Surface-directed spinodal decomposition in binary fluid mixtures on an amorphous wall: A molecular dynamics study
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| Format: | Preprint |
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2025
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| _version_ | 1866911306439720960 |
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| author | Zaidi, Syed Shuja Hasan Priya, Madhu Puri, Sanjay Jaiswal, Prabhat K. |
| author_facet | Zaidi, Syed Shuja Hasan Priya, Madhu Puri, Sanjay Jaiswal, Prabhat K. |
| contents | We present molecular dynamics (MD) results to discuss wetting kinetics in binary fluid mixtures ($A:B=50:50$) undergoing surface-directed spinodal decomposition (SDSD) on an amorphous wall. Our simulations show the formation of a wetting layer rich in the preferred $A$-type particles and bicontinuous domain morphology in the bulk. In addition, the mixture maintains connectivity between the bulk and the wetting layer through $A$-rich tubes throughout the depletion region. The wetting layer thickness coarsens as a power law, $R_1(t)\sim t^α$, with two distinct growth regimes of $α=1/3$ and $α=1$ active for at least a decade. The computed crossover time for $α=1/3 \to 1$ equaled the reported bulk crossover time, and the corresponding crossover length scale $R_c$ agrees well with the expression $Λ= \sqrt{2k/γ_0}$ given by Scholten et al.~[\emph{Macromolecules}2005, 38, 3515] for bicontinuous domains in aqueous polymer mixtures in the presence of only one dominant length scale. This agreement supports a hydrodynamic picture of diffusive growth for the interconnected wetting layer and bulk domains, where the bending contribution ($k$) of curvature-dependent $AB$ interfacial tension ($γ$) governs small-scale coarsening, producing $t^{1/3}$ growth. For length scales beyond $Λ$, capillary flows yield the viscous hydrodynamic regime ($\sim t$). Our results show no orientational effects on the domain coarsening parallel and perpendicular to the wall, contrasting many continuum models, including combinations with Flory-Huggins theory. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2512_06911 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Surface-directed spinodal decomposition in binary fluid mixtures on an amorphous wall: A molecular dynamics study Zaidi, Syed Shuja Hasan Priya, Madhu Puri, Sanjay Jaiswal, Prabhat K. Soft Condensed Matter Statistical Mechanics We present molecular dynamics (MD) results to discuss wetting kinetics in binary fluid mixtures ($A:B=50:50$) undergoing surface-directed spinodal decomposition (SDSD) on an amorphous wall. Our simulations show the formation of a wetting layer rich in the preferred $A$-type particles and bicontinuous domain morphology in the bulk. In addition, the mixture maintains connectivity between the bulk and the wetting layer through $A$-rich tubes throughout the depletion region. The wetting layer thickness coarsens as a power law, $R_1(t)\sim t^α$, with two distinct growth regimes of $α=1/3$ and $α=1$ active for at least a decade. The computed crossover time for $α=1/3 \to 1$ equaled the reported bulk crossover time, and the corresponding crossover length scale $R_c$ agrees well with the expression $Λ= \sqrt{2k/γ_0}$ given by Scholten et al.~[\emph{Macromolecules}2005, 38, 3515] for bicontinuous domains in aqueous polymer mixtures in the presence of only one dominant length scale. This agreement supports a hydrodynamic picture of diffusive growth for the interconnected wetting layer and bulk domains, where the bending contribution ($k$) of curvature-dependent $AB$ interfacial tension ($γ$) governs small-scale coarsening, producing $t^{1/3}$ growth. For length scales beyond $Λ$, capillary flows yield the viscous hydrodynamic regime ($\sim t$). Our results show no orientational effects on the domain coarsening parallel and perpendicular to the wall, contrasting many continuum models, including combinations with Flory-Huggins theory. |
| title | Surface-directed spinodal decomposition in binary fluid mixtures on an amorphous wall: A molecular dynamics study |
| topic | Soft Condensed Matter Statistical Mechanics |
| url | https://arxiv.org/abs/2512.06911 |