TY - JOUR A1 - Kricheldorf, H. A1 - Weidner, Steffen T1 - Cyclic and linear poly(L-lactide)s by ring-expansion polymerization with Bu2SnO, Oct2SnO, and Bu2SnS T2 - Journal of Polymer Science N2 - To elucidate the usefulness of commercial Bu2SnO as catalyst for syntheses of linear and/or cyclic polylactides L-Lactide was polymerized in bulk with variation of the LA/Cat ratio, temperature and time. Based on a ring-expansion polymerization (REP) mechanism cyclic polylactides (PLAs) with weight average molecular weights in the range of 200,000–300,000 are obtained at the highest temperature (180 °C). Polymerizations at 150 °C yielded crystalline, mainly cyclic polylactides which, after annealing, showed high melting temperatures (up to 197.5 °C) and high crystallinities (>80%). Polymerization at 120 °C confirmed the trend towards more linear chains with lower temperatures but yielded extended-ring crystals showing a “saw-tooth pattern” in the mass spectra. Oct2SnO gave similar results as Bu2SnO. Bu2SnS proved a sluggish polymerization catalyst, but a good transesterification catalyst in solid PLA. PB - Wiley CY - Hoboken, NJ KW - MALDI TOF MS KW - Biobased polymers KW - Polylactide KW - Ring-expansion polymerization PY - 2023 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/58412 AN - OPUS4-58412 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-584121 SN - 2642-4169 SP - 1 EP - 10 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany