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首页> 外文期刊>Macromolecular chemistry and physics >Anionic synthesis of [1,4-poly(diene)-b-syndiotactic poly(methyl methacrylate)] diblock copolymers: ~7Li NMR study of the intermediate reaction of lithium poly(diene) anion with 1,1-diphenylethylene
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Anionic synthesis of [1,4-poly(diene)-b-syndiotactic poly(methyl methacrylate)] diblock copolymers: ~7Li NMR study of the intermediate reaction of lithium poly(diene) anion with 1,1-diphenylethylene

机译：[1,4-聚（二烯）-b-间同立构聚（甲基丙烯酸甲酯）]二嵌段共聚物的阴离子合成：〜7Li NMR研究锂聚（二烯）阴离子与1,1-二苯乙烯的中间反应

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摘要

The end-capping with 1,1-diphenylethylene (DPE) of living 1,4-poly(diene) lithiated anions prepared in cyclohexane (Chx) and toluene is a major but poorly controlled step in the synthesis of syndiotactic poly(methyl methacrylate) (sPMMA) containing block copolymers. The kinetics of the reaction have been studied by means of ~7Li NMR not only in Chx and toluene but also in their mixtures with polar solvents, since the solvent polarity must be increased for MMA to be predominantly converted into sPMMA. Although the addition of a polar solvent (tetrahydrofuran (THF), diethyl ether) to Chx and toluene is known to increase the reactivity of living polymeric anions, contaminating lithium salts, such as lithium hydroxide, slow down the end-capping reaction even when 10 vol.-% polar solvent is added. Moreover, the polymeric diphenylalkyllithium anions are unstable in 1/9 (v/v) THF/Chx mixture, as a result of the nucleophilic attack of THF. On the basis of all these observations, new experimental conditions are proposed for improving the control of the anionic block copolymerization of 1,3-dienes and MMA to yield 1,4-poly(diene) and sPMMA containing block copolymers.
机译：在间同立构聚甲基丙烯酸甲酯的合成中，用1,1-二苯乙烯（DPE）对在环己烷（Chx）和甲苯中制备的活性1,4-聚（二烯）锂化阴离子进行封端（sPMMA）含嵌段共聚物。通过〜7Li NMR，不仅在Chx和甲苯中，而且还在与极性溶剂的混合物中通过〜7Li NMR研究了反应动力学，因为必须增加溶剂极性才能使MMA主要转化为sPMMA。尽管已知在Chx和甲苯中添加极性溶剂（四氢呋喃（THF），乙醚）可提高活性聚合阴离子的反应活性，但污染锂盐（如氢氧化锂）时，即使10加入体积％极性溶剂。此外，由于THF的亲核攻击，聚合的二苯基烷基锂阴离子在1/9（v / v）THF / Chx混合物中不稳定。基于所有这些观察结果，提出了新的实验条件，以改善对1，3-二烯和MMA的阴离子嵌段共聚的控制，以产生含1，4-聚二烯和sPMMA的嵌段共聚物。

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