Iron‐catalyzed radical polymerization of acrylamides in the presence of Lewis acid for simultaneous control of molecular weight and tacticity
Iron‐catalyzed radical polymerization of acrylamides in the presence of Lewis acid for simultaneous control of molecular weight and tacticity
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DOI：
10.1002/pola.21310
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发表时间：
2006-03
期刊：
影响因子：
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通讯作者：
Y. Sugiyama;K. Satoh;M. Kamigaito;Y. Okamoto
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文献类型：
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作者：
Y. Sugiyama;K. Satoh;M. Kamigaito;Y. Okamoto
这项工作是针对立体特异性活性自由基聚合的丙烯酰胺，如N，N-二甲基丙烯酰胺和N-异丙基丙烯酰胺与铁配合物和路易斯酸。在Y(OTf)3存在下，以[FeCp(CO)2]2与烷基碘化物[(CH3)2C(CO2Et)I]为引发剂，在甲苯/甲醇（1/1）中，在60℃下，dam与[FeCp(CO)2]2聚合，几乎可以定量地转化为分子量可控、高等规性（m > 80%）的聚合物。其中，fe -配合物从休眠物种的共价CI键产生自由基物种，而Lewis酸通过与聚合物末端和单体的酰胺基团的配位来控制聚合的立体化学。一系列路易斯酸也被用于铁(I)催化的dam聚合，Yb(OTf)3和Yb(NTf2)3被证明可以有效地得到等规聚合物，而不破坏类似于Y(OTf)3的分子量控制。此外，当与Y(OTf)3偶联时，与α，α-偶氮二异丁腈引发的体系相比，铁催化体系的同特异性略有增强。在聚合过程中只加入Y(OTf)3甲醇溶液，就可以通过一锅反应实现DMAM的立体嵌段聚合，得到无规-b-等规聚（DMAM）。在NIPAM与[FeCp(CO)2]2/Y(OTf)3的聚合中，得到了类似但略低的分子量和弹性控制。©2006 Wiley期刊公司[J] .化学工程学报，2006,31 (4):387 - 398
This work is directed to the stereospecific living radical polymerization of acrylamides such as N,N-dimethylacrylamide and N-isopropylacrylamide with an iron complex and a Lewis acid. DMAM was polymerized with [FeCp(CO)2]2 in conjunction with an alkyl iodide [(CH3)2C(CO2Et)I] as an initiator in the presence of Y(OTf)3 in toluene/methanol (1/1) at 60 °C to be converted almost quantitatively to the polymers with controlled molecular weights and high isotacticity (m > 80%), wherein the Fe-complex generates radical species from a covalent CI bond of the dormant species and the Lewis acid controls the stereochemistry of the polymerization via coordination with the amide groups of the polymer terminal and the monomer. A series of Lewis acids were also used for the iron(I)-catalyzed DMAM polymerization, and Yb(OTf)3 and Yb(NTf2)3 proved effective in giving isotactic polymers without deteriorating the molecular weight control similar to Y(OTf)3. Furthermore, a slight enhancement of isospecificity was observed for the iron-catalyzed system in comparison with the α,α-Azobisisobutyronitrile-initiated, when coupled with Y(OTf)3. Stereoblock polymerization of DMAM via a one-pot reaction was also achieved by just adding the Y(OTf)3 methanol solution in the course of the polymerization to give atactic-b-isotactic poly(DMAM). A similar but slightly lower control in the molecular weight and tacticity was achieved in the polymerization of NIPAM with [FeCp(CO)2]2/Y(OTf)3. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2086–2098, 2006