<i>In Situ</i> UV–Vis Spectroelectrochemical Studies on the Copolymerization of Diphenylamine and <i>o</i>-Phenylenediamine

Abstract

The in situ ultraviolet-visible (UV-Vis) spectroelectrochemical study on the copolymerization of diphenylamine (DPA) and o-phenylenediamine (OPD) has been performed at a constant potential of 0.8 V using indium tin oxide (ITO)-coated glass electrodes as working electrode. And also, as a comparison, the electrochemical homopolymerizations of DPA and OPD have been investigated by using the in situ spectroelectrochemical technique. The intermediate species generated during the electrochemical homopolymerization of DPA and OPD, and the copolymerization of DPA with OPD have been identified by using the in situ spectroelectrochemical procedure. The results reveal the formation of an intermediate in the initial stage of copolymerization through the cross-reaction of the cation radicals of DPA and OPD, and the absorption peak located at 538 nm in the UV-Vis spectra is assigned to this intermediate. To further investigate the copolymerization of DPA with OPD, cyclic voltammetry (CV) has been used to study the electrochemical ho-mopolymerization of DPA and OPD and also the copolymerization of DPA and OPD with different concentration ratios in solution. The different voltammetric characteristics between the homopolymerization and copolymerization processes exhibit the occurrence of the copolymerization, and the difference between the copolymerization of DPA and OPD with different concentration ratios shows the dependence of the copolymerization on the concentrations of DPA and OPD. The copolymer has also been characterized by Fourier transform infrared spectroscopy (FT-IR).

Electropolymerized polyaniline: A promising hole selective contact in organic photoelectrochemical cells

“…This decrease may be due to the growing rate of the end product formation, which occurs after increasing the monomer concentration and leads to the continuous decrease of the amount of intermediates. [31,32] Similar results were obtained for different number electropolymerization cycles.…”

Temperature Effect on Nucleation and Growth Mechanism of Poly(o-anisidine) and Poly(aniline) Electro-Synthesis

“…It is worth noting that PANI shows three absorption bands characteristic of ANI oligomers in its conductive state. The signal near 290 nm is characteristic of benzenoid rings π-π * transition, [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] present in both monomeric and oligomeric species formed from aniline derivatives. 44 In this case, it was found that at 268 K this signal appears at 276 nm whereas at 298 K appears at 290 nm, showing thus a batochromic shift of 14 nm that can be ascribed to conjugation increase of the formed oligomers, since the solution contains longer chain oligomers that are constituting the so called HDOR.…”

Electrochemical and Mass Change Study of the Growth of Poly-(o-Phenylenediamine) Films on Au Substrates

“…While numerous studies have been devoted to the characterization of PoPDA-modified electrodes, 3,8,17,[23][24][25][26][27] only a few investigations have focused on the electropolymerization process itself. 6,18,19,28,29 It has been suggested 18,[24][25][26][27][28][30][31][32] that the monomer (oPDA) can polymerize in two different ways, one of which results in a phenazinelike structure (Scheme 1) at low pH values.…”

“…While numerous studies have been devoted to the characterization of PoPDA-modified electrodes, 3,8,17,[23][24][25][26][27] only a few investigations have focused on the electropolymerization process itself. 6,18,19,28,29 It has been suggested 18,[24][25][26][27][28][30][31][32] that the monomer (oPDA) can polymerize in two different ways, one of which results in a phenazinelike structure (Scheme 1) at low pH values. 24,26,31 When solutions of higher pH are used for polymerization, the extent of conjugation is progressively lower, as indicated by the increasing quantity of free NH 2 groups at the electrode surface, 32 giving a PANI-like structure (Scheme 1), 18,25,27,28,30 as has been shown by X-ray photoelectron spectroscopy (XPS) analysis.…”

“…6,18,19,28,29 It has been suggested 18,[24][25][26][27][28][30][31][32] that the monomer (oPDA) can polymerize in two different ways, one of which results in a phenazinelike structure (Scheme 1) at low pH values. 24,26,31 When solutions of higher pH are used for polymerization, the extent of conjugation is progressively lower, as indicated by the increasing quantity of free NH 2 groups at the electrode surface, 32 giving a PANI-like structure (Scheme 1), 18,25,27,28,30 as has been shown by X-ray photoelectron spectroscopy (XPS) analysis. 26,32 However, there is little understanding as yet of the mechanism or efficiency of PoPDA formation by electrochemical methods.…”