摘要
考察了在以MoCl_(4-n)(OC_8H_(17))_n和MoCl_(5-n)(OC_8H_(17))_n为主催化剂,m-CH_3PhOAl(i-Bu)_2为助催化剂的体系中添加烯丙基卤(Allyl-X,X=Cl,Br和I)的丁二烯(Bd,聚合.结果表明Allyl-X时Bd聚合反应速率、催化剂利用率及表现活化能等均无明显影响,但却具有极明显的链转移作用,可使聚丁二烯的(?)从(100～150)×10~4降到(20～30)×10~4。文中对链转移的机理提出了解释,认为Allyl-X在催化体系中以分子态存在,Allyl-M-X分子和Bd分子都能与活性中心络合物上Mo形成π配位络合物,双方竞争Mo上的配位点足以阻碍Bd分子的进一步插入,从而导致了活性链提前转移,聚合物分子量剧降。
In the synthesis of polybutadiene with molybdenum systems composed of MoCl4_n (OC8H17)n and MoCl5-n (OC8Hl7)n as main catalyst ,m-CH3PhOAl(i-Bu)2 as cocatalyst , and allyl halide (CH2=CH-CH2 X , X=Cl , Br or I)as additives ,the polymerization rate ,the efficiency of catalyst and apparent activation energy far the polymerization were not influenced by allyl halides , but the chain transfer caused by allyl halides had marked effect on the average degree of polymerization and hence on the number average molecular weight . It was proposed that allyl halides were present as the molecular stateat the catalyst system , both allyl halides and butadiene could ligand to Mo(Ⅲ) of active center complex to form coordinating complex , and there was a competition between allyl halides and butadiene in the coordinating toward Mo (Ⅲ), which led to the insertion of butadiene into active center complex to be held up in polymerization and resulted in the active chain transfer and decreased the molecular weight of polybutadiene .
出处
《合成橡胶工业》
CAS
CSCD
北大核心
1993年第1期24-27,共4页
China Synthetic Rubber Industry
基金
国家自然科学基金
关键词
聚丁二烯
钼催化体系
烯丙基卤
polybutadiene
molybdenum cata- lyst
allyl halide
Ziegler-Natta catalyst
