Molecular dynamics simulation of sub-transition for polyethersulfone

Molecular dynamics (MD) simulations of a polyethersulfone (PES) chain are c arried out in the amorphous state by using the Dreiding 2.21 force field at four temperatures. Two types of molecular motion, i.e, rotations of phenyl ene rings and torsions of large segments containing two oxygen atoms, two s ulfur atoms, and five phenylene rings on the backbone, are simulated. The m odeling results show that the successive phenylene rings should be in-phase cooperative rotations, whereas the successive large segments should be out -of-phase cooperative torsions. By calculating the diffusion coefficient fo r the phenylene ring rotations, it is found that this rotation contributes to the beta -transition of PES.