Investigation of interaction among polyaniline, organic acid, and water

• Published in: Synthetic metals Vol. 158; no. 16; pp. 654 - 660
• Main Authors: Yang, Dali, Mattes, Benjamin R.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.09.2008; Amsterdam Elsevier Science; New York, NY
• Subjects: Aggregation; AMPSA; Applied sciences; DCAA; Emeraldine base; Exact sciences and technology; Gelation; GPC; H-bond; Organic polymers; Physicochemistry of polymers; Polyaniline; Properties and characterization; Solution and gel properties; UV–vis spectroscopy; DCAA; Aggregation; UV–vis spectroscopy; Emeraldine base; Gelation; AMPSA; GPC; Polyaniline; H-bond; Solvent effect; Chromatographic retention; UV-vis spectroscopy; Experimental study; Organic acids; Sulfonic acid; Gel permeation chromatography; Intermolecular interaction; Conducting polymers; Organic solution; Mixed solvent; Carboxylic acid; Molecular aggregation; Aniline polymer; Hydrogen bond
• ISSN: 0379-6779; 1879-3290
• DOI: 10.1016/j.synthmet.2008.04.017

In this work, gel permeation chromatography (GPC) and UV–vis spectroscopy are used to investigate interaction between organic acid and polyaniline (PANI) in emeraldine base (EB) form at a molecular level. Dichloroacetic acid (DCAA) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) are chosen to study the changes in the GPC chromatograms and the UV–vis spectra of the diluted EB/ N-methyl-2-pyrrolidinone (NMP) solutions when the acid was added in the solutions. The studies reveal that the organic acids form H-bonds with EB in an anhydrous solution. DCAA tends to form H-bonds with EB through intra-chain interactions whereas AMPSA tends to form H-bonds with EB through inter-chains. The inter-chain interaction among EB and AMPSA molecules results in the formation of clusters, which occupy a larger hydrodynamic volume and give much higher molecular weights than un-clustered EB molecules. Due to a strong affinity of AMPSA, water molecules are localized inside the clusters when water is present in the solution. Therefore, a small amount of water can rapidly initiate EB protonation (H 2O/AMPSA molar ratio > 5.0) at ambient conditions.