Group Contribution Coarse-Grained Molecular Simulations of Polystyrene Melts and Polystyrene Solutions in Alkanes Using the SAFT-γ Force Field

Jiménez-Serratos, Guadalupe; Herdes, Carmelo; Haslam, Andrew J.; Jackson, George; Müller, Erich A.

doi:10.1021/acs.macromol.6b02072

Cited by 33 publications

(46 citation statements)

References 73 publications

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“…This proposal is made on the basis of our observations of bis-PCBM/PS bilayers annealed at various temperatures, theoretical expectations (see for example refs. 63,64 ), and experimental findings from other polymer/solvent and polymer/fullerene systems 32,63,65 (see Supplementary Note 7 for details).…”

Section: Resultsmentioning

confidence: 99%

Interfacial width and phase equilibrium in polymer-fullerene thin-films

et al. 2019

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Domain composition and interfacial structure are critical factors in organic photovoltaic performance. Here, we report neutron reflectivity, grazing-incidence X-ray diffraction and atomic force microscopy measurements of polymer/fullerene thin-films to test a hypothesis that these partially miscible blends rapidly develop composition profiles consisting of coexisting phases in liquid-liquid equilibrium. We study a range of polymer molecular weights between 2 and 300 kg mol −1 , annealing temperatures between 120 and 170 o C, and timescales up to 10 min, yielding over 50 distinct measurement conditions. Model bilayers of fullerene-derivatives and polystyrene enable a rigorous examination of theoretical predictions of the effect of polymer mass and interaction parameter on the compositions, ϕ, and interfacial width, w, of the coexistent phases. We independently measure ϕ and w and find that both Flory-Huggins mean-field-theory and key aspects of self-consistent-field-theory are remarkably consistent with experiment. Our findings pave the way for predictive composition and interface design in organic photovoltaics based on simple experimental measurements and equilibrium thermodynamic theory.

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Section: Resultsmentioning

confidence: 99%

Interfacial width and phase equilibrium in polymer-fullerene thin-films

et al. 2019

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“…This is a well-established approach for classical Mie fluids. [66][67][68] Previous work 13 has suggested that the LJ-FH1 potential yields an accurate representation of the VLE envelope of neon, normal hydrogen, and helium. By performing GEMC simulations with the same potentials, we were able to reproduce their simulation results for neon and hydrogen, but obtained different results for helium.…”

Section: General Discussion Of Feynman-hibbs Correctionsmentioning

confidence: 99%

Equation of state and force fields for Feynman–Hibbs-corrected Mie fluids. I. Application to pure helium, neon, hydrogen, and deuterium

Aasen

Hammer

Ervik

et al. 2019

The Journal of Chemical Physics

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We present a perturbation theory that combines the use of a third-order Barker–Henderson expansion of the Helmholtz energy with Mie-potentials that include first- (Mie-FH1) and second-order (Mie-FH2) Feynman–Hibbs quantum corrections. The resulting equation of state, the statistical associating fluid theory for Mie potentials of variable range corrected for quantum effects (SAFT-VRQ-Mie), is compared to molecular simulations and is seen to reproduce the thermodynamic properties of generic Mie-FH1 and Mie-FH2 fluids accurately. SAFT-VRQ Mie is exploited to obtain optimal parameters for the intermolecular potentials of neon, helium, deuterium, ortho-, para-, and normal-hydrogen for the Mie-FH1 and Mie-FH2 formulations. For helium, hydrogen, and deuterium, the use of either the first- or second-order corrections yields significantly higher accuracy in the representation of supercritical densities, heat capacities, and speed of sounds when compared to classical Mie fluids, although the Mie-FH2 is slightly more accurate than Mie-FH1 for supercritical properties. The Mie-FH1 potential is recommended for most of the fluids since it yields a more accurate representation of the pure-component phase equilibria and extrapolates better to low temperatures. Notwithstanding, for helium, where the quantum effects are largest, we find that none of the potentials give an accurate representation of the entire phase envelope, and its thermodynamic properties are represented accurately only at temperatures above 20 K. Overall, supercritical heat capacities are well represented, with some deviations from experiments seen in the liquid phase region for helium and hydrogen.

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“…The crux of the methodology is that the equation of state parameters can be directly employed in molecular simulations, thanks to the one-to-one correspondence between the theory and the underlying models. SAFT force fields have been successful in describing thermophysical [5] interfacial [6,7], confined fluid [8] and transport properties [9,10] of a wide range of fluids and mixtures [11,12] including polymers [13].…”

Section: 1saft-cg Coarse Graining Methodologymentioning

confidence: 99%

Predicting the pressure dependence of the viscosity of 2,2,4-trimethylhexane using the SAFT coarse-grained force field

Zheng

Trusler

Bresme

et al. 2019

Fluid Phase Equilibria

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This work is framed within AIChE's 10 th Industrial Fluid Properties Simulation Challenge, with the aim of assessing the capability of molecular simulation methods and force fields to accurately predict the pressure dependence of the shear viscosity of 2,2,4-trimethylhexane at 293.15 K (20 °C) at pressures up to 1 GPa. In our entry for the challenge, we employ coarsegrained intermolecular models parametrized via a top-down technique where an accurate equation of state is used to link the experimentally-observed macroscopic volumetric properties of fluids to the force-field parameters. The state-of-the-art version of the statistical associating fluid theory (SAFT) for potentials of variable range as reformulated in the Mie incarnation is employed here. The potentials are used as predicted by the theory, with no fitting to viscosity data. Viscosities are calculated by molecular dynamics (MD) employing two independent methods; an equilibrium-based procedure based on the analysis of the pressure fluctuations through a Green-Kubo formulation and a non-equilibrium method where periodic perturbations of the boundary conditions are employed to simulate experimental shear stress conditions. There is an indication that, at higher pressures, the model predicts a solid phase (freezing) which we believe to be an artefact of the simplified molecular geometry used in the modelling. A comparison (made after disclosure of the experimental data) show that the model consistently underpredicts the viscosity by about 30%, but follows the pressure dependency accurately.

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Group Contribution Coarse-Grained Molecular Simulations of Polystyrene Melts and Polystyrene Solutions in Alkanes Using the SAFT-γ Force Field

Cited by 33 publications

References 73 publications

Interfacial width and phase equilibrium in polymer-fullerene thin-films

Interfacial width and phase equilibrium in polymer-fullerene thin-films

Equation of state and force fields for Feynman–Hibbs-corrected Mie fluids. I. Application to pure helium, neon, hydrogen, and deuterium

Predicting the pressure dependence of the viscosity of 2,2,4-trimethylhexane using the SAFT coarse-grained force field

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