TY - JOUR A1 - Kricheldorf, H. A1 - Weidner, Steffen T1 - SnOct 2-Catalyzed Syntheses of Cyclic Poly (l-lactide) s with Catechol as Low-Toxic Co-catalyst N2 - Polymerizations of l-lactide in bulk at 160 or 180 °C were performed with 1/1 mixtures of catechol (CA) or 4-tert-butylcatechol (BuCA) and tin(II)-2-ethylhexanoate (SnOct2) as catalysts and a variation of the Lac/Cat ratio. Weight average molar masses (Mw) up to 170,000 g mol−1 were obtained with CA and up to 120,000 g mol−1 with BuCA. The cyclic structure of the resulting poly(l-lactide)s was proven by MALDI-TOF mass spectrometry and by comparison of their hydrodynamic volumes with those of commercial linear poly(l-lactide)s. The predominance of even-numbered cycles increased with lower temperatures and shorter polymerization times. This fnding indicates that the cyclic architecture is the results of a ring-expansion polymerization mechanism. Addition of silylated BuCA as co-catalyst was less favorable than addition of free BuCA. KW - Polylactide KW - MALDI-TOF MS KW - Cyclization KW - Catalyst KW - Catechol KW - Toxicity PY - 2019 DO - https://doi.org/10.1007/s10924-019-01545-5 SP - 10924 PB - Springer AN - OPUS4-49210 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kricheldorf, Hans. R. A1 - Weidner, Steffen T1 - About the Toxicity of Polymerization Catalysts and Polymer Additives Based on Tin(II) Salts and Tin(IV) Compounds N2 - This article reviews and discusses information on the toxicity of numerous tin-based catalysts used in academic research and industrial production for the synthesis of various polymers, such as polyesters, polyurethanes, and polysiloxanes. Tin(IV) compounds used as additives and as PVC stabilizers are also considered. Emphasis is put on the differentiation between tin(II) salts on the one hand and tin(IV) compounds on the other hand. In the first chapter, historical facts about human contact with stannous ions are discussed, along with toxicity studies of canned foods and beverages. In the second part, toxicity tests based on cell cultures and medical applications of tin(II)-containing films or implants are described. The third part focuses on alkyl and aryl tin(IV) compounds. KW - Tin KW - Toxicity KW - Environment KW - Polymer catalysts KW - Polymer additives PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-642877 DO - https://doi.org/10.1021/acs.chas.5c00105 SN - 1871-5532 SP - 1 EP - 13 PB - American Chemical Society (ACS) AN - OPUS4-64287 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -