Abstract
Polypyrrole films have been characterized by simultaneous cyclic voltammetry driven force-displacement measurements. The aim was to clarify the role of cations in the electrolyte on the speed of response and on the strain of the film. The strain as a function of actuation frequency was studied in alkali metal chloride aqueous electrolytes. The intention was to test the hypothesis of the division of the inserted H2O molecules into categories: a smaller number strongly bound to the cation (corresponding to the inner solvation shell) and a larger number entering the film after the insertion of the cations because of forces related to osmotic pressure difference. The two processes have very different time constants: The solvated H2O molecules are associated directly with the cations, and are therefore inserted in a faster process, whereas the second type enters the film much more slowly. At higher frequencies, the strain depends almost exclusively on insertion of strongly solvated cations and therefore depends on the hydration number of the cations: Li+ (hydration number ~5.4) gives more strain than Na+ (~4.4) and much more than Cs+ (~0) as predicted by the model.
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References
Baughman RH (1996) Conducting polymer artificial muscles. Synth Met 78:339–353
Smela E (2003) Conjugated polymer actuators for biomedical applications. Adv Mater 15:481–494
Bay L, West K, Skaarup S, Sommer-Larsen P, Benslimane M, Gravesen P (2003) A conducting polymer artificial muscle with 12% linear strain. Adv Mater 15:310–313
Hara S, Zama T, Takashima W, Kaneto K (2006) Tris(trifluoromethylsulfonyl)methide-doped polypyrrole as a conducting polymer actuator with large electrochemical strain. Synth Met 156:351–355
Madden JD, Rinderknecht D, Anquetil PA, Hunter IW (2000) Fast contracting polypyrrole actuators. Synth Met 113:185–192
Skaarup S, Bay L, West K (2007) Polypyrrole actuators working at 2–30 Hz. Synth Met 157:323–326
Pei Q, Inganäs O (1993) Electrochemical applications of the bending beam method. 2. Electroshrinking and slow relaxation in polypyrrole. J Phys Chem 97:6034–6041
Careem MA, Vidanapathirana KP, Skaarup S, West K (2004) Dependence of force produced by polypyrrole-based artificial muscles on ionic species involved. Solid State Ionics 175:725–728
Gandhi MR, Murray P, Spinks GM, Wallace GG (1995) Mechanism of electromechanical actuation in polypyrrole. Synth Met 73:247–256
Skaarup S, Bay L, Vidanapathirana KP, Thybo S, Tofte P, West K (2003) Simultaneous anion and cation mobility in polypyrrole. Solid State Ionics 159:143–147
Velmurugu Y, Skaarup S (2005) Ion and solvent transport in polypyrrole: experimental test of osmotic model. Ionics 11:370–374
Bay L, Jacobsen T, Skaarup S, West K (2001) Mechanism of actuation in conducting polymers: osmotic expansion. J Phys Chem B 105:8492–8497
Skaarup S, West K, Gunaratne LMWK, Vidanapathirana KP, Careem MA (2000) Determination of ionic carriers in polypyrrole. Solid State Ionics 136–137:577–582
Skaarup S (2008) Hydration number of alkali metal ions determined by insertion in a conducting polymer. In: Ext. Abstract ICSM 2008. Brazil: Porto de Galinhas, PM14 p 56
Jafeen MJM, Careem M A, Skaarup S (2009) Direct determination of hydration numbers of alkali metals ions by insertion in a conducting polymer (in press)
Bay L, West K, Skaarup S (2002) Pentanol as co-surfactant in polypyrrole actuators. Polymer 43:3527–3532
Skaarup S (2006).Polypyrrole for Artificial Muscles: Ionic Mechanisms. In: Chowdari B V R, Careem M A, Dissanayake M A K L, Rajapakse R M G, Seneviratne V A (eds) Solid State Ionics: Advanced Materials for Emerging Technologies, World Scientific, Singapore pp 768–779
Benslimane M, Gravesen P, West K, Bay L, Skaarup S (2000) Conducting polymer materials and their mechanical properties for actuation: the case of polypyrrole. In: Proc 7th Int Conf New Actuators, Bremen, Germany, pp 635–638
West BJ, Otero TF, Shapiro B, Smela E (2009) Chronoamperometric study of conformational relaxation in PPy(DBS). J Phys Chem B 113:1277–1293
Wang X, Shapiro B, Smela E (2009) Development of a model for charge transport in conjugated polymers. J Phys Chem C 113:382–401
Wang X, Smela E (2006) Cycling conjugated polymers with different cations. Bar-Cohen Y (ed) Smart Structures and Materials 2006: Electroactive Polymer Actuators and Devices (EAPAD), Proc. SPIE vol. 6168: 61680 T-1-8
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M.J.M. Jafeen and M.A. Careem are grateful for the support from the International Science Programme, Uppsala, Sweden.
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Jafeen, M.J.M., Careem, M.A. & Skaarup, S. Speed and strain of polypyrrole actuators: dependence on cation hydration number. Ionics 16, 1–6 (2010). https://doi.org/10.1007/s11581-009-0393-6
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DOI: https://doi.org/10.1007/s11581-009-0393-6