Photophysical comparative study of amylose and polyvinyle pyrrolidone/single walled carbon nanotubes complex

Progressive addition of hydroxypropylated amylose (AmH), from 0.05 wt% to 4.5 wt%, to single-walled carbon nanotubes (SWNTs) in aqueous surfactant suspensions quenches the intrinsic near Infra-Red fluorescence of semiconducting SWNTs while dispersions obtained with a same amount of polyvinylpyrrolidone (PVP) remain luminescent. Near Infra-Red emission spectroscopy (fluorescence and Raman scattering) of the samples is used to characterize the supramolecular organization of these polymer/SWNT complexes. The SWNTs are found to be wrapped by the PVP chains and not by the AmH chains which rather form AmH/surfactant/SWNTs complexes. In PVP/SWNTs dispersion, the fluorescence line position and intensity are affected by dielectric screening. In the case of AmH/surfactant/SWNTs complex, dielectric screening plays also a role but quenching occurs above about 3 wt% of AmH. We attribute the quenching to the formation of a "composite like" microstructure by opposition to stabilized dispersion.