Lateral diffusion model for polymer dynamics in the melt: mean-squared displacement for monodisperse and polydisperse systems

A model is presented for the dynamics of dense systems of linear monodisperse and polydisperse polymers which is based upon the assumption that the primary mechanism for chain motion is a sliding of each chain along the contours of neighboring chains. A time-dependent efffective single-bead friction coefficiant is derived which accounts for the constraining nature of the neighboring chains on the motion of a given chain.