We present here the synthesis and structural characterization of hybrid Au-polypyrrole-Au and Ptpolypyrrole-Au nanowires together with a study of their electrical properties from room-temperature down to very low temperature. A careful characterization of the metal-polymer interfaces by transmission electron microscopy revealed that the structure and mechanical strength of bottom and upper interfaces are very different. Variable temperature electrical transport measurements were performed on both multiple nanowires -contained within the polycarbonate template -and single nanowires. Our data show that the three-dimensional Mott variable-range-hopping model provides a complete framework for the understanding of transport in PPy nanowires, including non-linear current-voltage characteristics and magnetotransport at low temperatures. † Research associate of the FNRS. ometry of the devices. Despite these experimental efforts, the electrical transport at nanoscale in conjugated polymers is still matter of debate. Until now, very few studies [4,9] focused on the synthesis and electrical characterization of hybrid conjugated polymer-metal nanowires. Moreover, none of them reported on the structural characterization of the metal-polymer interfaces, which could play an important role on the electrical properties of the nanodevices. We present here the synthesis and structural characterization of hybrid metal(Au or Pt)-polypyrrole(PPy)-metal(Au) nanowires together with a study of their electrical properties from roomtemperature down to very low temperature (T ≈ 0.5 K). Metallic segments, few microns long, serving as contacting electrodes are electrochemically synthetized within polycarbonate (PC) templates, before and after the PPy nanowire growth. Interestingly, the resulting metal-PPymetal hybrid nanowires have two morphologically different PPy-metal interfaces (see Fig. 1). In terms of mechanical robustness the PPy-onto-metal interface is smoother and more fragile than the metal-onto-PPy interface. By using Pt instead of Au for the first grown segment, much more robust nanowires have been fabricated. The present all-electrochemical technique allows controlled optimization of the mechanical strength arXiv:1112.4656v1 [cond-mat.mes-hall]

Multisegmented nanowires (NWs) based on poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy) are synthesized by an all-electrochemical template method for precise control over segment dimensions. We study the influence of different parameters on the growing process of the PEDOT segment and on the mechanical strength of the conjugated polymer/metal interfaces in tri-segmented Au-PEDOT-Au and tetra-segmented Au-PEDOT-PPy-Au NWs. The coexistence of PEDOT and PPy in tetra-segmented NWs is confirmed by high resolution transmission electron microscopy coupled with energy-dispersive X-ray analysis. We investigate the electrical transport of individual multisegmented NWs of both types at room temperature. An interesting feature of the tetra-segmented NWs compared to tri-segmented NWs is the switching of their electrical characteristics in function of the redox state of the two conjugated polymer blocks.

With the development of nanotechnology, there is a growing demand for advanced electronics based on functional nanomaterials. In this respect, owing to their unique properties, conducting polymers (CP) synthesized in the form of one-dimensional (1D) nanostructures are of particular interest. In this feature paper, we first report one of the most powerful techniques, the hard templating synthesis, for elaborating a large number of uniform 1D CP nanotubes or nanowires with precise control over lengths and diameters. Then, recent advances in the preparation, through electrochemical template synthesis, of various multi-segmented nanowires containing a combination of metallic and polymeric components are discussed. Hybrid metal-CP nanowires are promising high tech materials as they exhibit enhanced performances compared to their bulk counterparts and are of direct interest for developing novel multifunctional systems for a wide range of applications. Finally, some future directions for research in the area of multi-segmented nanowires are proposed.

We report on a facile method for the preparation of biocompatible and bioactive magnetic nanowires. The method consists of the direct deposition of polysaccharides by layer-by-layer (LbL) assembly onto a brush of metallic nanowires obtained by electrodeposition of the metal within the nanopores of an alumina template supported on a silicon wafer. Carboxymethylpullulan (CMP) and chitosan (CHI) multilayers were grown on brushes of Ni nanowires; subsequent grafting of an enzyme was performed by conjugating free amine side groups of chitosan with carboxylic groups of the enzyme. The nanowires are finally released by a gentle ultrasonic treatment. Transmission electron microscopy, electron energy-dispersive loss spectroscopy, and x-ray photoelectron spectroscopy indicate the formation of an homogeneous coating onto the nickel nanowires when one, two, or three CMP/CHI bilayers are deposited. This easy and efficient route to the biochemical functionalization of magnetic nanowires could find widespread use for the preparation of a broad range of nanowires with tailored surface properties.

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