含［N,O］配体的镍配合物/烷基铝催化甲基丙烯酸甲酯的聚合

制备了两种镍配合物二［N-(2-氧基-1-萘甲醛)缩-2,6-二异丙基苯胺］合镍［Ni(L₁)₂］和二［N-(2-氧基-1-萘甲醛)缩-邻甲基苯胺］合镍［Ni(L₂)₂］。研究了它们以普通烷基铝为助催化剂催化甲基丙烯酸甲酯(MMA)的聚合。结果表明,镍配合物的结构、聚合条件如单体浓度、Al与Ni物质的量比、聚合温度和聚合时间等对甲基丙烯酸甲酯聚合反应活性有很大的影响，当甲基丙烯酸甲酯浓度为0.8 mol·L^-1、n(Al)∶n(Ni)=400、温度为0 ℃时,催化活性达到110.7 kg-PMMA·(mol-Ni·h)^-1。随着聚合时间的延长，催化活性下降，而转化率则随着聚合时间的延长而缓慢增加。

Polymerization of methyl methacrylate(MMA)catalyzed by nickel complexes containing[N,O]ligands and alkylaluminum

Two nickel complexes, bis-［(N-2,6-diisopropylphenylimino)-2-oxy-1-naphthylmethyl-ene］nickel［Ni(L1)2］ and bis［(N-2-methyl-phenylimino)-2-oxy-1-naph- thylmethylene］nickel(Ni(L2)2), were prepared. In presence of equimolar PPh3 activated by alkylaluminum, polymerization of methyl methacrylate(MMA) catalyzed by the complexes was investigated. The results showed that the structure of nickel complexes and polymerization conditions (such as monomer concentration, polymerization temperature, solvent and Al/Ni molar ratio) had much influence on polymerization behaviors of the catalysts and properties of the product. Activity of 110.7 kg-PMMA·(mol-Ni·h)^－1 was attained under the following condition: methyl methacrylate concentration 0.8 mol·L^－1, Al/Ni molar ratio 400, polymerization temperature 0 ℃, hexane as the solvent. GPC results showed that average molecular weight(Mw) of products ranged from 1 967 to 6 255 and distribution of the molecular weight (Mw/Mn) ranged from 1.25 to 2.24. It was found that syndiotactic content of PMMA was predominated by 13CNMR and higher polymerization temperature was favorable to atactic content in PMMA.