Effect of unsaturation in bicarboxylic acid dopants for solid-state synthesis of polyaniline

• Published in: Polymer international 2016-06, Vol.65 (6), p.698-705
• Main Authors: Bhandari, Subhendu, Khastgir, Dipak
• Format: Article
• Language: English
• Subjects: Chemical bonds; Conducting polymers; conductivity; Conjugation; Dopants; Hopping (conductivity); Molecular structure; nanostructure; Organic acids; Polyanilines; supercapacitor; transport; unsaturated dopant
• ISSN: 0959-8103; 1097-0126
• DOI: 10.1002/pi.5120

Unsaturation in organic acid dopant structure enhances charge transport, and reduces the optical band gap and electrochemical capacitance in polyaniline. Highly crystalline behaviour is observed for a dopant with conjugated double bonds. Conjugation in the polymeric backbone leads to an electrical conducting nature for conducting polymers, and organic acids can be used as dopants to manipulate the electroactive behaviour. The present investigation deals with the effect of unsaturation in bicarboxylic acid dopant structures on the properties of polyaniline (PAni). PAni was synthesized via solvent‐free solid‐state polymerization. Oxalic acid, fumaric acid and trans,trans‐muconic acid containing 0, 1 and 2 double bonds, respectively, in their molecular structures were used as dopants. Fine particles directionally agglomerate to form nanowires. The use of a conjugated dopant results in highly crystalline PAni. With an increase in the number of double bonds in the dopant structure, the conductivity at room temperature increases, whereas the activation energy, hopping range, optical band gap and supercapacitive performance reduce. The inter‐chain hopping is expected to be favoured by the presence of unsaturation, and even more by conjugation in the dopant structure. © 2016 Society of Chemical Industry