Control over the Self-Assembly and Dynamics of Metallacarborane Nanorotors by the Nature of the Polymer Matrix: A Solid-State NMR Study

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• 作者：Jiri Brus ; Alexander Zhigunov ; Ji艡铆 Czernek ; Libor Kobera ; Mariusz Uchman ; Pavel Mat臎j铆膷ek
• 刊名：Macromolecules
• 出版年：2014
• 出版时间：September 23, 2014
• 年：2014
• 卷：47
• 期：18
• 页码：6343-6354
• 全文大小：702K
• ISSN：1520-5835

文摘

Solids that combine long-range order with rapid molecular reorientation offer a promising approach for the development of a novel class of functional materials with potential applications in materials science and nanotechnology. In this contribution, the capability of dicarbollide ions to undergo self-assembly processes with suitable macromolecules is demonstrated, and a strategy leading to the formation of structurally and dynamically well-defined amphidynamic polymeric composites is introduced. For this purpose, three amphidynamic nanocomposites were synthesized via the self-assembly of cobalt bis(dicarbollide) anions (CoD^{鈥?/sup>), with neutral poly(ethylene oxide) (PEO), and two isomers of poly(vinylpyridine), P2VP and P4VP, in protonated form. All of the systems were characterized by a combined study employing WAXS, advanced solid-state NMR, and quantum chemical calculations. It was found out that the interaction of neutral PEO with CoD鈥?/sup> ions driven by weak dihydrogen bonding resulted in the formation of a uniquely organized periodic structure. In contrast, the self-assembly of the systems based on the electrostatic interactions (charge-transfer-assisted hydrogen bonding) of P2(4)VP was controlled by the position of the positive charge in pyridine ring and resulted in unique well-defined orientations of the CoD鈥?/sup> ions (parallel and perpendicular) with respect to the polymer chains. In addition, the CoD鈥?/sup> ions exhibited uniaxial relatively large-amplitude rotational motions in all of the nanocomposites over the broad range of T_g. The motional amplitudes executed by the CoD鈥?/sup> ions are significantly more extensive than those of the polymer segments in all of the systems. Macromolecules thus represent a rigid support (stator) for the more mobile CoD鈥?/sup> ions (rotators). The obtained findings revealed that a relatively simple self-assembly procedure could be used for the preparation of well-defined amphidynamic nanocomposites, thereby opening a route to construct sophisticated supramolecular systems.}