length scale and particle length scale. On the global length scale, the localization of normal stress is quantified by the scaled normal stress difference between the interface and substrate. For all Pe L’s tested in this study, the scaled normal stress difference increases until the accumulation region reaches the substrate. After the maximum, the stress difference remains at the maximum at lower Pe L’s, while it decreases at higher Pe L’s. The microstructural analysis shows that this stress development is explained through the evolution of the particle contact number distribution at the interface and substrate. On the particle length scale, we derive the scaled local force applied to each type of particle by decomposing the local normal stress. At high Pe L’s, the scaled local force for the large particle is large compared to that for the small particle near the interface, indicating that the large particles are strongly pushed away from the interface. Associating the volume fraction profile with the local force field, we suggest that the strong scaled force for the large particle is attributed to the significant increase in the average number of small particles in contact with large ones. This study has significance in probing the drying mechanism of bidisperse colloidal films and the stratification mechanism.

show abstract

Dynamical Density Functional Theory for the Drying and Stratification of Binary Colloidal Dispersions

Cited by 20 publications

References 59 publications

Simultaneous Spatiotemporal Measurement of Structural Evolution in Dynamic Complex Media

Simultaneous Spatiotemporal Measurement of Structural Evolution in Dynamic Complex Media

Effect of Particle Interactions on the Assembly of Drying Colloidal Mixtures

Stratification Mechanism in the Bidisperse Colloidal Film Drying Process: Evolution and Decomposition of Normal Stress Correlated with Microstructure

Contact Info

Product

Resources

About