Abstract: | A DBSA (n‐dodecylbenzene sulfate)‐complexed aniline formaldehyde [AF(DBSA)1.0] was successfully synthesized with excess aniline (compared with formaldehyde) in the presence of n‐dodecylbenzene sulfonic acid (HDBSA), which was complexed with aniline monomer before polymerization. The resin was carefully characterized with 1H and 13C NMR, electron spectroscopy for chemical analysis, and Fourier transform infrared and was demonstrated to be a polymer in which anilines were all complexed with HDBSA and became anilinium salts. A drastic decrease of the maximum absorption wavelength (ultraviolet–visible spectra) of DBSA‐doped polyaniline [PANI(DBSA)0.5] was found when AF(DBSA)1.0 was mixed, and this resulted from the reduced conjugation length. A similar effect on PANI(DBSA)0.5 was found when free HDBSAs were mixed with PANI(DBSA)0.5. Visual inspection with an optical microscope revealed that PANI(DBSA)0.5/AF(DBSA)1.0 gave uniform morphologies in various compositions, showing possible miscibility for this system. X‐ray diffraction patterns of PANI(DBSA)0.5/AF(DBSA)1.0 showed that the layered structure of PANI(DBSA)0.5 was still present but became shorter in the polyblend because of the presence of AF(DBSA)1.0. Solid‐state 13C NMR spectra revealed that the reduced conjugation length was derived from the interaction of alkyl groups between HDBSA, complexed DBSA, and dopant DBSAs. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3116–3125, 2005 |