Radical Ring-Opening Copolymerization of Cyclic Ketene Acetals and Maleimides Affords Homogeneous Incorporation of Degradable Units
Radical Ring-Opening Copolymerization of Cyclic Ketene Acetals and Maleimides Affords Homogeneous Incorporation of Degradable Units
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DOI：
10.1021/acsmacrolett.7b00572
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发表时间：
2017-10-01
影响因子：
7.015
通讯作者：
Sumerlin, Brent S.
中科院分区：
文献类型：
--
作者：
Hill, Megan R.;Guegain, Elise;Sumerlin, Brent S.
供体受体(D-A)单体对的自由基共聚合为交替共聚物的发展提供了一个通用的平台。然而，由于使用传统的自由基聚合，所得到的共聚物通常仅限于不可降解的乙烯基聚合物。将自由基D-A共聚与自由基开环聚合(RROP)相结合，合成了一种高掺入可降解主链单元的交替共聚物。N-乙基马来酰亚胺(NEtMI)与环烯酮缩醛(CKA)2-亚甲基-4-苯基-1，3-二氧杂环戊烷(MPDL)交替共聚，通过可逆加成断裂链转移(RAFT)聚合实现了可控聚合。当单体混合物被加热时，在没有外源引发源的情况下发生自发共聚，这可能是因为共聚单体之间的电子差距很大。与苯乙烯的扩链反应得到了结构清晰的P(MPDL-ALT-NEtMI)-b-聚苯乙烯共聚物，均聚物和嵌段共聚物的降解表现为交替共聚物的完全分解。
Radical copolymerization of donor acceptor (D-A) monomer pairs has served as a versatile platform for the development of alternating copolymers. However, due to the use of conventional radical polymerization, the resulting copolymers have generally been limited to nondegradable vinyl polymers. By combining radical D-A copolymerization with radical ring-opening polymerization (rROP), we have synthesized an alternating copolymer with a high incorporation of degradable backbone units. Copolymerization of N-ethyl maleimide (NEtMI) with the cyclic ketene acetal (CKA) 2-methylene4-phenyl-1,3-dioxolane (MPDL) was demonstrated to proceed in an alternating fashion, and controlled polymerization was achieved using reversible addition fragmentation chain transfer (RAFT) polymerization. Spontaneous copolymerization, in the absence of an exogenous initiating source, occurred when the mixture of monomers was heated, presumably due to the large electron disparity between the comonomers. Chain-extension with styrene afforded well-defined P(MPDL-alt-NEtMI)-b-polystyrene copolymers, and degradation of the homopolymers and block copolymers showed complete breakdown of the alternating copolymer.