Elastic properties of poly(ethylene-glycol) studied by molecular dynamics stretching simulations

Unfolding and elastic properties of single poly(ethylene-glycol) (PEG) polymers were studied by molecular dynamics (MD) simulations. The simulations were performed in close resemblance to recent single molecule force spectroscopy experiments, and thus allowed an interpretation of these experiments at the atomic level. In agreement with these experiments, the water solvent was found to drastically affect the elastic properties of PEG. Our simulations explain this effect in terms of local helical structures which are stabilized through water bridges. Stretching forces of more than 100 pN were required to break these water bridges and thereby to destroy these helical structures.