Dynamics of unentangled cyclic and linear poly(oxyethylene) melts

Monodisperse low-molecular-weight (400-1500 g/mol) cyclic poly(oxyethylene)s (CPOE)s were synthesized from linear dihydroxy-terminated poly(oxyethylene)s (LPOE)s. The self-diffusion, NMR spin-spin relaxation, and zero-shear viscosity of CPOE and LPOE, as well as linear dimethoxy-terminated poly(oxyethylene) (LPOEDE), were measured in the melt state. The self-diffusion coefficients measured at 56 °C were ordered in the following sequence: LPOEDE > CPOE > LPOE, which is in excellent agreement with NMR spin-spin relaxation and viscosity data. The slower motion of LPOE compared to LPOEDE was attributed to chain-end hydrogen bonding. Scaling relations with molecular weight and activation energies were reconciled with chain-end and topological effects.