<?xml version="1.0" encoding="utf-8"?>
<export-example>
  <doc>
    <id>42600</id>
    <completedYear/>
    <publishedYear>2017</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>3767</pageFirst>
    <pageLast>3775</pageLast>
    <pageNumber/>
    <edition/>
    <issue>22</issue>
    <volume>55</volume>
    <type>article</type>
    <publisherName>Wiley Periodicals</publisherName>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>1</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Cyclic Polylactides via Simultaneous Ring-Opening Polymerization and Polycondensation Catalyzed by Dibutyltin Mercaptides</title>
    <abstract language="eng">L-Lactide is polymerized in bulk at 160 8C either with dibutyltin bis(benzylmercaptide) (SnSBzl), dibutyltin bis(benzothiazole 2-mercaptide) (SnMBT), or with dibutyltin bis(pentafluorothiophenolate) (SnSPF) as catalysts. SnSBzl yields linear polylactides having benzylthio-ester end groups in addition to cyclic polylactides, whereas SnMBT and SnSPF mainly or exclusively yield cyclic polylactides. This finding, together with model reactions, indicates that the SnS catalysts promote a combined ring-opening polymerization and polycondensation process including end-to-end cyclization. SnMBT caused slight racemization (3%–5%), when used at 160 8C. With SnSPF optically pure cyclic poly(L-lactide)s with high-molecular weights can be prepared at 160 8C.</abstract>
    <parentTitle language="eng">Journal of Polymer Science A - Polymer Chemistry</parentTitle>
    <identifier type="doi">10.1002/pola.28762</identifier>
    <enrichment key="date_peer_review">23.10.2017</enrichment>
    <author>H. R. Kricheldorf</author>
    <author>Steffen Weidner</author>
    <author>F. Scheliga</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Cyclopolymerization</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Catalysts</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>MALDI-TOF MS</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Polyester</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="literaturgattung" number="">Verlagsliteratur</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
  </doc>
  <doc>
    <id>42407</id>
    <completedYear/>
    <publishedYear>2017</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>Article 1600169, 1</pageFirst>
    <pageLast>6</pageLast>
    <pageNumber/>
    <edition/>
    <issue>1</issue>
    <volume>375</volume>
    <type>article</type>
    <publisherName>Wiley-VCH</publisherName>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>1</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Cyclization and dispersity of polyesters</title>
    <abstract language="eng">Two classes of polyesters were prepared by irreversible polycondensations.&#13;
The dependence of the dispersities on the experimental parameters such as synthetic method, chemical structure, molecular weight and initial monomer concentration was determined. At first it was demonstrated that it is essential for a correct calculation of Mn and Mw to include all oligomers down to the dimers in the evaluation of SEC curves. Furthermore, it was demonstrated for poly(e-caprolactone)s and polylactides that reversible polycondensations and ring-opening polymerizations with equilibration yield identical products.&#13;
Finally, the dependence of the dispersity on various experimental Parameters was determined for equilibrated poly(e-caprolactone)s and polylactides.</abstract>
    <parentTitle language="eng">Macomolecular Symposia</parentTitle>
    <identifier type="doi">10.1002/masy.201600169</identifier>
    <identifier type="issn">1022-1360</identifier>
    <identifier type="issn">1521-3900</identifier>
    <enrichment key="date_peer_review">23.10.2017</enrichment>
    <author>H. Kricheldorf</author>
    <author>Steffen Weidner</author>
    <author>F. Scheliga</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Irreversible polycondensation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Polycaprolactone</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Polylactide</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Dispersity</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="literaturgattung" number="">Verlagsliteratur</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
  </doc>
  <doc>
    <id>39753</id>
    <completedYear/>
    <publishedYear>2017</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1600331</pageFirst>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue>3</issue>
    <volume>218</volume>
    <type>article</type>
    <publisherName>Wiley</publisherName>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>1</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">The Role of Transesteriﬁcation in SnOct 2 - Catalyzed Polymerizations of Lactides</title>
    <abstract language="eng">l-lactide or meso-lactide are polymerized either at 120 °C where the polymerization process of l-lactide is accompanied by crystallization, or at 180 °C where poly(l-lactide) remains in the molten state. Polymerizations at 120 °C initially yield even-numbered chains (with respect to lactic acid units) having relatively low dispersity, but the fraction of odd-numbered chains increases with time and the entire molecular weight distribution changes. Traces of cyclics are only formed after 7 d. Polymerizations at 180 °C yield equilibrium of even and odd-numbered chains from the beginning, but at low monomer/initiator ratios and short reaction times (&lt;4 h) cyclics are again not formed. They appear at longer reaction times and entail higher dispersities. The results are discussed in terms of five different transesterification mechanisms.</abstract>
    <parentTitle language="eng">Macromolecular Chemistry and Physics</parentTitle>
    <identifier type="doi">10.1002/macp.201600331</identifier>
    <identifier type="issn">1022-1352</identifier>
    <enrichment key="date_peer_review">10.04.2017</enrichment>
    <author>Steffen Weidner</author>
    <author>H. R. Kricheldorf</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Polylactides</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>MALDI</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Transesterification</value>
    </subject>
    <subject>
      <language>deu</language>
      <type>uncontrolled</type>
      <value>Sn catalysts</value>
    </subject>
    <collection role="ddc" number="620">Ingenieurwissenschaften und zugeordnete Tätigkeiten</collection>
    <collection role="literaturgattung" number="">Verlagsliteratur</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
  </doc>
  <doc>
    <id>39748</id>
    <completedYear/>
    <publishedYear>2017</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1589</pageFirst>
    <pageLast>1596</pageLast>
    <pageNumber/>
    <edition/>
    <issue>9</issue>
    <volume>8</volume>
    <type>article</type>
    <publisherName>Royal Society of Chemistry</publisherName>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>1</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Cyclic poly(L-lactide)s via ring-expansion polymerizations catalysed by 2,2-dibutyl-2- stanna-1,3-dithiolane</title>
    <abstract language="eng">L-Lactides were polymerized in bulk at 120 or 160 °C with cyclic dibutyltin catalysts derived from 1,2-dimercaptoethane or 2-mercaptoethanol. Only linear chains having one benzyl ester and one OH-end group were obtained when benzyl alcohol was added. When L-lactides were polymerized with neat dibutyl-2-stanna-1,3-dithiolane, exclusively cyclic polylactides were formed even at 120 °C. The temperature, time and monomer/catalyst ratio (M/C) were varied. These results are best explained by a combination of ring-expansion polymerization and ring-extrusion of cyclic oligo- or polylactides with Elimination of the cyclic catalyst. Neither syntheses of linear polylactides nor of cyclic lactides involved racemization up to 20 h at 160 °C.</abstract>
    <parentTitle language="eng">Polymer Chemistry</parentTitle>
    <identifier type="doi">10.1039/C6PY02166B</identifier>
    <identifier type="issn">1759-9954</identifier>
    <identifier type="issn">1759-9962</identifier>
    <enrichment key="date_peer_review">10.04.2017</enrichment>
    <author>H. R. Kricheldorf</author>
    <author>Steffen Weidner</author>
    <author>F. Scheliga</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Ring-expansion polymerization</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>MALDI</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Polylactides</value>
    </subject>
    <collection role="ddc" number="620">Ingenieurwissenschaften und zugeordnete Tätigkeiten</collection>
    <collection role="literaturgattung" number="">Verlagsliteratur</collection>
    <collection role="fulltextaccess" number="">Datei im Netzwerk der BAM verfügbar ("Closed Access")</collection>
  </doc>
</export-example>
