Photo-Induced Ligation of Acrylonitrile-Butadiene Rubber: Selective Tetrazole鈥揈ne Coupling of Chain-End-Functionalized Copolymers of 1,3-Butadiene

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• 作者：Christoph J. D眉rr ; Paul Lederhose ; Lebohang Hlalele ; Doris Abt ; Andreas Kaiser ; Sven Brandau ; Christopher Barner-Kowollik
• 刊名：Macromolecules
• 出版年：2013
• 出版时间：August 13, 2013
• 年：2013
• 卷：46
• 期：15
• 页码：5915-5923
• 全文大小：375K
• 年卷期：v.46,no.15(August 13, 2013)
• ISSN：1520-5835

文摘

A highly selective photo-induced nitrile imine mediated tetrazole鈥揺ne coupling (NITEC) of chain-end-functionalized nitrile鈥揵utadiene rubber (NBR) is reported, providing nitrile rubbers with molar masses of up to 48 000 g路mol^鈥?. NBR was obtained via the reversible addition鈥揻ragmentation chain transfer (RAFT) mediated copolymerization of acrylonitrile and 1,3-butadiene employing a novel photoreactive tetrazole-functionalized trithiocarbonate. The herein reported tetrazole-functionalized trithiocarbonate represents鈥攖o the best of our knowledge鈥攖he first ever reported photoreactive RAFT agent capable of undergoing light-induced ligations with enes. Molar masses of the tetrazole-functionalized NBRs were in the range of 1000 to 38鈥?00 g路mol^鈥? with dispersities between 1.1 to 1.6. By an appropriate choice of the tetrazole substituents, a reaction of the in situ formed enophile with the double bonds or the nitrile moieties of the incorporated monomer units within the polymer backbone鈥攑resent in high excess relative to the dipolarophile linker molecule鈥攚as not observed. Underpinned by DFT calculations, the selectivity was identified to originate from a reduced LUMO energy level of the maleimide linker compared to the nonactivated backbone olefins when employing a nitrile鈥搃mine of moderate reactivity.