Theory of chain growth in chemical oxidative polymerization of aniline derivatives

Peculiarities of Oxidative Polymerization of Diarylaminodichlorobenzoquinones

“…The higher the pH value, the lower the reaction rate at the initial stage (curves 1-3). A similar picture is observed in the polymerization of aniline [13,53]. However, when the reaction is carried out under weak acidic and alkaline conditions (curves 4 and 5), the process of DADCB polymerization is somewhat different from the polymerization of aniline, which is characterized by a shortening of the induction period with the increase in the pH of the solution.…”

“…Since the observed effect applies to both aniline and DACB, it can be assumed that this phenomenon is not related to the number of aniline units in the monomer. The study of the effect of oxidant concentration on the polymerization of DACB showed that the increase in the oxidant/monomer ratio from 0.75 to 1.25 (Figure 3, curves 1 and 2) leads to the shortening of the induction period and the increase in speed, as is observed during the polymerization of aniline [53]. However, when the oxidant/monomer ratio is increased to 1.75 and further on to 2.5 (curves 3 and 4, respectively), a sharp increase in the induction period and a decrease in the reaction rate are observed, despite the fact that DACB is a bifunctional monomer and the oxidizer/monomer ratio of 2.5 corresponds to oxidation stoichiometry of its amino groups.…”

“…However, when the reaction is carried out under weak acidic and alkaline conditions (curves 4 and 5), the process of DADCB polymerization is somewhat different from the polymerization of aniline, which is characterized by a shortening of the induction period with the increase in the pH of the solution. In addition, during the polymerization of aniline, the kinetic curves acquire a two-step form [13,53], associated by the authors with a change in the oxidation reaction mechanism at high pH of the medium and with a different structure of the resulting intermediates. In our case, the induction period grows with the increase in pH, and the shape of the curves shows hardly any change.…”

Polyaniline Derivatives and Their Applications

“…The utility of this method enables easy scale-up to produce large quantities of PANI powders. As mentioned, the numerous side reactions and alternatively couplings likely occur simultaneously, which produces non-regiospecific PANI product [40,42,43]. However, PANI produced in this way does preferentially form p-substituted chains (despite equal likelihood for o-substitution), which has led to some authors suggesting an alternative initiation mechanism involving a phenazine initiation pathway (Figure 6) [39,40].…”

Emerging Applications of Versatile Polyaniline-Based Polymers in the Food Industry

“…The polymerisation of aniline can be done through oxidative polymerisation with an oxidant such as ammonium persulfate (APS), hydrogen peroxide, potassium iodate, cerium sulfate, potassium dichromate, potassium ferricyanide, or sodium vanadate, out of which the former is the most common [ 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ]. This is because aniline possesses aromatic amine, which tends to be oxidised due to its electron-donating capabilities [ 42 , 43 ]. In addition, polymerisation should be carried out in the presence of strong acids to stabilise the PANI chains [ 4 , 44 ].…”