ACTIVATION EFFECT OF ALKOXYSILANES AS EXTERNAL DONORS IN MGCL2-SUPPORTED ZIEGLER-NATTA CATALYSTS

被引：86

作者：

SACCHI, MC ^{[1
]}

FORLINI, F ^{[1
]}

TRITTO, I ^{[1
]}

MENDICHI, R ^{[1
]}

ZANNONI, G ^{[1
]}

NORISTI, L ^{[1
]}

机构：

[1] HIMONT CTR RICERCHE GIULIO NATTA,I-44100 FERRARA,ITALY

来源：

MACROMOLECULES | 1992年 / 25卷 / 22期

关键词：

D O I：

10.1021/ma00048a009

中图分类号：

O63 [高分子化学（高聚物）];

学科分类号：

070305 ; 080501 ; 081704 ;

摘要：

Three pairs of alkoxysilanes, (a) Me(EtO)3Si, Ph(EtO)3Si, (b) Ph2(MeO)2Si, Ph2(EtO)2Si, (c) Ph2(EtO)2Si, Ph(EtO)3Si, differing only in one parameter, have been used as external donors with the catalysts MgCl2/TiCl4 and MgCl2/DIBP/TlCl4 (DIBP = diisobutyl phthalate), using selectively C-13-enriched AlEt3 as cocatalyst. The heptane-insoluble fractions of all the samples have been characterized by C-13 NMR analysis and gel permeation chromatography. The catalyst chemical modifications due to the external donors have been studied by GC analysis of the base content of the solid catalyst under the polymerization conditions. On the basis of all these data we can conclude that (i) all the alkoxy silane donors used, even those that do not produce any evident increase of isotactic productivity, interact with the isospecific centers making them more stereospecific and more active and (ii) it is possible to modulate the activation of the isospecific centers and the poisoning of the nonstereospecific ones by varying the number and the relative bulkiness of both hydrocarbon and alkoxy substituents. The mechanism of the activation effect is discussed.

引用

页码：5914 / 5918

页数：5

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SACCHI, MC ;

TRITTO, I ;

SHAN, CJ ;

MENDICHI, R ;

NORISTI, L .

MACROMOLECULES, 1991, 24 (26) :6823-6826

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