A chitosan (CS)-grafted multiwalled carbon nanotubes (MWCNT) composite (CS-MWCNT) was prepared via covalently grafting a biocompatible polymer CS onto the surfaces of MWCNT and was characterized by Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–vis), and transmission electron microscopy (TEM). The interaction between MWCNT and CS was investigated and explained according to the FTIR and UV–vis results. More evidence for the presence of the CS-MWCNT was confirmed by TEM images. In the TEM images, a core-shell structure with nanotubes in the center and a CS layer lying around them was observed. The electrochemical properties of the CS-MWCNT were characterized by an electrodeposition method that involves depositing it on a Au electrode. The porous microstructure of the CS-MWCNT modified electrode was observed by scanning electron microscopy. The excellent electrocatalytic ability of the CS-MWCNT modified electrode towards hydrogen peroxide is applicable to the development of oxidase-based amperometric biosensors.

tion between PANI and MWNTs and the nature of chain growth have been investigated and explained according to the results of FT-IR analysis. The improvement of thermal stability and crystallinity of the nanocomposites have been evaluated by using TGA and XRD. The mechanism of charge transport in these composites has also been studied by measuring the DC conductivity of all samples and examining the temperature–conductivity relations. MWNT alignment should be possible with other nanometer-sized building composites films, offering a general route for controlled assembly of organized nanomaterials and devices.

Multiwalled carbon nanotubes (MWCNTs) were grafted by chitosan (CS); the product could disperse well in poly(vinyl alcohol) (PVA) aqueous solution with 2% (v/v) acetic acid solution.Because this product has potential in several biological fields, it was electrospun so as to enlarge the surface area. Raman spectra indicated that the electrospinning process did not severely alter the electron hybridization of carbon atoms within the nanotube framework. Moreover and interestingly, these nanofibers showed a novel sheath–core structure; the outer and inner diameters of these sheath–core nanofibers were about 200 nm and 100 nm,respectively. These nanofibers’ electrochemical properties were characterized by detection of hydrogen peroxide and voltammetric responses of potassium ferricyanide. The electrospun fibers’ web displayed faster electron transfer kinetics and better electrochemical properties than its cast film, which justified further applications in biological areas.

A new type of photo-responsive perylene diimide–azobenzene dyad (PDI–AZO) was synthesized by covalently adjoining azobenzene chromophore to N-imide position of perylene diimide. The optical properties, photoisomerization and self-assembly morphology of the resultant composites were characterized by UV–vis absorption, photoluminescence (PL) spectra and scanning electron microscope. Larger one-dimension nanobelts were observed in self-assembly PDI–AZO due to the strong molecule stacking. The red-shifted bands arise from the larger conjugation extension by p-electron overlap of perylene ring and azobenzene chromophore. The spectral changes upon the irradiation of ultraviolet light show that larger conjugation extension does not significantly affect the photochromism rate, but it retards the further photoisomerization of azobenzene units in PDI–AZO. The PL quenching of PDI–AZO is dominated by the transfer of the excitons before reverting to the ground state accompanied by the radiation due to the larger conjugation extension.  2007 Elsevier B.V. All rights reserved.

Perylene-sensitized multi-walled carbon nanotubes (PV-MWNT) have been prepared by a π-stacking between nanotubes and perylene derivatives, N,N'-diphenyl glyoxaline-3,4,9,10-perylene tetracarboxylic acid diacidamide (PV). The resultant nanocomposites have been characterized by transmission electron microscope (TEM), UV–vis absorption, photoluminescence (PL) and photocurrent spectra. Long range ordering can be observed in the form of PV-MWNT via π-stacking by TEM. Red-shift in the optical spectra consisting of the UV–vis absorption and PL spectra with the attraction of PV on the surface of the MWNTs were observed. The evident quenching in PL spectra of PV-MWNT was ascribed to the absorption and transfer of recombination energy by MWNT. Photosensitivity spectra demonstrated an increasing photocurrent in the ultraviolet region and a broadening photosensitivity in the red spectral region for solar cells based on PV-MWNT.