エチレンとプロピレンの交代的なステレオ特異的共ポリメリゼーションは,メタルロセンの触媒を用いて行われる
W Fan1, M K Leclerc, R M Waymouth
1Deparmtment of Chemistry, Stanford University, Stanford, California 94305-5080, USA.
Journal of the American Chemical Society
|September 27, 2001
まとめ
ブリッジメタロセンは,エチレン/プロピレンの交互のコポリメリゼーションを可能にし,特定の配列を生成します. メタロセンの構造は,活動性やステレオ化学などの共ポリマー特性に影響します.
科学分野:
- ポリマー化学のポリマー化学について
- 有機金属化学 有機金属化学
背景:
- メタロセンの触媒は,オレフィンポリメリゼーションに不可欠です.
- カタリスト構造がコポリメリゼーションに及ぼす影響を理解することは,ポリマーの性質を制御するための鍵です.
研究 の 目的:
- ブリッジメタロセネスを用いてエチレン/プロピレン共ポリメリゼーションを調査する.
- メタルロセンの構造 (置換物R,ブリッジE) が共ポリマー化行動とポリマー特性にどのように影響するか判断する.
主な方法:
- エチレンとプロピレンの共ポリメリゼーションには,様々なブリッジメタロセネス (炭素ブリッジとシリコンブリッジ) をMAOコカタリストで使います.
- コポリマー配列分布 (EPE+PEPトライアード),分子量,およびステレオ化学の分析.
主要な成果:
- ヘテロトップの活性部位を持つメタロセンは,エチレン/プロピレンコポリマー (61-76% EPE+PEPトライアード) を交互に生成した.
- シリコンブリッジメタロセネスは,炭素ブリッジメタロセネスと比較して,より高い活性と分子量を示したが,プロピレンの組み込みは低い.
- イソタクティックなPEPEP配列は,すべてのメタロセノスで一貫していましたが,EPPE配列の戦術性は様々でした.
結論:
- 置換物 (R) とブリッジ (E) の性質は,コポリメリゼーション活動,配列分布,分子量,ステレオ化学に大きく影響する.
- 交代共ポリメリゼーションは,ヘテロトップ的部位での連続的なモノマー挿入によって発生します.
- イソタクティックなEPPE配列は,チェーンイソメリゼーション (バックスキップ) による偶発的な複数の挿入を示唆しています.
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