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@INPROCEEDINGS{Frielinghaus:825991,
      author       = {Frielinghaus, Henrich and Holderer, Olaf and Allgaier, J.
                      and Helge Klemmer, Uni Köln},
      title        = {{A}mphiphilic {P}olymers with a {C}ontinuous {P}hilicity
                      {P}rofile in {B}icontinuous {M}icroemulsions {S}tudied by
                      {Q}uasielastic {N}eutron {S}cattering},
      school       = {HZB},
      reportid     = {FZJ-2017-00263},
      year         = {2016},
      abstract     = {Wherever surfactants are applied, it is of general interest
                      to use as little surfactant as possible. However, in e.g.
                      microemulsion systems increasing the solubilization capacity
                      of an amphiphilic mixture is always accompanied by the
                      formation of liquid crystalline mesophases. Integrating
                      amphiphilic block copolymers (so called efficiency boosters)
                      into the amphiphilic film leads to a considerable increase
                      of the efficiency. This effect is mainly due to an increase
                      of the bending rigidity of the amphiphilic film due to the
                      presence of polymer domains on either side of the film. The
                      formation of liquid crystalline mesophases was found to be
                      suppressed at low concentrations of block copolymers, while
                      it was enhanced at high concentrations. To break this
                      trade-off between surfactant efficiency and the
                      stabilization of liquid crystalline phases we studied a new
                      class of amphiphilic polymers - so called tapered polymers -
                      following the amphiphilicity profile going from diblock via
                      triblock to continuously tapered [1]. In contrast to the
                      commonly used diblock or triblock copolymers the molecular
                      structure of tapered polymers gradually changes from
                      hydrophilic to hydrophobic. The influence of this new class
                      of polymers on the properties of microemulsion systems was
                      investigated by systematic phase behaviour studies, SANS
                      (small angle neutron scattering) and NSE (neutron spin echo)
                      experiments. These measurements reveal that the polymers
                      cause a stiffening of the amphiphilic film while
                      simultaneously the saddle splay modulus increases
                      considerably less such that the formation of liquid
                      crystalline mesophases is suppressed while bicontinuous
                      structures are geometrically favored. In addition, these
                      findings are supported by theoretical calculations following
                      the works of Lipowsky [2]. Hence tapered amphiphilic
                      polymers not only increase the efficiency of surfactants,
                      but simultaneously suppress the formation of liquid
                      crystalline phases, and, thereby, greatly increasing their
                      application potential.The underlying NSE experiments for
                      this interpretation rely on smallest changes of the
                      relaxation curves (of ca. $1\%$ steps) for still small
                      changes of the bending rigidity (of ca. $10\%$ steps). This
                      high reliability of the experiments conducted at the SNS-NSE
                      displays the accuracy of the instrument itself and the
                      latest developments of the evaluation software, which were
                      necessary to interpret such tiny changes of the bending
                      rigidity reliably.[1] H.F.M. Klemmer, J. Allgaier, H.
                      Frielinghaus, O. Holderer, Soft Matter (submitted) 2016.[2]
                      C. Hiergeist, R. Lipowsky, Journal de Physique II,},
      month         = {Sep},
      date          = {2016-09-05},
      organization  = {QENS 2016 in Potsdam PROBINGS DYNAMIC
                       PHENOMENA FROM PICOSECONDS TO
                       NANOSECONDS, Potsdam (Germany), 5 Sep
                       2016 - 8 Sep 2016},
      subtyp        = {Other},
      cin          = {JCNS (München) ; Jülich Centre for Neutron Science JCNS
                      (München) ; JCNS-FRM-II / Neutronenstreuung ; JCNS-1},
      cid          = {I:(DE-Juel1)JCNS-FRM-II-20110218 /
                      I:(DE-Juel1)JCNS-1-20110106},
      pnm          = {6215 - Soft Matter, Health and Life Sciences (POF3-621) /
                      6G15 - FRM II / MLZ (POF3-6G15) / 6G4 - Jülich Centre for
                      Neutron Research (JCNS) (POF3-623)},
      pid          = {G:(DE-HGF)POF3-6215 / G:(DE-HGF)POF3-6G15 /
                      G:(DE-HGF)POF3-6G4},
      experiment   = {EXP:(DE-MLZ)KWS1-20140101 / EXP:(DE-MLZ)J-NSE-20140101 /
                      EXP:(DE-Juel1)SNS-NSE-20150203},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/825991},
}