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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.zeige mehrzeige weniger

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Metadaten
Autor*innen:Steffen WeidnerORCiD, A. Meyer, H. R. Kricheldorf
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
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