Electroactive Response Research Articles

Model study of IPMC beam electroactive response based on root deformation

Ionic polymer-metal composite (IPMC) is a type of electroactive polymer (EAP). In this paper, based on Nemat-Nasser model, an improved model is developed to explain the initial nonlinear response of electric actuation on the fixed end deformation. Three IPMC strip samples with different surface resistance are chosen for analysis. Further, from simulation and experiment results, it is found that the root deformation made the tip movement of the IPMC strip with little surface resistance, but this effect was less and less when the surface resistance reduced. The calculation results of this model for the fixed end show a more accurate simulation for the actual deformation of IPMC strips.

Actuation abilities of multiphasic electroactive polymeric systems

The need of low-cost, high-strain actuators has recently brought the attention on electroactive polymers. Specifically, a particular interest has been placed on dielectric-based electrostrictive polymers that are flexible, conformable, and with an easy manufacturing process. The purpose of this paper is to investigate the actuation abilities of such devices when several phases (i.e., dipolar and interfacial) contribute to the electroactive strain response. Based on a Debye-Langevin approach, the expression of each phase contribution will be investigated, and the response with several phase ratios discussed. In particular, it is shown that a trade-off exists between low electric-field response, where the main design parameter lies in the permittivity, and the high electric-field response, where a polarization saturation effect occurs that limits the electric-generated strain. In addition, it is shown both theoretically and experimentally that for a biphasic system, a particular crossing point appears in the strain response as a function of the electric field whatever the phase ratio, as well as in the frequency-domain electrical response.

Improving the optical and electroactive response of poly(vinylidene fluoride–trifluoroethylene) spin-coated films for sensor and actuator applications

Poly(vinylidene fluoride–trifluoroethylene), P(VDF–TrFE), thin-films have been processed by spin-coating with controlled thickness. The influence of the thermal annealing and poling conditions on the properties of the material has been investigated. It is shown that thermal annealing strongly influences the microstructure and ferroelectric phase transition of the copolymer but does not significantly affect the degree of crystallinity of the samples. By increasing the annealing temperature, the samples undergo a transition from a microporous to a microfibrillar microstructure, accompanied by a decrease in the gauche defect density within the molecular chains that increases the ferroelectric transition temperature and enthalpy, and also influences the optical transparency of the films, which can achieve transmittances larger that 95% in the visible spectral range. The piezoelectric response of the material can be maximized by increasing the poling temperature at the cost of a decrease in the optical transparency of the film, due to the microstructural changes induced by the electrical field and the temperature. An optical transmittance as high as 90% along the visible spectral range is nevertheless maintained, demonstrating the suitability of the material for electroactive applications where transparency is also a relevant issue.

Ion recognition properties of poly[Cu(3-MeOsalpd)] films

Poly[Cu(3-MeOsalpd)] films with good physical, chemical and electrochemical stability may be potentiodynamically electrodeposited with high deposition efficiency from acetonitrile solutions of the monomer. Comparative coulometric assays with the Ni-based analogue show that the metal in the salen motif does play a role in the electronic structure of the polymer, but that the electroactive response is ligand (not metal) based. The dynamics of redox switching are ultimately limited by coupled electron/counter ion diffusion, but this process is sufficiently rapid that it influences the voltammetric response only for thick films (Γ >420 nmol cm−2) at high scan rates. Redox cycling in monomer-free electrolyte shows a voltammetric signature that responds, via interaction with the pseudo-crown ether receptor sites, to the presence of Li+, K+, Mg2+ and Ba2+ ions in solution. The most prominent change is associated with the first anodic peak in the i-E signature. For each of the metal ions considered, this peak potential responds logarithmically to concentration in a manner that varies with individual complexed cation and film thickness and to an extent greater than predicted by the Nernst equation. The film characteristics offer some analytical promise, including a trade-off between sensitivity and dynamic range and signal amplification, possibly due to supramolecular effects.

Electrostriction in electro-viscoelastic polymers

Electrostrictive polyurethane (PU) elastomers belong to the class of materials commonly referred to as electroactive polymers (EAP). These materials have their use in a variety of applications, including biomimetics and microrobotics where traditional engineering components may fall short. PU is one of the materials considered for so called dielectric actuators, where the electromechanical response is generally due to Coulomb forces on the actuator electrodes, giving rise to a compressive pressure and thereby large deformations of the polymer. On the other hand, for more moderate electric fields, which may be more attractive in certain applications, a large part of the electroactive response for PU elastomers is due to inherent electrostriction. The latter phenomena is the focus of this work. As is common in elastomers, PU elastomers are viscoelastic. A coupled electro-viscoelastic phenomenological constitutive model for electrostrictive PU is proposed and fitted to experimental data available in the literature. The possibility of performing simulations of EAP is of interest as the number of applications grow. Considering this, the computational model is embedded in a coupled finite element formulation and, based on this, representative simulations of inhomogeneous boundary value problems are presented.

Bioactive and electroactive response of flexible polythiophene:polyester nanomembranes for tissue engineering

Download options Please wait... Article information DOI https://doi.org/10.1039/C2PY00584K Article type Paper Submitted 09 Dec 2011 Accepted 10 Jan 2012 First published 01 Feb 2012 Download Citation Polym. Chem., 2012,3, 979-991 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Bioactive and electroactive response of flexible polythiophene:polyester nanomembranes for tissue engineering M. M. Pérez-Madrigal, E. Armelin, L. J. del Valle, F. Estrany and C. Alemán, Polym. Chem., 2012, 3, 979 DOI: 10.1039/C2PY00584K To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Maria M. Pérez-Madrigal Elaine Armelin Luis J. del Valle Francesc Estrany Carlos Alemán

Electroactive Polymer “Artificial Muscle” Operable in Ultra-High Hydrostatic Pressure Environment

Transducers for high-power sonars, an important tool for undersea exploration and monitoring, may be required to work in deep water where pressures are higher than several tens of MPa. In contrast with the piezoelectric devices commonly used as high-power sonars for seabed resource exploration, electroactive polymers offer the benefits of high coupling efficiency, low cost, and the ability to form large area skins or other devices. One question about the use of electroactive polymers for sonar has been their ability to withstand the rigors of the deep-sea environment. In a recent experiment, we have verified that the dielectric elastomer type of electroactive polymer can maintain good operational characteristics even in an ultrahigh-pressure environment by showing that the electroactive strain response to an applied voltage was unaffected by externally applied pressures of up to 100 MPa.

Stability of the electroactive response of β-poly(vinylidene fluoride) for applications in the petrochemical industry

The stability of the electroactive response of poly(vinylidene fluoride), PVDF, in its β-phase to degradation by chemicals commonly used in the petrochemical industry has been investigated. The polymer was submitted to the effect of different chemicals, benzene, ethanol, methanol, ethyl benzene, isooctane, naphthalene and toluene, for different periods of time. The variations in the amount of β crystalline phase, dielectric and piezoelectric response were monitored over time. The results show that PVDF has very good resistance against the chemical attack of the aforementioned chemicals and no significant changes were detected both at a molecular level and in the electro active response. It can be concluded that PVDF shows high stability towards chemicals typically present in the petrochemical industry and can be used for a variety of applications, including sensors and actuators, without interference with its performance.

Synergistic effect of carbon nanofiber and carbon nanopaper on shape memory polymer composite

The present work studies the synergistic effect of carbon nanofiber (CNF) and carbon nanopaper on the shape recovery of shape memory polymer (SMP) composite. The combination of CNF and carbon nanopaper was used to improve the thermal and electrical conductivities of the SMP composite. The carbon nanopaper was coated on the surface of the SMP composite in order to achieve the actuation by electrical resistive heating. CNFs were blended with the SMP resin to improve the thermal conductivity to facilitate the heat transfer from the nanopaper to the underlying SMP composite to accelerate the electroactive responses.

Electro-active artificial muscle based on irradiation-crosslinked sulfonated poly(styrene-ran-ethylene)

In this study, a novel electro-active artificial muscle was developed with UV irradiation-crosslinked sulfonated poly(styrene-ran-ethylene) (XSPSE). The XSPSE ionic exchangeable membrane was crosslinked with vinyl silane by UV irradiation. The crosslinking mechanism between the SPSE backbone and vinyl silane was analyzed and checked by FT-IR spectra. AFM images showed that XSPSE membranes have better micro-phase separation morphology than pure SPSE membranes. Water uptake, ion exchange capacity, and sulfonation degree were characterized for both pure SPSE and silane crosslinked SPSE membranes. The electro-active bending responses of the XSPSE actuators under both direct current (DC) and alternating current (AC) excitations were investigated. The voltage–current behaviors of the actuators under AC excitations were also measured. Present results showed that the UV irradiation crosslinking method can greatly improve the actuation performance of SPSE artificial muscle.

Manganese oxide nanocomposites with improved surface area prepared by one-pot surfactant route for electro catalytic and biosensor applications

Braunite phase manganese oxide is naturally available in manganese–silicate rocks with minor amount of silicate content. New synthetic route is attempted to prepare the manganese oxide nanoparticle and silica incorporated manganese oxide nanocomposite in the present study. XRD patterns reveal the braunite phase formation for as synthesized manganese oxide nanocomposite and silica incorporated MnO2 nanocomposite materials. Improved BET surface area values are achieved by one step surfactant assisted method (i.e., 82 and 151 m2/g) compared to conventional route prepared manganese oxide nanomaterial. Flaky pastry type morphology was observed for as synthesized Si–MnO2 nanocomposites. Cyclic voltammetry studies predict the electrocatalytic activity of manganese oxide nanoparticle and Si–MnO2 nanocomposite in presence of electroactive redox couple. Si–MnO2 nanocomposite modified glassy carbon (GC) electrode shows the effective electroactive response in presence of Fe2+/Fe3+ redox couple at 0.69 V with current density of 0.343 × 10−5 A/cm2 compared to manganese oxide nanoparticle modified GC electrode. The biosensor responses for ascorbic acid have been tested in the present study and manganese oxide nanoparticle modified GC electrode shows effective response at low concentration of (1 × 10−5 M) ascorbic acid in phosphate buffer solution. Manganese oxide nanoparticle modified electrode shows the better response with current density value of 0.115 × 10−5 A/cm2 compared to Si–MnO2 nanocomposite.

Single walled carbon nanotube (SWNT)–polyimide nanocomposites as electrostrictive materials

The combination of properties offered by polymer nanocomposites provides opportunities for going beyond structural reinforcement where engineered electroactive responses and enhanced electrical and dielectric properties would result in multifunctionality. In our study, we show that adding single walled carbon nanotubes (SWNTs) to a non-actuating polyimide (PI) can create an electromechanical actuation response in the nanocomposite. The neat polyimide does not show any actuation response under an applied electric field, whereas the SWNT–PI composites above the percolation threshold exhibit an electrostrictive behavior that is highly dependent on SWNT content. Both bending and thickness–extension strains are obtained at very low electric field magnitudes; the study also evaluates the effect of applied electric field magnitude, frequency and SWNT content on the actuation strain and strain rate. Dielectric spectroscopy and thermally stimulated current measurements reveal an enhanced polarization in the presence of SWNTs. This enhancement is key to the actuation mechanism and is thought to arise from a combination of three sources: SWNTs acting as extended electrodes within the polymer, interfacial polarization and noncovalent interactions between the SWNTs and the polymer.

Electroactive response of mesoporous silica and its nanocomposites with conducting polymers

Electroactive response of suspensions of mesoporous silica and its nanocomposites with conducting polyaniline and copolyaniline inside its channels were examined under an electric field, mainly focusing on their rheological characteristics. Initially these conducting polymer/mesoporous silica nanocomposites were synthesized and their physical properties were studied by scanning electron microscopy, transmission electron microscopy and N2-adsorption isotherm. Then, mesoporous silica and its nanocomposites were dispersed in silicone oil as an electrorheological (ER) material. Typical ER behaviors of shear stress and shear viscosity curves as a function of electric field and shear rate were observed. Without an electric field, the suspensions behaved almost like a Newtonian fluid. However, under an electric field, their shear stresses increased with shear rate, demonstrating a yield stress. Compared with mesoporous silica and polyaniline, polyaniline/mesoporous silica-based ER fluid showed enhanced ER performance due to the anisotropic characteristics. In addition, it was found that a suggested shear stress model (Cho–Choi–Jhon model) well described the flow curves.

Performance of electroactive poly(vinylidene fluoride) against UV radiation

In this work, a study has been carried out to investigate the resistance of commercial poly(vinylidene fluoride) PVDF in its β phase to UV radiation using a xenon lamp. The radiation was applied for 10 weeks and, during this time, the variation in the chemical structure, crystallinity, dielectric and piezoelectric response was monitored. The results show that PVDF has a very good resistance against the effect of UV radiation as no significant changes were detected either at a molecular level or in the electro-active response. It can be concluded that PVDF shows high stability towards photodegradation and can be used for outdoor applications without loss in performance.

In situ observation of dynamic elastic modulus in polypyrrole actuators

Polypyrrole is a leading conducting polymer actuator, but the factors that influence its performance when actuated under load in devices (such as the polymer stiffness) are not yet fully understood. To this end, we have probed the dynamic elastic modulus of polypyrrole in situ during actuation in a variety of electrolytes. As part of this study, we demonstrate that the electroactive response in dilute 1-butyl-3-methylimidazolium hexafluorophosphate can be changed from cation- to anion-dominated by adjusting the applied potential waveform. We observe that when conservative electrochemical conditions are applied in order to avoid dual ion movement or significant transfer of neutral solvent, the stiffness is determined by level of counterion swelling. The elastic modulus decreases during the net influx of ions into the bulk polymer and increases as these ions are expelled, regardless of whether the electroactive response is cation- or anion-dominated or whether there is a neutral solvent present in the electrolyte. This effect is quite significant, and we have observed up to a 3× increase in elastic modulus upon actuation in neat 1-butyl-3-methylimidazolium hexafluorophosphate.

Fabrication of an interpenetrated network of carbon nanotubes and electroactive polymers to be used in oligonucletide biosensing

Layers of multiwall carbon nanotubes (MWNT), with different thickness, are built by sequential drop coating of a MWNT-Nafion ® dispersion in ethanol onto glassy carbon substrates. The layers form a 3D conductive network towards the electrochemical reactions of soluble redox couples (Fe 3+/2+) in aqueous solutions. Digital simulation of the electrochemical response suggests that the electron transfer is controlled by finite diffusion of the redox species inside the network. It is possible to create an interpenetrated network of carbon nanotubes and electroactive polymers (poly(hydroxynaphtoquinones)) by electropolymerization in nonaqueous media, which are electroactive in aqueous and nonaqueous media. The electrochemical response, both in cyclic voltammetry (CV) and square wave voltammetry (SWV), is significantly increased. In that way, the sensitivity of sensors (e.g. DNA biosensors based on the change of electroactive polymer response upon hybridization) could be improved.

Anisotropy of Electroactive Strain in Highly Stretched Polypyrrole Actuators

Oriented conducting polymer actuators are produced via stretching electrodeposited polypyrrole films to high elongations. An anisotropic electroactive strain response (ε⊥/ε∥ = 38) is observed due to chain alignment. Stretched films show an 80% increase in active strain and over 150% increase in conductivity when compared to unstretched films.

CO 2 sensing mechanisms of an electrocatalytic sensor based on a tungsten-stabilized bismuth oxide solid electrolyte and cyclic voltammetry measurement techniques

The CO 2 sensing mechanisms of an active, thick-film electrochemical sensor based on a tungsten-stabilized bismuth oxide solid electrolyte are investigated. CO 2 electroactive response appears to be directly related to the tungsten dopant within the solid electrolyte layer and is dependant on electrolyte porosity.

A novel reflective image display using total internal reflection

We are developing a new reflective display technology, based on total internal reflection, which achieves a large difference between the maximum and minimum reflectance values. This yields a surface with greatly improved legibility under a wide range of illumination conditions. Such devices can display an image with a maximum reflectance ranging from 55% under uniform background illumination to over 85% under common non-uniform illumination conditions, even at viewing angles greater than 80° from the surface normal. This approach, which we call ‘CLEAR’ (Charged Liquid Electro-Active Response), uses polymeric microstructures to efficiently redirect incoming ambient light back toward the viewer. One advantage of this technique is the ability to achieve bright, full-color images over a wide range of viewing angles, much like ink printed on paper. The displayed image can be updated rapidly since switching from the reflective state to the absorptive state requires only about a half-micron of motion of absorbing material into the evanescent field associated with TIR. This new approach offers significant advantages in a number of reflective display applications.

A cyclic voltammetric and coulometric study of a modified electrode prepared by electrooxidative polymerization of1,5-diaminonaphthalene in aqueous acidic medium

Abstract Poly 1,5-diaminonaphthalene films were prepared by using the repeated potential cycling technique and different amounts of charge in an aqueous acidic solution containing 0.1 M HClO 4 and 0.2 M NaClO 4 by sweeping the platinum electrode potential between 0.0 and 0.8 V at a scan rate of 20 mV/sec. The prepared film showed an electroactive redox response in acidic chloride solution. The factors affected the electroactivity of the film such as the scan repetition, the quantity of charge used during the film formation and the sweep rate were studied in details. No film was observed by utilizing controlled potential electrolysis. Comparative study between the stability and polymerization yield for the films prepared in acetonitrile and aqueous acidic solutions was carried out.