A Conducting Polymer Artificial Muscle with 12 % Linear Strain

Bay, Lasse; West, Keld; Sommer‐Larsen, Peter; Skaarup, Steen; Benslimane, Mohamed

doi:10.1002/adma.200390075

Cited by 205 publications

(147 citation statements)

References 25 publications

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“…Cation-transporting materials are important in actuators [23][24][25][26], but conformational relaxation in these materials is not yet understood. In this work we examine conformational relaxation effects in PPy doped with DBS, PPy(DBS), which has been used extensively, particularly in microactuators [23,24].…”

Section: Introductionmentioning

confidence: 99%

Chronoamperometric Study of Conformational Relaxation in PPy(DBS)

West¹

2009

J. Phys. Chem. B

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In conjugated polymer devices that switch from one oxidation level to another, such as artificial muscles, it is important to understand memory effects that stem from conformational relaxation movements of the polymer chains. Chronoamperometry during electrochemical switching of polypyrrole doped with dodecylbenzenesulfonate, PPy(DBS), is used to gain insight into the conformational relaxation kinetics. During oxidation and reduction (stepping to the anodic and cathodic voltages, respectively), an exponentially decaying current is observed, but a shoulder appears during reduction when the cathodic voltage is high enough. Subtracting an exponential curve fit from the reduction current yields a small current peak at the shoulder position. The position of this peak depends logarithmically on the applied cathodic potential, the anodic potential that was applied just prior to the reduction step, and on the time that the prior anodic voltage was held. These results are consistent with the electrochemically stimulated conformational relaxation (ESCR) model. BackgroundIn this thesis, polypyrrole doped with dodecylbenzenesulfonate, PPy(DBS), a conducting polymer, was electrochemically studied in an attempt to quantify the conformational relaxation which occurs during reduction and oxidation. Conducting polymers, and PPy(DBS) in particular, are used in actuators, such as artificial muscles, because of their ability to change volume. Previous work by the research group of Dr. Toribio F. Otero (a co-author on the journal paper in preparation as a result of this work) has extensively characterized the conformational relaxation in some types of conjugated polymers, and a model (Electrochemically Stimulated Conformational Relaxation, or ESCR) has evolved as a result. However, the model has not yet been applied to PPy(DBS). Not including conformational relaxation, PPy(DBS) has been extensively studied and characterized by many groups, including that of Dr. Elisabeth Smela, a co-advisor in this work. Therefore, the motivation for this thesis was primarily to bridge the gap between the two research groups by characterizing the conformational relaxation that occurs in PPy(DBS). Conjugated PolymersA conjugated polymer (CP) is a polymer containing alternating single and double bonds between repeating units. This structure allow CPs to conduct electricity when an electron is removed from one of the double bonds; the missing electron, or "hole" can move along the polymer chain.By removing electrons, CPs become positively charged (oxidized); adding electrons renders them electrically neutral (reduced). This oxidation and reduction can be accomplished 2 electrochemically, when the polymer is in direct contact with a solid conducting electrode and a liquid electrolyte.The electrochemical switching of CPs between the oxidized and reduced states is accompanied by transport of ions in the electrolyte in order to maintain charge neutrality. I.e., upon oxidation, the net positive charge on the polymer is compensated by either cation egress ...

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Section: Introductionmentioning

confidence: 99%

Chronoamperometric Study of Conformational Relaxation in PPy(DBS)

West¹

2009

J. Phys. Chem. B

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“…Bay et al has improved electrochemical strain of PPy doped with DBS from 2.5 % to 5.6 % by the addition of pentanol as a co-surfactant to DBS, 18 and from 5.6 % to 12 % by using a compliant gold electrode. 19 We have fabricated fibrous PPy-metal coil composites exhibiting 11.6 % apparent strain, and 23.2 % effective strain if PPy at the gap solely works as an actuator. 20 These results suggest that actuators based on CPs reported so far did not bring their ability into full play.…”

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confidence: 99%

Artificial Muscles Based on Polypyrrole Actuators with Large Strain and Stress Induced Electrically

Hara¹,

Zama

Takashima

et al. 2004

Polym J

167

120

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ABSTRACT:Conducting polymer actuators have been attracting researchers and engineers who need powerful and light actuators because of their electrically induced stress (3-5 MPa), 10 times larger than that (0.35 MPa) of vertebrate muscle fibres. The moderate electrically generated strain (1-3 %) has however been restricting their applications to robots, for instance, and therefore relatively huge and heavy electric motors have been inevitably used in the robotic industry. A polypyrrole (PPy) film, which was prepared electrochemically from methyl benzoate solution of tetra-n-butylammonium tetrafluoroborate (TBABF 4 ) on Ti electrode, exhibited 12.4 % strain and 22 MPa stress generated electrochemically in NaPF 6 aqueous solution. The large electrochemical strain and stress of BF 4 À -doped PPy should meet applications of artificial muscles particularly where strong force is required. These novel conducting polymer actuators could dramatically alter any technologies concerning movements. Besides fundamental properties of the PPy actuators, some newly-devised configurations of the actuators for practical use are important. In order to fabricate actuator devices particularly where multiple layers of PPy films were required to increase force, flexible and tough CF 3 SO 3 À -doped PPy films were more suitable than BF 4 À -doped PPy. KEY WORDSConducting Polymer Actuator / Electroactive Polymer / Artificial Muscle / Polypyrrole / Electrochemomechanical Deformation / Electrochemical Strain / Electrochemical Stress / Electroactive polymer (EAP) actuators are roughly divided into two categories based on their activation mechanism: electronic and ionic.1,2 Of electronic EAP actuators driven by electric field, electroelastomers or dielectric elastomers with up to 380 % strain developed by SRI International have attracted those who need powerful and speedy actuaors.3,4 Dielectric EAPs having low elastic stiffness and high dielectric constant actuate massively in an electrostatic field, and the higher electrostatic field induces larger force and strain of dielectric EAP. The disadvantage of the electronic EAP actuators is, without any doubt, their very high drive voltage of 1000-5000 V.2-5 On the other hand, ionic EAP actuators such as ionic polymer gels (IPGs), 6,7 ionomeric polymer-metal composites (IPMCs), 8,9 and conducting polymers (CPs) 10-13 can be operational under much milder conditions: pH change, temperature control, or low drive voltage (1-2 V), and thus suitable for portable, mobile, small, and simple actuator devices as artificial muscles; for instance, robots, powered suits, artificial limbs, medical devices, and replacement of conventional electric motors. When actuator devices are designed by using EAP materials, only CP actuators are realistic choice because of their large stress generated electrically, 2-3 orders of magnitude larger than that of IPGs and IPMCs. The moderate strain (1-3 %) of CP actuators has however been disappointing those who are in need of artificial muscles. Once the electrochemical strai...

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“…Corrugated free-standing PPy films have previously been shown to actuate to 12% linear strain under similar conditions at small applied stress. 32 By choosing proper dopant and solvent, the linear strain of PPy films can reach as high as 30%. 33 The smaller strains observed in the current study are likely due to a combination of the effect of corrugation, choice of dopant and the restricting effect of the rubber substrate.…”

Section: Resultsmentioning

confidence: 99%

Polypyrrole stretchable actuators

Zheng

Alici

Clingan

et al. 2012

J Polym Sci B Polym Phys

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Here, we report a simple way to prepare stretchable polypyrrole (PPy)-based actuator materials that can be operated over a wide dynamic strain range and generate useable actuation displacements and pressures. The stretchable actuators were prepared as a laminated composite of PPy and a gold-coated roughened rubber sheet. By manipulating the corrugated surface of the rubber substrate, the stretchability of PPy was greatly improved. Gold-coated rubbers could be stretched to 30 percent without significant change in electrical resistance. The corrugated PPy/gold/rubber laminates successfully showed -1 percents of actuation strain even when prestretched to 24 percent. The actuation strains were smaller than for similar free-standing PPy films and a detailed analysis of the effects of corrugation and of the rubber substrate are presented to predict actuation strain under various prestretch strains. Correspondence to: Geoffrey M Spinks (E-mail: gspinks@uow.edu.au) (Additional Supporting Information may be found in the online version of this article.) ABSTRACTHere we report a simple way to prepare stretchable polypyrrole (PPy) based actuator materials that can be operated over a wide dynamic strain range and generate useable actuation displacements and pressures. The stretchable actuators were prepared as a laminated composite of polypyrrole and a gold-coated roughened rubber sheet. By manipulating the corrugated surface of the rubber substrate, the stretchability of PPy was greatly improved. Gold-coated rubbers could be stretched to 30% without significant change in electrical resistance. The corrugated PPy/gold/rubber laminates successfully showed ~1% of actuation strain even when pre-stretched to 24%. The actuation strains were smaller than for similar free-standing PPy films and a detailed analysis of the effects of corrugation and of the rubber substrate are presented to predict actuation strain under various pre-stretch strains.

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A Conducting Polymer Artificial Muscle with 12 % Linear Strain

Cited by 205 publications

References 25 publications

Chronoamperometric Study of Conformational Relaxation in PPy(DBS)

Chronoamperometric Study of Conformational Relaxation in PPy(DBS)

Artificial Muscles Based on Polypyrrole Actuators with Large Strain and Stress Induced Electrically

Polypyrrole stretchable actuators

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