Vapor pressure and liquid density of fluorinated alcohols: Experimental, simulation and GC-SAFT-VR predictions

Silva, Gonçalo M. C.; Morgado, Pedro; Haley, Jessica D.; Trejos, Víctor M.; McCabe, Clare; Martins, Luís F. G.; Filipe, Eduardo J. M.

doi:10.1016/j.fluid.2016.06.011

Cited by 19 publications

(19 citation statements)

References 24 publications

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“…The density of HFB agrees with the results already obtained by our group within 0.2%. 23 Figure 1. Rotational conformers of EtOH and TFE: gauche (C 1 symmetry) and anti (C s symmetry).…”

Section: Methodsmentioning

confidence: 99%

Liquid Mixtures Involving Hydrogenated and Fluorinated Alcohols: Thermodynamics, Spectroscopy, and Simulation

Morgado¹,

García

Ilharco³

et al. 2016

J. Phys. Chem. B

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This article reports a combined thermodynamic, spectroscopic, and computational study on the interactions and structure of binary mixtures of hydrogenated and fluorinated substances that simultaneously interact through strong hydrogen bonding. Four binary mixtures of hydrogenated and fluorinated alcohols have been studied, namely, (ethanol + 2,2,2-trifluoroethanol (TFE)), (ethanol + 2,2,3,3,4,4,4-heptafluoro-1-butanol), (1-butanol (BuOH) + TFE), and (BuOH + 2,2,3,3,4,4,4-heptafluoro-1-butanol). Excess molar volumes and vibrational spectra of all four binary mixtures have been measured as a function of composition at 298 K, and molecular dynamics simulations have been performed. The systems display a complex behavior when compared with mixtures of hydrogenated alcohols and mixtures of alkanes and perfluoroalkanes. The combined analysis of the results from different approaches indicates that this results from a balance between preferential hydrogen bonding between the hydrogenated and fluorinated alcohols and the unfavorable dispersion forces between the hydrogenated and fluorinated chains. As the chain length increases, the contribution of dispersion increases and overcomes the contribution of H-bonds. In terms of the liquid structure, the simulations suggest the possibility of segregation between the hydrogenated and fluorinated segments, a hypothesis corroborated by the spectroscopic results. Furthermore, a quantitative analysis of the infrared spectra reveals that the presence of fluorinated groups induces conformational changes in the hydrogenated chains from the usually preferred all-trans to more globular arrangements involving gauche conformations. Conformational rearrangements at the CCOH dihedral angle upon mixing are also disclosed by the spectra.

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“…The density of HFB agrees with the results already obtained by our group within 0.2%. 23 Figure 1. Rotational conformers of EtOH and TFE: gauche (C 1 symmetry) and anti (C s symmetry).…”

Section: Methodsmentioning

confidence: 99%

Liquid Mixtures Involving Hydrogenated and Fluorinated Alcohols: Thermodynamics, Spectroscopy, and Simulation

Morgado¹,

García

Ilharco³

et al. 2016

J. Phys. Chem. B

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“…All together, these features have a number of thermodynamic consequences. Perfluorinated alcohols for example, have higher melting temperatures [ 20 , 21 ], and are more volatile (lower boiling temperatures) than hydrogenated alcohols, thus displaying a smaller liquid range. In other words, solidification is easier for perfluorinated substances.…”

Section: Introductionmentioning

confidence: 99%

Langmuir Films of Perfluorinated Fatty Alcohols: Evidence of Spontaneous Formation of Solid Aggregates at Zero Surface Pressure and Very Low Surface Density

et al. 2020

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In this work, Langmuir films of two highly fluorinated fatty alcohols, CF3(CF2)12CH2OH (F14OH) and CF3(CF2)16CH2OH (F18OH), were studied. Atomic Force Microscopy (AFM) images of the films transferred at zero surface pressure and low surface density onto the surface of silicon wafers by the Langmuir-Blodgett technique revealed, for the first time, the existence of solid-like domains with well-defined mostly hexagonal (starry) shapes in the case of F18OH, and with an entangled structure of threads in the case of F14OH. A (20:80) molar mixture of the two alcohols displayed a surprising combination of the two patterns: hexagonal domains surrounded by zigzagging threads, clearly demonstrating that the two alcohols segregate during the 2D crystallization process. Grazing Incidence X-ray Diffraction (GIXD) measurements confirmed that the molecules of both alcohols organize in 2D hexagonal lattices. Atomistic Molecular Dynamics (MD) simulations provide a visualization of the structure of the domains and allow a molecular-level interpretation of the experimental observations. The simulation results clearly showed that perfluorinated alcohols have an intrinsic tendency to aggregate, even at very low surface density. The formed domains are highly organized compared to those of hydrogenated alcohols with similar chain length. Very probably, this tendency is a consequence of the characteristic stiffness of the perfluorinated chains. The diffraction spectrum calculated from the simulation trajectories compares favorably with the experimental spectra, fully validating the simulations and the proposed interpretation. The present results highlight for the first time an inherent tendency of perfluorinated chains to aggregate, even at very low surface density, forming highly organized 2D structures. We believe these findings are important to fully understand related phenomena, such as the formation of hemi-micelles of semifluorinated alkanes at the surface of water and the 2D segregation in mixed Langmuir films of hydrogenated and fluorinated fatty acids.

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“…Figure compares perfluorodiglyme and perfluorotriglyme Δ H vap values calculated from experimental vapor pressures to those of their hydrogenated counterparts; values for n -alkanes (CH 3 –(CH 2 ) n −2 –CH 3 ), perfluoroalkanes (CF 3 –(CF 2 ) n −2 –CF 3 ), n -alcohols (CH 3 –(CH 2 ) n −1 –OH), and 1 H ,1 H -perfluoroalcohols (CF 3 –(CF 2 ) n −2 –CH 2 –OH) , are also included for comparison. The PFPEs have significantly lower values of Δ H vap than their hydrogenated analogues, a trend which is not evident when comparing perfluoroalkanes to alkanes or 1 H ,1 H -perfluoroalcohols to alcohols.…”

Section: Resultsmentioning

confidence: 99%

“…58 nalkanes (CH 3 −(CH 2 ) n−2 −CH 3 ), 58 perfluoroalkanes (CF 3 −(CF 2 ) n−2 − CF 3 ), 58 n-alcohols (CH 3 −(CH 2 ) n−1 −OH), 58 and 1H,1H-perfluoroalcohols (CF 3 −(CF 2 ) n−2 −CH 2 −OH). 59,60 Lines are provided as a visual guide only.…”

Section: ■ Simulation Methodsmentioning

confidence: 99%

Perfluoropolyethers: Development of an All-Atom Force Field for Molecular Simulations and Validation with New Experimental Vapor Pressures and Liquid Densities

et al. 2017

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A force field for perfluoropolyethers (PFPEs) based on the general optimized potentials for liquid simulations all-atom (OPLS-AA) force field has been derived in conjunction with experiments and ab initio quantum mechanical calculations. Vapor pressures and densities of two liquid PFPEs, perfluorodiglyme (CF-O-(CF-CF-O)-CF) and perfluorotriglyme (CF-O-(CF-CF-O)-CF), have been measured experimentally to validate the force field and increase our understanding of the physical properties of PFPEs. Force field parameters build upon those for related molecules (e.g., ethers and perfluoroalkanes) in the OPLS-AA force field, with new parameters introduced for interactions specific to PFPEs. Molecular dynamics simulations using the new force field demonstrate excellent agreement with ab initio calculations at the RHF/6-31G* level for gas-phase torsional energies (<0.5 kcal mol error) and molecular structures for several PFPEs, and also accurately reproduce experimentally determined densities (<0.02 g cm error) and enthalpies of vaporization derived from experimental vapor pressures (<0.3 kcal mol). Additional comparisons between experiment and simulation show that polyethers demonstrate a significant decrease in enthalpy of vaporization upon fluorination unlike related molecules (e.g., alkanes and alcohols). Simulation suggests this phenomenon is a result of reduced cohesion in liquid PFPEs due to a reduction in localized associations between backbone oxygen atoms and neighboring molecules.

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Vapor pressure and liquid density of fluorinated alcohols: Experimental, simulation and GC-SAFT-VR predictions

Cited by 19 publications

References 24 publications

Liquid Mixtures Involving Hydrogenated and Fluorinated Alcohols: Thermodynamics, Spectroscopy, and Simulation

Liquid Mixtures Involving Hydrogenated and Fluorinated Alcohols: Thermodynamics, Spectroscopy, and Simulation

Langmuir Films of Perfluorinated Fatty Alcohols: Evidence of Spontaneous Formation of Solid Aggregates at Zero Surface Pressure and Very Low Surface Density

Perfluoropolyethers: Development of an All-Atom Force Field for Molecular Simulations and Validation with New Experimental Vapor Pressures and Liquid Densities

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