Atom Transfer Radical Polymerization of 4-Vinylpyridine
Atom Transfer Radical Polymerization of 4-Vinylpyridine
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DOI：
10.1021/ma9816968
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发表时间：
1999-04
期刊：
影响因子：
5.5
通讯作者：
J. Xia;Xuan Zhang;K. Matyjaszewski
中科院分区：
文献类型：
--
作者：
J. Xia;Xuan Zhang;K. Matyjaszewski
Pyridine containing polymers have attracted much interest in recent years due to various applications such as water soluble polymers and coordination reagents for transition metals. 1 In contrast to 2-vinylpyridine (2VP), 2, 3 the living polymerization of 4-vinylpyridine (4VP) has not been well studied until recently. Thus, the living anionic polymerization of 4VP was carried out in a mixture of THF/DMF4 and later in a mixture of pyridine/THF. 5, 6 Controlled/“living” radical polymerization is currently attracting much attention. 7 A variety of functional monomers can be readily polymerized, and reaction conditions can be very tolerant in a radical process. Recently, controlled radical polymerization of 4VP was reported using the 2, 2, 6, 6-tetramethylpiperidine-N-oxyl (TEMPO) mediated stable free radical polymerization (SFRP) process. 8 Although a nearly linear increase of molecular weight along with an increase of conversion was observed, the polymerizations were carried out at high temperatures (130-145 C), and the polydispersities of the obtained polymers were relatively high (Mw/Mn≈ 1.2-1.5).Atom transfer radical polymerization (ATRP) is a relatively new and versatile method in the synthesis of polymers with controlled molecular weights and low polydispersities. 7 A large number of monomers can be polymerized in a well-controlled fashion. In this paper, we report the successful synthesis of well-defined poly-(4-vinylpyridine) by copper-mediated ATRP. 9 Polymerization of 4VP poses a very challenging problem for ATRP since both 4VP and P4VP are strong coordinating ligands that can compete for the binding of the metal catalysts in these systems. Since the monomer is normally present in large excess over the employed ligand, there is a possibility of the formation of pyridine-coordinated metal complexes in the polymerization solution. Pyridine-coordinated copper complexes are not effective catalysts for ATRP. For example, addition of 5 vol% pyridine to the polymerization solution of styrene catalyzed by CuBr complexed by 4, 4′-di (5-nonyl)-2, 2′-bipyridine (dNbpy) significantly slowed the polymerization rate. 10 When polymerization of 4VP was carried out using 1-phenylethyl bromide (PEBr) as the initiator and CuBr complexed by 2, 2′-bipyridine (bpy) as the catalyst in 2-propanol, a very slow polymerization rate was observed. Under the conditions of [4VP] 0) 4.55 M,[4VP] 0/[PEBr] 0) 95, and [PEBr] 0/
