Ethylene- co -norbornene Copolymerization Using a Dual Catalyst System in the Presence of a Chain Transfer Agent

• Published in: Polymers Vol. 11; no. 3; p. 554
• Main Authors: Boggioni, Laura, Sidari, Diego, Losio, Simona, Stehling, Udo M, Auriemma, Finizia, Malafronte, Anna, Di Girolamo, Rocco, De Rosa, Claudio, Tritto, Incoronata
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 22-03-2019; MDPI
• Subjects: Catalysis; Catalysts; Chain transfer; Chemical synthesis; Copolymerization; Copolymers; cycloolefin copolymerization; Dichlorides; Elastic properties; Ethylene; Experiments; Glass transition temperature; Mechanical properties; Metallocenes; Microstructure; Molecular weight; Polymerization; Polymers; segmented polymers; Transition metals; Zinc; Zirconium; ZnEt2; United States > US; ZnEt2; mechanical properties; segmented polymers; cycloolefin copolymerization; metallocenes
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym11030554

Ethylene-
-norbornene copolymers were synthesized by a dual catalyst system at three concentrations of norbornene in the feed and variable amounts of ZnEt₂, as a possible chain transfer agent. The dual catalyst system consists of two
-metallocenes, isopropyliden(η
cyclopentadienyl)(η⁵-indenyl)zirconium dichloride (
) and isopropyliden(η⁵-3-methylcyclopentadienyl)(η⁵-fluorenyl)zirconium dichloride (
), activated with dimethylanilinium tetrakis(pentafluorophenyl)borate, in presence of TIBA. Values of norbornene content, molecular mass, glass transition temperature, and reactivity ratios
and
of copolymers prepared in the presence of
+
are intermediate between those of reference copolymers. The study of tensile and elastic properties of ethylene-
-norbornene copolymers (poly(E-
-N)s) gave evidence that copolymers were obtained in part through transfer of polymer chains between different transition metal sites. Mechanical properties are clearly different from those expected from a blend of the parent samples and reveal that copolymers obtained in the presence of
+
and ZnEt₂ consist of a reactor blend of segmented chains produced by exchange from
to
and
to 2 acting as the ideal compatibilizer of chains produced by the chain transfer from
to
, and from
to
.