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  <doc>
    <id>47027</id>
    <completedYear/>
    <publishedYear>2018</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>lecture</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
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    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Syntheses of Cyclic Polymers via the ROPPOC Approach</title>
    <abstract language="eng">Different strategies for the synthesis of polylactides were presented with special focus on Ring-opening Polymerization (ROP) and simultaneous ROP and Polycondensation (ROPPOC) mechanism. The mechanism of the formation of cyclic Polyesters is discussed in detail and established theories about the formation of cycles in polycondensation reactions are critically reviewed.</abstract>
    <enrichment key="eventName">DSM Competence Meeting</enrichment>
    <enrichment key="eventPlace">Dalfsen, The Netherlands</enrichment>
    <enrichment key="eventStart">12.11.2018</enrichment>
    <enrichment key="eventEnd">13.11.2018</enrichment>
    <enrichment key="InvitedTalks">0</enrichment>
    <author>H. R. Kricheldorf</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Polylactide</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>MALDI-TOF mass spectrometry</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Polycondensation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Cycles</value>
    </subject>
    <collection role="ddc" number="620">Ingenieurwissenschaften und zugeordnete Tätigkeiten</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
    <collection role="literaturgattung" number="">Präsentation</collection>
  </doc>
  <doc>
    <id>38365</id>
    <completedYear/>
    <publishedYear>2016</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>lecture</type>
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    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
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    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Cyclization and dispersity of polyesters</title>
    <abstract language="eng">Starting out from Flory`s most probable Distribution concept, correct and incorrect evaluations of SEC measurements are discussed. Using the correct mode, polyesters prepared by irreversible and reversible polycondensation methods were studied. Polyesters of α,ω−alkanediols and isophthalic acid or polyesters of diphenols and sebacic acid were prepared by three different irreversible polyconcensation methods. Formation of cyclic oligo and polyesters was monitored by MALDI-TOF mass spectrometry and dispersities were measured by SEC. The results are compared with the theories of Flory and Odian. &#13;
Eqilibrated polyesters were prepared by reversible polycondensation of ethyl 6-hydroxycaproate or by alcohol-initiated ring-opening polymerization of ε-caprolactone. Various catalysts were compared. The influence of dilution and of di- or multifunctional initiators was evaluated. Furthermore, equilibrated polylactides were prepared from L- or meso-lactide at 120, 160 and 180°C. A fast even-odd equilibration was discovered in addition to reversible cyclization and intermolecular transesterification. The influence of these different equilibration mechanisms on the dispersity was investigated. The preparative and theoretical consequences are discussed.</abstract>
    <enrichment key="eventName">Polycondensation 2016</enrichment>
    <enrichment key="eventPlace">Moscow, Russia</enrichment>
    <enrichment key="eventStart">11.09.2016</enrichment>
    <enrichment key="eventEnd">15.09.2016</enrichment>
    <enrichment key="InvitedTalks">0</enrichment>
    <author>H. R. Kricheldorf</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Polyester</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Cyclization</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>MALDI-TOF MS</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>SEC</value>
    </subject>
    <collection role="ddc" number="543">Analytische Chemie</collection>
    <collection role="ddc" number="620">Ingenieurwissenschaften und zugeordnete Tätigkeiten</collection>
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    <collection role="literaturgattung" number="">Präsentation</collection>
  </doc>
  <doc>
    <id>46340</id>
    <completedYear/>
    <publishedYear>2018</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>lecture</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Cyclic Polyesters via ROPPOC or REP</title>
    <abstract language="eng">Various catalysts and polycondensation mechanisms (ROPPOC/REP/ROP)were presented and discussed with regard to the Formation of cyclic and linear polylactides. It could be shown that depending on the structure of the catalyst even- and od numbered cyclics were selectively formed. These data were supported by various analytical techniques like MALDI-TOF mass spectrometry and Size Exclusion Chromatography.</abstract>
    <enrichment key="eventName">Polycondensation 2018</enrichment>
    <enrichment key="eventPlace">Alexandria, VA, USA</enrichment>
    <enrichment key="eventStart">14.10.2018</enrichment>
    <enrichment key="eventEnd">17.10.2018</enrichment>
    <enrichment key="InvitedTalks">0</enrichment>
    <author>H. R. Kricheldorf</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Polycondensation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>MALDI-TOF MS</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Ring-opening polymerization</value>
    </subject>
    <collection role="ddc" number="620">Ingenieurwissenschaften und zugeordnete Tätigkeiten</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
    <collection role="literaturgattung" number="">Präsentation</collection>
  </doc>
  <doc>
    <id>61070</id>
    <completedYear/>
    <publishedYear>2024</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume/>
    <type>lecture</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Reversible Polycondensations and the Jacobson-Stockmayer Theory</title>
    <abstract language="eng">Reversible polycondensations are polycondensations that include equilibration reactions at any stage of the process. Syntheses of Polyesters in bulk involving transesterification reactions and syntheses of polyamides in bulk involving transamidation are typical examples. In 1950, Jacobson and Stockmayer published a first theory of reversible polycondensations based on experimental studies with aliphatic polyesters.[1,2] They explained the reversibility by the reversible formation of cyclic oligomers and low molar mass polymers from an active chain end (so-called “back-biting”). The formation of cycles via end-to-end cyclization was excluded in agreement with Flory´s theory of irreversible polycondensations.[3] The reinvestigation of the Jacobson-Stockmayer experiments by the authors in combination with theoretical considerations shows that the JS theory is wrong. [4,5] It turned out that the experimental scenario is far from the reality. In real polycondensations, intermolecular equilibration is faster than “back-biting”, and end-to-end cyclization is quite normal. The revised theory of step-growth polymerization predicts that in the ideal case of 100% conversion, all reaction products are cycles, regardless, of whether the step-growth polymerization is reversible or not.</abstract>
    <identifier type="url">https://polycond-2024.sciencesconf.org/</identifier>
    <enrichment key="eventName">Polycondensation 2024</enrichment>
    <enrichment key="eventPlace">Lyon, France</enrichment>
    <enrichment key="eventStart">15.09.2024</enrichment>
    <enrichment key="eventEnd">18.09.2024</enrichment>
    <enrichment key="InvitedTalks">1</enrichment>
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    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">true</enrichment>
    <author>H. R. Kricheldorf</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Polycondensation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Cyclisation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>MALDI TOF MS</value>
    </subject>
    <collection role="ddc" number="620">Ingenieurwissenschaften und zugeordnete Tätigkeiten</collection>
    <collection role="institutes" number="">6 Materialchemie</collection>
    <collection role="institutes" number="">6.3 Strukturanalytik</collection>
    <collection role="themenfelder" number="">Material</collection>
    <collection role="themenfelder" number="">Degradationsmechanismen</collection>
    <collection role="themenfelder" number="">Chemie und Prozesstechnik</collection>
    <collection role="themenfelder" number="">Chemische Charakterisierung und Spurenanalytik</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
    <collection role="literaturgattung" number="">Präsentation</collection>
  </doc>
</export-example>
