Preparation and Charge-Transfer Study in a Single-Walled Carbon Nanotube Functionalized with Poly(3,4-ethylenedioxythiophene)

Conductive and biocompatible coatings are currently in great demand. Poly(styrenesulfonic acid) (PSS)-stabilized poly(3,4-ethylenedioxythiophene) (PEDOT) is probably the most successful representative of this class of materials. For many of these applications, the PEDOT needs to be stabilized in the charged state by PSS, which compromises the biocompatibility of this polymer. Here, we propose an alternative stabilization of PEDOT by functionalized single-wall carbon nanotubes (SWCNTs). We functionalized SWCNTs using the 4-chlorobenzene-3-sulfonic acid group and prepared the composite by directly performing the polymerization of 3,4-ethylenedioxythiophene in the presence of functionalized SWCNTs. A study of the electronic structure of the SWCNTs, functionalized SWCNTs, and the composite by in situ Raman spectroelectrochemistry showed that the electronic structure of the SWCNTs and the behavior of SWCNTs are not significantly altered by functionalization or embedding into the composite, and the charged state of the nanotubes can be tuned efficiently by electrochemical doping. The films prepared from the composite exhibit conductivity similar to that of the PEDOT stabilized by PSS; hence, the proposed new composite can be suggested as a biocompatible alternative to PEDOT/PSS, for example, in bioelectrodes or in biocompatible sensors.