title: Molecular observation of contour-length fluctuations limiting topological confinement in polymer melts.
abstract: In order to study the mechanisms limiting the topological chain confinement in polymer melts, we have performed neutron-spin-echo investigations of the single-chain dynamic-structure factor from polyethylene melts over a large range of chain lengths. While at high molecular weight the reptation model is corroborated, a systematic loosening of the confinement with decreasing chain length is found. The dynamic-structure factors are quantitatively described by the effect of contour-length fluctuations on the confining tube, establishing this mechanism on a molecular level in space and time.
authors.affiliation: Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425 Jülich, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Wischnewski
authors.forename: M
authors.initials: M
authors.lastname: Monkenbusch
authors.forename: L
authors.initials: L
authors.lastname: Willner
authors.forename: D
authors.initials: D
authors.lastname: Richter
authors.forename: A E
authors.initials: AE
authors.lastname: Likhtman
authors.forename: T C B
authors.initials: TC
authors.lastname: McLeish
authors.forename: B
authors.initials: B
authors.lastname: Farago