Lower critical solution temperature behavior of poly(N-(2-ethoxyethyl)acrylamide) as compared with poly(N-isopropylacrylamide).
Lower critical solution temperature behavior of poly(N-(2-ethoxyethyl)acrylamide) as compared with poly(N-isopropylacrylamide).
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DOI：
10.1021/jp9052067
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发表时间：
2009-08
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影响因子：
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通讯作者：
Y. Maeda;J. Sakamoto;Shuangyin Wang;Yuuichi Mizuno
中科院分区：
文献类型：
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作者：
Y. Maeda;J. Sakamoto;Shuangyin Wang;Yuuichi Mizuno
用红外光谱法研究了聚（N-（2-乙氧基乙基）丙烯酰胺）（PEoEA，相变温度T（p）= 38 ℃）和聚（N-（2-乙氧基乙基）甲基丙烯酰胺）（PEoEMA，T（p）= 50 ℃）在水溶液中的温敏相分离。它们具有宽的转变温度区域（约25 ° C），并且它们的T（p）随着添加的甲醇浓度的增加而单调增加，这与聚（N-异丙基丙烯酰胺）（PNiPAM）的再入相分离不同。它们的酰胺I带由两个组分组成，分别归属于水溶液和甲醇/水混合物中的单氢键和双氢键C水平线O基团。在相分离和甲醇浓度增加的过程中，后者的强度降低，而nu（C-H）带发生红移。这些变化与PNiPAM的性质相同，尽管PNiPAM在C水平线O基团处具有更高的接受双氢键的倾向。N-（2-乙氧基乙基）丙烯酰胺和N-异丙基丙烯酰胺的共聚物在甲醇/水混合物中的行为随着PNiPAM含量的增加而逐渐接近PNiPAM的行为，这表明每个单体单元与溶剂分子之间的相互作用协同决定了它们作为一个整体的行为。
Temperature-responsive phase separation of poly(N-(2-ethoxyethyl)acrylamide) (PEoEA, phase transition temperature, T(p) = 38 degrees C) and poly(N-(2-ethoxyethyl)methacrylamide) (PEoEMA, T(p) = 50 degrees C) in aqueous solutions has been investigated by infrared spectroscopy. They had a wide transition temperature region ( approximately 25 degrees C), and their T(p) monotonically increased with increasing concentration of added methanol, unlike re-entrant phase separation of poly(N-isopropylacrylamide) (PNiPAM). Their amide I bands consisted of two components assignable to singly and doubly hydrogen bonding C horizontal lineO groups in both aqueous solutions and methanol/water mixtures. The intensity of the latter decreased during both phase separation and an increase in methanol concentration, whereas the nu(C-H) bands underwent red shifts. The changes were qualitatively the same as those of PNiPAM, although PNiPAM has a higher tendency to accept double hydrogen bonds at the C horizontal lineO groups. The behavior of the copolymers of N-(2-ethoxyethyl)acrylamide and N-isopropylacrylamide in methanol/water mixtures gradually approached that of PNiPAM with an increasing content of the latter, suggesting that the interaction between each individual monomer unit and solvent molecules cooperatively determines their behavior as a whole.