Copolymerization Of Non-conjugated Dienes With Olefins Catalyzed By Half-Sandwich Scandium Complexes

Cycloolefin copolymer (COC) is a copolymer material containing cyclic units in main chain of polymer. It is widely used as raw material for manufacturing electronic and optical components because of their unique physical and chemical properties. The cyclopolymerization of non-conjugated dienes with olefins is a efficient method for the preparation of COC materials. So far, a large number of catalysts based on various metals such as Ti, Zr, Y, Sm, and V have been reported for the homopolymerization of non-conjugated dienes. However, catalysts suitable for the copolymerization of non-conjugated dienes with other monomers are rather limited. The monomers utilized for the copolymerization of non-conjugated dienes were also limited only to ethylene and propylene. In this thesis, a series of half-sandwich scandium complexes Cp’Sc(CH2SiMe3)2(THF) (1a:Cp’= C5H5; 1b:Cp’= C5H4Me; 1c:Cp’= C5HMe4; 1d:Cp’= C5Me5; 1e:Cp’= C5Me4SiMe3), Cp’Sc(CH2SiMe3)2 (2: Cp’= C5Me4C6H4OMe-o; 3:Cp’ = C5Me4CH2CH2PPh2; 4:Cp’= C5Me4CH2CH(Ph) (NCHCHN(CH3)CH; 5:Cp’= C5Me4CH2SiMe2(O)PPh2) and Cp’Sc(CH2C6H4NMe2-o)2 (6a: Cp’= C5H5; 6b:Cp’= C5H4Me; 6c:Cp’= C5HMe4; 6d:Cp’= C5Me5; 6e:Cp’= C5Me4SiMe3) were synthesized and fully characterized by 1H,13C NMR, X-ray, and microelemental analyses. By modifying the Cp’ligands, the cyclopolymerization and cyclocopolymerization non-conjugated dienes such as 1,5-hexadiene (HD) and 1,6-heptadiene (HPD) have been achieved for the first time to afford a new family of cycloolefin copolymers with a wide range of non-conjugated diene contents and controlled microstructures in the presence of a half-sandwich scandium complex in combination with [Ph3C][B(C6F5)4].The catalytic activity and selectivity of all the half-sandwich scandium complexes in the homopolymerization of non-conjugated dienes was investigated. By use of the THF-free scandium catalyst systems 6a-6e/[Ph3C][B(C6F5)4], the homopolymerization of HD has been achieved to afford soluble cyclopolymers containing methylene-1,3-cyclopentane (MCP) units and 3-vinyltetramethylene (VTM) units. By modifying the Cp’ ligands, the microstructures and compositions of HD homopolymers can be adjusted. With regard to HPD homopolymerization, all the half-sandwich scandium complexes afford soluble cyclopolyolefins containing both six-member ring methylene-1,3- cyclohexane (MCH) units and five-member ring ethylene-1,2-cyclopentane (ECP) units. Whether or not the catalyst metal center bears a THF ligand shows significant influence on the molecular weight and microstructure of the resulting HPD homopolymers. These results strongly suggest that a subtle change in the ligand environment of the catalyst metal center can significantly alter non-conjugated dienes polymerization process. The catalytic activity and selectivity of all the half-sandwich scandium complexes in the copolymerization of non-conjugated dienes with mono-olefines was investigated. By modifying the Cp’ligands, both HD-styrene and HPD-styrene copolymerization have been achieved for the first time to afford a new family of cyclopolyolefins with a wide range of HD or HPD contents and controlled microstructures. By use of 5/[Ph3C][B(C6F5)4], the cyclocopolymerization of HD or HPD with styrene afford cyclopolyolefins containing both six-member ring units and five-member ring units together with atactic styrene-styrene sequences. However, in the presence of 6c-6e/[Ph3C][B(C6F5)4], the copolymerization of HD with styrene afforded a new family of polymer materials containing five-member rings units together with VTM units and unique syndiotactic styrene-styrene sequences. In addition, by use of 6e/[Ph3C][B(C6F5)4], the cycloterpolymerization of HD or HPD with ethylene and styrene has also been achieved for the first time to afford a new family of cyclopolyolefins containing both six-member ring units, five-member ring units and ethylene units together with unique syndiotactic styrene-styrene sequences. The composition of the copolymers can be controlled in a wide range simply by changing the co-monomer feeding ratios.The catalytic activity and selectivity of all the half-sandwich scandium complexes in the copolymerization of non-conjugated dienes with conjugated diene was investigated. By modifying the Cp’ligands, both random and alternating HD-isoprene and HPD-isoprene copolymerization have been achieved for the first time to afford a new family of cyclopolyolefins with cyclic units together with residual C=C double bonds units derived from the isoprene. By use of le or 2/[Ph3C][B(C6F5)4], the random copolymerization HD or HPD with isoprene have been achieved. The HD or HPD and isoprene contents in the corresponding random copolymers could be easily controlled by changing the monomer feed ratio. In the presence of 5/[Ph3C][B(C6F5)4], the copolymerization afford the corresponding HD—soprene and HPD-isoprene alternating copolymers. In the alternating copolymerization of non-conjugated dienes with isoprene, the complex 5 show the high stereoselectivity.