Polymerization of new aniline derivatives: synthesis, characterization and application as sensors

Abstract

This work is focused on modifying aniline monomers with various characteristics that allows one to study the effect of the substituent on the respective polymer. A series of new polyaniline (PANI) derivatives based on an ortho-substituted aniline derivative, 2-(1-methylbut-2-en-1-yl)aniline, were synthesized and characterized. The structures and composition of the polymers that we synthesized were confirmed by elemental analysis, proton nuclear magnetic resonance (¹H NMR) spectroscopy, carbon nuclear magnetic resonance (¹³C NMR) spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), and ultraviolet-visible spectroscopy (UV). Characterization by FT-IR and UV-visible spectroscopy techniques indicated that the polymers exist in protonated emeraldine forms. Scanning electron microscope (SEM) results revealed that the surface morphology of the resulting polymers changed from a heterogeneous hierarchical to spherical structure upon changing the substituent in the aniline monomers. The polymers are soluble in common organic solvents, so they can be used to make films. The electrical properties of the polymers were studied and their high sensitivity to moisture and ammonia was demonstrated. The results of the studies showed the prospects of using thin polymer films in the design of chemical sensors. The impact of the substituent on the polymer characteristics is rationalized in terms of steric and electronic effects.