Methodology for determination of Pani.DBSA content in conductive blends by using UV-Vis spectrometry

This paper describes a methodology for determination of polyaniline doped with dodecylbenzene sulfonic acid (Pani.DBSA) content in SBS/Pani.DBSA blends prepared by “in situ” polymerization based on UV-Vis spectrometry. For this procedure, the absorbances at 369 and 779 nm were chosen. The first peak at 369 nm is related to the π-π* transition of the benzenoid rings, and the second, at 779 nm is related to π-polaron transitions. It was possible to observe good agreement between the data obtained by UV-Vis procedure and by gravimetry. The best fit was observed when the amount of Pani.DBSA was determined from the data obtained at maximum absorbance at 369 nm. The small difference between the results obtained from calculations related to A779 and A369 may be attributed to the stronger influence of the doping level (protonation level) of polyaniline on the absorption at 779 nm. When analyzing a large amount of samples, the work becomes extremely tedious because of the excessive number of calculations involved. In order to make acquiring the results easier, this methodology was automatized and the computer code to do this is available in our laboratory.