ROP of L‐lactide and ε‐caprolactone catalyzed by tin( ii ) and tin( iv ) acetates–switching from COOH terminated linear chains to cycles
| Autor: | Steffen M. Weidner, Hans R. Kricheldorf |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Lactide
Polymers and Plastics chemistry.chemical_element 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Ring-opening polymerization 0104 chemical sciences Catalysis chemistry.chemical_compound End-group Monomer chemistry Polymer chemistry Materials Chemistry Reactivity (chemistry) Physical and Theoretical Chemistry 0210 nano-technology Tin Caprolactone |
| Zdroj: | Journal of Polymer Science. 59:439-450 |
| ISSN: | 2642-4169 2642-4150 |
| DOI: | 10.1002/pol.20200866 |
| Popis: | The catalytic potential of tin(II)acetate, tin(IV)acetate, dibutyltin-bis-acetate and dioctyl tin-bis-acetate was compared based on polymerizations of L-lactide conducted in bulk at 160 or 130C. With SnAc2 low-Lac/Cat ratios (15/1–50/1) were studied and linear chains having one acetate and one carboxyl end group almost free of cyclics were obtained. Higher monomer/catalyst ratios and lower temperatures favored formation of cycles that reached weight average molecular weights (Mw's) between 100,000 and 2,500,000. SnAc4 yielded mixtures of cycles and linear species under all reaction conditions. Dibutyltin- and dioctyl tin bis-acetate yielded cyclic polylactides under most reaction conditions with Mw's in the range of 20,000–80,000. Ring-opening polymerizations performed with e-caprolactone showed similar trends, but the formation of COOH-terminated linear chains was significantly more favored compared to analogous experiments with lactide. The reactivity of the acetate catalysts decreased in the following order: SnAc2> SnAc4>Bu2SnAc2 Oct2SnAc2. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Plný text