Dielectric Relaxation Behavior of Polymerized Ionic Liquid

• Published in: Macromolecules Vol. 43; no. 14; pp. 6092 - 6098
• Main Authors: Nakamura, Kenji, Saiwaki, Tatsuya, Fukao, Koji
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 27.07.2010
• Subjects: Applied sciences; Electrical, magnetic and optical properties; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Glass transition; Experimental study; Activation energy; Imidazolium(vinyl) salt polymer; Dielectric relaxation
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma100918e

Dynamic aspects of a polymerized ionic liquid, poly(1-ethyl-3-vinylimidazolium bis(trifluoromethanesulfonylimide)), were investigated using a broadband dielectric spectroscopy method in the frequency range of 10 mHz to 2 MHz and temperatures ranging from −90 to +90 °C. The polymerized ionic liquid shows three relaxation modes including the relaxation mode due to the effect of electrode polarization behavior. We attribute the slow relaxation mode to the segmental motion of the polymer main chain and the fast mode to the rotational motion of the polymer side chain. Relaxation times of these relaxation modes and the specific direct current conductivity showed an Arrhenius-type temperature dependence at temperatures above and below the glass transition temperature of the polymer. In order to explain the less fragile property of the polymerized ionic liquid, we propose that the ion transport mechanism is achieved by the formation and dissociation of ion-pairs formed between a positively charged 1-ethyl-3-vinylimidazolium monomer unit in a polymer chain and a negatively charged bis(trifluoromethanesulfonylimide).