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

Abstract

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 (CF₃–O–(CF₂–CF₂–O)2–CF₃) and perfluorotriglyme (CF₃–O–(CF₂–CF₂–O)₃–CF₃), 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^–1 error) and molecular structures for several PFPEs, and also accurately reproduce experimentally determined densities (<0.02 g cm^–3 error) and enthalpies of vaporization derived from experimental vapor pressures (<0.3 kcal mol–1). 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.

Authors:

Black, Jana E.  ^[1];

• Search DOE PAGES for author "Black, Jana E."
• Search DOE PAGES for ORCID "0000-0002-6368-8477"

Silva, Gonçalo M. C. ^[2]; Klein, Christoph ^[1]; Iacovella, Christopher R. ^[1]; Morgado, Pedro ^[2]; Martins, Luís F. G. ^[3]; Filipe, Eduardo J. M.  ^[2];

• Search DOE PAGES for author "Filipe, Eduardo J. M."
• Search DOE PAGES for ORCID "0000-0003-4440-7710"

McCabe, Clare  ^[4]

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• Search DOE PAGES for ORCID "0000-0002-8552-9135"

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1. Vanderbilt Univ., Nashville, TN (United States). Dept. of Chemical and Biomolecular Engineering; Vanderbilt Univ., Nashville, TN (United States). Multiscale Modeling and Simulation (MuMS)
2. Univ. de Lisboa, Lisboa (Portugal). Centro de Química Estrutural, Inst. Superior Técnico
3. Univ. de Lisboa, Lisboa (Portugal). Centro de Química Estrutural, Inst. Superior Técnico; Univ. de Évora, Évora (Portugal). Centro de Química de Évora
4. Vanderbilt Univ., Nashville, TN (United States). Dept. of Chemical and Biomolecular Engineering; Vanderbilt Univ., Nashville, TN (United States). Multiscale Modeling and Simulation (MuMS); Vanderbilt Univ., Nashville, TN (United States). Dept. of Chemistry

Publication Date:

Tue May 30 00:00:00 EDT 2017

Research Org.:

Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)

Sponsoring Org.:

USDOE Office of Science (SC); US Dept. of Education

OSTI Identifier:

1480285

Grant/Contract Number:  

AC02-05CH11231; ACI-1047828; ACI-1535150; P200A090323; UID/QUI/0100/2013; SFRH/BPD/81748/2011; PEst-OE/QUI/UI0619/2011

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry

Additional Journal Information:

Journal Volume: 121; Journal Issue: 27; Journal ID: ISSN 1520-6106

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS