Volume dependence of molecular flexibility in poly(ethylene oxide) under negative pressure

We use here molecular dynamics (MD) simulations to study the structure and mobility of bulk melt PEO at the molecular level in response to a volume ex pansion such as might occur at the interphase of compatibilized polymer ble nds. PEO is simulated under constant-pressure conditions and compared to lo wer density constant-volume systems in the range similar to 90-100% of the ambient pressure density at 343 K. Analyses include energies and pressure, conformational data, intra- and intermolecular structural features, and the evolution of chain mobility and mechanical properties. The decrease in den sity induces negative pressures and an increase in molecular mobility. More over, a decrease of 10% in density is found to correspond to a temperature shift of approximately 60 K for the polymer backbone torsional interconvers ion relaxation times around C-O bonds.