Electromechanical Response of Nanostructured Polymer Systems with no Mechanical Pre‐Strain

Shankar, Ravi; Ghosh, Tushar K.; Spontak, Richard J.

doi:10.1002/marc.200700033

Cited by 83 publications

(97 citation statements)

References 38 publications

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“…The films were then evaluated for electric-field-induced actuation under 300 % biaxial prestrain in the circular test configuration to permit direct comparison with existing EAPs [1]. Prestrain was necessary to reduce film thickness and, thus, the electrical potential required for actuation [44]. A circular active area in each prestrained test specimen (identified in Fig.…”

Section: Methodsmentioning

confidence: 99%

Electroactive Nanostructured Polymers as Tunable Actuators

2007

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Lightweight and conformable electroactive actuators stimulated by acceptably low electric fields are required for emerging technologies such as microrobotics, flat-panel speakers, micro air vehicles, and responsive prosthetics. High actuation areal strains (> 50 %) are currently afforded by dielectric elastomers at relatively high electric fields (> 50 V lm -1 ). In this work, we demonstrate that incorporation of a low-volatility, aliphatic-rich solvent into a nanostructured poly[styrene-b-(ethylene-co-butylene)-b-styrene] triblock copolymer yields physically crosslinked micellar networks that exhibit excellent displacement under an external electric field. Such property development reflects solvent-induced reductions in matrix viscosity and nanostructural order, as well as field-enhanced polarization of the styrenic units, which together result in ultrahigh areal actuation strains (> 200 %) at significantly reduced electric fields (< 40 V lm -1 ) with remarkably low cyclic hysteresis. Use of nanostructured polymers whose properties can be broadly tailored by varying copolymer characteristics or blend composition represents an innovative and tunable avenue to reduced-field actuation for advanced engineering, biomimetic, and biomedical applications. Polymeric electroactive materials are capable of mechanical actuation induced by an external electric field and thus afford tremendous promise in emerging technologies ranging from micro air vehicles and flat-panel speakers [1] to active video

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Section: Methodsmentioning

confidence: 99%

Electroactive Nanostructured Polymers as Tunable Actuators

2007

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“…The rigid sections act as the binding points between chains while the flexible segments allow for large deformations. Recently, Shankar et al [201,202] reported on nanostructured PS-block-poly-(ethylene-co-butylene)-block-PS (SEBS) triblock copolymers swollen with a midblock sensitive oil. At relatively high oil concentrations, the thermoplastic elastomer behaves as a physical network where glassy styrene micelles serve as thermally reversible crosslinks.…”

Section: Thermoplastic Polymersmentioning

confidence: 99%

“…These nanostructured polymers also display favorable actuation characteristics in their non-prestrained state when compared with non-prestrained VHB acrylic elastomers. [202] Unfortunately it appears as though large strains require low polymer loadings, while high blocking stress and breakdown field are limited to higher polymer loadings. The issue is the requirement for a midblock sensitive oil to allow for easier chain movement in the ethylene-co-butylene midblocks.…”

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confidence: 99%

Advances in Dielectric Elastomers for Actuators and Artificial Muscles

Brochu¹,

Pei²

2009

Macromol. Rapid Commun.

1,257

1,130

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A number of materials have been explored for their use as artificial muscles. Among these, dielectric elastomers (DEs) appear to provide the best combination of properties for true muscle-like actuation. DEs behave as compliant capacitors, expanding in area and shrinking in thickness when a voltage is applied. Materials combining very high energy densities, strains, and efficiencies have been known for some time. To date, however, the widespread adoption of DEs has been hindered by premature breakdown and the requirement for high voltages and bulky support frames. Recent advances seem poised to remove these restrictions and allow for the production of highly reliable, high-performance transducers for artificial muscle applications.

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“…Thus, the largest activation k V = k crit V if one chooses a prestretchλ 2 = λ crit . We recall that the existence of an optimal prestretch is also experimentally deduced in [10,14] and theoretically described in [4] . …”

Section: The Prestretched Casementioning

confidence: 85%

Compression-induced failure of electroactive polymeric thin films

Tommasi

Puglisi

Zurlo

2011

Applied Physics Letters

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The insurgence of compression induces wrinkling in actuation devices based on EAPs thin films leading to a sudden decrease of performances up to failure. Based on the classical tension field theory for thin elastic membranes (e.g.[11]), we provide a general framework for the analysis of the insurgence of in-plane compression in membranes of electroactive polymers (EAPs). Our main result is the deduction of a (voltage-dependent) domain in the stretch space which represents tensile configurations. Under the assumption of Mooney-Rivlin materials, we obtain that for growing values of the applied voltage the domain contracts, vanishing at a critical voltage above which the polymer is wrinkled for any stretch configuration. Our approach can be easily implemented in numerical simulations for more complex material behaviors and provides a tool for the analysis of compression instability as a function of the elastic moduli.Keywords: actuators, electroactive polymers (EAP), compression instability, non-linear elasticity.The growing interest in electroactive polymers as actuator devices, ranging from medical, biological, robotic, and energy harvesters, results from their qualities such as lightweight, small size, low-cost, flexibility, fast response [8,7,3]. A typical device consists of a thin sheet of electroactive polymer sandwiched between two compliant electrodes. The simple mechanism of actuation releases on an electromechanical coupling of the Coulomb forces acting between the electrodes and the elastic forces inside the layer. The electrostatic forces acting on the sheet faces induce a transversal extension that is used as a mean of actuation.In this paper we are mainly concerned with compression induced insta-

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Electromechanical Response of Nanostructured Polymer Systems with no Mechanical Pre‐Strain

Cited by 83 publications

References 38 publications

Electroactive Nanostructured Polymers as Tunable Actuators

Electroactive Nanostructured Polymers as Tunable Actuators

Advances in Dielectric Elastomers for Actuators and Artificial Muscles

Compression-induced failure of electroactive polymeric thin films

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