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@ARTICLE{Spehr:15647,
      author       = {Spehr, T.L. and Frick, B. and Zamponi, M. and Stuehn, B.},
      title        = {{D}ynamics of water confined to reverse {AOT} micelles},
      journal      = {Soft matter},
      volume       = {7},
      issn         = {1744-683X},
      address      = {Cambridge},
      publisher    = {Royal Society of Chemistry (RSC)},
      reportid     = {PreJuSER-15647},
      pages        = {5745 - 5755},
      year         = {2011},
      note         = {We acknowledge the ILL for the allocated beam time and the
                      co-financing of the PhD thesis of T. L. S. Financial support
                      by the DFG (project number STU 191/4-1) is acknowledged. A
                      portion of this research at ORNL's SNS was sponsored by the
                      Scientific User Facilities Division, Office of Basic Energy
                      Sciences, U.S. Department of Energy.},
      abstract     = {We use quasi-elastic neutron scattering (QENS) to study the
                      dynamics of water confined inside reverse micelles. As a
                      model system we use a water-in-oil droplet microemulsion
                      based on the anionic surfactant AOT (sodium
                      bis[2-ethylhexyl] sulfosuccinate), that forms spherical
                      water droplets coated by a monolayer of AOT dispersed in the
                      continuous oil matrix. Combining neutron time-of-flight
                      (TOF) and backscattering (BS) spectroscopy, we access the
                      dynamical behaviour of water over three decades in time from
                      pico- to nanoseconds. We investigate the influence of
                      reverse micelle size on the water dynamics by comparing two
                      sample systems with bigger and smaller water core radii of
                      about R-c approximate to 12 angstrom and 7 angstrom. The
                      temperature is varied over a range where both microemulsion
                      systems are stable, from room temperature down to the region
                      where the confined water is supercooled: 260 K <= T <= 300
                      K. Taking explicitly into account the previously measured
                      diffusion of entire reverse micelles in the oil matrix we
                      find the average mobility of the confined water to be
                      considerably slowed with respect to bulk water. The
                      translational diffusion decreases with decreasing reverse
                      micelle size. Dependent on the reverse micelle size we can
                      interpret our data by assuming two dynamically separated
                      water fractions. We identify the faster one with bulk-like
                      water in the middle of the core while the slower one seems
                      to be surfactant bound water. We find that 4 molecules of
                      water per AOT molecule are immobilized on the timescale of
                      QENS, i.e. shorter than nanoseconds.},
      keywords     = {J (WoSType)},
      cin          = {ICS-1 / JCNS (München) ; Jülich Centre for Neutron
                      Science JCNS (München) ; JCNS-FRM-II / JCNS-1},
      ddc          = {530},
      cid          = {I:(DE-Juel1)ICS-1-20110106 /
                      I:(DE-Juel1)JCNS-FRM-II-20110218 /
                      I:(DE-Juel1)JCNS-1-20110106},
      pnm          = {BioSoft: Makromolekulare Systeme und biologische
                      Informationsverarbeitung / Großgeräte für die Forschung
                      mit Photonen, Neutronen und Ionen (PNI)},
      pid          = {G:(DE-Juel1)FUEK505 / G:(DE-Juel1)FUEK415},
      experiment   = {EXP:(DE-MLZ)External-20140101},
      shelfmark    = {Chemistry, Physical / Materials Science, Multidisciplinary
                      / Physics, Multidisciplinary / Polymer Science},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000291354200037},
      doi          = {10.1039/c1sm05204g},
      url          = {https://juser.fz-juelich.de/record/15647},
}