42600 2017 eng 3767 3775 22 55 article Wiley Periodicals 1 -- -- -- L-Lactide is polymerized in bulk at 160 8C either with dibutyltin bis(benzylmercaptide) (SnSBzl), dibutyltin bis(benzothiazole 2-mercaptide) (SnMBT), or with dibutyltin bis(pentafluorothiophenolate) (SnSPF) as catalysts. SnSBzl yields linear polylactides having benzylthio-ester end groups in addition to cyclic polylactides, whereas SnMBT and SnSPF mainly or exclusively yield cyclic polylactides. This finding, together with model reactions, indicates that the SnS catalysts promote a combined ring-opening polymerization and polycondensation process including end-to-end cyclization. SnMBT caused slight racemization (3%–5%), when used at 160 8C. With SnSPF optically pure cyclic poly(L-lactide)s with high-molecular weights can be prepared at 160 8C. Journal of Polymer Science A - Polymer Chemistry 10.1002/pola.28762 23.10.2017 H. R. Kricheldorf Steffen Weidner F. Scheliga eng uncontrolled Cyclopolymerization eng uncontrolled Catalysts eng uncontrolled MALDI-TOF MS eng uncontrolled Polyester eng uncontrolled Ring-opening polymerization Ingenieurwissenschaften und zugeordnete Tätigkeiten Verlagsliteratur Datei im Netzwerk der BAM verfügbar ("Closed Access")