Enhanced Actuation Response of Nafion-Based Ionic Polymer Metal

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Enhanced Actuation Response of Nafion-Based Ionic Polymer Metal Composites by Doping BaTiO3 Nanoparticles Kan Bian, Hongguang Liu, Guoan Tai, Kongjun Zhu, and Ke Xiong J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.6b03273 • Publication Date (Web): 31 May 2016 Downloaded from http://pubs.acs.org on June 3, 2016

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The Journal of Physical Chemistry

Enhanced Actuation Response of Nafion-Based Ionic Polymer Metal Composites by Doping BaTiO3 Nanoparticles Kan Bian,†,a Hongguang Liu,†,a,b Guoan Tai,a Kongjun Zhu,a and Ke Xiong*,a a

The State Key Laboratory of Mechanics and Control of Mechanical Structures, College of Aerospace

Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China b

Faculty of Civil Engineering and Mechanics, Jiangsu University, Zhenjiang, 212013, China

Author Email Address: [email protected]

†

These authors contributed equally to this work.

*Corresponding author. Telephone: 025-84891502, Fax: 025-84891512. E-mail: [email protected]

ACS Paragon Plus Environment


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ABSTRACT Nafion-based composite membranes by doping BaTiO3 nanoparticles were prepared to fabricate high-performance

ionic

polymer

metal

composite

(IPMC)

actuators.

BaTiO3/Nafion

nanocomposites were evaluated in terms of their static mechanical properties, water uptake, surface resistivity, electrochemical impedance and actuation behaviors. The results show that the BaTiO3/Nafion based IPMCs have higher ionic conductivity and capacitance, and better actuator behavior in comparison with the pure Nafion-based counterpart. The membrane with 3 wt% BaTiO3 nanoparticles exhibits the best overall property under a 3 V DC or AC voltage excitation: exceptional deflections are obtained up to 101.4% under the DC input and 250% under the AC input at a frequency of 1 Hz, respectively; the blocking force is increased over 375% at the DC input, in sharp contrast to the pure Nafion sample. The improvements are attributed to the double-layer electrostatic effect which is induced by the broad dispersion of penetrated nanoparticles into electrodes. This study provides an innovative approach to develop high-performance IPMC actuators.


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1. INTRODUCTION Ionic polymer metal composite (IPMC) is one of the most smart materials because of its flexibility, lightweight, biocompatibility and a large displacement under a low potential.1‒4 The fascinating characteristics make it a wide range of industrial and medical applications in soft robotic actuators and artificial muscles as well as dynamic sensors in the micro-to-macro size range.4‒12 The typical bimorph structure of IPMC is composed of one ionically conductive electrolyte membrane covered with a metal layer on both sides. In the absence of electric field, the hydrated cations in the IPMC solution are distributed uniformly within the membrane; when an electric field is applied, the hydrated cations are forced to move toward the cathode, resulting in the IPMC to bend toward the anode side. Among the IPMCs, Nafion film (provided by Dupont) is one of the well-known commercial materials due to its chemical inertness and excellent thermal stability. Platinum (or gold) is traditionally used as a metal electrode material,3,4,13 however, the application of Nafion-based IPMC is limited, which results from easy-diffusion of water, relatively low actuation forces and low reproducibility of electrode performance and instability of electrodes.14-16 To address these problems above, many researchers have tried to improve the physical and chemical properties of IPMCs by doping nanoscale carbonaceous materials into Nafion films in recent years. Lee et al. improved the mechanical and actuation performance of IPMCs by preparing MWCNT/Nafion nanocomposites.16 Lian et al. enhanced the actuation performance of IPMCs by fabricating carbon nanotube-Nafion nanocomposites.17 Yip et al. developed CNT-based ionic polymer actuators that could be operable in a wide range of humilities.18 Jung et al. improved the actuation ability of IPMCs by incorporating graphene into Nafion films.19 These studies showed



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that the incorporation of CNTs into Nafion films leads to a significant improvement in the mechanical and actuation performance of Nafion-based IPMC actuators. However, the occurrence of strong Van der Waals forces and electrostatic interactions between the CNTs causes the aggregation of the CNTs in IPMCs, which compromises the performance of IPMCs by adding CNTs as reinforcement materials.20-22 In this work, we introduce electroactive BaTiO3 nanoparticles into Nafion-based IPMCs to fabricate high-performance IPMC actuators. BaTiO3 was considered as a reinforced filler for the Nafion membranes because it is a ferroelectric material with high dielectric constant and low dielectric loss. BaTiO3 nanoparticles-reinforced Nafion ion-exchange membranes were prepared by a solvent casting method and Pt electrodes were fabricated on both sides of the membrane by a chemical deposition method. The results showed that the addition of BaTiO3 nanoparticles remarkably improves the mechanical and electrical properties as well as the actuating ability. 2. EXPERIMENTAL SECTION 2.1 Materials A 5 wt% Nafion perfluorosulfonic acid (PFSA) polymer dispersion was purchased from Dupont Co. BaTiO3 nanoparticles with an average particle size of 100 nm were hydrothermally synthesized at 240 oC for 16 h. Dimethyl sulfoxide (DMSO) was purchased from Shanghai Shiyi Chemical Reagent Co., Ltd, China. Tetrammineplatinum(II) chloride (Pt[NH3]4Cl2) was received from Shanghai Jiuyue Chemical Co., Ltd, CHN. Sodium borohydride (NaBH4) and hydrazine hydrate (N2H4) were received from Sinopharm Chemical Reagent Co., Ltd, China.


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2.2 Preparation of BaTiO3 nanoparticles BaTiO3 nanoparticles were synthesized by a modified sol-hydrothermal route according to our previous work.23,24 Firstly, TiO2 sol was prepared by mixing Ti(C4H9O)4, ethanol, HNO3, and deionized water in the mole ratio of 1:18:3:0.06. Secondly, the as-prepared fresh TiO2 sol was dropped into a Ba(OH)2 solution under vigorous stirring. Thirdly, the mixed precursor solution was hydrothermally treated at 200 °C for 16 h. Finally, the yielding products were filtered, washed with deionized water and ethanol in sequence and then dried at 80 °C for 24 h. FESEM image and corresponding XRD pattern of BaTiO3 nanopowders are shown in Figure S1.

2.3 Preparation of the BaTiO3/Nafion Nanocomposite Membranes The concentration of the Nafion solution was concentrated into 25% at 50 oC in vacuum and then the Nafion solution and DMSO was mixed by a DMSO and Nafion volume ratio of 1:40 to make a casting solution. Bubbles in the solution were removed by ultrasonic irradiation for 20 min. Furthermore, the solution was poured equally into four square glass molds, and three of them were mixed with BaTiO3 nanoparticles with mass ratios of 100:1, 100:3 and 100:5, respectively. All the molds were irradiated by an ultrasound with a frequency and power of 40 kHz and 900 W for 2 h. Finally, they were kept in an oven at 60℃ for 10 h and then heated at 100 oC for 3.5 h to form a uniform soft membrane. 2.4 Preparation of Pt Electrodes The nanocomposite membrane was cut into strips with a length and width of 6 and 1 cm. Two sides of each strip were roughened with a metallographic sandpaper (type: W10) to enlarge the interfacial area contacted with electrodes and strengthen the physical adhesion between them. The strip was



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cleaned by ultrasound irradiation for 10 min and then deionized water. The pretreated strip was placed in 0.1 mol/L sulphuric acid solution (H2SO4) for 30 min. The next step was to perform the ion-exchanging process using 0.005 mol/L tetrammine platinum (Ⅱ) chloride (Pt[NH3]4Cl2) solution for about 14 h. Pt-IPMC membrane was produced by a two-step reduction method.16 2.5 Structural and Electrical Characterization Scanning electron microscope (SEM) and electron diffraction X-ray (EDX) analysis were performed with HITACHI S-4800 to observe the surfaces, cross-sections and elementary compositions of the IPMC samples. The electrochemical properties of the IPMCs were determined by electrochemical impedance spectroscopy (EIS) using an electrochemical analyzer (Princeton Applied Research, Parstat 4000). The EIS was investigated in the frequency range from 1 to 10 MHz with a potential amplitude of 10 mV. The mechanical properties of the BaTiO3/Nafion nanocomposite membranes were tested by an universal testing machine (QUASAR 2.5) which used ASTM D882 standards to obtain the samples’ mechanical properties including the elastic modulus and the ultimate stress. Water uptake (Wup) was determined by Wup = (Ww - Wd)/Wd × 100%, where Ww and Wd denote the weights of the fully swollen and the dry membranes, respectively. The

procedure of preparing the samples was as follows: firstly, the membranes were placed in deionized water at room temperature over one day; secondly, the adhering water on the surface of the membranes was quickly wiped off with an absorbent paper and the fully hydrated samples were immediately weighed; thirdly, the samples were dried at 65 oC for 24 h until the weight of the samples kept unchanged; finally, the surface resistance ( Rs ) were measured using a ST-2258C multifunction digital four-probe tester.


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Cyclic voltammetry (CV) measurements were performed in a three-electrode system on an electrochemical workstation (CHI 660C). We selected a Pt sheet with 1 × 1 cm2, Ag/AgCl (KCl, 3 M), and the IPMCs as counter, reference, and work electrodes, respectively. The electrical impedances of the IPMC samples were measured using a PARSTAT MC electrochemical testing platform in the frequency range of 100 kHz to 50 mHz at a voltage of 1 V. The samples were clamped between two Ag sheets and the measurements were carried out in deionized water at room temperature. The capacitance (C) of the samples was also measured using the same equipment under the same conditions. From the complex-impedance plot, the proton resistance (R) of the sample was calculated, and the proton conductivity (σ) was obtained by σ = h/(RA), where h and A are the thickness and the area of the sample, respectively. 2.6 Actuating Measurement The IPMC samples were cut into 25 × 4 mm2 with the electrode contact of 10 square millimeters at the both sides. The actuator was cantilevered using two parallel Ag plates at one end. All the samples were fully hydrated and all the measurements were carried out at room temperature in air. A power sourcemeter (Aglient E3631A) was used to supply a direct current (DC) input and a waveform generator (Aglient 33522B) was employed to activate the actuator. The deflections were detected a 2D laser displacement sensor (LMI Gocater 2330), and the deflection points occurred at a point of 10 mm distance away from the fixed point of the samples at 3 V DC or alternating current (AC) inputs. The maximum blocking force of the samples was determined at one end of the IPMCs using a load cell (FUTEK LSB 200, 10 g). 3. RESULTS AND DISCUSSION



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3.1. Structural Characterization of BaTiO3/IPMC Nanocomposites The schematic diagrams of the IPMCs actuators without and with BaTiO3 nanoparticles are shown in Figure 1 (on the left side). The actuators deflect toward the cathodes under an applied voltage due to the accumulation of the free cations on the anodes, respectively, as shown in Figure 1 (on the right side). In comparison, the IPMC with BaTiO3 nanoparticles has larger actuation strain, arising from higher dielectric modulus by introducing BaTiO3 nanoparticles into the IPMC matrix to enhance the capacity of charge accumulation of samples.25 BaTiO3 was considered as a reinforced filler for the Nafion-based membranes because it is a ferroelectric material with high dielectric constant and low dielectric loss.25 The SEM images and EDX analysis of the IPMC samples without and with 3 wt% BaTiO3 are measured, as shown in Figure 2. The SEM image of the pure Nafion film in Figure 2(a) indicates that a great amount of microscale particles accumulates in the surface of the membrane. The corresponding line EDX analysis indicates that the membrane is lack of Ba and Ti elements, as shown in Figure 2(b). By contrast, the IPMC membrane with 3 wt% BaTiO3 nanoparticles are densely and relatively uniform, as shown in Figure 2(c), and the atom contents of Ba, Ti and F are measured by the line EDX analyses shown in Figure 2(d). The SEM images and line EDX analyses of other weight ratios of BaTiO3 nanoparticles are similar to those of the IPMC with 3 wt% BaTiO3 nanoparticles. 3.2. Electrical and Mechanical Measurements of BaTiO3/IPMC Nanocomposites The water uptake, surface resistance and ionic conductivity of the IPMC membranes without and


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with 1, 3 and 5 wt% BaTiO3 nanoparticles are measured, as shown in Table 1. It is found that both the water uptake and surface resistance of the IPMC samples decrease with adding BaTiO3 nanoparticles in the nanocomposites. The result suggests that the addition of BaTiO3 nanoparticles facilitates the deposition of Pt particles on the surface of the membranes. Besides, the ionic conductivity of the BaTiO3/Nafion nanocomposite membrane is higher than that of the pure Nafion counterpart. Especially, the ionic conductivity of the membrane with 3 wt% BaTiO3 nanoparticles is around 100 % higher than that of pure Nafion counterpart. Furthermore, mechanical properties of the membranes were measured using an universal testing machine because their mechanical properties strongly influence the blocking force and durability of the actuators.26,27 The blocking force depends on two factors: 1) the bending stiffness of the actuator beam and 2) the product of Young's modulus and the moment of inertia of the cross-section of the film. So, to enhance the Young’s modulus is an effective approach to improve the blocking force of the IPMC. The mechanical properties of the hydrated ionic membranes with different weight ratios of BaTiO3 nanoparticles are displayed in Table 2. It is found that BaTiO3 nanoparticles as the additives remarkably improve the mechanical performances of the IPMC membranes: Young's modulus and the tensile strength increases with adding BaTiO3 nanoparticles, and the maximum Young’s modulus and tensile strength reach up to 115 ± 1.89 and 13.5 ± 0.454 MPa, respectively. The enhancements can be ascribed to the stress transfer from BaTiO3 nanoparticles to the nanocomposite matrix because of the high surface area of the nanoadditives. To explore the actuation behavior of the nanocomposite membranes, their electrochemical performances were characterized by cyclic voltammeter (CV) in aqueous electrolytes with a



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three-electrode system. Figure 3a shows the CV curves of the membranes without and with BaTiO3 nanoparticles in a 1 M KOH solution at a 100 mV s-1 scan rate in a potential window from -0.6 to 0 V. No remarkable peak appears in all the curves for the IPMCs without and with BaTiO3 nanoparticles. The quasi-rectangular CV curves signify not only the ideal double layer capacitor characteristic but also their rate capability even at a high scan rate, as shown in Figure 3b. The specific capacitances in CV measurements were calculated using the following equation C = sp

2 1 IdV ∫ 1 ∆V ⋅ v ⋅ S V

(1)

V

where ∆V, v, S are the potential window, scan rate, and S is the weight taken of the IPMC membranes. Namely, the specific capacitances from the integrated area of CV curves are plotted against scan rates, as presented in the inset of Figure 3a. The capacitances are 1.04, 2.79, 66.8 and 89.8 F/g at a scan for the membranes with the weight ratios of 0, 1, 3 and 5 wt% BaTiO3 nanoparticles. The IMPC membrane with 3 wt% BaTiO3 nanoparticles has a remarkably higher specific capacitance than other samples at all scan rates. The corresponding capacitance exhibits 66.8 F/g at a scan rate of 100 mV/s, which is 63 times higher than that of the pure Nafion membrane (1.04 F/g). Complex impedance plane plots of the membranes without and with BaTiO3 nanoparticles are shown in Figure 3(c). The measured frequency of the applied voltage varied from 0.05 Hz to 100 kHz. It can be found that all the plots exhibit a straight line, and the lack of semicircles in the plot suggests the good electrical contact between the sample and the electrodes.28,29 Furthermore, the proton resistances (R) of the samples were calculated from the intercept of the real axis of the impedance spectrum. Capacitance (C) of the IPMC samples in low frequencies was calculated by


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the equation C = 1/(Zim·ω), where ω = 2πf is the angular frequency and f is the ordinary frequency.28 Figure 3(d) shows the capacitance as a function of frequency (from 0.05 to 1 Hz) of the samples with different weight ratios of BaTiO3 nanoparticles. The capacitances of the samples with BaTiO3 nanoparticles were remarkably much higher than that of the pure Nafion-based sample. The enhancement can be ascribed to the high dielectric constant and low dielectric loss properties of BaTiO3. The results show that the capacitance of the sample with 3 wt% BaTiO3 is highest among all the samples. High capacitance implies a high energy storage ability of the IPMCs, which is an important property of an IPMC membrane.21 3.3. Actuation Properties of BaTiO3/IPMC Nanocomposites On the basis of electrical and mechanical properties of the IPMCs, we investigate the actuation responses of the membranes. Figure 4(a-d) shows the photographs of the IPMC samples without and with BaTiO3 nanoparticles. Obviously, the actuation strain of the IPMC samples with BaTiO3 nanoparticles is higher than that of the samples without the nanoparticles. The deflection curves with time were adopted to describe the actuation behavior. Figure S2(a-d) shows the time-dependent deflection curves of the IPMC samples with 0, 1, 3 and 5 wt% BaTiO3 under a 3 V DC driving voltage, respectively. The 3D graphs clearly exhibit the deformation process of the IPMC cantilever actuators. It is found that the deformations of the samples are not stable under the voltage, the drive speed of the samples with BaTiO3 is much faster than that of the pure Nafion membrane, and the deflection of the samples with BaTiO3 nanoparticles is larger than that of the pure membrane. To quantitatively explain the actuation responses, the time-dependent deflections of the set points, which are 10 mm away from the fixed points of the membranes, are measured, as shown in Figure



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5(a). Under a 3 V driving voltage, the deflections of the samples with 0, 1, 3 and 5 wt% BaTiO3 nanoparticles reach their extreme values in 8.6, 6, 5 and 5.8 s, respectively. The corresponding maximum deflections of the samples are 2.07, 2.45, 4.17 and 2.47 mm, respectively, which are marked with vertical dotted lines. Not only the deflection of the sample with 3 wt% BaTiO3 nanoparticles exhibits 101.4% enhancement over the pure counterpart, but also the drive speed displays a quicker response. Additionally, the blocking force is an important evaluation index of the IPMC actuators. Figure 5(b) shows the blocking force of the IPMC actuators with 0, 1, 3 and 5 wt% BaTiO3 nanoparticles. Similar to the maximum deflection, the IPMC sample with 3 wt% BaTiO3 nanoparticles has the highest blocking force up to 0.76 g, which is 375% enhancement than that of the pure sample with a blocking force of 0.16 g. The blocking force of both the samples with 1 and 5 wt% BaTiO3 nanoparticles is 0.35 g, around 118.8% exceeding that of the pure sample. The results demonstrate that doping BaTiO3 nanoparticles into the Nafion matrix remarkably improve the blocking force of the IPMCs due to increase their bending stiffness. The actuation performances of the dry-type IPMC actuators were evaluated with various harmonic electric inputs. Figure 6(a-c) depicts the deflections of the samples under a 3 V AC voltage with 0.1, 0.4 and 1 Hz excitations, respectively. It is found that the deformations of the BaTiO3 nanoparticles/Nafion-based IPMCs were remarkably larger than that of the pure Nafion-based membrane. The IPMC membrane with 3 wt% BaTiO3 nanoparticles shows the largest deflection with time under a 3 V AC input with 1 Hz, and the corresponding deflection is up to 250% enhancement over that of the pure IMPC. Figure 6(d) shows the peak displacements of the


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samples as a function of the frequency under a 3 V AC voltage. It can be observed that the displacements of the samples decrease with increasing frequency. The displacements of the IPMCs with BaTiO3 nanoparticles are much higher than that of the pure sample at a frequency of less than 1 Hz and larger displacement are obtained in the frequency range of 0.04-0.1 Hz due to the fully accumulations of hydrated cations on the cathode side,21,28-30 while the values of all the samples are very close when the frequency is higher than 5 Hz. Moreover, the samples exhibit very low displacements because there is not enough time for realizing fully accumulation of charge on the cathode at a high frequency of 10 Hz. 4. CONCLUSION In summary, BaTiO3/Nafion nanocomposite membranes with different weight ratios of BaTiO3 nanoparticles were fabricated. The addition of the BaTiO3 nanoparticles induces a remarkable enhancement in mechanical and electromechanical properties of the Nafion-based IPMC membranes. The composites have lower water uptake but better ionic conductivity and capacitance than those of the pure Nafion membranes, moreover, their Young's modulus and the tensile strength increase with doping BaTiO3 nanoparticles. Actuating measurements show that the membranes with BaTiO3 nanoparticles exhibit the best overall property than the pure counterpart. The improved actuation response is attributed to the double-layer electrostatic effect induced by the broad dispersion of penetrated nanoparticles into electrodes. This study opens a new avenue for developing high-performance IPMC actuator by doping metal oxide nanostructures.



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ASSOCIATED CONTENT Supporting Information FE-SEM image and corresponding XRD pattern of BaTiO3 nanopowders. The graphs of measured deflection curve versus time of the Pt-IPMCs with different weight ratios BaTiO3 under a 3 V DC excitation voltage. AUTHOR INFORMATION Corresponding Authors *E-mail: [email protected], Ph 86-25-84891502, Fax 86-25-84891512. Notes The authors declare no competing financial interest. ACKNOWLEDGEMENTS This research was supported by the National Natural Science Foundation of China (11502109, 11372132, 61474063 and 11302100), Jiangsu NSF (SBK2015022205), the Innovation Fund of NUAA (NE2015102), SKL Funding of NUAA (0415G02) and the Priority Academic Program Development of Jiangsu Higher Education Institutions. REFERENCES (1) Kong, L. R.; Chen, W. Carbon Nanotube and Graphene-based Bioinspired Electrochemical Actuators. Adv. Mater. 2014, 26, 1025-1043. (2) Park, J. H.; Lee, S. W.; Song, D. S.; Jho, J. Y. Highly Enhanced Force Generation of Ionic


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Polymer-Metal Composite Actuators via Thickness Manipulation. ACS Appl. Mater. Inter. 2015, 7, 16659-16667. (3) Shahinpoor, M.; Bar-Cohen, Y.; Simpson, J. O.; Smith, J. Ionic Polymer-Metal Composites (IPMCs) as Biomimetic Sensors, Actuators and Artificial Muscles - a Review. Smart Mater. Struct. 1998, 7, R15-R30. (4) Shahinpoor, M.; Kim, K. J. Ionic Polymer-Metal Composites: I. Fundamentals. Smart Mater. Struct. 2001, 10, 819-833. (5) Punning, A.; Kim, K. J.; Palmre, V.; Vidal, F.; Plesse, C.; Festin, N.; Maziz, A.; Asaka, K.; Sugino, T.; Alici, G.; et al. Ionic Electroactive Polymer Artificial Muscles in Space Applications. Sci. Rep. 2014, 4, 6913. (6) Wu, G.; Hu, Y.; Liu, Y.; Zhao, J. J.; Chen, X. L.; Whoehling, V.; Plesse, C.; Nguyen, G. T. M.; Vidal, F.; Chen, W. Graphitic Carbon Nitride Nanosheet Electrode-Based High-Performance Ionic Actuator. Nat. Commun. 2015, 6, 7258. (7) De Luca, V.; Digiamberardino, P.; Di Pasquale, G.; Graziani, S.; Pollicino, A.; Umana, E.; Xibilia, M. G. Ionic Electroactive Polymer Metal Composites: Fabricating, Modeling, and Applications of Postsilicon Smart Devices. J. Polym. Sci. Pol. Phys. 2013, 51, 699-734. (8) Shahinpoor, M.; Kim, K. J. Ionic Polymer-Metal Composites: IV. Industrial and Medical Applications. Smart Mater. Struct. 2005, 14, 197-214. (9) Jain, R. K.; Majumder, S.; Dutta, A. SCARA Based Peg-in-Hole Assembly using Compliant IPMC Micro Gripper. Robot Auton. Syst. 2013, 61, 297-311. (10) Aw, K. C.; McDaid, A. J. Bio-Applications of Ionic Polymer Metal Composite Transducers.



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Smart Mater. Struct. 2014, 23, 074005. (11) Kim, K. J.; Shahinpoor, M. Ionic Polymer-Metal Composites: II. Manufacturing Techniques. Smart Mater. Struct. 2003, 12, 65-79. (12) Palmre, V.; Pugal, D.; Kim, K. J.; Leang, K. K.; Asaka, K.; Aabloo, A. Nanothorn Electrodes for Ionic Polymer-Metal Composite Artificial Muscles. Sci. Rep. 2014, 4, 6176. (13) Dai, C. A.; Hsiao, C. C.; Weng, S. C.; Kao, A. C.; Liu, C. P.; Tsai, W. B.; Chen, W. S.; Liu, W. M.; Shih, W. P.; Ma, C. C. A Membrane Actuator Based on an Ionic Polymer Network and Carbon Nanotubes: the Synergy of Ionic Transport and Mechanical Properties. Smart Mater. Struct. 2009, 18, 085016. (14) Akle, B. J.; Bennett, M. D.; Leo, D. J. High-Strain Ionomeric-Ionic Liquid Electroactive Actuators. Sensor Actuat. A-Phys. 2006, 126, 173-181. (15) Lee, J. W.; Yoo, Y. T. Preparation and Performance of IPMC Actuators with Electrospun Nafion (R)-MWNT Composite Electrodes. Sensor Actuat. B-Chem. 2011, 159, 103-111. (16) Lee, D. Y.; Park, I. S.; Lee, M. H.; Kim, K. J.; Heo, S. Ionic Polymer-Metal Composite Bending Actuator Loaded with Multi-Walled Carbon Nanotubes. Sensor Actuat. A-Phys. 2007, 133, 117-127. (17) Lian, H. Q.; Qian, W. Z.; Estevez, L.; Liu, H. L.; Liu, Y. X.; Jiang, T.; Wang, K. S.; Guo, W. L.; Giannelis, E. P. Enhanced Actuation in Functionalized Carbon Nanotube-Nafion Composites. Sensor Actuat. B-Chem. 2011, 156, 187-193. (18) Yip, J.; Ding, F.; Yick, K. L.; Yuen, C. W. M.; Lee, T. T.; Choy, W. H. Tunable Carbon Nanotube Ionic Polymer Actuators that are Operable in Dry Conditions. Sensor Actuat. B-Chem.


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2012, 162, 76-81. (19) Jung, J. H.; Jeon, J. H.; Sridhar, V.; Oh, I. K. Electro-Active Graphene-Nafion Actuators. Carbon 2011, 49, 1279-1289. (20) Thomassin, J. M.; Kollar, J.; Caldarella, G.; Germain, A.; Jerome, R.; Detrembleur, C. Beneficial Effect of Carbon Nanotubes on the Performances of Nafion Membranes in Fuel Cell Applications. J. Membrane Sci. 2007, 303, 252-257. (21) Terasawa, N.; Mukai, K.; Asaka, K. Improved Performance of an Activated Multi-Walled Carbon Nanotube Polymer Actuator, Compared with a Single-Walled Carbon Nanotube Polymer Actuator. Sensor Actuat. B-Chem. 2012, 173, 66-71. (22) Terasawa,

N.; Takeuchi,

I.

Electrochemical and Electromechanical Properties

of

High-Performance Polymer Actuators Containing Vapor Grown Carbon Nanofiber and Metal Oxide. Sensor Actuat. B-Chem. 2013, 176, 1065-1073. (23) Zheng, H. J.; Zhu, K. J.; Wu, Q. L.; Liu, J. S.; Qiu, J. H. Preparation and Characterization of Monodispersed BaTiO3 Nanocrystals by Sol-Hydrothemal Method. J. Cryst. Growth 2013, 363, 300-307. (24) Sun, Q. M.; Gu, Q. L.; Zhu, K. J.; Wang, J.; Qiu, J. H. Stabilized Temperature-Dependent Dielectric Properties of Dy-Doped BaTiO3 Ceramics Derived from Sol-Hydrotherrnally Synthesized Nanopowders. Ceram. Int. 2016, 42, 3170-3176. (25) Hanemann,

T.;

Gesswein,

H.;

Schumacher,

B.

Development

of

New

Polymer-BaTiO3-Composites with Improved Permittivity for Embedded Capacitors. Microsyst. Technol. 2011, 17, 195-201.



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(26) Wang, Y. J.; Zhu, Z. C.; Chen, H. L.; Luo, B.; Chang, L. F.; Wang, Y. Q.; Li, D. C. Effects of Preparation Steps on the Physical Parameters and Electromechanical Properties of IPMC Actuators. Smart Mater. Struct. 2014, 23, 125015. (27) Lufrano, F.; Staiti, P. Performance Improvement of Nafion Based Solid State Electrochemical Supercapacitor. Electrochim. Acta 2004, 49, 2683-2689. (28) Panwar, V.; Ko, S. Y.; Park, J. O.; Park, S. Enhanced and Fast Actuation of Fullerenol/PVDF/PVP/PSSA Based Ionic Polymer Metal Composite Actuators. Sensor Actuat. B-Chem. 2013, 183, 504-517. (29) Wang, X. L.; Oh, I. K.; Cheng, T. H. Electro-Active Polymer Actuators Employing Sulfonated Poly(styrene-ran-ethylene) as Ionic Membranes. Polym. Int. 2010, 59, 305-312. (30) Nguyen, V. K.; Yoo, Y. T. A Novel Design and Fabrication of Multilayered Ionic Polymer-Metal Composite Actuators Based on Nafion/Layered Silicate and Nafion/Silica Nanocomposites. Sensor Actuat. B-Chem. 2007, 123, 183-190.


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Figure captions Figure 1. (a,c) Schematic diagrams showing the composition of IPMC actuators without and with BaTiO3 nanoparticles along with the ions repartition in the membrane, respectively. (b,d) The actuation mechanism of IPMC actuators without and with BaTiO3 nanoparticles, respectively. Figure 2. (a) SEM image of the pure IPMC membrane. (b) Cross-section SEM image of the pure IPMC membrane. (c) SEM image of the membrane with 3 wt% BaTiO3 nanoparticles. (d) Cross-section SEM image of the membrane without BaTiO3 nanoparticles. Insets in (b) and (d) are line EDX analysis of F, Ba and Ti elements corresponding to the arrows. Figure 3. (a) Cyclic voltammetry analysis of the IPMCs with different weight ratios of BaTiO3 nanoparticles at a scan rate of 100 mV/s. (b) Cyclic voltammetry analysis of the IPMCs with 3 wt% BaTiO3 nanoparticles at various scan rates. (c) Complex impedance plane plots of IPMCs with different weight ratios of BaTiO3 nanoparticles. (d) Capacitance as a function of the frequency of the IPMCs analysis of the IPMCs with different weight ratios of BaTiO3 nanoparticles under 1 V AC drive voltage. Figure 4. Photographs of deflects versus time of the IPMCs without (a) and without BaTiO3 nanoparticles of (b) 1, (c) 3 and (d) 5 wt%. A 3 V voltage was applied to excite the deflections. Figure 5. (a) Time-related to deflections of the IPMCs with different weight ratios of BaTiO3 nanoparticles. The set-points are 10 mm away from the fixed points and the actuators are excited by a 3 V DC voltage. (b) The blocking force of the IPMCs with different weight ratios of BaTiO3 nanoparticles under a 3 V DC voltage.



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Figure 6. Time-related deflections of the IPMCs with different weight ratios of BaTiO3 nanoparticles at AC frequencies: (a) 0.1, (b) 0.4 and (c) 1 Hz. The set points are 10 mm away from the fixed points and the actuators are excited by a 3 V DC voltage. (d) Deflections versus frequencies of the IPMCs. Table 1. Mechanical properties of hydrated ionic membranes. Table 2. Basic properties of the composite membranes.


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Figure 1



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Figure 2


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Figure 3



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Figure 4


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Figure 5



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Figure 6


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Table 1

Table 2



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TOC Graphic


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Enhanced Actuation Response of Nafion-Based Ionic Polymer Metal

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