Polyaniline-DBSA/polymer blends prepared via aqueous dispersions

Stable polyaniline-dodecyl benzene sulfonic acid (PANI-DBSA) aqueous disper sions were obtained by a unique method of aniline polymerization in the pre sence 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. T hese primary particles form aggregates, which further cluster into similar to 50 mu m agglomerates. PANI-DBSA/polymer blends were obtained by mixing a n aqueous PANI-DBSA dispersion with an aqueous emulsion of the matrix polym er, followed by water evaporation. These blends exhibit electrical conducti vity already at a very low PANI-DBSA content (0.5 wt.%). The conductivity l evel of the various blends depends on the PANI content, on the surfactant p resent 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 a nd melt blends). The PANI-DBSA particles strongly segregate within the poly mer matrix, already in the combined aqueous dispersion, and upon drying, a very fine conductive network is formed. This strong segregation tendency le ads to a conductive network formation already at low PANI-DBSA contents, th us generating the conductive blends. (C) 2000 Published by Elsevier Science S.A. All rights reserved.