Sn(II)2-ethylhexanoate-catalyzed polymerizations of L-lactide in solution – Solution grown crystals of cyclic Poly(L-Lactide)s
- L-lactide (LA) was polymerized in toluene by means of neat tin(II) 2-ethylhexanoate (SnOct2). Concentration, time and temperature were varied. The isothermally crystallized polyLAs (PLA) were characterized in the virgin state with regard to topology, molar mass, melting temperature (Tm), crystal modification, high or low Tm morphology, crystallinity and crystal thickness. Even a small amount of solvent favored cyclization relative to polymerization in bulk, so that cyclic polylactides were obtained at 115 ◦C and even at 95 ◦C. At all temperatures the α-modification of PLA was obtained along with crystallinities up to 90%. With 6 M solution the high Tm morphology with Tm’s > 190 ◦C was obtained at 115 ◦C. The crystal thickness of crystallites grown from solution at 115 ◦C was on the average 10–20% higher than that of PLA polymerized in bulk. At a polymerization temperature of 75 ◦C cyclization was incomplete and fewer perfect crystallites were formed. A new hypothesis for the crystalL-lactide (LA) was polymerized in toluene by means of neat tin(II) 2-ethylhexanoate (SnOct2). Concentration, time and temperature were varied. The isothermally crystallized polyLAs (PLA) were characterized in the virgin state with regard to topology, molar mass, melting temperature (Tm), crystal modification, high or low Tm morphology, crystallinity and crystal thickness. Even a small amount of solvent favored cyclization relative to polymerization in bulk, so that cyclic polylactides were obtained at 115 ◦C and even at 95 ◦C. At all temperatures the α-modification of PLA was obtained along with crystallinities up to 90%. With 6 M solution the high Tm morphology with Tm’s > 190 ◦C was obtained at 115 ◦C. The crystal thickness of crystallites grown from solution at 115 ◦C was on the average 10–20% higher than that of PLA polymerized in bulk. At a polymerization temperature of 75 ◦C cyclization was incomplete and fewer perfect crystallites were formed. A new hypothesis for the crystal growth of cyclic polyLAs is proposed.…
Autor*innen: | Steffen WeidnerORCiD, A. Meyer, H. R. Kricheldorf |
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Dokumenttyp: | Zeitschriftenartikel |
Veröffentlichungsform: | Verlagsliteratur |
Sprache: | Englisch |
Titel des übergeordneten Werkes (Englisch): | Polymer |
Jahr der Erstveröffentlichung: | 2022 |
Organisationseinheit der BAM: | 6 Materialchemie |
6 Materialchemie / 6.3 Strukturanalytik | |
Verlag: | Elsevier |
Verlagsort: | Oxford |
Jahrgang/Band: | 255 |
Aufsatznummer: | 125142 |
Erste Seite: | 1 |
Letzte Seite: | 9 |
DDC-Klassifikation: | Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten |
Freie Schlagwörter: | Crystalinity; MALDI-TOF MS; Polylactide; Polymerization |
Themenfelder/Aktivitätsfelder der BAM: | Material |
DOI: | 10.1016/j.polymer.2022.125142 |
ISSN: | 0032-3861 |
Verfügbarkeit des Dokuments: | Datei im Netzwerk der BAM verfügbar ("Closed Access") |
Datum der Freischaltung: | 18.07.2022 |
Referierte Publikation: | Ja |
Datum der Eintragung als referierte Publikation: | 18.08.2022 |