Suppression of sub-surface freezing in free-standing thin films of a coarse-grained model of water

Haji-Akbari, Amir; DeFever, Ryan S.; Sarupria, Sapna; Debenedetti, Pablo G.

doi:10.1039/c4cp03948c

Cited by 75 publications

(143 citation statements)

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“…It can be seen, in the first place, that the volumetric ice nucleation is almost seven orders of magnitude larger in the film geometry. This is contrary to what we had previously observed in the coarse-grained mW system, in which the nucleation rate decreases by seven orders of magnitude in going from the bulk to a 2.5-nm-thick freestanding nanofilm (29). This marked qualitative difference between the two systems is remarkable and will be further discussed below.…”

Section: Resultscontrasting

confidence: 55%

“…Unlike in TIP4P/ice, surface freezing is suppressed in the coarse-grained mW system (28,29). To explore the origin of this different behavior, we perform the same type of cage statistics analysis in the mW system, at the same temperature (and pressure) as TIP4P/ice.…”

Section: Resultsmentioning

confidence: 99%

“…Li et al (28) and Haji-Akbari et al (29) use forward-flux sampling (FFS) (30) to compute nucleation rates in droplets (28) and freestanding thin films (29) of supercooled mW. By comparing the nucleation rates in the bulk (29,31) and in confined (28,29) geometries, they both conclude that surface freezing is suppressed in the mW system. These findings are interesting in the sense that the mW system satisfies (32) the partial wettability condition articulated in refs.…”

mentioning

confidence: 99%

“…The model of choice for the overwhelming majority of computational studies of surface freezing has been the coarsegrained monoatomic water (mW) potential (27). Li et al (28) and Haji-Akbari et al (29) use forward-flux sampling (FFS) (30) to compute nucleation rates in droplets (28) and freestanding thin films (29) of supercooled mW. By comparing the nucleation rates in the bulk (29,31) and in confined (28,29) geometries, they both conclude that surface freezing is suppressed in the mW system.…”

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confidence: 99%

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Computational investigation of surface freezing in a molecular model of water

Haji-Akbari

Debenedetti

2017

Proc. Natl. Acad. Sci. U.S.A.

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Water freezes in a wide variety of low-temperature environments, from meteors and atmospheric clouds to soil and biological cells. In nature, ice usually nucleates at or near interfaces, because homogenous nucleation in the bulk can only be observed at deep supercoolings. Although the effect of proximal surfaces on freezing has been extensively studied, major gaps in understanding remain regarding freezing near vapor-liquid interfaces, with earlier experimental studies being mostly inconclusive. The question of how a vapor-liquid interface affects freezing in its vicinity is therefore still a major open question in ice physics. Here, we address this question computationally by using the forward-flux sampling algorithm to compute the nucleation rate in a freestanding nanofilm of supercooled water. We use the TIP4P/ice force field, one of the best existing molecular models of water, and observe that the nucleation rate in the film increases by seven orders of magnitude with respect to bulk at the same temperature. By analyzing the nucleation pathway, we conclude that freezing in the film initiates not at the surface, but within an interior region where the formation of doublediamond cages (DDCs) is favored in comparison with the bulk. This, in turn, facilitates freezing by favoring the formation of nuclei rich in cubic ice, which, as demonstrated by us earlier, are more likely to grow and overcome the nucleation barrier. The films considered here are ultrathin because their interior regions are not truly bulk-like, due to their subtle structural differences with the bulk.ice | nucleation | molecular simulations | surface freezing | statistical mechanics F reezing of water into ice is ubiquitous in nature and can occur in a wide range of environments, from biological cells (1) and soil (2) to meteors (3) and atmospheric clouds (4). Ice formation is particularly important in the atmospheric processes that exert a major influence on our weather and climate. Indeed, the radiative properties (4) and precipitation propensity (5) of a cloud are both determined by the amount of ice that it harbors. Not surprisingly, the liquid fraction of clouds is an extremely important input parameter in meteorological models (6). Freezing is a first-order phase transition and proceeds through a mechanism known as nucleation and growth. In mixed-phase clouds, which are responsible for the bulk of land surface precipitation (7), freezing is usually nucleationlimited, and individual freezing events are rare. Predicting the timing of such rare freezing events is important in modeling cloud microphysics. However, nucleation rates, which are volume-or area-normalized inverse nucleation times, can only be measured experimentally over a narrow range of temperatures and pressures (8), and extrapolations to other temperatures are nontrivial (9). In nature, homogeneous nucleation of ice is only likely at very low temperatures, and the majority of freezing events in mixed-phase clouds occur heterogeneously, at interfaces provided by external insol...

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Section: Resultscontrasting

confidence: 55%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Computational investigation of surface freezing in a molecular model of water

Haji-Akbari

Debenedetti

2017

Proc. Natl. Acad. Sci. U.S.A.

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“…For this adsorption energy the molecules basically face a hard wall which in turn could even hinder nucleation compared to the homogeneous case 33,[76][77][78] . By analyzing the distribution of pre-critical nuclei (see SI, Figure S8) we find that these avoid the neighborhood of the surface for mentioned E ads range.…”

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confidence: 99%

The Many Faces of Heterogeneous Ice Nucleation: Interplay Between Surface Morphology and Hydrophobicity

et al. 2015

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What makes a material a good ice nucleating agent? Despite the importance of heterogeneous ice nucleation to a variety of fields, from cloud science to microbiology, major gaps in our understanding of this ubiquitous process still prevent us from answering this question. In this work, we have examined the ability of generic crystalline substrates to promote ice nucleation as a function of the hydrophobicity and the morphology of the surface. Nucleation rates have been obtained by brute-force molecular dynamics simulations of coarse-grained water on top of different surfaces of a model fcc crystal, varying the watersurface interaction and the surface lattice parameter. It turns out that the lattice mismatch of the surface with respect to ice, customarily regarded as the most important requirement for a good ice nucleating agent, is at most desirable but not a requirement. On the other hand, the balance between the morphology of the surface and its hydrophobicity can significantly alter the ice nucleation rate and can also lead to the formation of up to three different faces of ice on the same substrate. We have pinpointed three circumstances where heterogeneous ice nucleation can be promoted by the crystalline surface: i) the formation of a water overlayer that acts as an in-plane template; ii) the emergence of a contact layer buckled in an ice-like manner; and iii) nucleation on compact surfaces with very high interaction strength. We hope that this extensive systematic study will foster future experimental work aimed at testing the physiochemical understanding presented herein.

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“Magic Numbers” in Self‐Faceting of Alcohol‐Doped Emulsion Droplets

Hacmon,

Liber,

Shool

et al. 2023

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Oil‐in‐water emulsion droplets spontaneously adopt, below some temperature Td, counterintuitive faceted and complex non‐spherical shapes while remaining liquid. This transition is driven by a crystalline monolayer formed at the droplets' surface. Here, we show that ppm‐level doping of the droplet's bulk by long‐chain alcohols allows tuning Td by >50 °C, implying formation of drastically different interfacial structures. Furthermore, “magic” alcohol chain lengths maximize Td. This we show to arise from self‐assembly of mixed alcohol:alkane interfacial structures of stacked alkane layers, co‐crystallized with hydrogen‐bonded alcohol dimers. These structures are accounted for theoretically and resolved by direct cryogenic transmission electron microscopy (cryoTEM), confirming the proposed structures. The discovered tunability of key properties of commonly‐used emulsions by minute concentrations of specific bulk additives should benefit these emulsions' technological applicability.

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Suppression of sub-surface freezing in free-standing thin films of a coarse-grained model of water

Cited by 75 publications

References 70 publications

Computational investigation of surface freezing in a molecular model of water

Computational investigation of surface freezing in a molecular model of water

The Many Faces of Heterogeneous Ice Nucleation: Interplay Between Surface Morphology and Hydrophobicity

“Magic Numbers” in Self‐Faceting of Alcohol‐Doped Emulsion Droplets

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