Water-soluble sulfonated carbon nanotubes were prepared by diazotization.On this basis

a series of sulfonated carbon nanotubes (1~2 nm

8 nm

10~20 nm

30~50 nm) modified polyaniline composites were synthesized successfully using in situ oxidative polymerization method.FTIR spectra shows that the intensity ratio of I1580/I1490 increases with the decrease of the diameters of CNTs.Simultaneously

it can be found from the UV-Vis spectra that the absorption peak around 800 nm of the composites blue-shifts compared to the polyaniline nanorods.Aforementioned results indicate that the presence of the - interaction between the PANI and the sulfonated carbon nanotubes

and the charge transfer composites are formed

which increase as the diameter of CNTs decreases.Field emission scanning electron microscope (FESEM) images show the PANI/sSWCNT composite displays the morphological structure of the bundle of nanotubes coated with PANI while the PANI/sMWCNT composites exhibit the morphology of single nanotube coated with PANI.And with the increase of the diameters of carbon nanotubes

the diameters of the PANI/sMWCNT composites thicken gradually.The cyclic voltammetry results demonstrate that the composites have higher specific capacitance (309~457 F/g) compared to the PANI nanorods (271 F/g)

and the specific capacitance of the composites increases with decreasing the diameter of CNTs.Moreover

the composites also have outstanding fast charge/discharge performance as electrode materials in the application of supercapacitors.