Propene-Ethene Copolymers Synthesised withCs-Symmetric Metallocenes and Different Cocatalysts
| Autor: | Barbro Löfgren, Tanja Seraidaris, Walter Kaminsky, Jukka Seppälä |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Polymers and Plastics
Chemistry Organic Chemistry Triad (anatomy) Borane Condensed Matter Physics Catalysis Propene chemistry.chemical_compound medicine.anatomical_structure Polymerization Sandwich compound Polymer chemistry Materials Chemistry Copolymer medicine Physical and Theoretical Chemistry Metallocene |
| Zdroj: | Macromolecular Chemistry and Physics. 206:1319-1325 |
| ISSN: | 1521-3935 1022-1352 |
| DOI: | 10.1002/macp.200400542 |
| Popis: | Propene-ethene copolymers with low to moderate amounts of ethene were synthesised with two C s -symmetric metallocene complexes, [(p-CH 3 OPh)2C(2,7-di- t BuFlu)-(Cp)]ZrCl 2 (I) and [(p-CH 3 OPh)2C(2,7-di- t BuFlu)(Cp)]HfCl2 (Ia). Methylalumoxane (MAO), N,N-dimethylanilinium tetra-(pentafluorophenyl)borate {[Me 2 HNPh][B(C 6 F 5 ) 4 ]}, trityl tetra(pentafluorophenyl)borate {[Ph3C][B(C6F5)4]) and tris-(pentafluorophenyl)borane [B(C 6 F 5 ) 3 ] were used as cocatalysts in the polymerisations. The differences in polymerisation activity, ethene incorporation rate and molecular weight as well as the microstructure and the thermal behaviour of the homo-and copolymers were studied. The different cocatalysts have a strong influence on the polymerisation activity and the syndiotacticity of the polymers, but only a minor influence on the ethene incorporation rate and the molecular weight. At 30 °C, the incorporation rate of ethene is ca. 25 times faster for complex I and ca. 16 times faster for complex Ia than the incorporation rate of propene. The thermal behaviour of the homo- and copolymers is dependent of the polymerisation temperature and the cocatalyst. I/MAO produces homo- and copolymers at 30 °C with more regular microstructure than I/[Me 2 HNPh][B(C 6 F 5 ) 4 ], I/ [Ph 3 C][B(C 6 F 5 ) 4 ] and I/B(C 6 F 5 ) 3 leading to homo- and copolymers with higher melting and crystallisation temperatures. On the contrary, at 0 °C I/[Me 2 HNPh][B(C 6 F 5 ) 4 ] and I/[Ph 3 C][B(C 6 F 5 ) 4 ] produce copolymers with higher propene sequence syndiotacticity and higher melting and crystallisation temperatures than I/MAO. The influence of the cocatalyst on the catalyst coordination environment is temperature-dependent and thereby the structure of the forming homo- or copolymers varies. |
| Databáze: | OpenAIRE |
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