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	Conformation transition and molecular mobility of isolated poly(ethylene oxide) chains confined in urea nanochannels
	Ye, Hai-Mu ; Peng, Min ; Xu, Jun ; Guo, Bao-Hua ; Chen, Qun ; Yun, Tian-Liang ; Ma, Hui
	2010-05-07 ; 2010-05-07
关键词	inclusion compound chain conformation C-13 spin-lattice relaxation time SOLID-STATE NMR 2ND-HARMONIC GENERATION INCLUSION-COMPOUNDS POLYETHYLENE OXIDE OLIGOMER COMPLEXES CRYSTAL-GROWTH POLYMER POLYETHERS COMPOUND TRANSFORMATION Polymer Science
中文摘要	Inclusion compounds formed from host small molecules and guest polymers have provided a novel platform to study the behavior of isolated polymer chains confined in nanochannels. In this article, the PEO chain conformation in the metastable poly(ethylene oxide) (PEO)-urea inclusion compound (IC) and its transition was characterized via a combination of different analytical methods. Based on the FTIR and Raman spectroscopy results, PEO chains in the metastable tetragonal IC are tentatively assigned to the tgg' conformation. The structural changes of the metastable tetragonal IC to the stable trigonal form were observed via in situ FTIR and ex situ WAXD. The transformation is a kinetic solid-solid process and can even occur at room temperature. The activation energy of about 222 kJ/mol indicates that the transition occurred via cooperative disruption of several hydrogen bonds. Measurement of the laboratory frame spin-lattice relaxation time T-1 (C-13) shows that molecular motions of the nanoconfined PEO chains are more intensive than the neat crystalline PEO but weaker than those of the neat amorphous PEO. Second harmonic generation microscopy demonstrates that the trigonal IC exhibits stronger nonlinear optical activity than the tetragonal IC. The intermolecular hydrogen bonding is attributed to the driving force for the transformation of the metastable tetragonal IC into the stable trigonal form. (c) 2007 Elsevier Ltd. All rights reserved.
语种	英语 ; 英语
出版者	ELSEVIER SCI LTD ; OXFORD ; THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND
内容类型	期刊论文
源URL	[http://hdl.handle.net/123456789/17419]
专题	清华大学
推荐引用方式 GB/T 7714	Ye, Hai-Mu,Peng, Min,Xu, Jun,et al. Conformation transition and molecular mobility of isolated poly(ethylene oxide) chains confined in urea nanochannels[J],2010, 2010.
APA	Ye, Hai-Mu.,Peng, Min.,Xu, Jun.,Guo, Bao-Hua.,Chen, Qun.,...&Ma, Hui.(2010).Conformation transition and molecular mobility of isolated poly(ethylene oxide) chains confined in urea nanochannels..
MLA	Ye, Hai-Mu,et al."Conformation transition and molecular mobility of isolated poly(ethylene oxide) chains confined in urea nanochannels".(2010).

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