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@ARTICLE{Hvelmann:834277,
      author       = {Hövelmann, Claas and Goossen, Sebastian and Allgaier, J.},
      title        = {{S}cale-{U}p {P}rocedure for the {E}fficient {S}ynthesis of
                      {H}ighly {P}ure {C}yclic {P}oly(ethylene glycol)},
      journal      = {Macromolecules},
      volume       = {50},
      number       = {11},
      issn         = {1520-5835},
      address      = {Washington, DC},
      publisher    = {Soc.},
      reportid     = {FZJ-2017-04259},
      pages        = {4169 - 4179},
      year         = {2017},
      abstract     = {Poly(ethylene glycol) (PEG) is ideally suited for the
                      synthesis of cyclic polymers. The cyclization reaction of
                      PEG via its tosylate intermediate is well established. We
                      improved the cyclization reaction and obtained cyclic raw
                      products in high yields. The quantities of linear precursor
                      and higher molecular weight condensation byproducts were
                      low. The latter byproducts can be removed efficiently by
                      classical fractionation using chloroform/heptane as
                      solvent/nonsolvent pair. For the removal of linear precursor
                      a process was developed which comprises the quantitative
                      oxidation of alcoholic PEG chain ends to carboxyl groups and
                      their subsequent removal with the help of a basic
                      ion-exchange resin. The efficient cleaning processes allowed
                      carrying out the ring closure reaction at relatively high
                      concentrations and so increasing sample quantities. As a
                      result, cyclic poly(ethylene glycol) was obtained in high
                      purity up to a molecular weight of 20 000 g/mol in
                      quantities of several grams. In order to monitor the
                      oxidation reaction and to prove the absence of linear
                      chains, a 1H NMR characterization technique was developed,
                      which is extremely sensitive up to high molecular weights.},
      cin          = {ICS-1 / Neutronenstreuung ; JCNS-1},
      ddc          = {540},
      cid          = {I:(DE-Juel1)ICS-1-20110106 / I:(DE-Juel1)JCNS-1-20110106},
      pnm          = {551 - Functional Macromolecules and Complexes (POF3-551) /
                      6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623)
                      / 6215 - Soft Matter, Health and Life Sciences (POF3-621)},
      pid          = {G:(DE-HGF)POF3-551 / G:(DE-HGF)POF3-6G4 /
                      G:(DE-HGF)POF3-6215},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000403530400008},
      doi          = {10.1021/acs.macromol.7b00361},
      url          = {https://juser.fz-juelich.de/record/834277},
}