Electrochemical oxidative polymerization of sodium 4-amino-3-hydroxynaphthalene-1-sulfonate and structural characterization of polymeric products

• Published in: Reactive & functional polymers Vol. 66; no. 12; pp. 1670 - 1683
• Main Authors: Ćirić-Marjanović, G., Trchová, M., Matějka, P., Holler, P., Marjanović, B., Juranić, I.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.12.2006; Elsevier Science
• Subjects: Applied sciences; Coupling mode; Electrochemical polymerization; Exact sciences and technology; Physicochemistry of polymers; Poly(sodium 4-amino-3-hydroxynaphthalene-1-sulfonate); Polymerization; Polymers and radiations; Redox form; Electrochemical polymerization; Poly(sodium 4-amino-3-hydroxynaphthalene-1-sulfonate); Redox form; Coupling mode; Aniline derivative polymer; Electrical conductivity; Electrical properties; Molecular structure; Aromatic polymer; Experimental study; Oligomer; Functional polymer; Conducting polymers; Polyelectrolyte; Sulfonate polymer; Electrochemical properties; Poly(sodium 4-amino-3-hydroxynaphthalene-l-sulfonate); Preparation; Naphthol derivatives
• ISSN: 1381-5148
• DOI: 10.1016/j.reactfunctpolym.2006.07.002

The new semiconducting, electroactive, water-soluble polymeric material has been synthesized by the electrochemical polymerization of sodium 4-amino-3-hydroxynaphthalene-1-sulfonate (AHNSA–Na salt), from its aqueous solution. The polymeric products were characterized by gel permeation chromatography (GPC), conductivity measurements, cyclic voltammetry, and UV–visible, FTIR, Raman, NMR ( 1H and 13C) and electron spin resonance (ESR) spectroscopic techniques. GPC profile evidenced chains of molecular weights up to ∼6300, and revealed oligomers (8-mer to 12-mer) as predominant species. FTIR spectroscopy findings of newly formed substitution patterns on naphthalene rings in the poly(AHNSA–Na salt) are well correlated with main coupling modes theoretically predicted by MNDO-PM3 semi-empirical quantum mechanical calculations. Based on these studies, it has been found that the poly(AHNSA–Na salt) consists mainly of dimer units formed via N–C6 and N–C8 coupling reactions. The paramagnetic nature of the poly(AHNSA–Na salt) has been proved by ESR spectroscopy, and its redox activity was confirmed by cyclic voltammetry. Intensity ratio of two new bands in the UV–visible spectrum assigned to the poly(AHNSA–Na salt) polaronic and bipolaronic forms, and the presence of naphthoiminoquinonoid and benzenoid segments detected by FTIR and Raman spectroscopy, indicate prevalence of partly and fully oxidized bipolaronic forms of the poly(AHNSA–Na salt).