Dynamic phase transition behavior and unusual hydration process in poly(ethylene oxide)‐b‐poly(N‐vinylcaprolactam) aqueous solution |
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| Authors: | Qiuwen Wang Hui Tang Peiyi Wu |
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| Affiliation: | Department of Macromolecular Science and Laboratory for Advanced Materials, State Key Laboratory of Molecular Engineering of Polymers, Collaborative Innovation Center of Polymers and Polymer Composite Materials, Fudan University, Shanghai, China |
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| Abstract: | Dynamic phase transition and self‐assembly mechanism of thermosensitive poly(ethylene oxide)‐b‐poly(N‐vinylcaprolactam) (PEO‐b‐PVCL) copolymer are explored deeply. A gradual dehydration process with predominated hydrophobic interactions among copolymer chains in the phase transition process distinguishes the copolymer from homopolymer. PVCL in the inner zone is restricted and counter‐balanced by the PEO segments based on the sequence order of representative groups during the heating‐cooling cycles. Remarkably, PEO shell experiences unusual hydration process, which is first discovered. This hydrophilic shell plays as water absorption sponge layer and captures expelled water from PVCL core, accompanied by gradient distribution of water existed in the assembly structures. Peculiarly, pseudo‐linear changes of the integral area of free C?O are presented compared with inflection point in the hydrated C?O integral area, which propose that a part of hydrated C?O forms incomplete dehydrated states. During the cooling process, perfect reversibility is observed without obvious hysteresis. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 385–396 |
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| Keywords: | dynamic phase transition FT‐IR and phase behavior incomplete dehydrated states pseudo‐linear changes self‐assembly thermodynamics two‐dimensional correlation spectroscopy unusual hydration |
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