Electrorheological Effect Research Articles

Exploring the potential of induced dipole-dominated electrorheological effect: advancing ER elastomers

Abstract Prior research has predominantly focused on traditional electrorheological (ER) effects while overlooking the transformative potential of induced dipoles in enhancing the overall performance of ER materials. In this study, we introduced a novel type of ER elastomer called induced dipole-dominated ER elastomer (ID-ERE). Through high-energy ball milling (HEBM) of the filler particles, the oxygen vacancies were produced within the particles that acted as local charge centers. In the presence of an external electric field (E), these oxygen vacancies induced the dipoles with significant dipole moments, thus amplifying the local electric field EL within the particle gaps. The powerful interactions of these dipoles significantly improved the overall performance of elastomer; the phenomenon referred to as the ID-ER effect. The viscoelastic results showed that ID-EREs have high field-induced storage modulus (G’ = 395.7 kPa), a significant increment in storage modulus (ΔG’ = 270.5 kPa) and high relative ER effect (ΔG’/G0 = 217.2%) at 3 kV mm−1. Additionally, after testing ID-EREs viscoelastic properties, it was discovered that excessive powder content leads to a decline in the elastomer’s performance. The results showed that ID-ERE’s viscoelastic, mechanical, dielectric, and overall efficiency is finer than the control ER elastomer (C-ERE) having unmilled TiO2 particles. Besides, the preparation method is straightforward, easily replicated, scalable, and cost effective. Thus, these ID-EREs should be a new generation of elastomer with the potential to be used in various automotive, robotics, construction, and electroactive actuators industries.

Acidic phosphonium-based ionic liquid encapsulated on titania particles with enhanced electrorheological response

Research on electrorheological (ER) fluids has led to significant advancements in the development of smart materials that adjust their viscosity in response to applied electric fields. This study focused on synthesizing titania ionogel-based particles (TiO2-IL) using an environmentally friendly sol-gel process involving tetrabutoxy-titanium (TBT) combined with an ionic liquid (IL), specifically 11-carboxyundecyl-triphenyl-phosphonium bromide. The successful incorporation of the IL into the TiO2 particles was confirmed through thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy and zeta potential analysis. The electrorheologial properties of TiO2-IL ionogel suspension in silicone oil were compared with those of pure TiO2 suspension. The addition of the ionic liquid (IL) significantly enhanced the electrorheological (ER) properties of the fluid, achieving a shear stress of approximately 1340 Pa at an electric field strength of 5 kV/mm. The fluid also exhibited excellent reversibility and a rapid response to changes in the electric field, which is attributed to the higher polarizability by the IL. Furthermore, the study observed low current density during operation, which helps maintain the fluid’s integrity and longevity under high electric fields. The fluids demonstrated stable ER effect across a temperature range of 40–70 ℃ and a reasonable sedimentation stability of around 80 %. These characteristics, combined with the moderate conditions for particle preparation, make the TiO2-IL fluid a promising candidate for ER applications.

Enhancing interfacial polarization and electrorheological effect of crosslinked poly(ionic liquid)s by doping aniline oligomer

Poly(ionic liquid)s (PILs) are providing potential platforms to develop next generation water-free polyelectrolyte-based electrorheological (ER) fluids because they well overcome water sensitivity problem of classic polyelectrolyte-based ER fluids by incorporating with large size fluoric counterions. Especially, crosslinked PILs (CPILs) can further broaden the working temperature range of ER effect compared to linear PILs. However, the crosslinking network easily restricts the ion dissociation due to decreased dielectric constant and thus weakens ion movement-induced interfacial polarization and ER effect. In this paper, we propose a way to improve ion dissociation and ion movement-induced interfacial polarization of CPILs by doping polar aniline oligomer to improve the dielectric constant of CPILs. Several kinds of CPILs are synthesized and then aniline oligomer is doped into CPILs by swelling method. The structure of doped CPILs is characterized by different techniques, the dielectric property of ER fluids of doped CPIL particles in silicone oil is analyzed by dielectric spectroscopy, and the ER effect of ER fluids of doped CPIL particles is measured by rheometer under electric fields. It shows that doping aniline oligomer can increase the dielectric intensity and decrease the relaxation time and corresponding activation energy of interfacial polarization and improve the ER effect of CPILs with a relatively loose crosslinking network, while doping aniline oligomer has no contribution to the interfacial polarization and ER effect of CPILs with a relatively tight crosslinking network.

Dielectric and Shear-Mechanical "Humps" in the Nonlinear Response of Polar Glassformers.

Many glassformers display electrorheological effects and a pronounced maximum in their frequency dependent nonlinear dielectric response. The latter so-called "hump" feature was often linked to correlated-particle motions and, so far, was not explored in the large-perturbation mechanical response of viscous liquids. To first clarify the electro-viscoelastic coupling in the linear domain, using the modified Gemant, DiMarzio, and Bishop model, it is demonstrated how the small-amplitude shear mechanical response of S-methoxy-PC, a derivative of propylene carbonate, can be related to its complex dielectric permittivity. Then, in the nonlinear regime, a "hump" feature is identified in the rheological third-order shear modulus of S-methoxy-PC and of another polar glassformer, propylene glycol. Thus, the observation of a "hump" in the cubic response of viscous liquids does not necessarily rely on the application of electrical fields.

Preparation and Electrorheological Behavior of Rare‐Earth La Ion Doping MIL‐125 Nanoparticles

Herein, rare‐earth element (lanthanum)‐doped MIL‐125 is synthesized via the solvothermal method. The morphology, physicochemical structure, specific surface area, and other characteristics of the synthesized material are characterized via scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, Brunauer Emmett Teller, X‐ray photoelectron spectroscopy, element mapping, etc. It is observed that appropriate La doping enhances the dielectric mismatch and conductive mismatch levels of the material. This enhancement leads to a stronger interface polarization capability, thereby influencing the material's dielectric properties. Ultimately, the electrorheological fluids with La‐doped MIL‐125 as the dispersive phase show an obvious electrorheological effect.

Model modification and influence of edge effect on effective area of giant electro-rheological polishing using plate electrodes

Abstract Giant electro-rheological polishing (GPRP) is recognized as an innovative ultra-precision machining technology with significant potential. However, the pronounced edge effect within the GPRP's polishing gap can introduce errors in calculating the effective area and designing the electrode structure. This, in turn, may lead to under-polishing and an increased risk of insulation breakdown. In this study, COMSOL was employed to investigate the electric field distribution characteristics within the polishing gap. This exploration aimed to refine the calculation model of the effective area, optimize the plate electrodes' structure and size, and diminish the likelihood of insulation breakdown. Through systematic finite element simulations, the impact of polishing voltage, inter-electrode gap, and plate length on the edge effect was thoroughly analyzed to ascertain its influence range. The simulation findings revealed that, while maintaining a constant inter-electrode gap for the tool electrode, variations in the polishing gap, polishing voltage, and plate length within specific ranges resulted in an edge effect influence range of approximately 1 mm. Moreover, when the machining gap, polishing voltage, and plate length remained unchanged, the edge effect influence range increased proportionally with the electrode gap within a specific range, approximately equivalent to the size of the electrode gap. Experimental validation of the giant electro-rheological effect confirmed the existence and influence range of the edge effect, aligning with the finite element simulation results. Ultimately, modifications to the calculation model of the effective area were proposed, along with a solution to optimize the electrode size and structure, with the objective of reducing the probability of insulation breakdown. In practical applications, this work can provide a valuable reference for electrode structure design, insulation breakdown improvement and parameter selection.

Rheology and electrorheological effects of waxy oils with different carbon number distribution

High-voltage electric treatment is an emerging technology for enhancing the cold flowability of crude oil. The primary mechanism involves the accumulation of charged particles (resins and asphaltenes) onto wax particles under the electric field. This electrorheological effect varies with different oil compositions. We have investigated the impact of resins and asphaltenes on the electrorheological behaviors of waxy oils. However, the impact of the carbon number distribution of wax on this effect remains unexplored. Therefore, the objective of this work is to investigate the interaction between waxes with various carbon numbers and charged particles and its impact on the electrorheological behaviors of waxy oils. Model waxy oils containing distinct wax fractions (paraffin and microcrystalline waxes) and varying charged particle concentrations were prepared and studied. The results unveiled that microcrystalline wax model oils exhibited substantial reductions in viscosity and yield stress after electric treatment, up to 80% and 60%, respectively, surpassing the improvements observed in paraffin wax model oils which were less than 50%. This disparity is attributed to the better capacity of resins and asphaltenes to be eutectic with paraffin wax, improving the original flowability of paraffin wax model oil, thus involving fewer charged particles in the interaction with wax under electric treatment, resulting in a weakened electrorheological effect. Resins and asphaltenes struggle to form eutectic mixtures with microcrystalline wax, resulting in minimal flowability improvement of microcrystalline wax model oils by charged particles. Consequently, under the electric field, a substantial proportion of free resins and asphaltenes can interact with microcrystalline wax particles, leading to superior electrorheological effects in microcrystalline wax model oils.

Enhancing the performance of electrorheological fluids by structure design

By incorporating polar fibers into the design of electrorheological (ER) fluids, a 130% performance improvement can be achieved with the addition of only 0.8 vol% of polar long fibers. We quantitatively analyzed the impact of relatively long fibers on improving ER performance by measuring the yield stress, shear stress, and current density after adding fibers. Both optical microscopy and transmission electron microscopy were used to observe and analyze the interaction between ER particles and polar fibers. The results indicate that, under the influence of an electric field, the fibers transform the one-dimensional chain-like structure into a two-dimensional mesh structure, greatly improving the ER performance. The transformation of structure induced by the polar fibers in the ER fluids amplifies the ER effect. However, the inclusion of non-polar fibers does not contribute to this enhancement, as a point of comparison. Moreover, to ensure the universality of this method, we used two different types of ER fluids in experiments. The utilization of this method offers a straightforward, environmentally friendly, and highly effective approach. Furthermore, this study provides a novel technical solution aimed at enhancing the performance of ER fluids.

Influence of alternating electric field on electrorheological effect of aqueous dispersions of stevensite

Upon deionization of the aqueous dispersion of stevensite, a type of smectite clay minerals, a low-viscosity colorless transparent dispersion is obtained. The phenomenon known as the electrorheological (ER) effect has been previously reported when a weak electric field of several V/mm is applied to the stevensite aqueous dispersion. In this study, the influence of the waveform and frequency of the electric field was investigated while keeping the electric field intensity constant. It was observed that as the acceleration of the applied electric field intensity increased, the stress response to the electric field improved. Increasing the frequency of the electric field led to a reduction in the induced stress; however, it improved the response rate of stress. It has been indicated that even at higher electric field frequencies, the potential for observing the ER effect exists with higher electric field intensities. Maintaining a low electrolyte concentration may facilitate the development of novel ER fluids capable of instantaneously responding to the application or removal of electric fields.

An energy perspective on the mechanism of crude oil electrorheological effect

Exposing a waxy crude oil to an electric field represents an emerging environmentally sound strategy for improving the cold flowability of oil. However, a substantial knowledge gap still exists regarding the quantitative relationship between the viscosity reduction and treatment parameters (field strength, treatment time, the volume of treated oil, etc.). This study endeavors to investigate the physical essence of the effect of these treatment parameters on the viscosity reduction and its duration. It was found when subjected to electric fields of varying strengths (0.5–5 kV/mm) for sufficient time, a same maximum viscosity reduction of approximately 40% can be achieved regardless of the applied field strength. Further research has elucidated that the factor determining the viscosity reduction is energy input, rather than the field strength as was reported previously, and the inputted energy may work in three stages: first, it works for initiating a decrease in viscosity. Subsequently, the continued energy input further reduces the oil viscosity and ultimately achieves a maximum reduction at that temperature. Then further inputted energy enhances the duration of the viscosity reduction. Fundamentally, the inputted energy density, i.e., the inputted energy per unit volume/mass of the oil, is the essential factor. These new findings facilitate further understanding of the negative electrorheological effect and its mechanism of crude oil and may help for the development of electric treaters for reducing crude oil viscosity.

Interfacial polarization and electrorheological effect of homo-poly(ionic liquid) and poly(ionic liquid)-hexyl methacrylate copolymer microsphere particles

Homo-poly(ionic liquid) (HomoPIL) microsphere particles of poly[2-(methacryloyloxy)ethyltrimethylammonium][bis(trifluoromethanesulfonyl)imide] (P[MTMA][TFSI]) and poly[2-(methacryloyloxy)ethyltrimethylammonium][hexafluorophosphate] (P[MTMA][PF6]), as well as their corresponding copolymer microsphere particles obtained through copolymerization with hexyl methacrylate (HMA), were synthesized as electrorheological (ER) materials. The morphology and structure of these synthesized particles were characterized using scanning electron microscopy (SEM), 1H nuclear magnetic resonance spectroscopy (1H NMR), Fourier-transform infrared spectroscopy (FT-IR), and small-angle X-ray scattering spectra (SAXS). Electrorheological measurements were conducted for these polyelectrolyte-based suspensions at room temperature, revealing that the HMA composition has a different effect on the ER effect of the two poly(ionic liquid)s. Differential scanning calorimetry (DSC) and temperature-modulated dielectric analysis (TMDA) were employed to investigate the effect of HMA composition on the glass transition temperature and interfacial polarization of these polyelectrolytes, suggesting that the incorporation of HMA affect the ER effect of PILs via changing the density of charge carriers and the counterion mobility. This study presents a potential approach for enhancing the electrorheological properties of poly(ionic liquid)s.

Development of Novel Hydraulic 3D Printed Actuator Using Electrorheological Fluid for Robotic Endoscopy

Endoscopy has made a significant and noteworthy contribution to the field of medical science and technology. Nevertheless, its potential remains constrained due to the limited availability of rigid or flexible endoscopes. This paper introduces a novel hydraulic actuator based on electrorheological fluid (ERF) as a pivotal advancement in bridging the existing gap within the realm of endoscopy. Following a comprehensive introduction that briefly outlines the electrorheological effect, the subsequent section is dedicated to the elucidation of the actuator’s development process. Challenges arise, particularly in terms of miniaturization and the realization of a hydraulically sealed system with integrated valve electrodes. An internal electrorheological valve system consisting of four valves that are controlled using a pulse-width modulated high voltage was suitable for position control of the antagonistic hydraulic actuators. High-precision stereolithography (SLA) printing has proven practical for manufacturing actuator components. For functional testing, a test bench was set up in which the actuator follows a setpoint through a PI control loop. The control deviation ranged from 0.6 to 1 degree, with a response time between 6 and 8 s. The experiments have demonstrated that through the use of ERF and integrated valve electrodes, a miniaturized functional actuator can be constructed.

IMPACT OF IONIC LIQUID ADMIXTUREON ELECTRORHEOLOGICAL AND TRIBOLOGICALPROPERTIES OF A HYDROCARBON LUBRICATING OIL

The article describes, the relationship between the generated and fading electrorheological effect and tribologicalproperties of hydrocarbon lubricating oils containing ionic liquid admixture. Two quasi-homogeneousmixtures were obtained as a result of miscibility tests: 1) the GP1 silicon damping oil containning ionic liquidCJ001, i.e. 1-methyl-3-octyloxymethylimidazolium tetrafluoroborate and 2) the PAO6 base polyalphaolefinoil containing ionic liquid CJ008, i.e. trihexyltetradecylphoshonium bis-(tri-fluoromethylsulfonyl)imide. Theconducted ER tests revealed differences between the electrorheological properties of the two mixtures. Afterincreasing the electric field strength to E = 0.3 kVmm–1 the ER effect of both mixtures disappeared. Forthese mixtures tribological tests were carried out on a four ball apparatus. The lubricity parameters of thetested ionic liquids are much better than base oils and the oil mixtures with ionic liquids also showed betterlubricating properties than their base oils.

Suppressing the self-discharge of high-frequency supercapacitors using electrolytes containing BaTiO3 nanoparticles

High-frequency supercapacitors (HF–SCs) are promising electric energy storage devices and alternating current line filters. However, severe self-discharge of HF–SCs causes significant energy loss and limits their applications. Current self-discharge suppression methods for supercapacitors typically lead to decreased rate performance and hence cannot be applied to HF–SCs directly. In this work, barium titanate (BTO) nanoparticles are employed as an electrolyte additive for HF–SCs to reduce self-discharge. By adding BTO nanoparticles into the electrolyte, both leakage current and decay of open circuit voltage of the devices are reduced without sacrificing the specific capacitance and high-frequency response. At a charging voltage of 2 V, the leakage current is reduced by 49 % (3.91 vs. 1.98 μA), while the time for the voltage to drop from 2.0 to 1.0 V is extended by 4.5 times (2300 vs. 10240 sec). When the HF–SCs with BTO electrolyte are employed to store the energy generated by a triboelectric nanogenerator, the time for charging the cells to 2.0 V is reduced by 82 %. Mechanistic analysis indicates that the reduced self-discharge can be attributed to the fluid electrorheological effect and the enhanced localized electric field within the gaps among BTO nanoparticles that lead to sluggish diffusion and migration of reactive species, so the diffusion-controlled faradaic reaction process is suppressed.

Design and rheological behaviour of lactic acid based cholesteric liquid crystalline materials with hydroquinone unit in the molecular core

In order to contribute to molecular structure – physical property relationship for chiral self-assembling materials, two chiral compounds derived from the lactic acid have been designed. Mesogenic core of materials consists of two benzoate units and one hydroquinone unit connected by the ester linkage groups and two flexible alkyl chains. Different lengths of the chiral alkyl chain were tested, while the length of the achiral alkyl was kept same for all materials. The mesomorphic properties were established by polarizing optical microscopy and differential scanning calorimetry. Both materials possess reasonably broad and stable cholesteric (N*) phase down to room temperature. The rheological characterisation was performed in the N* phase on the compound with shorter chiral alkyl chain using a rotational rheometer in a plate/plate geometry with and without external electric field applied perpendicularly to the flow direction. The results reveal a shear thinning behaviour, even without electric field applied. The N* phase exhibits a slight electrorheological effect, at low shear rates, that continuously decrease with the increase of the shear rate, due to the competition of the flow and electric fields. The mesomorphic behaviour of the designed materials was compared to structurally similar materials. Quite broad temperature range of the N* phase down to room temperature makes studied lactic acid derivatives as suitable chiral dopants for design of new multicomponent mixtures targeted for various applications in photonics and optoelectronics.

Preparation and enhanced electrorheological properties of elastomers filled with rod-shaped TiO2 particles

The morphology of dispersed particles has been proven to have a significant impact on performance of electrorheological (ER) materials, while there is a lack of relevant research on its impact on the properties of electrorheological elastomers (EREs). In this study, the TiO2 particles with spherical, short rod, and long rod shape were fabricated with sol-gel method, and the EREs were prepared with these three kinds of particles as dispersion phase. Particle characterization results show that the rod-shape TiO2 particles with larger average size exhibit a combination of anatase and brookite phase. The viscoelastic properties of three types of EREs under varying strain amplitude and shear frequency were tested. The results indicate that the long rod-shape TiO2 particles filled EREs shows higher storage modulus G′ and higher relative ER effect within the electric field from 0 to 3 kV/mm. The observations indicate the use of rod-shape TiO2 particles in the form of brookite phase may help enhance the ER properties of elastomers. The investigation contributes to the designing, preparation, and application of anisotropic ERE.

Electrorheological Effect of Suspensions of Polyaniline Nanoparticles with Different Morphologies.

Polyaniline (PANI) nanospheres, nanofibers, and nanoplates were prepared using the oxidative polymerization method. Scanning electron microscopy (SEM) was used to observe the three morphologies of PANI, and their structure was tested using infrared spectroscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. The influence of particle morphology on the electrorheological (ER) effect was studied through rheological experiments and molecular dynamics (MD) simulation. The experimental and simulation results indicate that without applying an electric field, the nanofibers easily form a three-dimensional network structure in the suspension, resulting in yield stress. The three-dimensional network structure of the nanoplate suspension becomes weaker and the PANI nanosphere suspension lacks the ability to form a three-dimensional network structure. After applying an electric field, under the same condition, the yield stress and electric field-induced shear stress increment of PANI nanofibers are the highest, followed by nanoplates, and those of PANI nanospheres are the lowest. This indicates that the ER effect increases with the increase in particle morphology anisotropy. Through three-dimensional visual simulation analysis, it can be concluded that the enhanced ER effect associated with increased particle anisotropy can be attributed to improved stability in the ER chain structure.

Electrorheological effect of self-crosslinked polymerized ionic liquids containing different types of ion spacers

In this paper, we synthesized five self-crosslinked polymerized ionic liquids (S-PILs) containing distinct ion spacers but identical mobile counterions. The structural characterization of these S-PILs was carried out using Fourier transform infrared spectroscopy and wide-angle X-ray scattering. The electrorheological (ER) effect was investigated using rheological measurement and broadband dielectric spectroscopy. The results showed that the ER effect of S-PIL with phosphorus-containing ion spacers was the weakest, that of S-PIL with imidazole-containing ion spacers and S-PIL with pyridine-containing ion spacers was increased, and that of S-PIL with amino-containing ion spacers was the strongest. Dielectric spectra analysis showed that the interfacial polarization time of S-PIL with phosphorus-containing ion spacers was the longest, resulting in its weakest ER effect. The interfacial polarization times of S-PIL with imidazole-containing ion spacers and S-PIL with pyridine-containing ion spacers were increased but their conductivities were relatively large, which led to strong electrode polarization and weakened their ER effect. S-PILs with amino-containing ion spacers had moderate conductivity and suitable polarization time, so they had the strongest ER effect. Finally, we discussed the reasons for these different conductivity and dielectric polarization by combining the dissociation degree of counterions calculated by Raman spectroscopy and the activation energy of ion movement calculated by conductivity data. The study provides a molecular-level understanding for the rational design and preparation of S-PILs with high ER performance.

Electrorheological effect of suspensions containing mixed size of poly(ionic liquid) microspheres

In this paper, the electrorheological (ER) effect of suspensions containing mixed size of poly(ionic liquid) (PIL) microspheres were studied by combining experiment and molecular dynamics simulation. The PIL microspheres with two particle sizes were prepared via a cooling-assisted phase separation method. The PIL microspheres were dispersed in silicone oil to form five kinds of suspensions with different volume ratios of large and small at a fixed particle volume fraction. The ER effect of these suspensions was measured by a rheometer. We established ER suspension models for five suspensions and simulated the rheological curves of the ER suspensions using molecular dynamics-stochastic rotation dynamics method. Both experiment and simulation results showed that the ER effect of suspensions containing mixed size of PIL microspheres was lower than that of suspensions containing uniform size of PIL microspheres. The reasons for the influence of mixed particle size on ER effect were analyzed through the three-dimensional visualization simulation results.

Suppressing the self-discharge of MXene-based supercapacitors by liquid crystal additive

MXenes are widely used as electrodes for supercapacitors (SCs) due to their excellent conductivity and abundant redox active sites. However, the severe self-discharge of MXene-based SCs results in significant energy loss, limiting their integration with various energy-harvesting devices. Here we introduced the nematic liquid crystal 4-n-pentyl-4′-cyanobiphenyl (5CB) molecules into Ti3C2Tx films and LiCl aqueous electrolytes to suppress the self-discharge rate. The nematic liquid crystal molecules would arrange parallel to each other when the Ti3C2Tx films were charged, while the electrolyte viscosity would increase due to the electrorheological effect, causing the slow cross-diffusion of active ions and reducing the self-discharge. As a result, the MXene-based SCs had a low voltage drop of 35% after 4600 s and a low leakage current of 3.0 µA, respectively. The MXene-based SCs could store energy more effectively, improving their practical application potential in integrated energy harvesting devices, for example, storing the electrical energy harvested by the triboelectric nanogenerators. This work proposed a simple strategy to suppress the self-discharge of Ti3C2Tx-based SCs by liquid crystal additive, which can be extended to other MXenes, promoting the applications of MXenes in energy storage devices and integrated electronics.