The reaction between fluorinated single-wall carbon nanotubes (F-SWNTs) and branched (M(w) = 600, 1800, 10000, and 25000 Da) or linear (M(w) = 25000 Da) polyethyleneimine (PEI) yields the covalent attachment of the polymer to the sidewalls of the nanotubes. The resulting PEI-functionalized SWNTs (PEI-SWNTs) were characterized by solid-state (13)C NMR, Raman spectroscopy, X-ray photoelectron spectroscopy, UV-vis spectroscopy, atomic force microscopy, transmission electron microscopy, and thermal gravimetric analysis studies. As expected, the number of polymer molecules per SWNT is larger for low molecular weight PEI than for high molecular weight PEI. However, above 1800 Da, the number of polymer molecules per SWNT does not vary as much. This is supported by Raman spectral data that shows the D:G ratio is relatively insensitive of the molecular weight for M(w) > 1800 Da. The PEI-SWNTs are shown to have solubility in aqueous media of up to 0.4 mg x mL(-1). Solid-state (13)C NMR shows the presence of carboxylate substituents that have been attributed to carbamate formation as a consequence of the reversable CO(2) absorption to the primary amine substituents of the PEI. Desorption of CO(2) is accomplished by heating under argon at 75 degrees C, while the dependence of the quantity of CO(2) absorbed on temperature and the molecular weight of the PEI is reported. Under the conditions investigated the maximum absorption of 9.2% w/w is observed for PEI(25000)-SWNT at 27 degrees C. The possible CO(2) absorption applications of the PEI-SWNTs is discussed.

Ultrasmall copper nanoparticles are produced by N,N,N',N'-tetramethyl-p-phenylenediamine (TMPDA) reduction of aqueous Cu(2+) on a hydrophobically immobilized sodium dodecylbenzenesulfonate (SDBS) surfactant template in the presence of sodium citrate at room temperature. Single-walled carbon nanotubes (SWNTs) act as a scaffold controlling the size of the SDBS micelle, which in turn confines a limited number of copper ions near the nanotube surface. TMPDA reduction forms copper nanoparticles as confirmed by X-ray photoelectron spectroscopy and electron diffraction, whose size was determined by atomic force microscopy and transmission electron microscopy to be approximately 2 nm. Particles formed in the absence of the SWNT immobilizer range from 2 to 150 nm.

Organically capped metal nanoparticles are an attractive alternative to more conventional oxide-passivated materials, due to the lower reaction temperatures and the possibility of tuning the organic coating. Sonochemical methods have been used to produce small (∼5 nm average size) air-stable aluminum nanoparticles capped with oleic acid. In order to understand the nature of the metal−organic bonding in the nanoparticles, we have used FTIR, XPS, and TOFMS−TPD techniques to study the organic passivation layer and its desorption at elevated temperatures. In the present case we find that the organic layer appears to be attached via Al−O−C bonds with the C atom formerly involved in the carboxylic acid functional group.