异戊二烯均相聚合催化剂

POLYMERIZATION OF ISOPRENE BY HOMOGENEOUS CATALYST

分别用C_6H_5CH_2Cl,CH_2-CHSiCl_3,CH_ SiHCl_2,(CH_3)_2SiCl_2,(CH_3)_3CCl,CH_2—CHCH_2Cl,Cl_3SiCH_2CH_2SiCl_3代替非均相催化剂Nd(naph)_3-Al_2Et_3Cl-Al(i-Bu)_2H(简称Nd-Cl-Al)中的助催化剂后,除C_6H_5CH_2Cl,CH_2=CHSiCl_3,CH_SiHCl_2形成悬浊催化剂外,在Cl/Nd<8(mol比)时,其他氯化物均形成均相催化剂,并能催化异戊二烯均相聚合,得到顺式-1,4含量约95％,[η]约3 dL/g的聚合物。分别用(CH_3)_3CCl和(CH_3)_2SiCl_2代替Cl所组成的两催化剂,其催化活性接近,最佳Al/Nd和Cl/Nd值分别为40和2.5;异戊二烯浓度为10％—20％时,转化率不随其浓度的改变而变化。符合一级反应动力学特征。

Homogeneous catalyst for the polymerization of isoprene was obtained by substituting the co-catalyst components in heterogeneous catalyst system Nd(naph)3-Al2Et3Cl3-Al(i-Bu)2H by (CH3)2SiCl2, (CH3)3CCl ,CH2 CHCH2Cl or Cl3SiCH2CH2SiCl3 .The results showed that when the molar ratio of Cl/Nd was lower than 8, the catalyst obtained was a homogeneous solution and could be used for the polymerization of isoprene into polyisoprene which contained 95% of cis -1,4 units and had a [η]of about 3 dL/g. The catalyst systems containing (CH3)3CCl and (CH3)2SiCl2 possessed similar activities, and their optimal Al/Nd and Cl/Nd molar ratios were 40 and 2.5 , respectively . When the concentration of isoprene was 10% 20% , the conversion ratios did not change with their concentrations , which indicated that it was a first order polymerization reaction .