TY - JOUR A1 - Weidner, Steffen A1 - Kricheldorf, H. T1 - Transesterification in alcohol-initiated ROPs of l- and meso-lactide catalyzed by Sn(II) and Sn(IV) compounds at low temperatures T2 - Macromolecular Chemistry and Physics N2 - The purpose of this study is to shed more light on the transesterification processes in alcohol-initiated and tin(II) 2-ethylhexanoate (SnOct2)-catalyzed polymerizations of lactides at low or moderate temperatures. Ethanol-initiated polymerizations are conducted in concentrated solutions at 80 °C and a strong dependence of even/odd equilibration on the alcohol/Sn ratio. Around or above 120 °C cyclization of poly(l-lactide) via “backbiting” occurs as a third mechanism. However, poly(m-lactide) shows a higher cyclization tendency and yields cyclics even at 100 °C. Combinations of ethanol and certain cyclic dibutyltin(IV) catalysts also yield cyclic oligomers of l-lactide at 80 °C. Reaction conditions allowing for a total suppression of all transesterification reactions are not found, but even-numbered poly(m-lactide)s with a purity >95% are obtained at 70 or 60 °C. PB - Wiley-VCH CY - Weinheim KW - Cyclization KW - MALDI-TOF MS KW - Polyester KW - Polylactide KW - Transesterification PY - 2018 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/46705 AN - OPUS4-46705 SN - 1022-1352 SN - 1521-3935 VL - 219 IS - 24 SP - 1800445, 1 EP - 10 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany