A Monte Carlo density functional theory for the competition between inter and intramolecular association in inhomogeneous fluids

Marshall, Bennett D.; García-Cuéllar, Alejandro J.; Chapman, Walter G.

doi:10.1063/1.4807587

Cited by 3 publications

(6 citation statements)

References 47 publications

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“…In the ideal low-density limit, X a = 1 for all a ∈ Γ , which results in lim ρ→0 A Wert = 0. A Wert here is thus a residual contribution from association A assoc , and the expected expression [33,34,40] is recovered after substituting Equation (63) in Equation 61:…”

Section: Open Chain Clustersmentioning

confidence: 99%

“…The calculated surface tension and solid/fluid partitioning of four-segment chain molecules exhibiting intra-and intermolecular hydrogen bonding were found to be in excellent agreement with simulation. The method is computationally very demanding for molecules with more than five segments, and in later work the authors proposed an approach to speed up the calculation through the use of Monte Carlo ensemble averages to compute a number of the integrals required [63]. An extension for the case of mixtures of associating chains with multiple sites in a water-like solvent was also developed [64].…”

Section: Introductionmentioning

confidence: 99%

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Intramolecular bonding in a statistical associating fluid theory of ring aggregates

et al. 2019

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The first-order thermodynamic perturbation theory of Wertheim (TPT1) is extended to treat ring aggregates, formed by inter-and intramolecular association. The expression for the residual association contribution to the Helmholtz free energy for ring aggregates, incorporating the appropriate terms in Wertheim's fundamental graph sum of the TPT1 density expansion, is derived to calculate the distribution of the molecular bonding states. This requires the introduction of two new parameters to characterise each possible ring type: the ring size τ , which is equal to one in the case of intramolecular association, and a parameter W that captures the likelihood of two ring-forming sites bonding. The resulting framework can be incorporated in equations of state that account for the residual association contribution to the free energy, such as the statistical associating fluid theory (SAFT) family, or the cubic plus association (CPA) equation of state. This extends the applicability of these equations of state to mixtures with an arbitrary number of association sites capable of hydrogen bonding to form intramolecular and intermolecular rings. The formalism is implemented within SAFT-VR Mie to calculate the fluid-phase equilibria of model chain-like molecules containing two associating sites A and B, allowing for the formation of open-chain aggregates and intramolecular bonds. The effect of adding a second component that competes for the association sites that mediate intramolecular association in the chain is also examined. Accounting for intramolecular bonding is shown to have a significant impact on the phase equilibria of such systems.

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Section: Open Chain Clustersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Intramolecular bonding in a statistical associating fluid theory of ring aggregates

et al. 2019

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“…Also The chain integral can be broken down to give the chain connectivity where and The ring integrals described in eq are computationally very intensive because they require n -body integrals for n -mer rings. Here we will use the Monte Carlo DFT developed by Marshall et al, which is much faster than doing actual integrals. The integrals are written as ensemble averages over a single-chain probability distribution function and are evaluated using Monte Carlo simulations.…”

Section: Model and Theorymentioning

confidence: 99%

“…All of these theories, though successfully applied to homogeneous (bulk) systems, are not written in a way that allows for an easy extension to study inhomogeneous systems. Recently, Marshall et al , developed a DFT in Wertheim’s perturbation theory framework to study intramolecular association of chains in an inhomogeneous system. While this theory is a significant contribution, it was developed for the specific case of just two sites on a chain without any solvent in the system.…”

Section: Introductionmentioning

confidence: 99%

Competition between Intra- and Intermolecular Association of Chain Molecules with Water-like Solvent

Ballal

Chapman

2015

J. Phys. Chem. B

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Fluid properties and phase behavior of systems such as glycol ethers, carboxylic acids, and proteins are affected by the competition between intra- and intermolecular hydrogen bonding. Here we study this competition by extending Wertheim's first-order thermodynamic perturbation theory to include intramolecular hydrogen bonding in chain molecules in the presence of an explicit water-like solvent. The theory derived here is found to be in good agreement with molecular simulation. It is shown that intramolecular association is most important for shorter chains at low temperature, low density, and high chain concentration. The theory is also extended into a density functional theory formalism to study the effect of intramolecular association on the structuring of the different segments of the molecules close to a hydrophobic surface. Intramolecular association is found to be enhanced close to the surface, with the total density of the system having the most effect on structuring close to the surface.

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“…Woodward has investigated a mixture of polymers and hard spheres in slit pores [14,15] have analysed a mixture of hard-sphere chains confined in a slit. Marshall et al [17] have developed an MC DFT for chain molecules with intra and intermolecular association and applied for tetramer fluid in planar hard slit pores. Structure of size symmetric hard-sphere dimers in the vicinity of a hard wall have been considered by Labík et al [18].…”

Section: Introductionmentioning

confidence: 99%

Interfacial properties of linear molecules modelled by dimer near a hard wall. A Monte Carlo and a density functional theory investigation

2014

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The density profile, g(x), and angular orientation function, , of a dimer molecule formed by two tangentially tethered hard spheres with both equal and different diameters, are studied by means of Monte Carlo (MC) simulation. Density functional theory (DFT) is used for the case where both sphere diameters are equal. For this case, the MC and DFT results for g(x) are in good agreement. At low densities, the contact value for g(x) is less than 1, its value at a large distance from the wall. This contrasts with a monomer hard-sphere fluid, where the contact value of g(x) is always greater than or equal to 1. This result is a consequence of the hindered rotation of dimers near the wall what lowers their entropy in comparison with its value in the bulk. This conjecture is confirmed by our MC studies of dimers formed by hard spheres of unequal size.

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A Monte Carlo density functional theory for the competition between inter and intramolecular association in inhomogeneous fluids

Cited by 3 publications

References 47 publications

Intramolecular bonding in a statistical associating fluid theory of ring aggregates

Intramolecular bonding in a statistical associating fluid theory of ring aggregates

Competition between Intra- and Intermolecular Association of Chain Molecules with Water-like Solvent

Interfacial properties of linear molecules modelled by dimer near a hard wall. A Monte Carlo and a density functional theory investigation

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