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@ARTICLE{Lund:14581,
      author       = {Lund, R. and Pipich, V. and Willner, L. and Radulescu, A.
                      and Colmenero, J. and Richter, D.},
      title        = {{S}tructural and thermodynamic aspects of the
                      cylinder-to-sphere transition in amphiphilic diblock
                      copolymer micelles},
      journal      = {Soft matter},
      volume       = {7},
      issn         = {1744-683X},
      address      = {Cambridge},
      publisher    = {Royal Society of Chemistry (RSC)},
      reportid     = {PreJuSER-14581},
      pages        = {1491 - 1500},
      year         = {2011},
      note         = {The authors acknowledge the University of the Basque
                      Country and Basque Country Government (Ref. No. IT-436-07,
                      Depto. Educacion, Universidades e InvestigacionS, and
                      iNANOGUNE research project within Etortek program) and the
                      Spanish Minister of Education (Grant No. MAT 2007-63681) for
                      their support. The support of the European Community within
                      the SOFTCOMP Network of Excellence (NoE) program is also
                      gratefully acknowledged.},
      abstract     = {The structure of diblock copolymers micelles depends on a
                      delicate balance of thermodynamic forces driving the system
                      towards equilibrium and kinetic factors which limit the
                      systems' exploration of the phase space. The factors
                      governing the morphological transition between cylindrical
                      and spherical micelles are related to a fine balance between
                      entropic forces from chains within the micellar core and
                      corona. In order to understand and control these structures,
                      it is important to gain insight into the fundamental
                      thermodynamic driving forces governing the structure and
                      answer fundamental questions concerning its equilibrium
                      nature. In this work we aim to understand the relationship
                      between thermodynamics and morphological transitions by
                      investigating the detailed structure of a system undergoing
                      a cylinder-to-sphere transition. We focus on the structural
                      properties of micelles constituted of
                      poly(ethylene-alt-propylene)-poly(ethylene oxide)
                      (PEP1-PEO1, the numbers indicate the molar mass in kg/mole)
                      diblock copolymers in dimethylformamide (DMF)/water solvent
                      mixtures. This system is ideal for fundamental studies as it
                      represents a classical well-segregated block copolymer
                      micelle system where the interfacial tension can be
                      controlled in detail without significantly changing other
                      thermodynamic properties. Using small-angle neutron
                      scattering (SANS) it is shown that the system undergoes a
                      cylinder-to-sphere transition upon addition of DMF which
                      lowers the interfacial tension. By applying a detailed
                      thermodynamic model we show that both the dependence of the
                      structural parameters with the interfacial tension as well
                      as the morphological transition can be quantitatively
                      understood. The transition itself is governed by the
                      interfacial tension which dictates the stretching of chains
                      within both corona and core. At high interfacial tensions
                      (in water-rich solutions) discrepancies between structural
                      data and predictions from the thermodynamic model are
                      observed. A qualitative comparison with some preliminary
                      results on the chain exchange kinetics in the system show
                      that these deviations coincide with the region where this
                      equilibration mechanism is not active, i.e. when the
                      kinetics are frozen at high interfacial tensions.},
      keywords     = {J (WoSType)},
      cin          = {PGI-4 / ICS-1 / JCNS-2 / Jülich Centre for Neutron Science
                      JCNS (JCNS) ; JCNS / JCNS-1},
      ddc          = {530},
      cid          = {I:(DE-Juel1)PGI-4-20110106 / I:(DE-Juel1)ICS-1-20110106 /
                      I:(DE-Juel1)JCNS-2-20110106 / I:(DE-Juel1)JCNS-20121112 /
                      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)KWS2-20140101},
      shelfmark    = {Chemistry, Physical / Materials Science, Multidisciplinary
                      / Physics, Multidisciplinary / Polymer Science},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000287091600030},
      doi          = {10.1039/c0sm00894j},
      url          = {https://juser.fz-juelich.de/record/14581},
}