The coalescence of polystyrene in correlated binary solvents

Besford, Quinn A.; Liu, Maoyuan; Beattie, James K.; Gray‐Weale, Angus

doi:10.1002/polb.24003

Cited by 3 publications

(3 citation statements)

References 33 publications

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“…This suggests that the driving mechanism is outside of the conceptual-lock of hydrogen bonding (or at least the domination aspect thereof). Previously, we have observed that dipolar dispersion forces contribute significantly to the thermodynamics at solid and liquid–vapor interfaces, as well as in bulk systems. ,, Therefore, these same forces were investigated for the complex dipolar MeOH–water mixtures. Our methods allow the computation of dipolar interactions as a pair-interaction in solution between molecules (eq ).…”

Section: Resultsmentioning

confidence: 99%

Dipolar Dispersion Forces in Water–Methanol Mixtures: Enhancement of Water Interactions upon Dilution Drives Self-Association

2022

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Mixtures of short-chain alcohols and water produce anomalous thermodynamic and structural quantities, including molecular segregation into water-rich and alcohol-rich components. Herein, we used molecular dynamics simulations with polarizable models to investigate interactions that could drive the self-association of water molecules in mixtures with methanol (MeOH). As water was diluted with MeOH, significant changes in the distribution of molecules and solvation properties occurred, where water exhibited a clear preference for self-association. When common structural quantities were analyzed, it was found that there was a clear reduction in water–water hydrogen bonding and tetrahedral order (both in terms of typical bulk behavior), contrary to the observed water self-association. However, when dipolar dispersion forces between all molecules as a function of system composition were analyzed, it was found that water–water dipolar interactions became significantly stronger with dilution (6-fold stronger interaction in 75% MeOH compared to 0% MeOH). This was only observed for water, where MeOH–MeOH interactions became weaker as the systems were more dilute in MeOH. These forces result from specific dipole orientations, likely occurring to adopt lower energy configurations (i.e., head-to-tail or antiparallel). For water, this may result from lost other interactions (e.g., hydrogen bonding), leading to more rotational freedom between the dipole moments. These intriguing changes in dipolar interactions, which directly result from structural changes, can therefore explain, in part, the driving force for water self-association in MeOH–water mixtures.

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Section: Resultsmentioning

confidence: 99%

Dipolar Dispersion Forces in Water–Methanol Mixtures: Enhancement of Water Interactions upon Dilution Drives Self-Association

2022

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“…Complex solvation phenomena occur in polar liquids, which include specific ion effects in aqueous 1,2 and nonaqueous systems, 3 solvophobic effects that reduce the solubility and drive the coalescence of apolar species immersed in polar liquids 4,5 as well as the high surface energies of polar liquids. 6 The mechanistic driving force behind these phenomena is not well understood but is likely related to the perturbation of the liquid's structure by solutes and interfaces 7 and how that enhances or diminishes intermolecular correlations.…”

Section: Introductionmentioning

confidence: 99%

Long-range dipolar order and dispersion forces in polar liquids

Besford

Christofferson

Liu

et al. 2017

The Journal of Chemical Physics

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Complex solvation phenomena, such as specific ion effects, occur in polar liquids. Interpretation of these effects in terms of structure and dispersion forces will lead to a greater understanding of solvation. Herein, using molecular dynamics, we probe the structure of polar liquids through specific dipolar pair correlation functions that contribute to the potential of mean force that is "felt" between thermally rotating dipole moments. It is shown that unique dipolar order exists at separations at least up to 20 Å for all liquids studied. When the structural order is compared with a dipolar dispersion force that arises from local co-operative enhancement of dipole moments, a strong agreement is found. Lifshitz theory of dispersion forces was compared with the structural order, where the theory is validated for all liquids that do not have significant local dipole correlations. For liquids that do have significant local dipole correlations, specifically liquid water, Lifshitz theory underestimates the dispersion force by a factor of 5-10, demonstrating that the force that leads to the increased structure in liquid water is missed by Lifshitz theory of van der Waals forces. We apply similar correlation functions to an ionic aqueous system, where long-range order between water's dipole moment and a single chloride ion is found to exist at 20 Å of separation, revealing a long-range perturbation of water's structure by an ion. Furthermore, we found that waters within the 1st, 2nd, and 3rd solvation shells of a chloride ion exhibit significantly enhanced dipolar interactions, particularly with waters at larger distances of separation. Our results provide a link between structures, dispersion forces, and specific ion effects, which may lead to a more robust understanding of solvation.

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“…By this definition, the conformation of a single polymer chain in the brush is not independent of its neighbors, meaning that transitions in polymer conformation tend to be rapid, communal, and dramatic across the range from fully swollen to collapsed. The stimuli that cause these polymer transitions come in many forms, such as environmental (pH, [ 1 ] ionic strength, [ 2 ] solvent, [ 3 ] temperature, [ 4 ] solutes [ 5 ] ) and applied (direct contact, [ 6 ] shear flow [ 7 ] ). As the polymers undergo conformational transitions, the interactions between chains and the orientation of surface‐exposed groups changes significantly.…”

Section: Introductionmentioning

confidence: 99%

Spatially Resolving Polymer Brush Conformation: Opportunities Ahead

Besford

Uhlmann

Fery

2022

Macro Chemistry & Physics

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Surfaces that respond to local environmental stimuli offer intriguing possibilities for new surface-based sensing concepts to emerge. An attractive concept is to push beyond the milli-to micrometer lateral resolution limit in sensing, toward the ultimate surface-sensitive device; one capable of real-time sensing of the nanoscopic, or molecular "touch." This sensing needs an approach that is capable of spatially transducing information on nanotouch. Polymer brushes are a class of surface that provides dramatic changes in surface properties depending on stimuli that affect the conformation of end-tethered polymer chains. However, the brush response is typically quantified by measuring changes in polymer brush "height". That is, the ensemble average distance over which polymer density exists away from the anchoring surface (i.e., a single parameter to describe the surface). Moving beyond this conceptual paradigm of quantifying the ensemble average height in a single dimension over the entire surface under applied stimuli, developing methods for spatially resolving chain conformation has the very real potential to lead to extraordinary possibilities in the applied sciences. In this perspective, the current paradigms and methods forward for extracting rich details on polymer brush conformational dynamics that is spatially resolved, which can lead to new understandings of surface contact, are discussed and pointed out.

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The coalescence of polystyrene in correlated binary solvents

Cited by 3 publications

References 33 publications

Dipolar Dispersion Forces in Water–Methanol Mixtures: Enhancement of Water Interactions upon Dilution Drives Self-Association

Dipolar Dispersion Forces in Water–Methanol Mixtures: Enhancement of Water Interactions upon Dilution Drives Self-Association

Long-range dipolar order and dispersion forces in polar liquids

Spatially Resolving Polymer Brush Conformation: Opportunities Ahead

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