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@ARTICLE{Bras:894130,
      author       = {Bras, Ana and Arizaga, Ana and Agirre, Uxue and Dorau,
                      Marie and Houston, Judith and Radulescu, Aurel and Kruteva,
                      Margarita and Pyckhout-Hintzen, Wim and Schmidt, Annette M.},
      title        = {{C}hain-{E}nd {E}ffects on {S}upramolecular {P}oly(ethylene
                      glycol) {P}olymers},
      journal      = {Polymers},
      volume       = {13},
      number       = {14},
      issn         = {2073-4360},
      address      = {Basel},
      publisher    = {MDPI},
      reportid     = {FZJ-2021-03057},
      pages        = {2235},
      year         = {2021},
      abstract     = {In this work we present a fundamental analysis based on
                      small-angle scattering, linear rheology and differential
                      scanning calorimetry (DSC) experiments of the role of
                      different hydrogen bonding (H-bonding) types on the
                      structure and dynamics of chain-end modified poly(ethylene
                      glycol) (PEG) in bulk. As such bifunctional PEG with a molar
                      mass below the entanglement mass Me is symmetrically
                      end-functionalized with three different hydrogen bonding
                      (H-bonding) groups: thymine-1-acetic acid (thy),
                      diamino-triazine (dat) and 2-ureido-4[1H]-pyrimidinone
                      (upy). A linear block copolymer structure and a
                      Newtonian-like dynamics is observed for PEG-thy/dat while
                      results for PEG-upy structure and dynamics reveal a sphere
                      and a network-like behavior, respectively. These
                      observations are concomitant with an increase of the
                      Flory–Huggins interaction parameter from PEG-thy/dat to
                      PEG-upy that is used to quantify the difference between the
                      H-bonding types. The upy association into spherical clusters
                      is established by the Percus–Yevick approximation that
                      models the inter-particle structure factor for PEG-upy.
                      Moreover, the viscosity study reveals for PEG-upy a shear
                      thickening behavior interpreted in terms of the free path
                      model and related to the time for PEG-upy to dissociate from
                      the upy clusters, seen as virtual crosslinks of the formed
                      network. Moreover, a second relaxation time of different
                      nature is also obtained from the complex shear modulus
                      measurements of PEG-upy by the inverse of the angular
                      frequency where G’ and G’’ crosses from the
                      network-like to glass-like transition relaxation time, which
                      is related to the segmental friction of PEG-upy polymeric
                      network strands. In fact, not only do PEG-thy/dat and
                      PEG-upy have different viscoelastic properties, but the
                      relaxation times found for PEG-upy are much slower than the
                      ones for PEG-thy/dat. However, the activation energy related
                      to the association dynamics is very similar for both
                      PEG-thy/dat and PEG-upy. Concerning the segmental dynamics,
                      the glass transition temperature obtained from both
                      rheological and calorimetric analysis is similar and
                      increases for PEG-upy while for PEG-thy/dat is almost
                      independent of association behavior. Our results show how
                      supramolecular PEG properties vary by modifying the
                      H-bonding association type and changing the molecular
                      Flory–Huggins interaction parameter, which can be further
                      explored for possible applications},
      cin          = {JCNS-FRM-II / MLZ / JCNS-1 / JCNS-4},
      ddc          = {540},
      cid          = {I:(DE-Juel1)JCNS-FRM-II-20110218 / I:(DE-588b)4597118-3 /
                      I:(DE-Juel1)JCNS-1-20110106 / I:(DE-Juel1)JCNS-4-20201012},
      pnm          = {6G4 - Jülich Centre for Neutron Research (JCNS) (FZJ)
                      (POF4-6G4) / 632 - Materials – Quantum, Complex and
                      Functional Materials (POF4-632)},
      pid          = {G:(DE-HGF)POF4-6G4 / G:(DE-HGF)POF4-632},
      experiment   = {EXP:(DE-MLZ)KWS2-20140101},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {34300992},
      UT           = {WOS:000677180200001},
      doi          = {10.3390/polym13142235},
      url          = {https://juser.fz-juelich.de/record/894130},
}