| There were a lot of attentions on polynorbornene owing to its high thermostability, strong corrosion resistance, high optical transparency and good electrical performance, and so on. However, their application was limited because of poor solubility and processability. Norbornene with ester functional polar groups could be effectively copolymerized by using an effective and stable late transition metal catalyst for improving the performance of copolymers. Relative to the early transition catalysts, the late transition metal nickel and palladium catalysts bearing N,O-type ligands had high activities, good tolerance for polar groups and therefore are suitable for realizing the copolymerization of norbornene and polar olefin monomers. In this thesis, a series of Ni(II) complexes containing bis(β-benzocyclohexan-ketoarylimino) ligands and Pd(II) complexes bearing single β-Benzocyclohexan-ketoarylimino ligands were mainly studied.A series novel Ni(II) complexes bearing bis(P-Benzocyclohexan-ketoarylimino) ligands, Ni{C10H8(O)C[N(Ar)]CH3}2(Ar=2,6-iPr2C6H3,2-ClC6H4, C6H5), have been synthesized by the ligands exchange reaction of β-benzocyclohexan-ketoarylimines and [Et4N]2NiBr4and characterized by X-ray single crystal diffraction. In the presence of B(C6F5)3, all above nickel(II) catalysts exhibited high activity of105(gpolymer/molNi·h) toward the vinyl-addition type copolymerization of norbornene (NB) with5-norbornene-2-carboxylic ester (NB-COOCH3) at60℃in toluene. It was also found that the catalytic activity of the Ni(II) complex was obviously influenced by the ligand structure. The Ni(II) complex that with stereo isopropyl groups on the ortho-position of the N-aryl moiety is the highest and with chloride group on the corresponding position displayed slightly higher activity, which imply the catalytic activities could be greatly improved by enhancing the steric hindrance and introducing electron-withdrawing groups on the skeleton of ligand. The obtained copolymers displayed excellent thermal stability (Td=430.98-398.23℃), high molecular weight (Mw=3.95×104-2.31×105g/mol) and relatively narrow molecular weight distribution (PDI≈2). And the NB-COOCH3contents in copolymers could be adjusted to be8.94-73.3mol%by varying NB-COOCH3feed ratios from10to80mol%. The introduction of ester functionalized groups is helpful to enhance the solubility of copolymers and film-forming properties, and the copolymer films with good mechanical properties and high transparency (79-89%) could be obtained by solution processing.Another series novel Pd(II) complexes bearing single β-Benzocyclohexan-ketoarylimino ligands,{C1oH8(O)C[N(Ar)]CH3}Pd(CH3)(PPh3)(Ar=2,6-’Pr2C6H3,2,6-Me2C6H3,2-CIC6H4, C6H5), have been synthesized by the ligand exchange reaction of β-benzocyclohexan-ketoarylimine and (COD)MePdbyCl. After activation with B(C6Fs)3, the above Pd(II) catalytic systems could exhibit high activities(104-105gpolymer/molpd’h) for the copolymerization of norbornene (NB) and5-norbornene-2-yl acetate (NB-OCOCH3) at35℃. It was also worth noting that Pd(II) complex showed the highest activity when the substituted group at the ortho-position of the N-aryl moiety is the steric hindrance isopropyl groups. And the Pd(II) complex with chloride substituted group displayed a little higher activity than that of the Pd(II) complex without chloride substituted group on the corresponding position. The obtained vinyl-addition type copolymers were confirmed to be noncrystalline and possessed excellent thermal stability(Td>350℃)。 Unfortunately, the solubility of all copolymers was too poor to carry out for subsequent characterization and solution processing. |
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