Polyaniline-DBSA/polymer blends prepared via aqueous dispersions

Stable polyaniline-dodecyl benzene sulfonic acid (PANI-DBSA) aqueous dispersions were obtained by a unique method of aniline polymerization in the presence of DBSA, through an anilinium-DBSA complex appearing as solid needle-like particles, in an aqueous medium. The average size of the PANI primary particles, determined by small angle X-ray scattering (SAXS), is 18.7 nm. These primary particles form aggregates, which further cluster into similar to 50 mu m agglomerates. PANI-DBSA/polymer blends were obtained by mixing an aqueous PANI-DBSA dispersion with an aqueous emulsion of the matrix polymer, followed by water evaporation. These blends exhibit electrical conductivity already at a very low PANI-DBSA content (0.5 wt.%). The conductivity level of the various blends depends on the PANI content, on the surfactant present in the polymer matrix emulsion, and it is practically independent of the polymer matrix nature. Thus, a similar structuring mechanism prevails in these blends, irrespective of the polymer matrix (contrary to solution and melt blends). The PANI-DBSA particles strongly segregate within the polymer matrix, already in the combined aqueous dispersion, and upon drying, a very fine conductive network is formed. This strong segregation tendency leads to a conductive network formation already at low PANI-DBSA contents, thus generating the conductive blends. (C) 2000 Published by Elsevier Science S.A. All rights reserved.