Behavior of Water during Temperature-Induced Phase Separation in Poly(vinyl methyl ether) Aqueous Solutions. NMR and Optical Microscopy Study

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• 作者：Jir虒í ; Spe虒va虂č ; ek ; Lenka Hanykova虂 ; Jan Labuta
• 刊名：Macromolecules
• 出版年：2011
• 出版时间：April 12, 2011
• 年：2011
• 卷：44
• 期：7
• 页码：2149-2153
• 全文大小：839K
• 年卷期：v.44,no.7(April 12, 2011)
• ISSN：1520-5835

文摘

The behavior of water during the temperature-induced phase separation in PVME/D₂O solutions was investigated by ¹H NMR methods and optical microscopy. A fast exchange between water (HDO) bound in mesoglobules and free water was found from ¹H NMR spin鈭抯pin relaxation measurements at temperature above the LCST transition for semidilute PVME/D₂O solutions where the exchange time is 1.2 ms for c = 6 wt %. In contrast, there is a slow exchange between bound and free water in highly concentrated PVME solutions and the residence time of the bound water 2 s was found for concentrations c = 20鈭?0 wt % using one-dimensional NOE ¹H NMR experiment. A 3 order of magnitude slower exchange in highly concentrated PVME/D₂O solutions is in accord with our optical microscopy findings that globular-like structures are here approximately 20 times larger than in PVME solution with c = 6 wt %.