Effect of polymerization conditions on the syndiotactic-specificity in radical polymerization of N-isopropylacrylamide and fractionation of the obtained polymer according to the stereoregularity
Effect of polymerization conditions on the syndiotactic-specificity in radical polymerization of N-isopropylacrylamide and fractionation of the obtained polymer according to the stereoregularity
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聚合条件对 N-异丙基丙烯酰胺自由基聚合中间同立构专一性的影响以及所得聚合物根据立构规整性的分级
DOI：
10.1016/j.polymer.2005.05.043
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发表时间：
2005
期刊：
影响因子：
4.6
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
研究了六甲基磷酰胺（HMPA）存在下n -异丙基丙烯酰胺（NIPAAm）的自由基聚合反应。添加过量的HMPA可诱导并发特异性，并随着饲料单体的消耗逐渐增强。将[HMPA]0/[NIPAAm]0的比例提高至5，并将聚合时间延长至96h（外消旋率为72%），得到的聚（NIPAAm）s的同时性得到改善。从己烷-四氢呋喃混合物中再沉淀得到的聚合物可以分馏出更多的立体调控聚（NIPAAm）。结果表明，立体调节多的聚（NIPAAm）溶解度低于立体调节少的聚（NIPAAm）。此外，在分馏共规聚（NIPAAm）水溶液的透光率分析中观察到不寻常的滞后现象。
Radical polymerization of N-isopropylacrylamide (NIPAAm) was examined in the presence of hexamethylphosphoramide (HMPA). The addition of an excess amount of HMPA induced syndiotactic-specificity that gradually enhanced as the feed monomer was consumed. The syndiotacticity of the obtained poly(NIPAAm)s was improved by increasing the [HMPA]0/[NIPAAm]0ratio to five and prolonging the polymerization time to 96h (racemo=72%). It was also revealed that more stereoregulated poly(NIPAAm) could be fractionated by reprecipitating the resulting polymers from hexane–THF mixture. This result suggested that more stereoregulated poly(NIPAAm) showed a lower solubility than less stereoregulated poly(NIPAAm)s. Furthermore, unusual hysteresis was observed in transmittance analysis of an aqueous solution of the fractionated syndiotactic poly(NIPAAm).
影响因子：
1.6
作者：
Mana Ito;Takashi Ishizone
通讯作者：
Mana Ito;Takashi Ishizone
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