TY - JOUR A1 - Weidner, Steffen A1 - Kricheldorf, H. R. T1 - The Role of Transesterification in SnOct 2 - Catalyzed Polymerizations of Lactides T2 - Macromolecular Chemistry and Physics N2 - l-lactide or meso-lactide are polymerized either at 120 °C where the polymerization process of l-lactide is accompanied by crystallization, or at 180 °C where poly(l-lactide) remains in the molten state. Polymerizations at 120 °C initially yield even-numbered chains (with respect to lactic acid units) having relatively low dispersity, but the fraction of odd-numbered chains increases with time and the entire molecular weight distribution changes. Traces of cyclics are only formed after 7 d. Polymerizations at 180 °C yield equilibrium of even and odd-numbered chains from the beginning, but at low monomer/initiator ratios and short reaction times (<4 h) cyclics are again not formed. They appear at longer reaction times and entail higher dispersities. The results are discussed in terms of five different transesterification mechanisms. PB - Wiley KW - Polylactides KW - MALDI KW - Transesterification KW - Sn catalysts PY - 2017 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/39753 AN - OPUS4-39753 SN - 1022-1352 VL - 218 IS - 3 SP - 1600331 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany