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Authors
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Pietsch, T. ; Cheval, N. ; Appelhans, D. ; Gindy, N. ; Voit, B. ; Fahmi, A.
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Title
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Cation-induced unidirectional self-assembly of amino-terminated poly(propylene imine) dendrimers
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Date
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24.01.2011
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Abstract
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Nanofabrication via directed self-assembly of hybrid materials into well-defined nanostructures is a powerful tool to produce functional building blocks, which possess unique optical, magnetic, and electronic properties that are essential for the next generation of nanodevices. In particular, hybrid materials based on dendrimers in combination with inorganic components resemble an ideal functional system for nanostructuring via hierarchical self-assembly. Recently, it has been shown that dendrimers can act as unimolecular micelles for the controlled synthesis and stabilization of inorganic nanoparticles.13 The large number of functional groups in the dendritic motif and their unique molecular architecture also give rise to a great diversity of self-assembled structures.49 Herein, we present a simple approach to fabricate inorganic nanofibers based on the directed self-assembly of amino-terminated poly(propylene imine) (PPI) dendrimers in aqueous media. The fabrication of such one-dimensional (1D) nanostructures has attracted an increasing interest due to their potential applications in nanoscale devices,10 nano- and microelectronics,11 data storage,12 and sensor arrays.13 Previously, it has been demonstrated that maltose-functionalized PPI dendrimers can be used to template metal and semiconductor nanoparticles in aqueous media.3, 14 However, so far the self-assembly of dendrimers has been studied predominantly on surfaces and in thin films.1517 For example, De Schryver et al.6, 1820 demonstrated in a series of reports that long fibers of shape-persistent polyphenylene dendrimers can be generated via spin-coating and drop-casting of solutions onto solid substrates. They claim that the formation of nanofibers is a result of dominant pp stacking interactions at increased dendrimer concentrations upon solvent evaporation for film deposition. Only recently, Newkome et al.21 presented dendrimer-based nanofibers, which are formed in solution by multiple ion pairing. They used carboxylate-terminated dendrimers, which become insoluble upon ion pairing with a rigid macrocycle leading to the formation of fibrous precipitates.
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Journal
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Small 7 (2011) 221-225
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DOI
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https://doi.org/10.1002/smll.201001461
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