ISOSPECIFIC POLYMERIZATION OF METHYL-METHACRYLATE INITIATED BY CHIRAL ZIRCONOCENEDIMETHYL/PH(3)CB(C6F5)(4) IN THE PRESENCE OF LEWIS-ACID

被引：121

作者：

DENG, H ^{[1
]}

SHIONO, T ^{[1
]}

SOGA, K ^{[1
]}

机构：

[1] TOKYO INST TECHNOL,RESOURCES UTILIZAT RES LAB,MIDORI KU,YOKOHAMA,KANAGAWA 227,JAPAN

来源：

MACROMOLECULES | 1995年 / 28卷 / 09期

关键词：

D O I：

10.1021/ma00113a008

中图分类号：

O63 [高分子化学（高聚物）];

学科分类号：

070305 ; 080501 ; 081704 ;

摘要：

Polymerization of methyl methacrylate (MMA) was conducted with the catalyst systems of rac-Et(Ind)(2)Zr(CH3)(2)/Ph(3)CB(C6F5)(4), rac-Et(IndH(4))(2)Zr(CH3)(2)/Ph(3)CB(C6F5)(4), and rac-Me(2)Si(Ind)(2)Zr(CH3)(2)/Ph(3)CB(C6F5)(4). These catalysts only were found to be inactive. However, the addition of suitable Lewis acids like alkylzinc and alkylaluminum compounds gave highly isotactic PMMA. The isotactic pentad [mmmm] in PMMA as well as the propagation rate constant (k(p)) depended significantly upon the zirconocene compounds. Both the microstructure ([mmmm]) and propagation rate constant (k(p)) increased in the following order: Me(2)Si(Ind)(2) < Et(IndH(4))(2) < Et(Ind)(2). The microstructure of PMMA was also affected slightly by alkylzinc compounds: (CH2)(2)CH=CH2 < CH2CH3 > (CH2)(3)CH3. When the polymerization was initiated by the rac-Et(Ind)(2)Zr(CH3)(2)/Ph(3)CB(C6F5)(4)/Zn(C2H4CH=CH2)(2) catalyst system at 0 degrees C in toluene, the molecular weight of PMMA increased in proportion to the conversion of MMA. The increase of temperature from 0 to 80 degrees C caused a decrease in isotactic pentad content by approximately 10%. The isotactic polymerization of MMA was revealed to proceed by an enantiomorphic site-controlled mechanism.

引用

页码：3067 / 3073

页数：7

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