Effects of multiwall carbon nanotubes on the polymerization model of aniline

Abstract

In this paper, chemical polymerization of aniline and aniline/multi-walled carbon nanotubes (MWCNTs) is investigated, and a modified polymerization model is proposed based on the obtained experimental results. In the experimental section, the variation in temperature of the reaction mixture was measured during the polymerization reaction. According to the obtained thermographs, it was concluded that the polymerization of aniline or aniline/MWCNTs takes place in three different steps. In the first step, some nuclei of phenazine-type trimers are formed for pure aniline while for aniline/MWCNTs, aniline molecules are adsorbed on the nanotubes surfaces. In the second step, cation-radical polymerization occurs at a high speed where there are a significant number of monomers around the growing chains. It is proposed that in the third step a new polymerization reaction begins on the pre-synthesized polymers. For pure PANI, it seems that only oligomers are created in this step while for PANI/MWCNTs, long chain polymers can also grow. Experimental results show that the enthalpy of polymerization reduces while polymerization yield increases with the weight percent of MWCNTs, which can be explained by the new observed polymerization model.