GPC characterization of emeraldine base in NMP containing ionic liquids

• Published in: Synthetic metals Vol. 157; no. 22; pp. 988 - 996
• Main Authors: Yang, Dali, Fadeev, Andrei G., Adams, Phillip N., Mattes, Benjamin R.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.11.2007; Amsterdam Elsevier Science; New York, NY
• Subjects: Aggregation; Applied sciences; Emeraldine base; Exact sciences and technology; GPC; Hydrogen bond; Ionic liquid; LiCl; Molecular weight determination; Organic polymers; Physicochemistry of polymers; Polyaniline; Properties and characterization; Solution and gel properties; UV–vis spectroscopy; Aggregation; UV–vis spectroscopy; LiCl; Emeraldine base; Molecular weight determination; GPC; Polyaniline; Ionic liquid; Hydrogen bond; Solvent effect; Imidazole derivatives; Iminium compounds; LiCI; UV-vis spectroscopy; Experimental study; Gel permeation chromatography; Conducting polymers; Organic solution; Mixed solvent; Ionic strength; Molecular aggregation; Pyrrolidone derivatives; Saline solution; Aniline polymer
• ISSN: 0379-6779; 1879-3290
• DOI: 10.1016/j.synthmet.2007.10.002

Strong aggregation between chains of polyaniline (PANI) emeraldine base (EB) molecules dissolved/dispersed in N-methyl-2-pyrrolidinone (NMP) results in a multi-modal molecular weight distribution in gel permeation chromatograph (GPC) results, regardless of how low the concentration of EB is. The addition of a salt, such as lithium chloride (LiCl), is known to improve EB solubility in NMP by deaggregating the polymer chains. However, we have found that ionic liquids, such as 1-methyl-3-butyl imidazolium tetrafluoroborate ([BMIM][BF 4]) or 1-methyl-3-ethyl imidazolium tetrafluoroborate ([EMIM][BF 4]), not only have less impact on the EB chain conformation than LiCl does, but also deaggregate the EB molecules more effectively. A mono-distributed GPC peak is obtained for EB ( M w up to 3 × 10 5 g/mol) dissolved in the NMP/ionic liquid solutions. Therefore, the EB molecular weight distribution is characterized more accurately by using the NMP/ionic liquid solution than the NMP/LiCl solution.