Titanium norbornene polymerization with

Polyethylene-Wock-poly(clhylcnc-co-norbornene) (PE-fo-P(E-co-NBl ) block copolymer was successfully synthesized by a titanium complex with two non-symmetric bidentate /J-cnaminokclonalo ligands [136,137]. Bis(pyrrolide-imine)titanium complex also has the ability to produce the PE-fo-P(E-co-NBE) block copolymer. PE-fo-PS was synthesized via sequential monomer addition during homogeneous polymerization with bis(phenoxy-imine)metal catalysts [138]. 

The alkyl-substituted titanium carbene complex 18 reacts with norbornene 24 to form a new titanacycle 25, which can be employed for the ROMP of 24 (Scheme 14.13). The titanacycle generated by the reaction of the Tebbe reagent with 24 is also used as an initiator for the same polymerization [23]. These preformed titanacyclobutanes also initiate ROMP of various other strained olefin monomers [24],... 

The polymerization proceeds without termination or chain transfer to give poly-norbomene with a narrow molecular weight distribution [35], After an induction period, the rate of monomer consumption (rate of polymerization) becomes constant, indicating a zero-order dependence on the monomer concentration. The induction period is caused by part of titanacycle 7 undergoing non-productive, but rapidly reversible, cleavage to norbornene and the titanium methylene complex, Eq. (17 a). 

Poly(ethylene-co-norbomene-2,3-dicarboxylic acid anhydride) was prepared by co-polymerizing the respective monomers with the transition metal catalyst, di(3-t-butyl-2-hydroxy-l-(A-phenyhmino)benzene) titanium(IV). The polymerization was conducted at ambient temperature using methylaluminoxane as co-catalyst. After a 10 minute polymerization reaction scoping period 0.02 mol% of norbornene-2,3-dicarboxylic acid anhydride was incorporated into the co-polymer. 

In 2000, Fujita and coworkers reported bis(pyrrolide-iniine)titanium complexes for ethylene polymerization, however, living behavior was not observed (Yoshida et al., 2000). As a result, Fujita and coworkers turned their attention to the copolymerization of ethylene and norbornene (Yoshida et al., 2002 Yoshida et al., 2003 Yoshida et al., 2004). At 25 X, 47a-d/MAO (Figure 9.6) furnished poly(E-a/t-NB) with narrow molecular-weight distributions and high molecular weights MJM = 1.10-1.24, = 127000-600000g/mol). A linear increase of... 

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