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Ethylene‐norbornene copolymers prepared with metallocene‐ based catalysts: new sequence assignments by 13 C NMR
Author(s) -
Tritto Incoronata,
Boggioni Laura,
Sacchi Maria Carmela,
Locatelli Paolo,
Ferro Dino R.,
Provasoli Augusto
Publication year - 1999
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/(sici)1521-3927(19990501)20:5<279::aid-marc279>3.0.co;2-#
Subject(s) - metallocene , norbornene , copolymer , ethylene , materials science , polymer chemistry , catalysis , sequence (biology) , polymerization , organic chemistry , chemistry , polymer , composite material , biochemistry
A series of ethylene‐norbornene copolymers were synthesized in the presence of zirconocenes with different symmetries and ligand patterns and at different norbornene (N)/ethylene (E) mole ratios. Copolymers were characterized by 13 C NMR spectroscopy; Inadequate NMR sequences were used also. The comparison of 13 C NMR spectra of copolymers prepared with different norbornene content and the correlation between 13 C NMR chemical shifts and conformational structures of the chain on the basis of molecular mechanics calculations were performed. Preliminary assignments were revised and new comonomer sequences such as ENNE which contain meso and racemo NN dyads were assigned.