Synthesis and characterization of conducting poly(2-ethylaniline) nanoparticle: Effect of surfactant template on morphology and electrical conductivity

Abstract

Abstract Poly(2-ethylaniline) (PEAn) was synthesized via emulsion polymerization using 2-ethylaniline as a monomer, ferric chloride (FeCl3) as an oxidant, and various surfactants as shape templates. The effects of FeCl3 concentrations, surfactant types and surfactant concentrations were systematically investigated. Five surfactants namely cetyltrimethyl- ammonium bromide (CTAB), benzyldodecyldimethyl-ammonium bromide (BDAB), and dimethyldioctadecyl ammonium bromide (DODAB) as cationic surfactants, sodium dodecyl sulfate (SDS) as an anionic surfactant, and polysorbate 20 (TW20) as a non-ionic surfactant were utilized as the surfactant templates. The PEAn particle shapes were found to be irregular, globular, and fibrillar, with the sizes varying from 127 to 840 nm depending on the surfactant type and concentration. PEAn with the fibrillar shape provided higher electrical conductivity than PEAn with the globular shape, as observed in the cationic surfactant templates at 1 CMC namely CTAB, BDAB, and DODAB. Herein, the PEAn electrical conductivity was in the range from 5.74 × 10−6 to 7.79 × 10-2 S cm-1, as varied by the synthesis conditions. The PEAn as synthesized by the BDAB emulsion system at 1 CMC provided the higher electrical conductivity value of 7.79 × 10-2 ± 7.52 × 10-4 S cm-1, relative to CTAB, DODAB, SDS, and TW20, due to the obtained PEAn fibrillar shape and the benzene ring of BDAB which facilitated the electron delocalization. Thermal stability of PEAn in various synthesis conditions was investigated. The PEAn without a surfactant provided the highest thermal stability; as it produced a higher char yield than the PEAn synthesized in other conditions.