The copolymerization of conjugated dienes monomers and olefin is of particular interest since the resulting copolymers containing double bonds into the chain backbone are suitable of many practical applications. In spite of this interest these materials are difficult to obtain because the completely different behavior of the two class of monomers for a given catalytic system. It appears that the only efficient catalytic systems for the synthesis of poly(ethene-co-1,3-butadiene) under reasonable experimental conditions are those developed by Boisson et. al. based on neodymium complexes.1 In this case an alternating structure with butadiene mainly inserted in trans-1,4 configuration was observed. More recently the efforts to expand the variety of group 4 complexes able to efficiently polymerize olefins has resulted in a mushrooming of catalytic system based on non-cyclopentadienyl ligands.2 In particular, we became interested in a new class of group 4 metal catalyst precursors which incorporate a tetradentate ligand having two phenolate units linked through a 1,ω-dithiaalkanediyl bridge S(CH2)nS (n = 2 and 3).3 Namely, the dichloro{1,4-dithiabutanediyl-2,2'-bis(4,6-di-tert-butyl-phenoxy)}titanium complex having 1,4-dithiabutanediyl bridge possesses C2-symmetry and was shown to be highly active, after proper activation, in isospecific styrene. Here we report on the ability of the dichloro{1,4-dithiabutanediyl-2,2'-bis(4,6-di-tert-butyl-phenoxy)}titanium complex activated by methylalumoxane to promote the copolymerization of ethylene with butadiene with high activity. The single site behavior of the catalytic system is pointed out by the monomodal molecular weight distributions of the polymers with polydispersity indexes close to 2. The reactivity ratios values and the microstructure analysis by 13C NMR indicate an alternating distribution of the two monomer in the polymer chain.

Ethylene-butadiene copolymerization promoted by titanium complex containing a tetradentate [OSSO]-type bis(phenolato) ligand

CAPACCHIONE, Carmine;PROTO, Antonio
2008-01-01

Abstract

The copolymerization of conjugated dienes monomers and olefin is of particular interest since the resulting copolymers containing double bonds into the chain backbone are suitable of many practical applications. In spite of this interest these materials are difficult to obtain because the completely different behavior of the two class of monomers for a given catalytic system. It appears that the only efficient catalytic systems for the synthesis of poly(ethene-co-1,3-butadiene) under reasonable experimental conditions are those developed by Boisson et. al. based on neodymium complexes.1 In this case an alternating structure with butadiene mainly inserted in trans-1,4 configuration was observed. More recently the efforts to expand the variety of group 4 complexes able to efficiently polymerize olefins has resulted in a mushrooming of catalytic system based on non-cyclopentadienyl ligands.2 In particular, we became interested in a new class of group 4 metal catalyst precursors which incorporate a tetradentate ligand having two phenolate units linked through a 1,ω-dithiaalkanediyl bridge S(CH2)nS (n = 2 and 3).3 Namely, the dichloro{1,4-dithiabutanediyl-2,2'-bis(4,6-di-tert-butyl-phenoxy)}titanium complex having 1,4-dithiabutanediyl bridge possesses C2-symmetry and was shown to be highly active, after proper activation, in isospecific styrene. Here we report on the ability of the dichloro{1,4-dithiabutanediyl-2,2'-bis(4,6-di-tert-butyl-phenoxy)}titanium complex activated by methylalumoxane to promote the copolymerization of ethylene with butadiene with high activity. The single site behavior of the catalytic system is pointed out by the monomodal molecular weight distributions of the polymers with polydispersity indexes close to 2. The reactivity ratios values and the microstructure analysis by 13C NMR indicate an alternating distribution of the two monomer in the polymer chain.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11386/3041025
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