Diverse approaches to star polymers via cationic and radical RAFT cross-linking reactions using mechanistic transformation
Diverse approaches to star polymers via cationic and radical RAFT cross-linking reactions using mechanistic transformation
复制标题
DOI：
10.1039/c7py01401e
复制
发表时间：
2017-10
影响因子：
4.6
通讯作者：
Mineto Uchiyama;K. Satoh;Thomas G. McKenzie;Q. Fu;G. Qiao;M. Kamigaito
中科院分区：
文献类型：
--
作者：
Mineto Uchiyama;K. Satoh;Thomas G. McKenzie;Q. Fu;G. Qiao;M. Kamigaito
通过阳离子可逆加成断裂链转移(RAFT)聚合，生成大分子RAFT试剂作为支链聚合物，然后采用三种不同的方法以二乙烯基单体为核心进行嵌段共聚和随后的交联反应，成功地合成了核心交联型星形聚合物。采用了以下三种方法：(I)一锅阳离子RAFT嵌段聚合和二乙烯基醚的同时交联反应；(Ii)机械转化为自由基RAFT嵌段聚合和同时具有乙烯基醚和丙烯酸酯部分的杂二乙烯基单体的同时交联反应；以及(Iii)异二乙烯基单体中乙烯基醚部分的一锅阳离子RAFT选择性嵌段共聚，然后机械转化为残留在二嵌段聚合物的侧基上的丙烯酸酯部分的自由基交联反应。这三种方法都不需要金属催化剂，均能以较高的产率(80%~94%)、控制臂数(NARM=15~40)和大小(Dn=18~28 nm，Dw/Dn=1.03~1.06)，合成相对分子质量可控(MW=2~6×105)、分子量分布窄(MW/Mn=1.1~1.4)的核心交联星形聚合物。
Core cross-linked star polymers were successfully synthesized via cationic reversible addition fragmentation chain-transfer (RAFT) polymerization, which produces macro RAFT agents as the arm polymers, followed by three different approaches used for the block copolymerization of divinyl monomers as the core and subsequent cross-linking reaction. The following three approaches were used: (i) one-pot cationic RAFT block polymerization and the simultaneous cross-linking reaction of divinyl ether; (ii) mechanistic transformation to radical RAFT block polymerization and the simultaneous cross-linking reaction of a hetero divinyl monomer, which possesses both vinyl ether and acrylate moieties; and (iii) one-pot cationic RAFT selective block copolymerization of the vinyl ether moiety in the hetero divinyl monomer, followed by mechanistic transformation to a radical cross-linking reaction of the acrylate moiety that remained in the pendant groups of the diblock polymer. All three methods were free from metal catalysts and produced core cross-linked star polymers with controlled molecular weights (Mw = 2–6 × 105), narrow molecular weight distributions (Mw/Mn = 1.1–1.4), and controlled arm numbers (Narm = 15–40) and sizes (Dn = 18–28 nm, Dw/Dn = 1.03–1.06) in relatively high yields (80–94%).