DBSA-CTAB mixture as the surfactant system for the one step inverse emulsion polymerization of aniline: Characterization and blend with epoxy resin

- PAni.DBSA with outstanding EMI SE (−45 dB) was synthesized in the presence of CTAB.
- PAni.DBSA with flake-like structure and superior conductivity was obtained.
- CTAB confined in PAni.DBSA improves processability of epoxy-based dispersions.

Polyaniline doped with dodecylbenzene sulfonic acid (PAni.DBSA) with outstanding electrical conductivity and electromagnetic interference shielding effectiveness (EMI SE) was successfully obtained by performing the inverse emulsion polymerization of aniline in toluene medium and in the presence of a mixture of dodecylbenzene sulfonic acid (DBSA) and cetyl trimethylammonium bromide (CTAB) as the surfactant system. The optimum CTAB/DBSA molar ratio was found to be 0.5, giving rise to PAni.DBSA with higher electrical conductivity, EMI SE of −45 dB in the X-band microwave range (8.2-12.4 GHz), which corresponds to an increase of almost 100% related to the PAni.DBSA sample obtained without the presence of CTAB. The CTAB confinement in the PAni.DBSA particles was confirmed by thermogravimetric analysis. The morphology of this sample is characterized by thin lamellar structures with thickness around 100-150 nm. The presence of CTAB confined in the PAni.DBSA aggregates resulted in epoxy resin/PAni.DBSA dispersion with lower viscosity, caused by the presence of smaller particle size as observed by scanning electron microscopy. The electric conductivity was also increased by the presence of PAni.DBSA prepared with CTAB as the co-surfactant.