Laminated TaS2/Polymer Nanocomposites through Encapsulative Precipitation of Exfoliated Layers

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• 作者：Lei Wang and Mercouri G. Kanatzidis
• 刊名：Chemistry of Materials
• 出版年：2001
• 出版时间：October 2001
• 年：2001
• 卷：13
• 期：10
• 页码：3717 - 3727
• 全文大小：180K
• 年卷期：v.13,no.10(October 2001)
• ISSN：1520-5002

文摘

Several TaS₂/polymer nanocomposites prepared through the encapsulative precipitationmethod are described. Namely, the encapsulation of poly(ethylene oxide) (PEO), polyethyleneimine (PEI), and poly(vinylpyrrolidinone) (PVP) into TaS₂ was examined in detail, and thenanocomposites were characterized by a wide variety of techniques. The nanocompositesdisperse in water and are easily cast into free-standing films. The flexible metallic TaS₂/polymer nanocomposite films display bulk superconductivity. In addition, in this work theexfoliation properties of Li_xTaS₂ were systematically explored, and it was found that materialprepared from controlled lithiation with 0.2 equiv of LiBH₄ exfoliates well in water and hashigh affinity for various polymers. The likely conformation of PEO molecules sandwichedbetween the TaS₂ slabs was explored with analysis of the X-ray diffraction patterns of ahighly oriented Li_x(PEO)_yTaS₂ nanocomposite films. The one-dimensional electron densitymaps, obtained for Li_x(PEO)_yTaS₂, can be explained with two sheets of PEO chains (bilayer)that adopt a conformation similar to that found in a type II PEO-HgCl₂ complex. The chainsare arranged with the -CH₂- groups facing the TaS₂ layers and the -O- atoms towardthe center of the gallery, where the Li⁺ ions seem to be located. Solid state ⁷Li NMRmeasurements indicate that Li_x(PEO)_yTaS₂ provides a more facile hopping environment forLi ions than pristine Li_xTaS₂.