Thermoreversible gels of polyaniline: Viscoelastic and electrical evidence on fusible network structures

T. Vikki, Janne Ruokolainen, Olli Ikkala (Corresponding Author), Pentti Passiniemi, Heikki Isotalo, Mika Torkkeli, Ritva Serimaa

Research output: Contribution to journalArticleScientificpeer-review

69 Citations (Scopus)


We demonstrate thermoreversible gelation of a conductive polymer, i.e., rubber-like melt processible electrically conducting compounds. Combination of viscoelastic and electrical conductivity measurements suggests network formation in the gel state and gel melting at elevated temperatures. The gels have been prepared by dissolving polyaniline in dodecylbenzenesulfonic acid (DBSA) using formic acid as a processing medium which was removed at the end. Importantly, without formic acid, reversible gelation and particle-free materials were not achieved even at the resolution of optical microscopy. For T < Tgel the materials behave elastically in compression experiments, the storage and loss moduli do not depend much on frequency, and the electrical conductivity is primarily electronic, probably due to high chain-to-chain hopping conductivity. For T > Tgel the onset of liquid-like flow is detected using modified ball drop method by dynamic mechanical analysis, the dynamic moduli become strongly frequency dependent, and the electrical conductivity drops orders of magnitude to the value corresponding to the ionic conductivity of DBSA, suggesting that the chains are not in direct contact. The physical cross-links are probably localized mesomorphic domains which allow melting.

Original languageEnglish
Pages (from-to)4064-4072
Issue number14
Publication statusPublished - 1997
MoE publication typeA1 Journal article-refereed


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