Mechanism of isotactic styrene polymerization with a C 6F 5-substituted bis(phenoxyimine) titanium system
Type
ArticleAuthors
Caporaso, Lucia
Loria, Marianna
Mazzeo, Mina
Michiue, Kenji
Nakano, Takashi
Fujita, Terunori
Cavallo, Luigi

KAUST Department
KAUST Catalysis Center (KCC)Physical Sciences and Engineering (PSE) Division
Chemical Science Program
Date
2012-11-13Permanent link to this record
http://hdl.handle.net/10754/562411
Metadata
Show full item recordAbstract
We report a combined, experimental and theoretical, study of styrene polymerization to clarify the regio- and stereocontrol mechanism operating with a C 6F 5-substituted bis(phenoxyimine) titanium dichloride complex. Styrene homopolymerization, styrene-propene and styrene-ethene-propene copolymerizations have been carried out to this aim. A combination of 13C NMR analysis of the chain-end groups and of the microstructure of the homopolymers and copolymers reveals that styrene polymerization is highly regioselective and occurs prevalently through 2,1-monomer insertion. DFT calculations evidenced that steric interaction between the growing chain and the monomer in the transition state insertion stage is at the origin of this selectivity. The formation of isotactic polystyrene with a chain-end like microstructure is rationalized on the base of a mechanism similar to that proposed for the syndiospecific propene polymerization catalyzed by bis(phenoxyimine) titanium dichloride complexes. Finally, a general stereocontrol mechanism operative in olefin polymerization with this class of complexes is proposed. © 2012 American Chemical Society.Publisher
American Chemical Society (ACS)Journal
MacromoleculesISSN
00249297ae974a485f413a2113503eed53cd6c53
10.1021/ma301631b