Polypyrrole + polyacrylate composites, kinetic study

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Switzerland), 1997-05, Vol.429 (1), p.19-25
• Main Authors: Otero, T.F., González-Tejera, M.J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemistry; Composites; Electrochemistry; Exact sciences and technology; General and physical chemistry; Kinetics; Kinetics and mechanism of reactions; Physicochemistry of polymers; Polyacrylate; Polymerization; Polymers and radiations; Polypyrrole
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/S0022-0728(97)00148-4

Polypyrrole + polyacrylate (PAA −) composites were electrogenerated by anodic polarization of a platinum electrode in aqueous solution of the monomer and the electrolyte. The charges consumed during polymerization and the weight of the dry film were obtained for each sample. The electroactivity of each film was obtained voltammetrically. Productivities of the polymerization charges (mg mC −1), storage efficiencies of the electroactive films (mC mg −1) and their ratio were determined. When the polyelectrolyte concentration increases from 5 × 10 −4 to 5 × 10 −2 M, the polymerization rate goes through a maximum at 7 × 10 −3 M polyacrylate. The film formed at this maximum rate has the maximum storage efficiency and the minimum ratio between productivity and storage efficiency. Low conductivities of the polyacrylate solution and strong interactions between PAA − and the growing films seem to be responsible for the low productivities and storage efficiencies at low and high concentrations of polyacrylate. A reaction order of 0.85 with respect to the monomer was obtained by ex situ ultramicrogravimetric following of the kinetics at different pyrrole concentrations ranging between 0.3 and 1 M. Average efficiencies of the polymerization charge of 5.8 × 10 −4 mg mC −1 and average storage efficiencies of 120 mC mg −1 were obtained. Higher and more stable values were obtained using 1 M pyrrole, but more variable values from more dilute solutions. Experimental results are discussed in terms of the parallel electropolymerization of polypyrrole, electrochemical degradation and PAA − incorporation and passivation of the composite. The relative rate of these processes is a function of the relative pyrrole/PAA − ratio in the solution, and consequently so are the composition and properties of the resulting film.