Efficient Synthesis of Narrowly Dispersed Brush Polymers via Living Ring-Opening Metathesis Polymerization of Macromonomers

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• 作者：Yan Xia ; Julia A. Kornfield ; Robert H. Grubbs
• 刊名：Macromolecules
• 出版年：2009
• 出版时间：June 9, 2009
• 年：2009
• 卷：42
• 期：11
• 页码：3761-3766
• 全文大小：210K
• 年卷期：v.42,no.11(June 9, 2009)
• ISSN：1520-5835

文摘

Various macromonomers (MMs) were efficiently synthesized through the copper-catalyzed “click” coupling of a norbornene moiety to the chain end of poly(methylacrylate), poly(t-butylacrylate), and polystyrene that were prepared using atom transfer radical polymerization. Ring-opening metathesis polymerization (ROMP) of these MMs was carried out using the highly active, fast-initiating ruthenium catalyst (H₂IMes)(pyr)₂(Cl)₂RuCHPh in THF at room temperature. ROMP of MMs was found to be living with almost quantitative conversions (>90%) of MMs, producing brush polymers with very low polydispersity indices of 1.01−1.07 and high M_n’s of 200−2600 kDa. The efficient ROMP of such MMs provides facile access to a variety of brush polymers and overcomes previous difficulties in the controlled polymerization of MMs. Atomic force microscopy of the brush polymer products revealed extended, wormlike shapes as a result of significant steric repulsion of densely grafted side chains.