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@INPROCEEDINGS{Richter:1008203,
      author       = {Richter, Dieter and Allgaier, J. and Monkenbusch, Michael
                      and Kruteva, Margarita},
      title        = {{O}n the dynamics of large ring polymers in the melt - a
                      {SANS}, neutron spin echo and {PFG} - {NMR} study},
      reportid     = {FZJ-2023-02249},
      year         = {2023},
      abstract     = {The non-crossing requirement in non-concatenated ring
                      polymers creates topological constraints, which impose
                      important restrictions on the phase space of the system. For
                      ring polymers interpenetration is costly entropically and
                      compact structures evolve for high molecular weights - ring
                      polymers are assumed to become mass fractals confining rings
                      into territories. Other than the dynamics of linear or
                      branched chains that predominantly takes place via the chain
                      ends, rings do not feature ends and their dynamics is
                      considered to be self-similar and thus fundamentally
                      different to those of chains displaying ends. The present
                      state of the art model for the description of the internal
                      relaxations in dense ring systems was developed by
                      Rubinstein et al. /1/. This self-consistent Fractal Loopy
                      Globule (FLG) model is based on the conjecture that the
                      overlap criterion /2,3/ in the packing model for
                      entanglements also governs the rule for overlapping loops in
                      polymer rings. The constant overlap of loops is conjectured
                      to occur in a self-similar way over a wide range of length
                      scales from the elementary loop size Ne up to ring size R.
                      The dynamics of such rings in a melt is governed by
                      topological constraints that dilute with progressing time,
                      because with time loops of increasing sizes are relaxed and
                      cease to be obstacles.Recently, combining results of SANS
                      /4/ with PFG- NMR and NSE the unique topology driven
                      self-similar internal ring dynamics predicted by the FLG
                      model could be verified experimentally /5/: We find the
                      center of mass diffusion taking place in three dynamic
                      regimes from short to long times: (i) a strongly
                      sub-diffusive regime, where the center-of-mass mean square
                      displacement scales as $t^\alpha$ (0.4 ≤ $\alpha$ ≤ 0.6)
                      , until it reaches roughly the value $R_g^2;$ (ii) a second
                      regime with a $t^0.75$ scaling that (iii) at roughly 2.5
                      $R_g^2$ crosses over to Fickian diffusion. While the second
                      anomalous diffusion regime has been found in simulations and
                      was predicted by theory, we attribute the first one to the
                      effect of cooperative dynamics resulting from the
                      correlation hole potential. The internal dynamics at scales
                      below the elementary loop size is well described by ring
                      Rouse motion. At larger scales the dynamics is self-similar
                      and follows very well the predictions of the scaling models
                      with preference for the FLG model.ReferencesReferences:1. T.
                      Ge, S. Panyukov, and M. Rubinstein, Macromolecules 49,
                      708–722 (2016)2. T. A. Kavassalis and J. Noolandi,
                      Macromolecules 22, 2709–2720 (1989)3. L. J. Fetters, D. J.
                      Lohse, D. Richter, T. A. Witten, and A. Zirkel,
                      Macromolecules (1994)4. M. Kruteva, J. Allgaier, M.
                      Monkenbusch, L. Porcar, and D. Richter, ACS Macro Letters ,
                      507–511 (2020)5. M. Kruteva,M. Monkenbusch, J. Allgaier,
                      O. Holderer, S. Pasini, I. Hofmann and D. Richter, Phys.
                      Rev. Lett. (2020)},
      month         = {Jun},
      date          = {2023-06-14},
      organization  = {Flagship Workshop Ring Polymer
                       Dynamics, Monash University Prato
                       Centre (Italy), 14 Jun 2023 - 16 Jun
                       2023},
      subtyp        = {Invited},
      cin          = {JCNS-2 / PGI-4 / JARA-FIT / JCNS-1},
      cid          = {I:(DE-Juel1)JCNS-2-20110106 / I:(DE-Juel1)PGI-4-20110106 /
                      $I:(DE-82)080009_20140620$ / I:(DE-Juel1)JCNS-1-20110106},
      pnm          = {632 - Materials – Quantum, Complex and Functional
                      Materials (POF4-632) / 6G4 - Jülich Centre for Neutron
                      Research (JCNS) (FZJ) (POF4-6G4)},
      pid          = {G:(DE-HGF)POF4-632 / G:(DE-HGF)POF4-6G4},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/1008203},
}