The Stereocomplex Formation in Poly(methyl methacrylate) and the Stereospecific Polymerization of Its Monomer
The Stereocomplex Formation in Poly(methyl methacrylate) and the Stereospecific Polymerization of Its Monomer
复制标题
聚甲基丙烯酸甲酯立体络合物的形成及其单体的立体定向聚合
DOI：
10.1295/polymj.1.46
复制
发表时间：
1970
期刊：
影响因子：
2.8
通讯作者：
H. Inagaki
中科院分区：
文献类型：
--
作者：
T. Miyamoto;H. Inagaki
利用薄层色谱、超离心、X射线衍射、粘度计和高分辨核磁共振等技术，详细研究了等规和间规聚甲基丙烯酸甲酯（PMMA）分子间立体复合物的形成。结果表明：1：1（iso/synd）配合物是PMMA的主要结构，当游离间同立构分子存在于溶液中时，1：1配合物与游离间同立构分子进一步缔合，形成1：2（iso/synd）配合物。因此，有证据表明立构嵌段PMMA和由比例为1：2（iso/synd）的全同立构和间同立构PMMA形成的立构复合物之间的立体化学特性。在此基础上，我们得出结论：在甲基丙烯酸甲酯（MMA）与不同类型的Grignard催化剂的立体定向聚合过程中，可以形成1：2的立体络合物。与上述结论相关的是，在全同立构或间同立构PMMA存在下，MMA与正丁基氯化镁在甲苯中于−50°C进行立体定向聚合。结果表明，MMA的立体定向聚合与立体复合物的形成密切相关。全同立构聚合物链的存在优先促进MMA聚合成间同立构聚合物链，而间同立构聚合物链的存在似乎是引发聚合成全同立构聚合物链的先决条件，只要该催化体系在-50 °C下使用。
The stereocomplex formation between isotactic and syndiotactic poly(methyl methacrylate) (PMMA) molecules is studied in detail, using the techniques of thin layer chromatography (TLC), ultracentrifugation, X-ray diffraction, viscometry, and high-resolution NMR. It is shown that the 1:1 (iso/synd) complex is formed as the primary structure; further associations between the 1:1 complex and free syndiotactic molecules, when they exist in solution, occur to form the 1:2 (iso/synd) complex.The so-called “stereoblock” PMMA samples prepared with n-butylmagnesium chloride and diphenylmagnesium are analyzed by using tic technique. Evidence is thus shown for the stereochemical identity between the stereoblock PMMA and the stereocomplex which is formed by isotactic and syndiotactic PMMA in the ratio 1:2 (iso/synd). On the basis of this result, we conclude that the 1:2 stereocomplex may be formed during stereospecific polymerization of methyl methacrylate (MMA) with different Grignard’s types of catalysts.In relation to the above conclusion stereospecific polymerizations of MMA at −50°C with n-butylmagnesium chloride in toluene were carried out in the presence of either isotactic or syndiotactic PMMA. The results suggest that the stereospecific polymerization of MMA is closely linked to the stereocomplex formation. The presence of the isotactic polymer chains promotes preferentially the polymerization of MMA to the syndiotactic polymer chains, while the presence of the syndiotactic polymer chains appears to be a prerequisite for initiating the polymerization to the isotactic polymer chains so far as this catalytic system is employed at −50°C.