Poly(N-methylaniline) vs. polyaniline: An extended pH range of polaron stability as revealed by Raman spectroelectrochemistry

A comparative study of polyaniline (PANI) and poly(N-methylaniline) (PNMA) has been performed by means of Raman spectroelectrochemical technique at 633 nm and 785 nm laser line excitations. The exci-tation wavelengths used fall into a resonance with the blue colored semi-and full-oxidized forms of these conducting polymers. The dependence of Raman features on electrode potential and solution acidity was studied, and relative content of polaronic and bipolaronic states was evaluated. In an acidic solution, the semioxidized emeraldine form of either PANI or PNMA exists in equilibrium between their polaronic and bipolaronic states. In a neutral or even slightly alkaline solution, this equilibrium for PANI shifts to bipo-laron state, resulting in loss of its conductance. For PNMA, however, the relative content of polaron state appears high enough even in pH-neutral soulions, thus determining a higher conductivity of PNMA in pH -neutral environment as compared to that of PANI. A mechanistic interpretation for this, based on differ-ences in the chemical structures of these polymers, is also presented. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

A comparative study was conducted on polyaniline and poly(N-methylaniline) using Raman spectroelectrochemical technique, revealing that in neutral or slightly alkaline solutions, poly(N-methylaniline) exhibits higher conductivity compared to polyaniline due to differences in their chemical structures.