Synthesis of end-functionalized poly(norbornene)s via ring-opening metathesis polymerization
Synthesis of end-functionalized poly(norbornene)s via ring-opening metathesis polymerization
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DOI：
10.1021/ma010878q
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发表时间：
2001-12-04
期刊：
影响因子：
5.5
通讯作者：
Grubbs, RH
中科院分区：
文献类型：
--
作者：
Bielawski, CW;Benitez, D;Grubbs, RH
合成了一系列末端带有乙酰氧基、羟基和乙烯基的聚异戊二烯（PNB）。使用异戊二烯、基于铼的烯烃复分解催化剂（PCy 3）（2）Cl 2 Ru双键CHPh和作为链转移剂（CTA）的乙酸烯丙酯制备在一端具有乙酰氧基且在另一端具有乙烯基的PNB。采用活性更高的催化剂（1，3-二均三甲苯基-4，5-二氢咪唑-2-亚基）（PCy_3）Cl_2 Ru双键CHPh和1，4-二乙酰氧基-2-丁烯作为CTA，得到了在聚合物链两端带有乙酰氧基的遥爪PNB。通过改变初始单体/CTA比率来控制分子量，并且与它们的理论值一致。使用类似的程序，也通过降解高分子量PNB获得乙酰氧基封端的PNB。乙酰氧基基团的去除得到相应的羟基封端的聚合物与数均官能度接近2。提出了形成末端官能化聚合物的机制。提出了用凝胶渗透色谱（GPC）表征PNB的校正因子。
The synthesis of a variety of poly(norbornene)s (PNB)s bearing acetoxy, hydroxy, and vinyl end groups was accomplished. PNBs with an acetoxy group at one terminus and a vinyl group at the other were prepared using norbornene, ruthenium-based olefin metathesis catalyst (PCy3)(2)Cl2Ru double bond CHPh, and allyl acetate as a chain transfer agent (CTA). Employing a more active catalyst, (1,3-dimesityl-4,5-dihydroimidazol-2-ylidene)(PCy3)Cl2Ru double bond CHPh, and 1,4-diacetoxy-2-butene as the CTA afforded telechelic PNBs bearing acetoxy groups at both ends of the polymer chains. Molecular weights were controlled by varying the initial monomer/CTA ratio and were in agreement with their theoretical values. Using a similar procedure, acetoxy end-terminated PNBs were also obtained by degradation of high molecular weight PNB. Removal of the acetoxy groups afforded the corresponding hydroxy-terminated polymers with number-averaged functionalities close to two. Mechanisms are proposed for the formation of the end-functionalized polymers. Correction factors for characterizing PNBs by gel permeation chromatography (GPC) are also suggested.