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@ARTICLE{Franz:280564,
      author       = {Franz, Cornelius and Lange, Frank and Golitsyn, Yury and
                      Hartmann-Azanza, Brigitte and Steinhart, Martin and
                      Krutyeva, Margarita and Saalwächter, Kay},
      title        = {{C}hain {D}ynamics and {S}egmental {O}rientation in
                      {P}olymer {M}elts {C}onfined to {N}anochannels6215},
      journal      = {Macromolecules},
      volume       = {49},
      number       = {1},
      issn         = {1520-5835},
      address      = {Washington, DC},
      publisher    = {Soc.},
      reportid     = {FZJ-2016-00332},
      pages        = {244 - 256},
      year         = {2016},
      abstract     = {We study changes in the dynamics of polymer chains confined
                      to cylindrical nanochannels within aluminum oxide membranes.
                      Specifically, a proton time-domain NMR technique is used to
                      assess the effect of transient wall contacts on the
                      time-averaged orientational order of poly(butadiene)
                      segments in melts with different molecular weights (MW).
                      Previous work has evidenced that the weakly interacting
                      polymer, residing in ∼100 μm long, 20 and 60 nm wide
                      channels, shows no significant confinement-related changes
                      in the segmental (α) relaxation time and only weak (less
                      than a factor of 2) changes in the micrometer-scale
                      diffusivity. In the relevant temperature range above 340 K,
                      we here use samples with pores oriented at different angles
                      with respect to the main magnetic field to study the
                      macroscopic anisotropy of segmental rotations and the effect
                      of slower motions in regimes III and IV of the tube model up
                      to the milliseconds time scale. We show that the pore walls
                      exert a significant orientation effect on the chains,
                      measured in terms of a time-averaged order parameter with a
                      related length scale of one to a few nanometers, coexisting
                      for high molecular weight (MW) inhomogeneously with
                      bulk-like behavior in the pore center. Low MW with fewer
                      than about 10 entanglements as well as low MW liquids
                      exhibit a homogeneous response, with an overall residual
                      orientation that represents a diffusively averaged quantity
                      reflecting the pore geometry. We support our findings by a
                      simulation model based upon one-dimensional curvilinear
                      chain diffusion along the primitive path. The study is
                      complemented by deuterium NMR experiments on a labeled
                      poly(dimethylsiloxane) sample, in which strong surface
                      contacts prevent full diffusive averaging.},
      cin          = {ICS-1 / Neutronenstreuung ; JCNS-1},
      ddc          = {540},
      cid          = {I:(DE-Juel1)ICS-1-20110106 / I:(DE-Juel1)JCNS-1-20110106},
      pnm          = {551 - Functional Macromolecules and Complexes (POF3-551) /
                      6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623)
                      / 6215 - Soft Matter, Health and Life Sciences (POF3-621)},
      pid          = {G:(DE-HGF)POF3-551 / G:(DE-HGF)POF3-6G4 /
                      G:(DE-HGF)POF3-6215},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000368322000028},
      doi          = {10.1021/acs.macromol.5b02309},
      url          = {https://juser.fz-juelich.de/record/280564},
}