Tunable size and shape of conductive poly(N‐methylaniline) based on surfactant template and doping

Abstract

Poly(N-methylaniline) (PNMA) is one of the polyaniline derivatives with N-substituted position. Polyaniline derivatives have attracted attention due to their higher solubility in common solvents than pristine polyaniline, but they still possess lower electrical conductivity. In this work, PNMA was synthesized via chemical oxidative polymerization in an ethanol-water system. The effect of surfactant type, namely anionic sodium dodecylbenzenesulfonate (SDBS), cationic cetyltrimethylammonium bromide and non-ionic Tween20, on the electrical conductivity, doping level and morphology was investigated. PNMA prepared with the SDBS system possessed the highest electrical conductivity among the obtained PNMAs with and without surfactants. The effect of N HClO 4 /N NMA dopant mole ratios on the re-doping, crystallinity, morphology and particle size was also examined. Using an N HClO 4 /N NMA mole ratio of 10:1 in the re-doping process provided the highest electrical conductivity of 15.53 ± 2.5 S cm −1 , a doping level of 55.59%, along with hollow spherical particles with the thinnest membrane. Electron microscopy images revealed that the morphology of PNMA particles depended mainly on the surfactant type but not the N HClO 4 /N NMA mole ratio.

Synthesis and Characterization of Hollow-Sphered Poly(N-methyaniline) for Enhanced Electrical Conductivity Based on the Anionic Surfactant Templates and Doping

“…PNMA synthesized in SDBS showed the highest σ among all surfactants used. The highest σ of the PNMA synthesized in SDBS at 5CMC after the re-doping process was 15.53 ± 2.5 S cm −1 [13].…”

“…A PANI derivative namely poly(N-methylaniline) (PNMA) contains a methyl substituent at the nitrogen heteroatom which contributes to an increase in solubility in organic solvents. The PNMA three redox states are the fully reduced leucoemeraldine form (LE), the conducting emeraldine form (E), and the fully oxidized pernigraniline form (PE) [13] (Scheme 1). Nonetheless, the electrical conductivity (σ) of PANI derivatives is still low relative to the unsubstituted PANI [14].…”

“…PNMA was synthesized via chemical oxidative polymerization without surfactant and with different anionic surfactants and concentrations. The polymerization mechanism was given in details in the previous work [13]. Briefly, NMA monomers are oxidized to NMA radical cations by an oxidizing agent (APS) in the initial step.…”

“…In addition, there has been no report on the influence of anionic surfactant types and concentrations on the PNMA synthesis. In this work, PNMA was prepared via a simple emulsion polymerization using solely anionic surfactants acting as the templates and co-dopants [13]. N-methylaniline (NMA) and ammonium persulfate (APS) were used as the monomer and oxidizing agent, respectively at the APS to NMA ratio of 1:1 following the previous work [13].…”

“…In this work, PNMA was prepared via a simple emulsion polymerization using solely anionic surfactants acting as the templates and co-dopants [13]. N-methylaniline (NMA) and ammonium persulfate (APS) were used as the monomer and oxidizing agent, respectively at the APS to NMA ratio of 1:1 following the previous work [13]. The ethanol:water mixture with hydrochloric acid (HCl) was used as the solvent.…”