Intramolecular association in flexible hard chain molecules

Ghonasgi, D.; Pérez, V.; Chapman, Walter G.

doi:10.1063/1.468317

Cited by 61 publications

(55 citation statements)

References 41 publications

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“…Wertheim's theoretical framework has now been extended to deal with association into ring-like structures [53,54,[79][80][81][82][83][84][85], double bonding [85,86], and the effects of cooperative bonding on the energetics of the association interactions [84,87,88]. A number of recent developments have been made to increase the scope and general applicability of Wertheim's approach [89][90][91][92][93][94][95][96], largely motivated by a new found interest in the theory as applied to the description of the effect of association on the properties and phase behaviour of proteins and patchy colloids (e.g., see references [97][98][99][100][101][102][103][104][105][106][107][108]).…”

Section: Introductionmentioning

confidence: 99%

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

et al. 2015

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(2015) The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids, Molecular Physics, 113:9-10, 948-984, DOI: 10.1080/00268976.2015 An accurate representation of molecular association is a vital ingredient of advanced equations of state (EOSs), providing a description of thermodynamic properties of complex fluids where hydrogen bonding plays an important role. The combination of the first-order thermodynamic perturbation theory (TPT1) of Wertheim for associating systems with an accurate description of the structural and thermodynamic properties of the monomer fluid forms the basis of the statistical associating fluid theory (SAFT) family of EOSs. The contribution of association to the free energy in SAFT and related EOSs is very sensitive to the nature of intermolecular potential used to describe the monomers and, crucially, to the accuracy of the representation of the thermodynamic and structural properties. Here we develop an accurate description of the association contribution for use within the recently developed SAFT-VR Mie framework for chain molecules formed from segments interacting through a Mie potential [T. Lafitte, A. Apostolakou, C. Avendaño, A, Galindo, C. S. Adjiman, E. A. Müller, and G. Jackson, J. Chem. Phys. 139, 154504 (2013)]. As the Mie interaction represents a soft-core potential model, a method similar to that adopted for the Lennard-Jones potential [E. A. Müller and K. E. Gubbins, Ind. Eng. Chem. Res. 34, 3662 (1995)] is employed to describe the association contribution to the Helmholtz free energy. The radial distribution function (RDF) of the Mie fluid (which is required for the evaluation of the integral at the heart of the association term) is determined for a broad range of thermodynamic conditions (temperatures and densities) using the reference hyper-netted chain (RHNC) integral-equation theory. The numerical data for the association kernel of Mie fluids with different association geometries are then correlated for a range of thermodynamic states to obtain a general expression for the association contribution which can be applied for varying values of the Mie repulsive exponent. The resulting SAFT-VR Mie EOS allows for a much improved description of the vapour-liquid equilibria and single-phase properties of associating fluids such as water, methanol, ammonia, hydrogen sulphide, and their mixtures. A comparison is also made between the theoretical predictions of the degree of association for water and the extent of hydrogen bonding obtained from molecular simulations of the SPC/E and TIP4P/2005 atomistic models.

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Section: Introductionmentioning

confidence: 99%

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

et al. 2015

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“…To account for the possibility of intramolecular association Sear and Jackson 12 modified TPT by adding a ring graph to the fundamental graph sum. In a separate approach Ghonasgi and Chapman 13,14 developed a theory to account for intramolecular association; their theory was found to be in excellent agreement with molecular simulations.…”

Section: Introductionmentioning

confidence: 83%

“…(15) and (16) can be neglected. Equations (15) and (16) (14). The resulting segmental densities are (27) We will find it necessary to employ a two point chain density ) , (…”

Section: Ii: Theorymentioning

confidence: 99%

A perturbation density functional theory for the competition between inter and intramolecular association

Marshall

García-Cuéllar

Chapman

2012

The Journal of Chemical Physics

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Using the framework of Wertheim's thermodynamic perturbation theory we develop the first density functional theory which accounts for intramolecular association in chain molecules. To test the theory new Monte Carlo simulations are performed at a fluid solid interface for a 4 segment chain which can both intra and intermolecularly associate. The theory and simulation results are found to be in excellent agreement. It is shown that the inclusion of intramolecular association can have profound effects on interfacial properties such as interfacial tension and the partition coefficient.

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“…In this work, we follow Ghonasgi and Chapman 17,18 and consider molecules which consist of a chain of m hard spherical segments of diameter σ bonded at hard sphere contact. Each position on the chain is occupied by a certain species of segment, so there are m species of segments in total.…”

Section: Theorymentioning

confidence: 99%

“…17,18 SJ developed a bulk equation of state in the framework of Wertheim's thermodynamic perturbation theory (TPT). [19][20][21][22][23] Wertheim developed a multi density statistical mechanical formalism, where each bonding state of a molecule is assigned a density, which is ideal for short range directional interactions.…”

Section: Introductionmentioning

confidence: 99%

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

Marshall

García-Cuéllar

Chapman

2013

The Journal of Chemical Physics

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A Monte Carlo density functional theory is developed for chain molecules which both intra and intermolecularly associate. The approach can be applied over a range of chain lengths. The theory is validated for the case of an associating 4-mer fluid in a planar hard slit pore. Once validated, the new theory is used to study the effect of chain length and temperature on the competition between intra and intermolecular association near a hard wall. We show that this competition enhances intramolecular association near wall contact and inverts the chain length dependence of the fraction bonded intermolecularly in the inhomogeneous region. © 2013 AIP Publishing LLC.

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Intramolecular association in flexible hard chain molecules

Cited by 61 publications

References 41 publications

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

A perturbation density functional theory for the competition between inter and intramolecular association

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

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