Significant effect of hydrogen‐bonding interaction on syndiotactic‐specificity in radical polymerization of N‐isopropylacrylamide
Significant effect of hydrogen‐bonding interaction on syndiotactic‐specificity in radical polymerization of N‐isopropylacrylamide
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氢键相互作用对 N-异丙基丙烯酰胺自由基聚合中间同立构特异性的显着影响
DOI：
10.1002/pola.20315
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Tsuneyuki Sato
中科院分区：
文献类型：
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作者：
Tomohiro Hirano;H. Miki;M. Seno;Tsuneyuki Sato
一般来说，甲基丙烯酸的衍生物，如甲基丙烯酸酯和甲基丙烯酰胺，通过自由基聚合得到富间间规的聚合物。此外，甲基丙烯酸酯是目前研究最多的立体定向聚合单体之一，已有大量报道不仅通过阴离子聚合，而且还通过自由基聚合法合成了多种立体规则聚合物。然而，无论聚合条件如何，丙烯酸衍生物如丙烯酸酯和丙烯酰胺都会产生无规聚合物，而且关于聚合的立体专一性的报道也很有限。因此，人们认为-甲基的空间相互作用是控制乙烯基聚合物立体结构的重要因素之一。聚(N-异丙基丙烯酰胺)[Poly(NIPAAm)]是一种被广泛研究的开关器件，由于Poly(NIPAAm)具有较低的临界溶解温度(LCST)，介于30-35之间。为了控制临界溶解温度，许多研究人员研究了NIPAAm的自由基共聚合，因为其临界溶解温度取决于包括共聚物组成的微观结构。然而，尽管大分子的立体结构往往对聚合物的性能有很大的影响，但由于NIPAAm也是一种丙烯酸衍生物，所以关于其立体规整性的报道很少。最近，有报道称，通过NIPAAm的阴离子聚合，可以保护酸性质子，制备立体规整的聚(NIPAAm)。例如，三甲基硅基保护的NIPAAm衍生物与t-C4H9Li/n-(C4H9)3Al在-40℃的甲苯溶液中进行阴离子聚合，得到了meo(M)二聚体含量为97%的高等规聚(NIPAAm)。5通过甲氧甲基保护的NIPAAm衍生物与1，1-二苯基-3-甲基戊基锂/二乙基锌在四氢呋喃(THF)中在-78℃下进行阴离子聚合，也可以得到外消旋(R)二元体含量为77%的间规聚合物(NIPAAm)。然而，这些方法的工业应用将是困难的，因为这些聚合除了聚合反应外，还需要额外的操作，如保护单体和解除聚合物保护。
In general, methacrylic acid derivatives such as methacrylates and methacrylamides give syndiotacticrich polymers by a radical polymerization. Furthermore, methacrylates is one of the most intensively investigated monomers in regard of stereospecificity of polymerization, and there are a lot of reports on synthesis of a wide range of stereoregular polymers not only by an anionic polymerization but by a radical polymerization. However, acrylic acid derivatives such as acrylates and acrylamides give atactic polymers regardless of polymerization conditions and there are limited reports on stereospecificity of polymerization. Therefore, it is accepted that steric interaction by the-methyl group is one of the important factors to control stereostructure of vinyl polymers. Poly (N-isopropylacrylamide)[poly (NIPAAm)] has been widely investigated as a switching device, since poly (NIPAAm) shows a lower critical solution temperature (LCST) that lies between 30 and 35 C. 1–4 To control the LCST, many researchers investigated radical copolymerization of NIPAAm, because the LCST depends on the microstructure including a copolymer composition. However, although polymer properties are often significantly influenced by the stereostructure of macromolecules, there are few reports on a stereoregularity of poly (NIPAAm) since NIPAAm is also one of the acrylic acid derivatives.Recently, it was reported that stereoregular poly-(NIPAAm) could be prepared by an anionic polymerization of NIPAAm, of which the acidic proton was protected. For instance, an anionic polymerization of a trimethylsilyl-protected NIPAAm derivative with t-C4H9Li/n-(C4H9) 3Al in toluene at–40 C gave a highly isotactic poly (NIPAAm) with meso (m) diad content of 97%. 5 A syndiotactic poly (NIPAAm) with racemo (r) diad content of 77% was also obtained by an anionic polymerization of a methoxymethyl-protected NIPAAm derivative with 1, 1-diphenyl-3-methylpentyllithium/diethylzinc in tetrahydrofuran (THF) at–78 C. 6 However, an industrial application of these methods would be difficult, since these polymerizations require extra operations such as protection of monomers and deprotection of polymers in addition to the polymerization reaction.
DOI：
10.1002/1097-4636(20001215)52:4
发表时间：
2000-12-15
期刊：
JOURNAL OF BIOMEDICAL MATERIALS RESEARCH
影响因子：
--
作者：
Hoffman, AS;Stayton, PS;Miyata, T
通讯作者：
Miyata, T