Efficient encapsulation of conducting polyaniline chains inside carbon nanotubes: a new strategy to prepare endohedral CNT materials

In this paper we report on an inter-diffusion polymerization method to encapsulate polyaniline (PANi) chains inside multiwalled carbon nanotubes (MWCNTs) based on CNT nano-porous membranes. The MWCNT's inner cavity with a diameter around 15 nm is designed to be the only path for the diffusion of the aniline monomer and the initiator, which achieves an efficient and controllable infilling of PANi inside the CNT cavity. The energy filtered transmission electron microscopy (EFTEM) and Raman spectroscopy confirm the successful encapsulation of PANi chains inside CNTs. The new PANi@CNT hybrid exhibits excellent gas sensitivity towards NH3 or HCl in a wide concentration range. This new method (inter-diffusion polymerization) is believed to be much more efficient and tunable in preparing novel endohedral nanotube materials compared to traditional capillary infilling approaches.