Electroactive Polymer Materials Research Articles

High performance PVC/ [AMI]mNTF2 ionic gel sensors for smart wearable applications

Plasticized polyvinyl chloride (PVC) gel as an electroactive polymer material has attracted increasing interest for the construction of flexible devices with the integration of actuation and self-sensing. However, the insufficient sensing ability of traditional PVC gels limits their applications. In this paper, a PVC ionic gel sensor based on the physical blending of PVC gel and the ionic liquid 1-allyl-3-methylimidazolium bisimide ([AMI]mNTF2) is presented. With the addition of ionic liquids, the PVC molecular chains and ions formed stable conductive pathways, resulting in increased conductivity and sensing performance of the PVC gel. The proposed sensor exhibits excellent sensing properties of high resolution (0.12 %) and fast response time (95 ms), along with high sensitivity (GF=27.8), which is more than seven times that of the traditional PVC gel. Furthermore, it was successfully utilized for human motion detection and remote control of a robotic hand, demonstrating the feasibility of the sensor for smart wearable applications in the future.

Thermodynamic model for voltammetric responses in conducting redox polymers.

Electroactive polymer materials are known to play important roles in a vast spectrum of modern applications such as in supercapacitors, fuel cells, batteries, medicine, and smart materials, etc. They are usually divided into two main groups: first, conducting π-conjugated organic polymers, which conduct electricity by cation-radicals delocalized over a polymer chain; second, redox polymers, which conduct electricity via an electron-hopping mechanism. Polymer materials belonging to these two main groups have been thoroughly studied and their thermodynamic and kinetic models have been built. However, in recent decades a lot of mixed-type materials have been discovered and investigated. To the best of our knowledge, a thermodynamic-based description of conducting redox polymers (CRPs) has not been provided yet. In this work, we present a thermodynamic model for voltammetric responses of conducting redox polymers. The derived model allows one to extract thermodynamic parameters of a CRP including the polaron delocalization degree and redox active groups interaction constant. The model was verified with voltammetric experiments on three recently synthesized CRPs and showed a satisfactory predictive ability. The simulated data are in good agreement with the experiment. We believe that developing theoretical descriptions for CRPs and other types of electroactive materials with the ability to simulate their electrochemical responses may help in future realization of new systems with superior characteristics for electrochemical energy storage, chemical sensors, pharmacological applications, etc.

Optimizing electromechanical performance of multilayered multiwalled carbon nanotube/silicone rubber composites via filler content distribution modulation

AbstractDielectric elastomers are widely used as electroactive polymer materials due to their high energy density, high strain, and low loss. However, the practical applications are limited sometimes by their low electromechanical strain ability due to relatively low dielectric permittivity for polymers. Herein, multiwalled carbon nanotube (MWCNT) filled silicone rubber (SR) composites with a five‐layered structure are prepared with the outer two layers of neat SR while the middle three layers are MWCNT filled SR, in which the former functions as insulating layers while the latter acts as the dielectric permittivity enhancement layers. Further, by differing the MWCNT content within the middle three layers, we find that as the concentration distribution increases from 1:1:1 to 1:2:1 and 1:3:1, both Young's modulus and dielectric permittivity gradually improve while dielectric loss remains extremely low even though the total MWCNT content reaches 1.6 wt%. With the combined effects of dielectric permittivity and modulus, the composite with evenly distributed MWCNT content (1:1:1) shows the highest actuation strain under a given electric field strength. Meanwhile, the electric breakdown strength of the composite 1:1:1 is also the highest, leading ultimately to a maximum actuation strain of 10.87% at the breakdown strength of 14.6 kV/mm.

Adulteration of Milk Identification Using Ionic Polymer Metal Composite as Sensor

Milk adulteration is found as one of the social problems throughout the globe. Consumption of adulterated milk causes various diseases in humans and great concern to the food industry. Adulteration is generally done by adding chemicals to the milk, especially water. Inappropriately, milk is being very easily adulterated throughout the world and significantly worse in developing and underdeveloped countries due to the absence of adequate monitoring and lack of proper law implementation. The international and national research surveys presented the use of various electrochemical, nanomaterial, and thermal sensing mechanisms for the detection of adulteration in milk (example: spectroscopic methods, thermal sensors, chitosan-multiwalled carbon nanotubes, etc.). However, the ionic polymer metal composite (IPMC) is used as a sensor or actuator; for this application, IPMC is explored as a sensor for detecting the impurities in milk. IPMC used in this experiment is Nafion base, which is a sulfonated tetrafluoroethylene based fluoropolymer-copolymer. In this letter, the authors took the opportunity to use the electroactive polymer material IPMC as a taste sensor.

Poly(o-phenylenediamine)/ poly(butylene succinate-co-butylene adipate) blend as electroactive material for actuator application

Flexible and efficient electroactive polymeric materials that can convert electrical energy into mechanical work are potential be used as artificial muscles in soft robots, sensors and wearable technology. This work reports on the development of flexible electroactive material based on poly(butylene succinate-co-butylene adipate) (PBSA) as a matrix and poly(o-phenylenediamine) (PoPD) as a conductive filler. The PBSA film flexibility was modified by using dibutyl phthalate (DBP) as a plasticizer. The doped PoPD (dPoPD) particles with the polar free = NH substitution were synthesized and doped with perchloric acid. The prepared dPoPD/PBSA blends possess the enhanced mechanical and electrical properties compared to the pristine PBSA film. The dPoPD/PBSA blend with the dPoPD loading of 0.05%v/v provided the highest storage modulus (2.2 × 106 Pa) at 100 rad/s, the dielectric constant (28) at 40 Hz, and the electrical conductivity (2.67 × 10−9 S/cm). On the other hands, the 0.01%v/v dPoPD/PBSA blend showed the highest deflection distance of 9.71 mm, whereas the highest dielectrophoresis force density was obtained from the 0.05%v/v dPoPD/PBSA blend at 70 V/mm. This work presents the new biobased/conductive polymer blends and demonstrates that the bending response and the required dielectrophoresis force are not inclusively related and each can be individually tailored to meet the soft robot requirements.

Tuning the Ferroelectric Phase Transition of P(VDF-TrFE) through a Simple Approach of Modification by Introducing Double Bonds.

Electroactive polymer (EAP) is a kind of intelligent material that, driven by external electric field, could produce changes in shape or volume. As an important class of EAP materials, poly(vinylidene fluoride) (PVDF) based relaxor ferroelectric polymers show remarkable potential for applications in sensors, actuator, and artificial muscles because of their excellent electrostrictive properties. However, the strain of PVDF-based relaxor ferroelectrics relies strongly on a high electric field, which seriously damages their reliability and limits their practical applications as wearable devices. To explore more suitable materials for actuator applications, in this present work, we report the influences of a double bond (DB) on the electroactive properties of P(VDF-TrFE) (TrFE: trifluoroethylene). The crystalline phase of P(VDF-TrFE) is partially destroyed after the DB is introduced, and the molecular chain flexibility of the product P(VDF-TrFE-DB) can be greatly improved. Therefore, P(VDF-TrFE-DB) has a larger electric displacement while having a lower dipole orientation electric field compared with that of P(VDF-TrFE). The result confirms that the DB could tune the ferroelectric properties and effectively reduce the driving electric field of the PVDF-based relaxor ferroelectric polymers. This work offers a strategy for the preparation of novel EAPs with low driving electric fields.

Applications of Soft Dendritic Colloids in Li-Ion Batteries with Advanced Structure-Derived Performance

Adoption of electric vehicles and increasing demands of consumer electronics require electrochemical energy storage devices with high capacity and rate capabilities. Supply-chain and material-cost concerns as well as charge-rate limitations associated with irreversible lattice changes motivates the replacement of mixed-metal oxide cathodes in lithium-ion batteries (LIBs). Electrochemically active polymeric materials have emerged as promising candidates to replace metal oxides due to their high tunability and increased capacity. However, many of these materials suffer from poor intrinsic electronic conductivity and may be soluble into the electrolyte, causing irreversible capacity fade. Nanostructuring and composite formation are two polymer processing methods that can be leveraged to combat these drawbacks. The introduction of new nanostructured and nanocomposite cell components can decrease diffusion length scales, increase mechanical stability, and allow for higher electronic conductivity in polymer electrodes. Herein, we utilize a new class of polymeric materials called soft dendritic colloids (SDCs) as a platform for creating such nanocomposites. These fibrillar polymeric particles, formed via turbulent solvent-nonsovent induced phase separation, have hierarchical morphology, large aspect ratios and demonstrate pronounced adhesion and network-forming behavior. SDC-based materials have shown impressive results as nonwoven polyvinylidene difluoride separators in Li-ion batteries. Herein, we propose and present their use as Li-ion battery electrodes with advanced structural properties, derived from electroactive polymeric materials.

Retraction statement: A concise review on the elastomeric behavior of electroactive polymer materials

Retraction statement: A concise review on the elastomeric behavior of electroactive polymer materials

Novel poly(diaquabis(1,10-phenanthroline)copper(II)chloride) modified glassy carbon electrode for square wave voltammetric determination of aspirin in tablet samples

In this study, potentiodynamically fabricated poly (diaquabis(1,10-phenanthroline) copper(II)chloride) modified glassy carbon electrode (poly(A2P2CuC)/GCE) is reported for detection of aspirin in tablet samples. EIS and CV analysis of Fe(CN)6]3-/4- at the modified electrode revealed surface modification by an electroactive polymer material that improved electrode effective surface area and charge transfer resistance. An oxidative peak without a reductive peak in the reverse scan direction for aspirin at poly(A2P2CuC/GCE augmented by peak potential shift with scan rate showed the irreversibility of the electrochemical oxidation of ASA at the electrode. A better R2 (0.9983) for dependence of peak current on square root of scan rate than R2 (0.9612) on scan rate indicated that oxidation of aspirin at poly(A2P2CuC)/GCE was predominantly diffusion mass transport controlled. Under optimized PBS pH (5.5), and square wave parameters, oxidative peak current response of poly(A2P2CuC)/GCE showed linear dependence on the concentration of aspirin in the range 1–200 ​μM with associated %RSD under 3.7% (n ​= ​3), limit of detection 0.039 ​μM, and limit of quantification and 0.13 ​μM. Spike recovery result in the range 96.5–100.5% with %RSD under 1.9% (n ​= ​3), and interference recovery in the range 97.2–103.4% in the presence of 50–200% of uric acid, ascorbic acid, and glucose as potential interferents validated the applicability of the developed method for determination of aspirin content in tablet samples. Detection of aspirin in the studied tablet samples in an amount 99.4–101.5% of their nominal values with %RSD under 2.6% using the present method showed the applicability of the method to control the aspirin content in tablet samples. The present method showed better performance over the previously reported methods for determination of aspirin in tablet samples making it an excellent candidate.

A comparison of plane, slow pneu-net, and fast pneu-net designs of soft pneumatic actuators based on bending behavior

Soft robots are developed getting inspired by the bio-living organism. These robots require soft actuators such as pneumatic, hydraulic, electro-active polymer and shape-memory materials for their actuations. Out of these actuators, soft pneumatic actuators (SPAs) are the most commonly utilized actuators due to their lightweight and high output at very low actuating pressure. SPAs are developed using hyperelastic materials such as silicon rubber; some commercially available hyperelastic materials are ecoflex, dragon skin, and elastosil. The present work focuses on analyzing three different designs of SPAs considering ecoflex material. The mechanical properties of ecoflex are evaluated experimentally. Three SPAs designs including plane, soft pneu-net (sPN), and fast pneu-net (fPN) are computationally analyzed and compared based on their bending behavior under similar loading and boundary conditions. For computational analysis, finite element theory is utilized considering the Ogden model for hyperelastic materials. Obtained simulation results depict that for similar loading and boundary conditions, the SPA with fPN design creates a larger bending angle compared to plane and sPN designs.

Wave energy harvesting using Silicone as Electro-active Polymers

Wave energy is one of the renewable resources, which is very little exploited at the moment. Note that the energy transmitted through this energy is important, 140 to 700 TWh/year according to the WEC (World Energy Council), that is 1 to 5% of the world's electricity demand. The mechanical energy of the waves can be converted into electricity thanks to a completely flexible system based on the technology of electro-active polymers (EAP). These materials have the ability to generate a voltage when subjected to a certain stress and conversely to deform when subjected to an electrical voltage, hence the importance of developing conductive materials. The EAP material selected for the study is silicone rubber. Thus, the formulation of composite materials from a silicon elastomer matrix loaded with conductive carbon particles (graphite, graphite nanosheets and multi-wall carbon nanotubes) is the route followed for the formation of deformable electrodes.

Structure-property relationships in three-phase relaxor-ferroelectric terpolymers

Poly(vinylidenefluoride-trifluoroethylene)-based (P(VDF-TrFE)-based) terpolymers represent a new class of electroactive polymer materials that are relaxor-ferroelectric (RF) polymers and that offer unique and attractive property combinations in comparison with conventional ferroelectric polymers. The RF state is achieved by introducing a fluorine-containing termonomer as a “defect” into the ferroelectric P(VDF-TrFE) copolymer, which reduces the interaction between the VDF/TrFE dipoles. The resulting terpolymer exhibits a low Curie transition temperature and small remanent and coercive fields yielding a slim hysteresis loop that is typical for RF materials. Though the macroscopic behavior is similar to RF ceramics, the mechanisms of relaxor ferroelectricity in semi-crystalline polymers are different and not fully understood yet. Structure-property relationships play an important role in RF terpolymers, as they govern the final RF properties. Hence, a review of important characteristics, previous studies and relevant developments of P(VDF-TrFE)-based terfluoropolymers with either chlorofluoroethylene (CFE) or chlorotrifluoroethylene (CTFE) as the termonomer is deemed useful. The role of the termonomer and of its composition, as well as the effects of the processing conditions on the semi-crystalline structure which in turn affects the final RF properties are discussed in detail. In addition, the presence of noteworthy transition(s) in the mid-temperature range and the influence of preparation conditions on those transitions are reviewed. A better understanding of the fundamental aspects affecting the semi-crystalline structures will help to elucidate the nature of RF activity in VDF-based terpolymers and also help to further improve their applications-relevant electroactive properties.

Recent progress in preparation process of ionic polymer-metal composites

Ionic polymer-metal composite (IPMC) is a typical electroactive polymers material, which has the advantages of light weight, fast response, good flexibility, large deformation range and good biocompatibility, it has a broad application prospect in the fields of soft robot, biomedicine, micro/nano object operation and so on. In this paper, the deformation mechanism of IPMC is briefly described, and then the fabrication technology of IPMC at present stage is mainly introduced, it includes electroless plating, electroplating, sputtering deposition, solution casting, hot pressing, direct assembly and other preparation processes. From the point of view of the most basic preparation process of IPMC, the various preparation methods and the problems faced in the preparation process of IPMC were discussed and analyzed. Finally, the preparation process of IPMC was summarized, and the challenges and future development of IPMC were prospected. Through the summary of this paper, it is helpful to consider all kinds of factors comprehensively, and then develop a new preparation technology, which can promote the rapid application and development of IPMC.

Multi-stimuli Responsive Natural Fibers Immobilized with Silver Nanoparticles via Plasma-activated Generation of Polyaniline

Functionalization of natural fibers with electroactive polymeric materials can create conductive surfaces with multifunctional properties. Herein, we develop smart fibers using plasma supported coating of wool fabrics with various polyaniline derivatives (PANi) in the presence/absence of in-situ prepared silver nanoparticles (AgNPs). Nanostructural thin film of PANi was synthesized in-situ employing plasma-pretreatment to assess the polymerization process. AgNPs were immobilized in-situ during the formation of PANi starting from silver nitrate (AgNO3) by taking benefit of the reducing ability from the electroconductive polymer derivatives. Some selected electroactive polymers were applied starting from aromatic amines, including m-anisidine, o-phenylenediamine and p-nitroaniline. The morphological characteristics of the produced fabrics were studied by scan electron microscope (SEM). The chemical analysis was studied by energy-dispersive X-ray analyzer and Fourier transform infrared (FTIR) spectra. As monitored by CIE Lab colorimetric measurements, instant reversible color variations were monitored by recording the colorimetric measurements of the produced sensor fabrics. By changing the sort of the electroactive polymer and the inclusion of silver nanoparticles, the imparted characteristics of the developed wool fabrics, including antimicrobial, electroactivity and stimuli-responsive effects were explored for a diversity of promising medical applications.

Retracted: A concise review on the elastomeric behavior of electroactive polymer materials

In recent 20 years, electronic equipment has been developing rapidly in the direction of light, miniaturization, flexibility, and integration. It is urgent to meet the needs of matching energy supply system to solve the practical application requirements in the fields of intelligent communication and mobile medical treatment. Electroactive polymers (EAPs) are recommendable material for manifesting muscle-like actuation. The dielectric elastomers (DEs) obtained from the EAPs are quite capable of inducing electrical energy and transmute it into mechanical energy. DEs are capacitors covered by an outer elastic membrane, sandwiched between the two docile electrodes. In the beginning, for getting the efficient responses out of the DE actuators, the material requirements and electromechanical principal are applied. Viscoelastic damping, low dielectric loss, stretch ability, and dielectric permittivity are the desirable characteristics that we are expecting in a polymer. In the current research, we are going to adopt the sequential approach by describing the advances, challenges, and applications of DEAs in the coming future.

Preparation and Characterization of CCTO/PDMS Dielectric Elastomers with High Dielectric Constant and Low Dielectric Loss.

Dielectric elastomer (DE) is a type of electric field type electroactive polymer material that can produce greater deformation under the action of an electric field and has a faster recovery speed. It has the advantages of high energy density, large strain, low quality, and commercialization, and has become the most widely concerned and researched electroactive polymer material. In this study, copper calcium titanate (CCTO) particles with a large dielectric constant were selected as the filling phase, and a silicone rubber (PDMS) with better biocompatibility and lower elastic modulus was used as the matrix to prepare CCTO/PDMS, which is a new type of dielectric elastomer material. The structure of the dielectric elastomer is analyzed, and its mechanical properties, dielectric properties, and driving deformation are tested. Then, KH550, KH560, and KH570 modified CCTO is used in order to improve the dispersibility of CCTO in PDMS, and modified particles with the best dispersion effect are selected to prepare dielectric elastomer materials. In addition, mechanical properties, dielectric properties, and driving deformation are tested and compared with the dielectric elastomer material before modification. The results show that as the content of CCTO increases, the dielectric constant and elastic modulus of the dielectric elastomer also increase, and the dielectric loss remains basically unchanged at a frequency of 100 Hz. When the filling amount reaches 20 wt%, the dielectric constant of the CCTO/PDMS dielectric elastomer reaches 5.8 (100 Hz), an increase of 120%, while the dielectric loss at this time is only 0.0038 and the elastic modulus is only 0.54 MPa. When the filling amount is 5 wt%, the dielectric elastomer has the largest driving deformation amount, reaching 33.8%. Three silane coupling agents have been successfully grafted onto the surface of CCTO particles, and the KH560 modified CCTO has the best dispersibility in the PDMS matrix. Based on this, a modified CCTO/PDMS dielectric elastomer was prepared. The results show that the improvement of dispersibility improves the dielectric constant. Compared with the unmodified PDMS, when the filling content is 20 wt%, the dielectric constant reaches 6.5 (100 Hz). Compared with PDMS, it has increased by 150%. However, the improvement of dispersion has a greater increase in the elastic modulus, resulting in a decrease in its strain parameters compared with CCTO/PDMS dielectric elastomers, and the electromechanical conversion efficiency has not been significantly improved. When the filling amount of modified CCTO particles is 5 wt%, the dielectric elastomer has the largest driving deformation, reaching 27.4%.

Hardware-in-the-loop simulation of wave energy converters based on dielectric elastomer generators

Dielectric elastomer generators (DEGs) are soft electrostatic generators based on low-cost electroactive polymer materials. These devices have attracted the attention of the marine energy community as a promising solution to implement economically viable wave energy converters (WECs). This paper introduces a hardware-in-the-loop (HIL) simulation framework for a class of WECs that combines the concept of the oscillating water columns (OWCs) with the DEGs. The proposed HIL system replicates in a laboratory environment the realistic operating conditions of an OWC/DEG plant, while drastically reducing the experimental burden compared to wave tank or sea tests. The HIL simulator is driven by a closed-loop real-time hydrodynamic model that is based on a novel coupling criterion which allows rendering a realistic dynamic response for a diversity of scenarios, including large scale DEG plants, whose dimensions and topologies are largely different from those available in the HIL setup. A case study is also introduced, which simulates the application of DEGs on an OWC plant installed in a mild real sea laboratory test-site. Comparisons with available real sea-test data demonstrated the ability of the HIL setup to effectively replicate a realistic operating scenario. The insights gathered on the promising performance of the analysed OWC/DEG systems pave the way to pursue further sea trials in the future.

Dielectric Elastomers UV-Cured from Poly(dimethylsiloxane) Solution in Vinyl Acetate.

Poly(dimethylsiloxane) (PDMS) has been extensively used as an electroactive polymer material because it exhibits not only excellent moldability but also mechanical properties sufficient enough for electroactive performance despite low dielectric permittivity. Its low dielectric property is due to its molecular non-polarity. Here, we introduce a polar group into a PDMS elastomer by using vinyl acetate (VAc) as a crosslinker to improve the dielectric permittivity. We synthesized a high-molecular weight PDMS copolymer containing vinyl groups, namely poly(dimethylsiloxane-co-methylvinylsiloxane) (VPDMS), and prepared several of the VPDMS solutions in VAc. We obtained transparent PDMS films by UV curing of the solution layers. Electromechanical actuation-related physical properties of one of the UV-cured films were almost equivalent to or superior to those of platinum-catalyzed hydrosilylation-cured PDMS films. In addition, saponification of the UV-cured film significantly improved the electrical and mechanical properties (ɛ′ ~ 44.1 pF/m at 10 kHz, E ~ 350 kPa, ɛ ~ 320%). The chemical introduction of VAc into PDMS main chains followed by saponification would offer an efficacious method of enhancing the electroactive properties of PDMS elastomers.

A robust and computationally efficient finite element framework for coupled electromechanics

Electro-active polymers (EAPs) are increasingly becoming popular materials for actuators, sensors, and energy harvesters. To simulate the complex behaviour of actuators under coupled loads, particularly in the realm of soft robotics, biomedical engineering and energy harvesting, finite element simulations are proving to be an indispensable tool. In this work, we present a novel finite element framework for the simulation of coupled static and dynamic electromechanical interactions in electro-active polymeric materials. To model the incompressible nature of EAPs, a two-field mixed displacement–pressure formulation which, unlike the commonly-used mixed three-field and F-bar formulations, is applicable for both nearly and fully incompressible materials, is employed. For the spatial discretisation, innovative quadratic Bézier triangular and tetrahedral elements are used. The governing equations for the coupled electromechanical problem are solved using a monolithic scheme; for elastodynamics simulations, a state-of-the-art implicit time integration is adapted. The accuracy and the computational efficiency of the proposed framework are demonstrated by studying several benchmark examples in computational electromechanics which include simulations of a spherical gripper in elastostatics and a dielectric pump in elastodynamics. Such complex simulations clearly depict the advantages of the proposed finite element framework over the Q1/P0 and Q1-F-bar elements. Furthermore, the superiority of the proposed framework in accurately capturing complex coupled electromechanical interactions in thin electro-active polymeric shells is demonstrated by studying a thin helical actuator under different excitation frequencies and by reproducing buckling instabilities in thin semi-cylindrical and semi-spherical shells. With the ability to simulate various elastostatics and elastodynamics phenomena using a single finite element framework for bulk as well as thin dielectric elastomers while using coarse structured or unstructured meshes that can be readily generated using existing mesh generators, this novel framework offers a robust, accurate, and computationally efficient numerical framework for computational electromechanics.

The square rod-shaped ionic polymer-metal composite and its application in interventional surgical guide device

ABSTRACT Ionic polymer-metal composite (IPMC) is an electro-active polymer material, which has many advantages such as small size, light weight, low driving voltage, large strain, and good biocompatibility. However, the conventional sheet IPMC has the shortcoming of only bending in the two-dimensional plane, which greatly limits the application of IPMC in the field of interventional surgery. In this work, a square rod-shaped IPMC with multi-degree-of-freedom motion was fabricated, and the displacement and blocking force of the square rod-shaped IPMC in different directions are measured and analyzed under the DC voltage signal. An interventional catheter was designed using the square rod-shaped IPMC in order to achieve active guidance, and a simulation experiment platform and a model of human aorta were built to successfully complete the in vitro simulation experiment of interventional surgery, which preliminarily verified the feasibility of the square rod-shaped IPMC in the field of interventional surgery.