Lanthanide triflates-mediated emulsion cationic polymerization of p-alkoxystyrenes in aqueous media
Lanthanide triflates-mediated emulsion cationic polymerization of p-alkoxystyrenes in aqueous media
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DOI：
10.1021/ma0000069
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发表时间：
2000-06-27
期刊：
影响因子：
5.5
通讯作者：
Sawamoto, M
中科院分区：
文献类型：
--
作者：
Satoh, K;Kamigaito, M;Sawamoto, M
用稀土金属三氟酸盐[Ln(OTf)(3)]在水中进行乳液阳离子聚合；Ln = Yb, Sc, Dy, Sm, Gd, Nd；OTf = OSO2CF3]是众所周知的耐水路易斯酸。即使存在大量的表面活性剂，如十二烷基卤化铵、十二烷基苯磺酸钠和聚（乙烯基甲基醚），在30℃下，Ln(OTf)(3)与pMOS- hcl加合物(1)一起在水介质中诱导对甲氧基苯乙烯（pMOS）的阳离子聚合。阳离子表面活性剂（如十二烷基三甲基氯化铵）的使用加速了聚合，使聚合物的分子量得到控制，分子量分布（MWDs） （M-w/M-n近似于1.4）比不使用表面活性剂的聚合物更窄。Ln(OTf)(3)的活性随中心金属的路易斯酸度或离子半径的减小而降低。1/Yb(OTf)(3)体系也诱导了对叔丁基苯乙烯（tBOS）在水介质中的聚合。tBOS在水中的均聚性不如pMOS可控。在表面活性剂的存在下，pMOS和tBOS的随机共聚也以长寿命的方式进行。乳液阳离子聚合最有可能是通过有机相中休眠的C-Cl聚合物末端产生的碳阳离子物质和从水相进入的Ln(OTf)(3)进行的。
Emulsion cationic polymerization in water Was achieved with rare earth metal triflates [Ln(OTf)(3); Ln = Yb, Sc, Dy, Sm, Gd, and Nd; OTf = OSO2CF3] that are well-known as water-tolerant Lewis acids. Even in the presence of a large amount of surfactants such as dodecylammonium halides, sodium laurylbenzenesulfate, and poly(vinyl methyl ether), Ln(OTf)(3) induced cationic polymerizations of p-methoxystyrene (pMOS) in aqueous media in conjunction with the pMOS-HCl adduct (1) at 30 degrees C. In particular, the use of cationic surfactants such as dodecyltrimethylammonium chloride accelerated the polymerization and gave polymers of controlled molecular weights and narrower molecular weight distributions (MWDs) (M-w/M-n similar to 1.4) than those in the absence of surfactants. The activity of Ln(OTf)(3) reduced with decreasing the Lewis acidity or the ionic radii of the central metal. The 1/Yb(OTf)(3) system also induced the polymerization of p-tert-butoxystyrene (tBOS) in aqueous media. The homopolymerization of tBOS in water was found to be less controllable than that of pMOS. Random copolymerization of pMOS and tBOS also proceeded in a long-lived fashion in the presence of surfactants. The emulsion cationic polymerization most probably proceeds via the carbocationic species generated from the dormant C-Cl polymer terminal in the organic phase and Ln(OTf)(3) entering from the aqueous phase.