Vinyl-addition copolymerization of norbornene and polar norbornene derivatives using novel bis(β-ketoamino)Ni(II)/B(C_6F _5)_3/AlEt_3 catalytic systems

摘要

Copolymerization of norbornene (NBE) and polar norbornene derivatives undergoes vinyl polymerization by using novel catalyst systems formed in situ by combining bis(β-ketoamino)Ni(II) complexes {Ni[R_1-C(O) CHC(NR_3)R_2]_2 (R_l = R_2 = CH_3, R_3 = naphthyl, 1; R_1 = R_2 = CH_3, R_3 = C_6H_5, 2; R_1 = CV6H_5, R_2 = CH_3, R_3 = naphthyl, 3; R_l = R_2 = CH_3, R_3 = 2, 6-(CH_3)_2C_6H_3, 4; R_1 = R_2 = CH_3, R_3 = 2, 6-′Pr_2C _6H_3 5; R_1 = C_6H_5, R _2 = CH_3, R_3 = 2, 6-′Pr_2C _6H_3, 6)} and B(C_6F_5) _3/AlEt_3 in toluene. The 1/B(C_6F _5)_3/AlEt_3 catalytic system is effective for copolymerization of NBE with NBE - OCOCH_3 and NBE - CH_2OH, respectively, and copolymerization activity is followed in the order of NBE - CH_2OH > NBE - OCOCH_3 > NBE - CN. The molecular weights of the obtained poly(NBE/NBE - CH_2OH) reached 5.97 × 10~4 to 2.07 × 10~5 g/mol and the NBE - CH _2OH incorporation ratios reached 7.0-55.4 mol % by adjusting the comonomer feedstock composition. The copolymerization of NBE and NBE - CH _2OH also depend on catalyst structures and activity of catalyst followed in the order of 2 > 1 > 3 > 5 > 4 > 6. The molecular weights and NBE - CH2OH incorporation ratios of poly(NBE/NBE - CH_2OH) were adjustable to be 1.91-5.37 × 10~5 g/mol and 9.5-41.1 mol % - OH units by using catalysts 1-6. The achieved copolymers were confirmed to be vinyl-addition type, noncrystalline and have good thermal stability (T_d = 380-410°C).