Surface modification of polyaniline nanorods with thiol-terminated poly(ethylene oxide)

Electrochemically grown polyaniline (PAni) thin films have been shown to react efficiently with thiols, which can dramatically change the surface properties of the material without significantly impacting bulk conductivity. Such films, however, are difficult to process and are unsuitable for many applications. Here, we demonstrate the grafting of thiol-terminated poly(ethylene oxide) (PEG-SH) of various molecular weights onto PAni nanorods. The resulting materials are characterized by spectroscopic, microscopic, and thermal analytical methods to demonstrate the covalent attachment of the PEG polymers to the nanorods. The derivatized nanorods are water dispersible and maintain their original morphology and electroactivity. The number of thiols bound to the nanoparticles under a given set of conditions decreases as the size increases, but the total mass of PEG increases with increasing size. The reaction proceeds at room temperature, but is much faster at higher temperature and greater PEG density is observed.