双膦胺镍-甲基铝氧烷体系催化苯乙烯聚合

研究了具有新型结构的双膦胺镍配合物N,N-双(二苯膦基)-对甲氧基苯胺二氯化镍-甲基铝氧烷(PNP-N i-MAO)催化体系对苯乙烯聚合的催化性能,考察了聚合温度、n(A l)∶n(PNP-N i)、PNP-N i的浓度和苯乙烯的浓度对催化活性、苯乙烯转化率、聚苯乙烯相对分子质量及其分布的影响,并用核磁共振和凝胶色谱对聚苯乙烯的结构进行了表征。实验结果表明,在聚合温度25℃、聚合时间1h、n(A l)∶n(PNP-N i)=300、c(苯乙烯)=2.3m ol/L、c(PNP-N i)=0.4mm ol/L、甲苯为溶剂的适宜条件下,苯乙烯的转化率可达95%以上,催化活性达到5×105g/(m ol.h)左右。核磁共振和凝胶色谱表征结果显示,所得聚苯乙烯为无规结构,重均相对分子质量约为1×104,相对分子质量分布Mw/Mn约为2。

Styrene Polymerization Catalyzed by Bis (Diphenylphosphino) Amine Nickel( Ⅱ )-Methylaluminoxane System

A new nickel(Ⅱ)diphosphinoamine complex,(N,N)-bis(diphenylphosphino)p-methoxyaniline nickel(Ⅱ)dichloride(PNP-Ni),as catalyst of styrene(St)polymerization was synthesized,and polymerization over PNP-Ni-MAO(methylaluminoxane)catalytic system was investigated.Effects of polymerization temperature,mole ratio of MAO to PNP-Ni,PNP-Ni concentration and St concentration on polymerization were studied.Under optimal polymerization conditions:c(PNP-Ni)(0.4)mmol/L,c(St)(2.3)mol/L,polymerization temperature(25℃,)polymerization time 1h,n(Al) ∶n(PNP-Ni)300,and toluene as solvent,activity of PNP-Ni-MAO system was 5×10~5g/(mol·h)and St conversion could reach more than 95%.The obtained polystyrene was in atactic microstructure,confirmed by means of ~1H NMR and ~(13)C NMR characterization.The weight-average relative molecular mass was about 1×10~4 and its relative molecular mass distribution M_w/M_n was about 2 characterized by GPC.