Poly(oxyethylene)-cation interactions in aqueous solution: a molecular dynamics study

摘要

We have performed molecular dynamics simulations of a poly(oxyethylene) (POE) chain with 15 ethylene oxide units in an aqueous solution in the presence of potassium cations for 1 ns. The effect of the potassium ions on the POE aqueous solution characteristics are examined for the energetics, the hydration, the chain conformation and dynamics, and the solvent structure in comparison to those in the absence of cations. The POE's helical conformation is considerably distorted by complex formations with K~+, and a significant perturbation of the POE hydration by K~+ is observed. The competition between the K~+-water and the K~+-POE associations is found to be heavily shifted toward the latter. Furthermore, the POE-water pair interaction energy drastically decreases upon addition of K~+. The observations, along with the decreased chain flexibility, point to the salting-out of POE salt aqueous solutions.