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SnOct2-catalyzed and alcohol-initiated ROPS of L-lactide - Control of the molecular weight and the role of cyclization
- Ring-opening polymerizations (ROP) of l-lactide (LA) are conducted in bulk at 130, 160, or 180 °C and are initiated with two different alcohols at 160 °C. The lactide/initiator ratio (LA/In) is varied from 50/1 (20/1 at 180 °C) to 900/1 and the lactide/catalyst ratio (LA/Cat) between 2000/1 and 8000/1. At all temperatures a nearly perfect control of number average molecular weight (Mn) via the LA/In ratio is feasible up to LA/In = 200/1, but at higher ratios the Mn value lags behind the theoretical values and the discrepancy increases with higher LA/Cat ratios. Variation of the LA/Cat ratio influences the formation of cycles but does not significantly influence Mn, when the LA/In ratio is kept constant. The formation of cycles is favored by lower In/Cat ratios and is the main reason for the unsatisfactory control of Mn at high LA/In ratios. The results also suggest that the cycles are mainly or exclusively formed by end-to-end cyclization and not, as believed previously, byRing-opening polymerizations (ROP) of l-lactide (LA) are conducted in bulk at 130, 160, or 180 °C and are initiated with two different alcohols at 160 °C. The lactide/initiator ratio (LA/In) is varied from 50/1 (20/1 at 180 °C) to 900/1 and the lactide/catalyst ratio (LA/Cat) between 2000/1 and 8000/1. At all temperatures a nearly perfect control of number average molecular weight (Mn) via the LA/In ratio is feasible up to LA/In = 200/1, but at higher ratios the Mn value lags behind the theoretical values and the discrepancy increases with higher LA/Cat ratios. Variation of the LA/Cat ratio influences the formation of cycles but does not significantly influence Mn, when the LA/In ratio is kept constant. The formation of cycles is favored by lower In/Cat ratios and is the main reason for the unsatisfactory control of Mn at high LA/In ratios. The results also suggest that the cycles are mainly or exclusively formed by end-to-end cyclization and not, as believed previously, by back-biting.…
Autor*innen: | H. R. Kricheldorf, Steffen WeidnerORCiD, F. Scheliga |
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Dokumenttyp: | Zeitschriftenartikel |
Veröffentlichungsform: | Verlagsliteratur |
Sprache: | Englisch |
Titel des übergeordneten Werkes (Englisch): | Macromolecular chemistry and physics |
Jahr der Erstveröffentlichung: | 2022 |
Organisationseinheit der BAM: | 6 Materialchemie |
6 Materialchemie / 6.3 Strukturanalytik | |
Veröffentlichende Institution: | Bundesanstalt für Materialforschung und -prüfung (BAM) |
Verlag: | Wiley-VCH |
Verlagsort: | Weinheim |
Aufsatznummer: | 2100464 |
Erste Seite: | 1 |
Letzte Seite: | 10 |
DDC-Klassifikation: | Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten |
Freie Schlagwörter: | Cyclization; MALDI-TOF MS; Polylactide; Ring-opening polymerization |
Themenfelder/Aktivitätsfelder der BAM: | Material |
DOI: | 10.1002/macp.202100464 |
URN: | urn:nbn:de:kobv:b43-543066 |
ISSN: | 1521-3935 |
Verfügbarkeit des Dokuments: | Datei für die Öffentlichkeit verfügbar ("Open Access") |
Lizenz (Deutsch): | Creative Commons - CC BY-NC - Namensnennung - Nicht kommerziell 4.0 International |
Datum der Freischaltung: | 11.02.2022 |
Referierte Publikation: | Ja |
Datum der Eintragung als referierte Publikation: | 21.02.2022 |
Schriftenreihen ohne Nummerierung: | Wissenschaftliche Artikel der BAM |