Metal-nanofiber composites composite nanofibers

S. Virji, R. Kojima, J. D. Fowler, R. B. Kaner, and B. H. Weiller, Polyaniline nanofiber—metal salt composite materials for arsine detection, Chem. Mater., 21, 3056-3061 (2009). 

The polymer resulting from oxidation of 3,5-dimethyl aniline with palladium was also studied by transmission electron microscopy (Mallick et al. 2005). As it turned out, the polymer was formed in nanofibers. During oxidative polymerization, palladium ions were reduced and formed palladium metal. The generated metal was uniformly dispersed between the polymer nanofibers as nanoparticles of 2 mm size. So, Mallick et al. (2005) achieved a polymer- metal intimate composite material. This work should be juxtaposed to an observation by Newman and Blanchard (2006) that reaction between 4-aminophenol and hydrogen tetrachloroaurate leads to polyaniline (bearing hydroxyl groups) and metallic gold as nanoparticles. Such metal nanoparticles can well be of importance in the field of sensors, catalysis, and electronics with improved performance. 

It is reasonable that, in the synthesis of polymer nanocomposites, the y-ray irradiation method is convenient for growing nanofibers and nanowires of metal chalcogenides due to the shape-control of the macromolecules formed in situ. Figure 7.38 shows some of the resulting nanofiber-dispersed polymer composites,... 

K. MaUick, M.J. Witcomb, A. Dinsmore, and M.S. Scurrell, Fabrication of a metal nanoparticles and polymer nanofibers composite material by in situ chemical synthetic route, Langmuir, 21, 7964-7967 (2005). 

A gas-solid reaction was further introduced to the electrospiiming technique to incorporate semiconductor nanostructures into polymer nanofibers with better dispersion. The production of well-dispersed PbS nanoparticles in polymer fiber matrices has been achieved by this method (Lu et al., 2005). First, metal salt and polymer were codissolved into one solvent to make a homogeneous solution. Then the above solution was electrospun to obtain polymer/metal salt composite nanofibers. The composite nanofibers were finally exposed to HaS gas at room temperature to synthesize PbS nanoparticles in situ in polymer nanofibers. 

In addition to in situ reduction by the CPs, metal nanoparticles can also be synthesized on the surface of the CPs via a reduction process in the presence of other reducing agents. Yan and co-workers prepared PANI/Pt composite nanofibers by reducing a Pt salt with ethylene glycol on the surface of PANI nanofibers [78]. The diameter of PANI nanofibers was about 60 nm, and that of as-synthesized Pt nanoparticles (PtNPs) was only about 1.8 nm as calculated from X-ray diffraction (XRD) data. The small size of PtNPs on the CP matrix enhanced the electrocatalytic activity for the methanol oxidation reaction. 

Acids can act as dopants for polyaniline therefore, if the nanofibers are first doped with these acids, and subsequently exposed to the metal ions, precipitates should be formed on the surface of the nanofibers, leading to inorganic-polyaniline nanofiber composites. This idea has been applied in Section 7.3.5 to improve the detection of H2S. Another possibility is to use nanofibers as nucleation seeds to collect inorganic nanoparticles from supersaturated solutions [148]. 

Virji, S., J.D. Fowler, C.O. Baker, J. Huang, R.B. Kaner, and B.H. Weiller. 2005. Polyaniline nanofiber composites with metal salts Chemical sensors for hydrogen sulfide. Small 1 (6) 624-627. 

This section studies the effect of the structure and composition of carbon nanofibers obtained by co-catalyst washed and not washed from the metal catalyst on the kinetics and properties of vulcanized ethylene propylene diene rubber. It is shown that the fibers obtained on the co-catalyst accelerate the crosslinking of EPDM, improve the physical and mechanical properties, increase the molecular mobility. The purpose of this research—investigation of the carbon nanofibers influence produced by co-catalysts on the physical and mechanical properties and structure of synthetic EPDM. 

ElectrochemicaUy active materials such as activated carbons, carbon aerogels, and carbon foams (aU derived from polymers) oxides, hydrous oxides, carbides, and nitrides are used to form composites with carbon nanofibers. Additional active materials such as oxides, hydrous oxides, and carbides can be combined to form a composite. Process requires dispersion in water with carbon nanofiber and subsequent filtralion and washing. Capacitance of 249 F /g was measured from a RuOj xHjO metal oxide and carbon nanofiber composite. 

Halpin-Tsai equation. The different types of composite nanofibers reported in the research literature fall into three broad classes those based on carbons, on silicate clays, and on metal particles. 

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