Chain-growth polycondensation for well-defined aramide. Synthesis of unprecedented block copolymer containing aramide with low polydispersity.
Chain-growth polycondensation for well-defined aramide. Synthesis of unprecedented block copolymer containing aramide with low polydispersity.
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明确芳纶的链增长缩聚。
DOI：
10.1021/ja021188k
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发表时间：
2002
影响因子：
15
通讯作者：
A. Yokoyama
中科院分区：
文献类型：
--
作者：
T. Yokozawa;Miyuki Ogawa;A. Sekino;Ryuji Sugi;A. Yokoyama
合成了具有一定相对分子质量和低多分散性的聚对苯甲酰胺及其嵌段共聚物。4-氨基苯甲酸苯酯在链式缩聚条件下不发生聚合反应，生成聚对苯甲酰胺。然而，4-(4-辛氧基苯氨基)苯甲酸苯酯(1b)在碱和4-硝基苯甲酸苯酯(2)作为引发剂的存在下，在室温下以链增长缩聚的方式聚合，得到了具有4-辛氧基苯基作为酰胺中氮的保护基团的明确的芳香族聚酰胺。模型反应证实，三氟乙酸(TFA)在不破坏酰胺键的情况下，使该保护基团完全脱保护。通过嵌段共聚物的合成，证明了这种方法对低多分散性的聚对苯甲酰胺的适用性。因此，4-(辛氨基)苯甲酸苯酯(1a)在2和碱的存在下聚合，然后将1b和碱添加到预聚体的反应混合物中，得到相对分子质量可控且多分散性低的1a和1b嵌段共聚物。用TFA对嵌段共聚物进行处理，得到了聚(N-辛基-对苯甲酰胺)/聚(对苯甲酰胺)可溶嵌段共聚物。嵌段共聚物的超分子组装的扫描电子显微镜图像显示为片状结构的大束和聚集体。
Poly(p-benzamide) with a defined molecular weight and a low polydispersity and a block copolymer containing this well-defined aramide was synthesized. Phenyl 4-aminobenzoate, which would yield poly(p-benzamide), did not polymerize under the conditions of chain-growth polycondensation. However, phenyl 4-(4-octyloxybenzylamino)benzoate (1b) polymerized at room temperature in the presence of base and phenyl 4-nitrobenzoate (2) as an initiator in a chain-growth polycondensation manner to give well-defined aromatic polyamides having the 4-octyloxybenzyl groups as a protecting group on nitrogen in an amide. It was confirmed by a model reaction that deprotection of this protecting group proceeded completely with trifluoroacetic acid (TFA) without breaking the amide linkage. The utility of this approach to poly(p-benzamide) with a low polydispersity was demonstrated by the synthesis of block copolymers. Thus, phenyl 4-(octylamino)benzoate (1a) polymerized in the presence of 2 and base, followed by addition of 1b and base to the reaction mixture of the prepolymer to yield the block copolymer of 1a and 1b with a controlled molecular weight and a low polydispersity. The block copolymer was treated with TFA, resulting in a soluble block copolymer of poly(N-octyl-p-benzamide) and poly(p-benzamide). The SEM images of the supramolecular assemblies of the block copolymer showed mum-sized bundles and aggregates of flake structures.