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The effect of inorganic and organic macromolecular structures on the performance of metallocene polymerization catalysts
Author(s) -
Ciardelli Francesco,
Altomare Angelina,
Bronco Simona,
Oulderrahmania Lotfi,
Masi Francesco
Publication year - 2000
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/1521-3900(200007)156:1<147::aid-masy147>3.0.co;2-r
Subject(s) - metallocene , steric effects , polymerization , polymer chemistry , polymer , ethylene , macromolecule , chain transfer , copolymer , catalysis , chemistry , materials science , olefin fiber , organic chemistry , chemical engineering , radical polymerization , biochemistry , engineering
After a short comparative analysis of different macromolecular ligands reported in the relevant literature, the presentation will be centered on the results obtained in the authors' laboratory using structurally defined inorganic supports in terms also of their macromolecular structure. Zeolites and mesomorphous silica can link, after proper chemical modification of their surface with MAO, unmodified metallocene complexes through cage entrapment and weak interactions, thus allowing the transfer from the solution to the solid phase. The metallocene complexes in their new phase are characterized by the catalytic behavior in olefin polymerization after activation with MAO. A decrease of productivity is generally observed depending on the type of support. The steric hindrance provided by the support is evidenced by the depression of chain transfer rate with formation of higher molecular weight polymers. Also shape selectivity is observed during copolymerization of ethylene with α‐olefins having variable size. These steric effects are released when going from HY zeolite to MCM silica.