本研究以不同的有機鈷金屬錯合物CoII(salen), CoII(H2O)2(dmgBF2)2, CoII(salen-OMe)及CoII(salen-NO2)調控丙烯酸甲酯(MA)的自由基聚合反應。在反應過程中我們利用紫外可見光譜追蹤聚合反應，並透過數值分析方法計算出在平衡時CoII及CoIII-R的濃度。藉由平衡時CoII與CoIII-R的比例以及從一級反應動力學曲線圖得到聚合反應時自由基的濃度我們可以推算各個鈷金屬錯合物在調控丙烯酸甲酯的自由基聚合反應時的平衡常數Keq = 9.5 × 107 M-1(CoII(salen))、7.9 × 107 M-1(CoII(H2O)2(dmgBF2)2)、2.7 × 107 M-1(CoII(salen-OMe))及1.1 × 109 M-1(CoII(salen-NO2))。同時我們也發現平衡常數與其對應的有機鈷金屬錯合物的氧化還原半電位呈現線性關係。平衡常數、氧化還原半電位與調控機制之間的關聯性可以幫助我們對鈷調控自由基聚合反應有更深入的了解。

Cobalt mediated radical polymerization (CMRP) of methyl acrylate was performed with CoII(salen), CoII(H2O)2(dmgBF2)2, CoII(salen-NO2) ,and CoII(salen-OMe) at 60 °C and its CoII/CoIII equilibrium constant have been measured by using UV-vis spectroscopy to determine the concentration of cobalt species ([CoII] and [CoIII-P]) and the first order kinetic plots to obtain the radical concentration ([P•]). With the increasing information of Keq values in different CMRP systems, a linear correlation between the CoII/CoIII reduction potential (E1/2) and log(Keq) was discovered. The connection of reduction potential, equilibrium constant, and control mechanism would contribute to the understanding of CMRP process.

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