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@ARTICLE{Bhowmik:154875,
      author       = {Bhowmik, D. and Pomposo, J. A. and Juranyi, F. and García
                      Sakai, V. and Zamponi, M. and Arbe, A. and Colmenero, J.},
      title        = {{I}nvestigation of a {N}anocomposite of 75 wt $\%$
                      {P}oly(methyl methacrylate) {N}anoparticles with 25 wt $\%$
                      {P}oly(ethylene oxide) {L}inear {C}hains: {A} {Q}uasielatic
                      {N}eutron {S}cattering, {C}alorimetric, and {WAXS} {S}tudy},
      journal      = {Macromolecules},
      volume       = {47},
      number       = {9},
      issn         = {1520-5835},
      address      = {Washington, DC},
      publisher    = {Soc.},
      reportid     = {FZJ-2014-04118},
      pages        = {3005 - 3016},
      year         = {2014},
      abstract     = {We have investigated the thermal behavior, local structure,
                      and dynamics in a system where 25 wt $\%$ PEO [poly(ethylene
                      oxide)] linear chains are mixed with 75 wt $\%$ PMMA
                      [poly(methyl methacrylate)] soft nanoparticles. Calorimetric
                      and wide-angle X-ray scattering experiments point to a weak
                      penetration of the PEO chains in the nanoparticles,
                      qualifying the mixture as a nanocomposite. Quasi-elastic
                      neutron scattering (QENS) experiments on partially
                      deuterated samples has selectively revealed the component
                      dynamics in the system. The α-methyl group dynamics of
                      PMMA, which fall within the QENS time scale in the
                      temperature range investigated, are hardly affected by the
                      presence of PEO except for hints of a more heterogeneous
                      environment in the nanocomposite than in bulk PMMA. The
                      effects on the dynamics of PEO are more interesting. The
                      observation of dynamics in the microseconds range for the
                      PEO component of the nanocomposite at temperatures at which
                      the calorimetric experiments indicate the freezing of its
                      segmental relaxation provides evidence for confined dynamics
                      below the main glass transition of the
                      mixture—attributable to the effective glass transition of
                      the slow component. A parallel study on an equivalent blend
                      of PEO and linear PMMA chains shows that these effects are
                      independent of the topology of the PMMA. However, well above
                      the effective glass transition of the slow component, the
                      dynamics of PEO differ in both systems. In the linear blend,
                      PEO segments move with the typical features of supercooled
                      polymers in metastable equilibrium, while in the
                      nanocomposite PEO dynamics exhibit an anomalously strong
                      deviation from Gaussian behavior. This deviation grows with
                      increased mobility of the nanoparticles. PEO segments are
                      seemingly trapped in effective cages imposed by the
                      nanoparticles for a very long time—more than 2 orders of
                      magnitude longer than in bulk or when surrounded by linear
                      PMMA chains—before the subdiffusive process leading to
                      segmental relaxation sets in. We speculate that local loops
                      in the surface of the nanoparticles may play an important
                      role in this trapping mechanism.},
      cin          = {Neutronenstreuung ; JCNS-1 / JCNS (München) ; Jülich
                      Centre for Neutron Science JCNS (München) ; JCNS-FRM-II /
                      ICS-1},
      ddc          = {540},
      cid          = {I:(DE-Juel1)JCNS-1-20110106 /
                      I:(DE-Juel1)JCNS-FRM-II-20110218 /
                      I:(DE-Juel1)ICS-1-20110106},
      pnm          = {451 - Soft Matter Composites (POF2-451) / 54G - JCNS
                      (POF2-54G24)},
      pid          = {G:(DE-HGF)POF2-451 / G:(DE-HGF)POF2-54G24},
      experiment   = {EXP:(DE-MLZ)SPHERES-20140101},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000336020900028},
      doi          = {10.1021/ma500215f},
      url          = {https://juser.fz-juelich.de/record/154875},
}