Concurrent N-alkylation and doping of polyaniline by alkyl halides

The N-alkylation of polyaniline (PANi) was investigated by treating the ful ly reduced state (leucoemeraldine or LM) and the 50% oxidized state (emeral dine or EM) directly with various alkyl halides. The degree of alkylation o f LM is low (<10%), while that of EM base is much higher (can be >30%), sug gesting that the imine nitrogen is more reactive as a nucleophile than the amine nitrogen in the alkylation reaction. Evidence of concurrent doping of PANi during the N-alkylation process was obtained using UV-visible absorpt ion spectroscopy, FTIR spectroscopy, XPS, and conductivity measurement. The electrical conductivity of the N-alkylated PANi is strongly dependent on t he degree of alkylation. The effects of the various alkyl halides, solvents , and reaction temperatures on the degree of alkylation and reaction rate w ere studied. The mechanism of the N-alkylation reaction and the structure o f the resulting product were postulated.