QUANTUM-CHEMISTRY-BASED FORCE FIELD FOR 1,2-DIMETHOXYETHANE AND POLY(ETHYLENE OXIDE) IN AQUEOUS SOLUTION

An atomistic force field for simulations of 1,2-dimethoxyethane (DME) and poly(ethylene oxide) (PEO) in aqueous solution is presented. The force field is parametrized to reproduce energies of complexes of DME and water as determined from high-level quantum chemistry calculations. The quantum chemistry calculations reveal that the binding of DME to water is comparable to water−water binding in water dimer, indicating strong hydrogen bonding between DME and water. We find that the binding energy of water to DME in the tgt conformation (−7.7 kcal/mol) is greater than that for the other low energy DME conformers (−6.1 kcal/mol for ttt and −6.4 kcal/mol for tg+g- respectively), due to the strong interaction of the water hydrogen atoms with both ether oxygen atoms in the tgt conformer. The accuracy of the force field is verified through a series of molecular dynamics simulations of DME−water solutions performed as a function of temperature and composition. Comparison of simulation values for density, excess vol...