In situ Raman spectroscopic studies on potential-induced structural changes in polyaniline thin films synthesized via surface-initiated electropolymerization on covalently modified gold surface

The work describes the in situ Raman spectroelectrochemical studies on polyaniline (PANi) thin films covalently bound to the modified gold surface. The PANi thin films were synthesized via surface-initiated electrochemical polymerization on gold substrates initially modified by the formation of self-assembled monolayer of 4-aminothiophenol, or comparatively by the electrografting of 4-nitrobenzenediazonium salt followed by the electrochemical reduction of aromatic nitro-groups to form aniline-containing monolayer. Due to the defined surface-chain bonding and the ordered polymer structure, the obtained thin PANi films exhibit a narrow peak separation of the polymer redox transitions and negatively shifted potential of its full oxidation, as revealed by the PANi Raman spectra recorded at controlled potentials and cyclic voltammetry measurements.