Controlled Functionalization of Crystalline Polystyrenes via Activation of Aromatic C-H Bonds

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• 作者：Jihoon Shin ; Stephen M. Jensen ; Jinhun Ju ; Sunwoo Lee ; Zhigang Xue ; Seok Kyun Noh ; Chulsung Bae
• 刊名：Macromolecules
• 出版年：2007
• 出版时间：November 27, 2007
• 年：2007
• 卷：40
• 期：24
• 页码：8600 - 8608
• 全文大小：188K
• 年卷期：v.40,no.24(November 27, 2007)
• ISSN：1520-5835

文摘

The iridium-catalyzed functionalization of the C-H bond of commercial polystyrenes with threetypes of tacticities (syndiotactic, isotactic, atactic) using boron reagents is reported. The boronate ester group inthe polystyrene was further converted to hydroxy and arene via oxidation and Suzuki-Miyaura cross-coupling,respectively. These functionalizations proceeded without affecting the tacticity or chain length of the startingpolymer, and the functional group concentration was easily controlled by changing the ratio of boron reagent topolymer repeating unit. The size and concentration of the functional group in the syndiotactic polystyrenes werefound to have huge impacts on the thermal properties of the functionalized polymers. The incorporation of evena small amount (<5 mol %) of the bulky boronate ester group induced complete disappearance of crystallinityfor the boryl-functionalized syndiotactic polystyrene. The high crystallinity and melting temperature of syndiotacticpolystyrene were not significantly changed, however, until 10 mol % hydroxy group was incorporated into thepolymer, presumably owing to the small size of hydroxy group.