TY - JOUR A1 - Weidner, Steffen A1 - Meyer, A. A1 - Kricheldorf, H. T1 - Cyclic polyglycolides via ring-expansion polymerization with cyclic tin catalysts T2 - European Polymer Journal N2 - Glycolide was polymerized in bulk with two cyclic catalysts − 2,2-dibutyl-2-stanna-1,3-dithiolane (DSTL) and 2-stanna-1,3-dioxa-4,5,6,7-dibenzepane (SnBiph). The monomer/initiator ratio, temperature (140 – 180 °C) and time (1–––4 days) were varied. The MALDI TOF mass spectra exclusively displayed peaks of cyclic polyglycolide (PGA) and revealed an unusual “saw-tooth pattern” in the mass range below m/z 2 500 suggesting formation of extended ring crystallites. The DSC measurements indicated increasing crystallinity with higher temperature and longer time, and after annealing for 4 d at 160 °C a hitherto unknown and unexpected glass transition was found in the temperature range of 170–185 °C. Linear PGAs prepared by means of metal alkoxides under identical conditions did not show the afore-mentioned features of the cyclic PGAs, neither in the mass spectra nor in the DSC measurements. All PGAs were also characterized by SAXS measurements, which revealed relatively small L-values suggesting formation of thin crystallites in all cases with little influence of the reaction conditions. PB - Elsevier Ltd. KW - Polyglycolide KW - MALDI-TOF MS KW - Ring-expansion polymerization KW - Crystals PY - 2024 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/59554 AN - OPUS4-59554 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595541 SN - 0014-3057 VL - 207 SP - 1 EP - 9 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany