利用Ni-based/MAO觸媒系統進行甲基丙烯酸三丁酯和原冰烯單聚合和共聚合反應的探討

Abstract

在本研究中，利用Ni(acac)2/MAO此一觸媒系統對甲基丙烯酸三丁酯和原冰烯二種單體的單聚合和共聚合反應做了系統性的研究。這個觸媒系統對於這兩種單體的單聚合反應表現出較高的活性，而在這兩種單體的共聚反應中，隨著甲基丙烯酸三丁酯的加入會導致相對應於原冰烯單聚合反應時的反應活性的逐漸降低。在另一方面，當我們加入少量的原冰烯到共聚合反應系統時，我們可以發現一個相當大的活性損失對應於甲基冰烯酸三丁酯的單聚合反應,這些結果我們將定性的以Ystenes.所提出的trigger coordination mechanism理論來解釋。 由NMR的分析中，原冰烯單聚合物全飽和的結構透露了這兩種單體是以烯類加成的反應型態來進行共聚。而反應競爭比的量測也指出了原冰烯有較高的共聚反應活性(rNB=5.4 and rtBMA=0.0196)，這可以用之前的配位機制來解釋。在DSC和TGA的熱分析中，我們可以得知甲基冰烯酸三丁酯和原冰烯反應獲得的共聚物的玻璃轉移溫度的範圍在100~250℃之間，而且在200~250℃的範圍裡會有一個酐鍵的產生。最後這些共聚物由於本身不定型態的原因因此是透明的，且有著相較一般的COC共聚合物較大的極性，也因此是較佳的有機溶液溶解度的材料。

The homopolymerization and copolymerization of tert-butyl methacylate (tBMA) and norbornene (NB) with nickel (Ⅱ) acetylacetonate [Ni(acac)2] in combination with methylaluminoxane (MAO) were systematically investigated in this study. This catalytic system shows a higher activity towards homopolymerization of both norbornene and tert-butyl methacrylate. For random copolymerization, an increase in the initial tert-butyl methacrylate leads to gradual loss of activity relative to nobornene homopolymerization. On the other hand, a drastic loss of activity, relative to tert-butyl methacrylate homopolymerization, was found for very low feed contents of norbornene. These results are qualitatively interpreted using the trigger coordination mechanism proposed by Ystenes. From the NMR analysis, the fully saturated structure of polynorbornene indicates that these two monomers polymerize by an ethylenc type addition reaction. Determination of reactivity ratios indicates a much higher reactivity for norbornene than tBMA (rNB=5.4 and rtBMA=0.0196), which is interpreted by the corordination mechanism. From the thermal analyses of DSC and TGA, these acrylate-norbornene copolymers exhibit glass transition temperature (Tg) ranging from 100℃ to 250℃ depending on compositions and have an anhydrate bond formating from 200℃ to 250℃. Finally, these copolymers are transparent as amorphous with higher polarity relative to other cyclo-olefin copolymer and more solvable materials in organic solvent.