Infrared spectroscopic study on LCST behavior of poly(N,N-bis(2-methoxyethyl)acrylamide)
Infrared spectroscopic study on LCST behavior of poly(N,N-bis(2-methoxyethyl)acrylamide)
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DOI：
10.1016/j.eurpolymj.2013.01.002
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发表时间：
2013-03-01
影响因子：
6
通讯作者：
Maeda, Yasushi
中科院分区：
文献类型：
--
作者：
Hidaka, Takashi;Sugihara, Shinji;Maeda, Yasushi
用红外光谱研究了聚(N，N-双(2-甲氧基乙基)丙烯酰胺)(PbMoEA)在水和醇/水混合物中的相分离行为和溶剂化行为。红外光谱的临界变化表明，PbMoEA在54℃左右的水中经历了相分离。相分离过程中Nu(C-H)带的红移和酰胺羰基的蓝移表明其烷基和酰胺基团部分脱水。相变温度(T-p)随甲醇浓度的增加而单调增加，而在正丙醇/水混合物中则呈折返曲线。随着乙醇浓度的增加，酰胺羰基的蓝移和Nu(C-H)的红移分别表明烷基周围疏水水分子与烷基之间的氢键数目减少。前者使溶液不稳定，使T-p降低，而后者使T-p升高。在乙醇浓度较低的正丙醇/水混合物中，前者的优势降低了PbMoEA的T-p，而在甲醇/水混合物中则相反。N-异丙基丙烯酰胺(NiPAm)和N，N-二(2-甲氧基乙基)丙烯酰胺(BMoEA)无规共聚物在甲醇/水混合溶剂中的行为表明，不仅共聚单体的含量对T-p有重要影响，至少二聚体的序列也是重要的，也就是说，相邻单体单元之间的相互作用影响共聚物的T-p。(C)2013爱思唯尔有限公司。保留所有权利。
The phase separation behavior and solvation of poly(N,N-bis(2-methoxyethyl)acrylamide) (PbMoEA) in water and alcohol/water mixtures were investigated by infrared (IR) spectroscopy. A critical change in IR spectrum informs that PbMoEA undergoes the phase separation at around 54 degrees C in water. The red shift of nu(C-H) band and the blue shift of amide carbonyl band during the phase separation indicate that its alkyl and amide groups are partially dehydrated. The transition temperature (T-p) monotonically increases with increasing concentration of methanol, whereas it draws a re-entrant curve in 1-propanol/water mixtures. The blue shift of amide carbonyl band and the red shifts of nu(C-H) bands with increasing alcohol concentration indicate decreases in the number of hydrogen bonds to the carbonyl groups and that of hydrophobically hydrating water molecules around the alkyl groups, respectively. The former effect destabilizes the solutions and lowers T-p whereas the latter raises T-p. The dominance of the former lowers the T-p of PbMoEA in 1-propanol/water mixtures at low alcohol concentrations, and the opposite is the case in methanol/water mixtures. The behavior of random copolymers of N-isopropylacrylamide (NiPAm) and N,N-bis(2-methoxyethyl)acrylamide (bMoEA) in methanol/water mixtures indicates that not only the comonomer content but also at least diad monomer sequence is important for T-p, in other words, the interaction between adjacent monomer units affects the T-p of copolymers. (C) 2013 Elsevier Ltd. All rights reserved.