Abstract
We investigate the effects of both triethylene glycol (TEG) and polyethylene glycol (PEG) on the structure and transport of an excess proton (H + ) in aqueous solution. A new reactive force field (ReaxFF) parameterisation is carried out to better describe proton transfer of H + with PEG polymers in aqueous solution via training against density functional theory (DFT) calculations. Using this ReaxFF parameterisation, reactive molecular dynamics simulations are carried out for three different systems containing H + : bulk water, aqueous TEG, and aqueous PEG with a single, oriented polymer chain. The H + diffusivity is suppressed due to the presence of TEG and enhanced in the oriented chain PEG system, particularly along the axis parallel to the PEG chain, relative to bulk water. The enhancement in proton mobility along the chain axis is mainly due to the structural, rather than vehicular, component. From free energy calculations for H+ transfer, the increase in proton mobility is not due to a reduction in activation energy. From pair distribution function analysis of the local structure for water and hydronium we hypothesise the increased mobility is due to an entropic effect, specifically a favourable hydrogen bond network for long range proton transport due to the oriented PEG chain.
Original language | English |
---|---|
Pages (from-to) | 381-393 |
Number of pages | 13 |
Journal | Molecular Simulation |
Volume | 45 |
Issue number | 4-5 |
DOIs | |
State | Published - Mar 24 2019 |
Funding
CONTACT Marshall T. McDonnell [email protected] Supplemental data for this article can be accessed at https://doi.org/10.1080/08927022.2018.1557328. *Notice: This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Govern-ment retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/ doepublic-access-plan).
Keywords
- Proton transport
- ReaxFF
- polyethylene glycol
- water