Monofunctional metathesis polymers via sacrificial diblock copolymers
Monofunctional metathesis polymers via sacrificial diblock copolymers
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DOI：
10.1002/anie.200602323
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发表时间：
2006-01-01
影响因子：
16.6
通讯作者：
Kilbinger, Andreas F. M.
中科院分区：
文献类型：
--
作者：
Hilf, Stefan;Berger-Nicoletti, Elena;Kilbinger, Andreas F. M.
开环烯烃复分解聚合（ROMP）是合成高功能化聚合物的有力手段第一个明确定义的基于钛、钼和钨[3]的ROMP催化剂体系对官能团的耐受性相对较低。这种低耐受性可以在复分解聚合物的末端功能化中得到利用。金属中心的高亲氧性使得在聚合混合物中加入醛可以实现末端功能化基于钌[5]的后过渡金属催化剂不允许烯烃与醛的复分解功能化。尽管如此，文献中已经描述了几种途径，用于钌催化的复分解聚合物的末端功能化。在聚合物的链端终止钌碳的最常用方法是加入乙基乙烯醚亚甲基被转移到聚合物上，同时将催化剂从聚合物链端分离。结果表明，劈裂后的费雪型烃在一定条件下可发生进一步的烯烃复分解反应然而，对于大多数聚合物合成应用，该物种可被视为无活性。在乙烯基硫化物的存在下，可以证明这种“菲舍尔碳烯”作为链转移剂反应生成单功能聚合物用这种方法制备的聚合物具有广泛的多分散性指数（PDI在1.3 ~ 3之间）。
Ring-opening olefin metathesis polymerization (ROMP) is a powerful tool for the synthesis of highly functionalized polymers.[1] The first well-defined ROMP catalyst systems based on titanium,[2] molybdenum, and tungsten [3] exhibited relatively low tolerance toward functional groups. This low tolerance could be exploited in the end-functionalization of metathesis polymers. The high oxophilicity of the metal centers made end functionalization possible by addition of aldehydes to the polymerization mixture.[4] Late-transitionmetal catalysts based on ruthenium [5] do not allow for olefin metathesis functionalization with aldehydes. Nonetheless, several pathways have been described in the literature for the end functionalization of ruthenium-catalyzed metathesis polymers.The most common method of terminating a ruthenium carbene at the chain end of a polymer is achieved by adding ethyl vinyl ether.[6] A methylene group is transferred onto the polymer while cleaving the catalyst off the polymer chain end at the same time. It could be shown that the cleaved-off Fischer-type carbene can undergo further olefin metathesis reactions under certain conditions.[7] For most polymer synthetic applications, however, this species can be regarded as inactive. In the presence of vinyl sulfides it could be shown that such “Fischer carbenes” react as chain-transfer agents to yield monofunctional polymers.[8] The polymers that were prepared in this way show broad polydispersity indices (PDI between 1.3 and 3).