New Polymeric Composite Materials, Chapter 11

$15.95

An Overview of Preparation, Properties and Applications of Ionic Polymer Composite Actuators

Inamuddin and Ajahar Khan

It deals with the basic information regarding to the materials and their types used for manufacturing IPMC actuators using various fabrication processes under optimum experimental parameters and possible applications. Among the variety of electroactive polymers recently developed IPMCs are good candidates for use in bio-related, robotics and aerospace applications because of their biocompatibility. Several fabrication processes, their performance and mechanical characteristics, a number of recent applications of IPMCs have been reported in this chapter. The control and various factors affecting performance of IPMC have also been reported.

Keywords
Ionic Polymer Metal Composites, Bending Actuator, Electroless Plating, Structure of IPMC

Published online 11/1/2016, 61 pages

DOI: http://dx.doi.org/10.21741/9781945291098-11

Part of New Polymeric Composite Materials

References
[1] Y. Bar-Cohen, No TitleElectroactive polymer [EAP] actuators as artificial muscles, 1st ed, SPIE Press, Bellingham, Washington, 2001.
[2] R. Tiwari, E. Garcia, The state of understanding of ionic polymer metal composite architecture: a review, Smart Mater. Struct. 20 (2011) 83001.
[3] K. Sadeghipour, R. Salomon, S. Neogi, Development of a novel electrochemically active membrane and “smart” material based vibration sensor/damper, Smart Mater. Struct. 1 (1992) 172.
[4] K. Oguro, H. Takenaka, Y. Kawami, Actuator element, (1993).
[5] K. Asaka, K. Oguro, Y. Nishimura, M. Mizuhata, H. Takenaka, Bending of Polyelectrolyte Membrane-Platinum Composites by Electric Stimuli I. Response Characteristics to Various Waveforms., Polym. J. 27 (1995) 436–440. doi:10.1295/polymj.27.436.
[6] M.S. M. Mojarrad, No Title, in: Proc. SPIE Smart Struct. Mater. Symp., 1997: p. 294.
[7] J.S. Y. Bar-Cohen, M. Shahinpoor, J.O. Harrison, No Title, in: Proc. SPIE Smart. Struct. Mater. Symp., 1999: pp. 3669, 51.
[8] K. Asaka, K. Oguro, Bending of polyelectrolyte membrane platinum composites by electric stimuli: Part II. Response kinetics, J. Electroanal. Chem. 480 (2000) 186–198. doi:http://dx.doi.org/10.1016/S0022-0728(99)00458-1.
[9] P.G. de Gennes, K. Okumura, M. Shahinpoor, K.J. Kim, Mechanoelectric effects in ionic gels, EPL (Europhysics Lett. 50 (2000) 513.
[10] B. Bhandari, G.-Y. Lee, S.-H. Ahn, A review on IPMC material as actuators and sensors: Fabrications, characteristics and applications, Int. J. Precis. Eng. Manuf. 13 (2012) 141–163. doi:10.1007/s12541-012-0020-8.
[11] Inamuddin, R.K. Jain, S. Hussain, M. Naushad, Poly (3,4-ethylenedioxythiophene): polystyrene sulfonate zirconium(IV) phosphate compsiteionomeric membrane for artifical muscle application. RSC Adv 5 (2015) 84526-84534.
[12] G. Alici, G. Spinks, N.N. Huynh, L. Sarmadi, R. Minato, Establishment of a biomimetic device based on tri-layer polymer actuators—propulsion fins, Bioinspir. Biomim. 2 (2007) S18.
[13] S. McGovern, G. Alici, V.-T. Truong, G. Spinks, Finding NEMO (novel electromaterial muscle oscillator): a polypyrrole powered robotic fish with real-time wireless speed and directional control, Smart Mater. Struct. 18 (2009) 95009.
[14] G. Alici, M.J. Higgins, Normal stiffness calibration of microfabricated tri-layer conducting polymer actuators, Smart Mater. Struct. 18 (2009) 65013.
[15] Y. Bar-Cohen, Q. Zhang, Electroactive Polymer Actuators and Sensors, MRS Bull. 33 (2008) 173–181. doi:10.1557/mrs2008.42.
[16] Y. Bar-Cohen, No Title Electroactive polymer (EAP) actuators as artificial muscles: reality, potential, and challenges, 2nd ed, SPIE Publications, Bellingham, Washington, 2004.
[17] J.-Y. Jung, I.-K. Oh, Novel Nanocomposite Actuator Based on Sulfonated Poly(styrene-b-ethylene-co-butylene-b-styrene) Polymer, J. Nanosci. Nanotechnol. 7 (2007) 3740–3743. doi:10.1166/jnn.2007.004.
[18] J. Lu, S.-G. Kim, S. Lee, I.-K. Oh, Fabrication and actuation of electro-active polymer actuator based on PSMI-incorporated PVDF, Smart Mater. Struct. 17 (2008) 45002.
[19] K. Ikeda, M. Sasaki, H. Tamagawa, {IPMC} bending predicted by the circuit and viscoelastic models considering individual influence of Faradaic and non-Faradaic currents on the bending, Sensors Actuators B Chem. 190 (2014) 954–967. doi:http://dx.doi.org/10.1016/j.snb.2013.09.016.
[20] G. M’boungui, B. Semail, F. Giraud, A.A. Jimoh, Development of a novel plane piezoelectric actuator using Hamilton’s principle based model and Hertz contact theory, Sensors Actuators A Phys. 217 (2014) 116–123. doi:http://dx.doi.org/10.1016/j.sna.2014.06.026.
[21] M. Shahinpoor, K.J. Kim, Ionic polymer–metal composites: IV. Industrial and medical applications, Smart Mater. Struct. 14 (2005) 197–214. doi:10.1088/0964-1726/14/1/020.
[22] M.J. Han, J.H. Park, J.Y. Lee, J.Y. Jho, Ionic Polymer-Metal Composite Actuators Employing Radiation-Grafted Fluoropolymers as Ion-Exchange Membranes, (2006) 219–222. doi:10.1002/marc.200500694.
[23] J.-H. Jeon, S.-P. Kang, S. Lee, I.-K. Oh, Novel biomimetic actuator based on {SPEEK} and {PVDF}, Sensors Actuators B Chem. 143 (2009) 357–364. doi:http://dx.doi.org/10.1016/j.snb.2009.09.020.
[24] G.-H. Feng, J.-W. Tsai, Investigation of electrical to mechanical energy conversion of a three-dimensional four-electrode multidirectional-controllable IPMC transducer with/without an optical fiber enclosed, Smart Mater. Struct. 20 (2011) 15027.
[25] Y. Fang, X. Tan, A novel diaphragm micropump actuated by conjugated polymer petals: Fabrication, modeling, and experimental results, Sensors Actuators A Phys. 158 (2010) 121–131. doi:http://dx.doi.org/10.1016/j.sna.2009.12.012.
[26] H. Lei, W. Li, X. Tan, Encapsulation of ionic polymer-metal composite (IPMC) sensors with thick parylene: Fabrication process and characterization results, Sensors Actuators A Phys. 217 (2014) 1–12. doi:http://dx.doi.org/10.1016/j.sna.2014.05.013.
[27] M.M. M. Shahinpoor, K.J. Kim, Artificial muscles: applications of advanced polymeric nanocomposites, Taylor and Francis, New York, 2007.
[28] M. Shahinpoor, Y. Bar-Cohen, J.O. Simpson, J. Smith, Ionic polymer-metal composites (IPMCs) as biomimetic sensors, actuators and artificial muscles – a review, Smart Mater. Struct. 7 (1998) R15.
[29] A. Khan, Inamuddin, R.K. Jain, M. Naushad, Fabrication of a silver nano powder embedded kraton polymer actuator and its characterization, RSC Adv. 5 (2015) 91564–91573. doi:10.1039/C5RA17776F.
[30] J.S. Y. Bar-Cohen, S. Leary, A. Yavrouian, K. Oguro, S. Tadokoro, J. Harrison, J. Smith, No Title, in: Proc. SPIE Smart. Struct. Mater. Symp., 2000: p. 140.
[31] M. Shahinpoor, Conceptual design, kinematics and dynamics of swimming robotic structures using ionic polymeric gel muscles, Smart Mater. Struct. 1 (1992) 91.
[32] K. Oguro, Y. Kawami, H. Takenaka, Bending of an ion-conducting polymer film-electrode composite by an electric stimulus at low voltage, J. Micromachine Soc. 5 (1992) 27–30.
[33] Inamuddin, A. Khan, R.K. Jain, M. Naushad, Development of sulfonated poly(vinyl alcohol)/polpyrrole based ionic polymer metal composite (IPMC) actuator and its characterization, Smart Mater. Struct. 24 (2015) 95003. http://stacks.iop.org/0964-1726/24/i=9/a=095003.
[34] M. Shahinpoor, K.J. Kim, Ionic polymer-metal composites: I. Fundamentals, Smart Mater. Struct. 10 (2001) 819.
[35] S. Nemat-Nasser, J.Y. Li, Electromechanical response of ionic polymer-metal composites, J. Appl. Phys. 87 (2000) 3321. doi:10.1063/1.372343.
[36] M. Shahinpoor, K.J. Kim, D.J. Leo, Ionic polymer-metal composites as multifunctional materials, Polym. Compos. 24 (2003) 24–33. doi:10.1002/pc.10002.
[37] M. Shahinpoor, Ionic polymer–conductor composites as biomimetic sensors, robotic actuators and artificial muscles—a review, Electrochim. Acta. 48 (2003) 2343–2353. doi:http://dx.doi.org/10.1016/S0013-4686(03)00224-X.
[38] A.J. Grodzinsky, Electromechanics of deformable polyelectrolyte membranes., Cambridge, 1974.
[39] B.J. Akle, D.J. Leo, Single-Walled Carbon Nanotubes — Ionic Polymer Electroactive Hybrid Transducers, J. Intell. Mater. Syst. Struct. 19 (2007) 905–915. doi:10.1177/1045389X07082441.
[40] I.W. Hunter, S. Lafontaine, A comparison of muscle with artificial actuators, in: Tech. Dig. IEEE Solid-State Sens. Actuator Work., IEEE, n.d.: pp. 178–185. doi:10.1109/SOLSEN.1992.228297.
[41] H.-I. Kim, D.-K. Kim, J.-H. Han, Study of flapping actuator modules using IPMC, in: Y. Bar-Cohen (Ed.), 2007: p. 65241A. doi:10.1117/12.715633.
[42] Inamuddin, A. Khan, R.K. Jain, M. Naushad, Study and preparation of highly water-stable polyacrylonitrile-kraton-graphene composite membrane for bending actuator toward robotic application, J. Intell. Mater. Syst. Struct. 27 (2016). doi:10.1177/1045389X15596627.
[43] D. Pugal, K. Jung, A. Aabloo, K.J. Kim, Ionic polymer-metal composite mechanoelectrical transduction: review and perspectives, Polym. Int. 59 (2010) 279–289. doi:10.1002/pi.2759.
[44] A. Punning, M. Kruusmaa, A. Aabloo, Surface resistance experiments with {IPMC} sensors and actuators, Sensors Actuators A Phys. 133 (2007) 200–209. doi:http://dx.doi.org/10.1016/j.sna.2006.03.010.
[45] S.J. Kim, S.-M. Kim, K.J. Kim, Y.H. Kim, An electrode model for ionic polymer–metal composites, Smart Mater. Struct. 16 (2007) 2286.
[46] M. Shahinpoor, K.J. Kim, The effect of surface-electrode resistance on the performance of ionic polymer-metal composite (IPMC) artificial muscles, Smart Mater. Struct. 9 (2000) 543.
[47] M. Shahinpoor, K.J. Kim, Novel ionic polymer–metal composites equipped with physically loaded particulate electrodes as biomimetic sensors, actuators and artificial muscles, Sensors Actuators A Phys. 96 (2002) 125–132. doi:http://dx.doi.org/10.1016/S0924-4247(01)00777-4.
[48] C.K. Chung, P.K. Fung, Y.Z. Hong, M.S. Ju, C.C.K. Lin, T.C. Wu, A novel fabrication of ionic polymer-metal composites (IPMC) actuator with silver nano-powders, Sensors Actuators B Chem. 117 (2006) 367–375. doi:http://dx.doi.org/10.1016/j.snb.2005.11.021.
[49] B.J. Akle, No Title Electrochemical response in ionic polymer transducers: an experimental and theoretical study, Virginia Polytechnic Institute and State University, 2005.
[50] K. Kanamura, H. Morikawa, T. Umegaki, Observation of Interface Between Pt Electrode and Nafion Membrane, J. Electrochem. Soc. 150 (2003) A193. doi:10.1149/1.1531970.
[51] M. Tsuda, W.A. Diño, H. Kasai, Behavior of hydrogen atom at Nafion–Pt interface, Solid State Commun. 134 (2005) 601–605. doi:http://dx.doi.org/10.1016/j.ssc.2005.03.006.
[52] A. Gruger, A. Régis, T. Schmatko, P. Colomban, Nanostructure of Nafion® membranes at different states of hydration: An {IR} and Raman study, Vib. Spectrosc. 26 (2001) 215–225. doi:http://dx.doi.org/10.1016/S0924-2031(01)00116-3.
[53] K.A. Mauritz, R.B. Moore, State of Understanding of Nafion, (2004).
[54] D. Seeliger, C. Hartnig, E. Spohr, Aqueous pore structure and proton dynamics in solvated Nafion membranes, Electrochim. Acta. 50 (2005) 4234–4240. doi:http://dx.doi.org/10.1016/j.electacta.2005.03.071.
[55] G. Polizos, Z. Lu, D.D. Macdonald, E. Manias, State of Water in Nafion 117 Proton Exchange Membranes Studied by Dielectric Relaxation Spectroscopy, MRS Proc. 972 (2006) 972-NaN-7. doi:10.1557/PROC-0972-AA08-07.
[56] N.P. Berezina, N.A. Kononenko, A.A.-R. Sytcheva, N. V Loza, S.A. Shkirskaya, N. Hegman, A. Pungor, Perfluorinated nanocomposite membranes modified by polyaniline: Electrotransport phenomena and morphology, Electrochim. Acta. 54 (2009) 2342–2352. doi:http://dx.doi.org/10.1016/j.electacta.2008.10.048.
[57] S.S. K. Oguro, N. Fujiwara, K. Asaka, K. Onishi, Smart Struct. Mater Symp. Proc. SPIE 3669 (1999) 64-71.
[58] S. Nemat-Nasser, Y. Wu, Comparative experimental study of ionic polymer–metal composites with different backbone ionomers and in various cation forms, J. Appl. Phys. 93 (2003) 5255. doi:10.1063/1.1563300.
[59] Z. Lu, M. Lanagan, E. Manias, D.D. Macdonald, Two-Port Transmission Line Technique for Dielectric Property Characterization of Polymer Electrolyte Membranes, J. Phys. Chem. B. 113 (2009) 13551–13559. doi:10.1021/jp9057115.
[60] M.W. Verbrugge, Analysis of Promising Perfluorosulfonic Acid Membranes for Fuel-Cell Electrolytes, J. Electrochem. Soc. 137 (1990) 3770. doi:10.1149/1.2086299.
[61] S. Ford, G. Macias, R. Lumia, Single active finger IPMC microgripper, Smart Mater. Struct. 24 (2015) 25015.
[62] P. Choi, N.H. Jalani, R. Datta, Thermodynamics and Proton Transport in Nafion, J. Electrochem. Soc. 152 (2005) E123. doi:10.1149/1.1859814.
[63] Inamuddin, A. Khan, M. Luqman, A. Dutta, Kraton based ionic polymer metal composite (IPMC) actuator, Sensors Actuators A Phys. 216 (2014) 295–300. doi:http://dx.doi.org/10.1016/j.sna.2014.04.015.
[64] K. Onishi, S. Sewa, K. Asaka, N. Fujiwara, K. Oguro, Morphology of electrodes and bending response of the polymer electrolyte actuator, Electrochim. Acta. 46 (2001) 737–743. doi:http://dx.doi.org/10.1016/S0013-4686(00)00656-3.
[65] L. Naji, J.A. Chudek, R.T. Baker, Time-Resolved Mapping of Water Diffusion Coefficients in a Working Soft Actuator Device, J. Phys. Chem. B. 112 (2008) 9761–9768. doi:10.1021/jp803792c.
[66] N. Jin, B. Wang, K. Bian, Q. Chen, K. Xiong, Performance of ionic polymer-metal composite (IPMC) with different surface roughening methods, Front. Mech. Eng. China. 4 (2009) 430–435. doi:10.1007/s11465-009-0053-6.
[67] R. Tiwari, No Title Modeling and characterization of IPMC energy harvesters, Lambert Academic, Saarbrucken, 2010.
[68] S.-M. Kim, K.J. Kim, Palladium buffer-layered high performance ionic polymer–metal composites, Smart Mater. Struct. 17 (2008) 35011.
[69] I.-S. Park, K.J. Kim, Multi-fields responsive ionic polymer–metal composite, Sensors Actuators A Phys. 135 (2007) 220–228. doi:http://dx.doi.org/10.1016/j.sna.2006.07.014.
[70] J.-W. Lee, Y.-T. Yoo, The Structure and Performance of Ionic Polymer-Metal Composite Actuators Prepared via Electroless Plating Process Using Various Alcohols, Macromol. Symp. 249–250 (2007) 56–60. doi:10.1002/masy.200750309.
[71] D.Y. Lee, K.J. Kim, S. Heo, M.H. Lee, B.Y. Kim, Application of an Equivalent Circuit Model for Ionic Polymer-Metal Composite (IPMC) Bending Actuator Loaded With Multiwalled Carbon Nanotube (M-CNT), Key Eng. Mater. 309–311 (2006) 593–596. doi:10.4028/www.scientific.net/KEM.309-311.593.
[72] H. Takenaka, E. Torikai, Y. Kawami, N. Wakabayashi, Solid polymer electrolyte water electrolysis, Int. J. Hydrogen Energy. 7 (1982) 397–403. doi:http://dx.doi.org/10.1016/0360-3199(82)90050-7.
[73] R.P. HAMLEN, C.E. KENT, S.N. SHAFER, Electrolytically Activated Contractile Polymer, Nature. 206 (1965) 1149–1150. doi:10.1038/2061149b0.
[74] T.K.K. N. Fujiwara, Y. Nishimura, K. Oguro, E. Torikai, No Title, 1997.
[75] T.K.K. N. Fujiwara, Y. Nishimura, K. Oguro, E. Torikai, No Title, 1998.
[76] V. Palmre, D. Brandell, U. Mäeorg, J. Torop, O. Volobujeva, A. Punning, U. Johanson, M. Kruusmaa, A. Aabloo, Nanoporous carbon-based electrodes for high strain ionomeric bending actuators, Smart Mater. Struct. 18 (2009) 95028.
[77] N. Fujiwara, K. Asaka, Y. Nishimura, K. Oguro, E. Torikai, Preparation of Gold−Solid Polymer Electrolyte Composites As Electric Stimuli-Responsive Materials, Chem. Mater. 12 (2000) 1750–1754. doi:10.1021/cm9907357.
[78] E. Frackowiak, F. Béguin, Electrochemical storage of energy in carbon nanotubes and nanostructured carbons, Carbon N. Y. 40 (2002) 1775–1787. doi:http://dx.doi.org/10.1016/S0008-6223(02)00045-3.
[79] I.S. Park, R. Tiwari, K.J. Kim, Sprayed Sensor Using IPMC PAINT, Adv. Sci. Technol. 61 (2008) 59–64. doi:10.4028/www.scientific.net/AST.61.59.
[80] J.N. Barisci, G.G. Wallace, D. Chattopadhyay, F. Papadimitrakopoulos, R.H. Baughman, Electrochemical Properties of Single-Wall Carbon Nanotube Electrodes, J. Electrochem. Soc. 150 (2003) E409. doi:10.1149/1.1593045.
[81] J. Brufau-Penella, M. Puig-Vidal, P. Giannone, S. Graziani, S. Strazzeri, Characterization of the harvesting capabilities of an ionic polymer metal composite device, Smart Mater. Struct. 17 (2008) 15009.
[82] D.Y. Lee, I.-S. Park, M.-H. Lee, K.J. Kim, S. Heo, Ionic polymer–metal composite bending actuator loaded with multi-walled carbon nanotubes, Sensors Actuators A Phys. 133 (2007) 117–127. doi:http://dx.doi.org/10.1016/j.sna.2006.04.005.
[83] I. Kang,Y.Y. Heung, J.H. Kim, J.W. Lee, R. Gollapudi, S. Subramaniam, S. Narasimhadevara, D. Hurd, G. R. Krikera, V. Shanov, M.J. Schulz, D. Shi, J. Boerio, S. Mall, M.R. Wren, Introduction to carbon nanotube and nanofiber smart materials, Compos. Part B Eng. 37 (2006) 382–394.
[84] Y.Y. V.K. Nguyen, H.T. Lim, J.W. Lee, Effect of reduction temperature on electrode formation and performance of ionic polymer metal composites, Proc. SPIE Smart Struct. Mater. Symp, 2006: p. 616813.
[85] M.H.L. S. Heo, K.J. Kim, D.Y. Lee, S. Vemuri, No Title, in: Proc. SPIE Smart Struct. Mater. Symp, 2005: p. 194.
[86] D.Y. Lee, M.-H. Lee, K.J. Kim, S. Heo, B.-Y. Kim, S.-J. Lee, Effect of multiwalled carbon nanotube (M-CNT) loading on M-CNT distribution behavior and the related electromechanical properties of the M-CNT dispersed ionomeric nanocomposites, Surf. Coatings Technol. 200 (2005) 1920–1925. doi:http://dx.doi.org/10.1016/j.surfcoat.2005.08.024.
[87] R.J. Lawrance, L.D. Wood, U.S. Patent 4 272 353 9, 1981.
[88] S,.Surampudi, S. R. Narayanan, E. Vamos, H. Frank and G. Halpert, Advances in Direct Methanol Fuel Cells, J. Power Sources, 47 (1994) 377-385..
[89] C. Yi-Lin, C. Tse-Chuan, Metals and alloys bonded on solid polymer electrolyte for electrochemical reduction of pure benzaldehyde without liquid supporting electrolyte, J. Electroanal. Chem. 360 (1993) 247–259. doi:http://dx.doi.org/10.1016/0022-0728(93)87017-P.
[90] D.W. Dewulf, A.J. Bard, The electrochemical reduction of CO2 to CH4 and C2H4 at Cu/Nafion electrodes (solid polymer electrolyte structures), Catal. Letters. 1 (1988) 73–79. doi:10.1007/BF00765357.
[91] U. Johanson, U. Mäeorg, V. Sammelselg, D. Brandell, A. Punning, M. Kruusmaa, A. Aabloo, Electrode reactions in Cu–Pt coated ionic polymer actuators, Sensors Actuators B Chem. 131 (2008) 340–346. doi:http://dx.doi.org/10.1016/j.snb.2007.11.044.
[92] B.-K. Fang, M.-S. Ju, C.-C.K. Lin, A new approach to develop ionic polymer–metal composites (IPMC) actuator: Fabrication and control for active catheter systems, Sensors Actuators A Phys. 137 (2007) 321–329. doi:http://dx.doi.org/10.1016/j.sna.2007.03.024.
[93] G. Di Pasquale, L. Fortuna, S. Graziani, M. La Rosa, D. Nicolosi, G. Sicurella, E. Umana, All-Organic Motion Sensors: Electromechanical Modeling, IEEE Trans. Instrum. Meas. 58 (2009) 3731–3738. doi:10.1109/TIM.2009.2019321.
[94] T.-G. Noh, Y. Tak, J.-D. Nam, H. Choi, Electrochemical characterization of polymer actuator with large interfacial area, Electrochim. Acta. 47 (2002) 2341–2346. doi:http://dx.doi.org/10.1016/S0013-4686(02)00089-0.
[95] J. Sunghee, S. Jeomsik, K. Gyuseok, L. Sukmin, M. Museong, Effects of the electrode interface on the electric properties of IPMC for artificial muscles, in: R. Magjarevic, J.H. Nagel (Eds.), World Congr. Med. Phys. Biomed. Eng. 2006 August 27 — Sept. 1, 2006 COEX Seoul, Korea “Imaging Futur. Med., Springer Berlin Heidelberg, Berlin, Heidelberg, 2007: pp. 2973–2976. doi:10.1007/978-3-540-36841-0_752.
[96] B.J. Akle, D.J. Leo, M.A. Hickner, J.E. McGrath, Correlation of capacitance and actuation in ionomeric polymer transducers, J. Mater. Sci. 40 (2005) 3715–3724. doi:10.1007/s10853-005-3312-x.
[97] K.J. Kim, M. Shahinpoor, A novel method of manufacturing three-dimensional ionic polymer–metal composites (IPMCs) biomimetic sensors, actuators and artificial muscles, Polymer (Guildf). 43 (2002) 797–802. doi:http://dx.doi.org/10.1016/S0032-3861(01)00648-6.
[98] K.J. Kim, M. Shahinpoor, Development of three-dimensional polymeric artificial muscles, in: Y. Bar-Cohen (Ed.), 2001: p. 223. doi:10.1117/12.432650.
[99] B. Akle, D. Leo, M. Bennett, K. Wiles, J. McGrath, Direct assembly process for fabrication of ionomeric polymer devices, United States Patent Application 20060266642, 2006.
[100] D. Griffiths, V.B. Sundaresan, B. Akle, P. Vlachos, D. Leo, Micro deposition method: a novel fabrication method for ionic polymer metallic composites, in: Y. Bar-Cohen (Ed.), 2008: p. 69270C. doi:10.1117/12.776462.
[101] K.J. Kim, M. Shahinpoor, Effect of the surface-electrode resistance on the actuation of ionic polymer-metal composite (IPMC) artificial muscles, in: Y. Bar-Cohen (Ed.), 1999: pp. 308–319. doi:10.1117/12.349703.
[102] M. Bennett, D. Leo, Morphological and electromechanical characterization of ionic liquid/Nafion polymer composites, in: Y. Bar-Cohen (Ed.), 2005: p. 506. doi:10.1117/12.599849.
[103] T.A. Zawodzinski, Water Uptake by and Transport Through Nafion® 117 Membranes, J. Electrochem. Soc. 140 (1993) 1041. doi:10.1149/1.2056194.
[104] V. Panwar, C. Lee, S.Y. Ko, J.-O. Park, S. Park, Dynamic mechanical, electrical, and actuation properties of ionic polymer metal composites using PVDF/PVP/PSSA blend membranes, Mater. Chem. Phys. 135 (2012) 928–937. doi:http://dx.doi.org/10.1016/j.matchemphys.2012.05.081.
[105] V. Panwar, K. Cha, J.-O. Park, S. Park, High actuation response of PVDF/PVP/PSSA based ionic polymer metal composites actuator, Sensors Actuators B Chem. 161 (2012) 460–470. doi:http://dx.doi.org/10.1016/j.snb.2011.10.062.
[106] A.K. Phillips, R.B. Moore, Ionic actuators based on novel sulfonated ethylene vinyl alcohol copolymer membranes, Polymer (Guildf). 46 (2005) 7788–7802. doi:http://dx.doi.org/10.1016/j.polymer.2005.02.123.
[107] D. Kim, K.J. Kim, J. Nam, V. Palmre, Electro-chemical operation of ionic polymer–metal composites, Sensors Actuators B Chem. 155 (2011) 106–113. doi:http://dx.doi.org/10.1016/j.snb.2010.11.032.
[108] T. Kwon, J.-W. Lee, H. Cho, D. Henkensmeier, Y. Kang, S.M. Hong, C.M. Koo, Ionic polymer actuator based on anion-conducting methylated ether-linked polybenzimidazole, Sensors Actuators B Chem. 214 (2015) 43–49. doi:http://dx.doi.org/10.1016/j.snb.2015.03.007.
[109] K.J. Kim, M. Shahinpoor, Ionic polymer–metal composites: II. Manufacturing techniques, Smart Mater. Struct. 12 (2003) 65.
[110] S.J. Lee, M.J. Han, S.J. Kim, J.Y. Jho, H.Y. Lee, Y.H. Kim, A new fabrication method for IPMC actuators and application to artificial fingers, Smart Mater. Struct. 15 (2006) 1217.
[111] B. Kim, B.M. Kim, J. Ryu, I.-H. Oh, S.-K. Lee, S.-E. Cha, J. Pak, Analysis of mechanical characteristics of the ionic polymer metal composite (IPMC) actuator using cast ion-exchange film, in: Y. Bar-Cohen (Ed.), 2003: p. 486. doi:10.1117/12.484296.
[112] R.-J. Chung, T.-S. Chin, L.-C. Chen, M.-F. Hsieh, Preparation of gradually componential metal electrode on solution-casted NafionTM membrane, Biomol. Eng. 24 (2007) 434–437. doi:http://dx.doi.org/10.1016/j.bioeng.2007.07.003.
[113] Y. Zhang, C. Ma, L. Dai, Electrode Preparation and Electro-deformation of Ionic Polymer-metal Composite (IPMC), in: IEEE Int. Conf. Nano/Micro Eng. Mol. Syst., 2007.
[114] T. Johnson, F. Amirouche, Multiphysics modeling of an IPMC microfluidic control device, Microsyst. Technol. 14 (2008) 871–879. doi:10.1007/s00542-008-0603-6.
[115] M. Siripong, S. Fredholm, Q.A. Nguyen, B. Shih, J. Itescu, J. Stolk, A Cost-Effective Fabrication Method for Ionic Polymer-Metal Composites, MRS Proc. 889 (2005) 889-W04-3. doi:10.1557/PROC-0889-W04-03.
[116] T. NAKAMURA, T. IHARA, T. HORIUCHI, T. MUKAI, K. ASAKA, Measurement and Modeling of Electro-Chemical Properties of Ion Polymer Metal Composite by Complex Impedance Analysis, SICE J. Control. Meas. Syst. Integr. 2 (2009) 373–378. doi:10.9746/jcmsi.2.373.
[117] H.D. Çilingir, M. Papila, “Equivalent’’ Electromechanical Coefficient for IPMC Actuator Design Based on Equivalent Bimorph Beam Theory, Exp. Mech. 50 (2010) 1157–1168. doi:10.1007/s11340-009-9311-0.
[118] Y. Bar-Cohen, X. Bao, S. Sherrit, S.-S. Lih, Characterization of the electromechanical properties of ionomeric polymer-metal composite (IPMC), in: Y. Bar-Cohen (Ed.), 2002: pp. 286–293. doi:10.1117/12.475173.
[119] S. Zamani, S. Nemat-Nasser, Controlled actuation of Nafion-based ionic polymer-metal composites (IPMCs)with ethylene glycol as solvent, in: Y. Bar-Cohen (Ed.), 2004: p. 159. doi:10.1117/12.539075.
[120] Y. Bar-Cohen, T. Xue, M. Shahinpoor, J. O. Simpson, and J. Smith, “Flexible, low-mass robotic arm actuated by electroactive polymers (EAP),” Proceedings of the SPIE International Smart Materials and Structures Conference, SPIE Paper No. 3329-07, San Diego, CA, 1-6 March 1998.
[121] K.O. M. Konyo, S. Tadokoro, T. Takamori, in: Proc. IEEE Int. Conf. Robot. Autom., 2000: p. 3416.
[122] M. Shahinpoor, Continuum electromechanics of ionic polymeric gels as artificial muscles for robotic applications, Smart Mater. Struct. 3 (1994) 367.
[123] R. Lumia, M. Shahinpoor, Microgripper design using electroactive polymers, in: Y. Bar-Cohen (Ed.), 1999: pp. 322–329. doi:10.1117/12.349689.
[124] N. Bhat, W.-J. Kim, Precision force and position control of an ionic polymer metal composite, Proc. Inst. Mech. Eng. Part I J. Syst. Control Eng. 218 (2004) 421–432. doi:10.1177/095965180421800601.
[125] S. Holmberg, P. Holmlund, R. Nicolas, C.-E. Wilén, T. Kallio, G. Sundholm, F. Sundholm, Versatile Synthetic Route to Tailor-Made Proton Exchange Membranes for Fuel Cell Applications by Combination of Radiation Chemistry of Polymers with Nitroxide-Mediated Living Free Radical Graft Polymerization, Macromolecules. 37 (2004) 9909–9915. doi:10.1021/ma0353641.
[126] V.K. Nguyen, Y. Yoo, A novel design and fabrication of multilayered ionic polymer-metal composite actuators based on Nafion/layered silicate and Nafion/silica nanocomposites, Sensors Actuators B Chem. 123 (2007) 183–190. doi:http://dx.doi.org/10.1016/j.snb.2006.08.013.
[127] M. Shahinpoor, K.J. Kim, Ionic polymer–metal composites: III. Modeling and simulation as biomimetic sensors, actuators, transducers, and artificial muscles, Smart Mater. Struct. 13 (2004) 1362.
[128] S.J. Kim, M.S. Kim, S.R. Shin, I.Y. Kim, S.I. Kim, S.H. Lee, T.S. Lee, G.M. Spinks, Enhancement of the electromechanical behavior of IPMCs based on chitosan / polyaniline ion exchange membranes fabricated by freeze-drying, 14 (2005) 889–894. doi:10.1088/0964-1726/14/5/025.
[129] R.K. Jain, U.S. Patkar, S. Majumdar, Micro gripper for micromanipulation using IPMCs (ionic polymer metal composites), J. Sci. Ind. Res. (India). 68 (2009) 23–28.
[130] G. Filipcsei, J. Fehér, M. Zrı́nyi, Electric field sensitive neutral polymer gels, J. Mol. Struct. 554 (2000) 109–117. doi:http://dx.doi.org/10.1016/S0022-2860(00)00564-0.
[131] J. Fehér, G. Filipcsei, J. Szalma, M. Zrı́nyi, Bending deformation of neutral polymer gels induced by electric fields, Colloids Surfaces A Physicochem. Eng. Asp. 183–185 (2001) 505–515. doi:http://dx.doi.org/10.1016/S0927-7757(01)00562-3.
[132] K. Asaka, N. Fujiwara, K. Oguro, K. Onishi, S. Sewa, State of water and ionic conductivity of solid polymer electrolyte membranes in relation to polymer actuators, J. Electroanal. Chem. 505 (2001) 24–32. doi:http://dx.doi.org/10.1016/S0022-0728(01)00445-4.
[133] K. Onishi, S. Sewa, K. Asaka, N. Fujiwara, K. Oguro, The effects of counter ions on characterization and performance of a solid polymer electrolyte actuator, Electrochim. Acta. 46 (2001) 1233–1241. doi:http://dx.doi.org/10.1016/S0013-4686(00)00695-2.
[134] T.J. Lu, A.G. Evans, Design of a high authority flexural actuator using an electro-strictive polymer, Sensors Actuators A Phys. 99 (2002) 290–296. doi:http://dx.doi.org/10.1016/S0924-4247(02)00005-5.
[135] K. Jung, J. Nam, H. Choi, Investigations on actuation characteristics of {IPMC} artificial muscle actuator, Sensors Actuators A Phys. 107 (2003) 183–192. doi:http://dx.doi.org/10.1016/S0924-4247(03)00346-7.
[136] J.D. Nam, H.R. Choi, Y.S. Tak, K.J. Kim, Novel electroactive, silicate nanocomposites prepared to be used as actuators and artificial muscles, Sensors Actuators A Phys. 105 (2003) 83–90. doi:http://dx.doi.org/10.1016/S0924-4247(03)00066-9.
[137] J.W. Paquette, K.J. Kim, D. Kim, Low temperature characteristics of ionic polymer–metal composite actuators, Sensors Actuators A Phys. 118 (2005) 135–143. doi:http://dx.doi.org/10.1016/j.sna.2004.08.006.
[138] Y. Yun, V. Shanov, Y. Tu, M.J. Schulz, S. Yarmolenko, S. Neralla, J. Sankar, S. Subramaniam, A Multi-Wall Carbon Nanotube Tower Electrochemical Actuator, Nano Lett. 6 (2006) 689–693. doi:10.1021/nl052435w.
[139] A. Punning, M. Kruusmaa, A. Aabloo, A self-sensing ion conducting polymer metal composite (IPMC) actuator, Sensors Actuators A Phys. 136 (2007) 656–664. doi:http://dx.doi.org/10.1016/j.sna.2006.12.008.
[140] V.K. Nguyen, J.W. Lee, Y. Yoo, Characteristics and performance of ionic polymer–metal composite actuators based on Nafion/layered silicate and Nafion/silica nanocomposites, Sensors Actuators B Chem. 120 (2007) 529–537. doi:http://dx.doi.org/10.1016/j.snb.2006.03.015.
[141] E. Shoji, D. Hirayama, Effects of Humidity on the Performance of Ionic Polymer−Metal Composite Actuators: Experimental Study of the Back-Relaxation of Actuators, J. Phys. Chem. B. 111 (2007) 11915–11920. doi:10.1021/jp074611q.
[142] K.Y. Choi, H.G. Lim, S.R. Yun, J. Kim, K.S. Kang, The Cause of Nanohole and Nanoparticle Formation on Au-Electrode after Actuation of Electro-Active Paper Actuator, J. Phys. Chem. C. 112 (2008) 16204–16208. doi:10.1021/jp802635x.
[143] J.K. Park, R.B. Moore, Influence of Ordered Morphology on the Anisotropic Actuation in Uniaxially Oriented Electroactive Polymer Systems, ACS Appl. Mater. Interfaces. 1 (2009) 697–702. doi:10.1021/am8002268.
[144] J. Li, K.G. Wilmsmeyer, J. Hou, L.A. Madsen, The role of water in transport of ionic liquids in polymeric artificial muscle actuators, Soft Matter. (2009). doi:10.1039/b904443d.
[145] S. Liu, R. Montazami, Y. Liu, V. Jain, M. Lin, X. Zhou, J.R. Heflin, Q.M. Zhang, Influence of the conductor network composites on the electromechanical performance of ionic polymer conductor network composite actuators, Sensors Actuators A Phys. 157 (2010) 267–275. doi:http://dx.doi.org/10.1016/j.sna.2009.11.022.
[146] D.-J. Guo, S.-J. Fu, W. Tan, Z.-D. Dai, A highly porous nafion membrane templated from polyoxometalates-based supramolecule composite for ion-exchange polymer-metal composite actuator, J. Mater. Chem. 20 (2010) 10159. doi:10.1039/c0jm01161d.
[147] J.K. Park, P.J. Jones, C. Sahagun, K.A. Page, D.S. Hussey, D.L. Jacobson, S.E. Morgan, R.B. Moore, Electrically stimulated gradients in water and counterion concentrations within electroactive polymer actuators, Soft Matter. 6 (2010) 1444. doi:10.1039/b922828d.
[148] Y. Lian, Y. Liu, T. Jiang, J. Shu, H. Lian, M. Cao, Enhanced Electromechanical Performance of Graphite Oxide-Nafion Nanocomposite Actuator, J. Phys. Chem. C. 114 (2010) 9659–9663. doi:10.1021/jp101337h.
[149] J. Santos, B. Lopes, P.J.C. Branco, Ionic polymer–metal composite material as a diaphragm for micropump devices, Sensors Actuators A Phys. 161 (2010) 225–233. doi:http://dx.doi.org/10.1016/j.sna.2010.04.032.
[150] J.-W. Lee, Y.-T. Yoo, Preparation and performance of {IPMC} actuators with electrospun Nafion®–MWNT composite electrodes, Sensors Actuators B Chem. 159 (2011) 103–111. doi:http://dx.doi.org/10.1016/j.snb.2011.06.057.
[151] B. Gaihre, G. Alici, G.M. Spinks, J.M. Cairney, Synthesis and performance evaluation of thin film PPy-PVDF multilayer electroactive polymer actuators, Sensors Actuators A Phys. 165 (2011) 321–328. doi:http://dx.doi.org/10.1016/j.sna.2010.10.009.
[152] Y. Liu, R. Zhao, M. Ghaffari, J. Lin, S. Liu, H. Cebeci, R.G. de Villoria, R. Montazami, D. Wang, B.L. Wardle, J.R. Heflin, Q.M. Zhang, Equivalent circuit modeling of ionomer and ionic polymer conductive network composite actuators containing ionic liquids, Sensors Actuators A Phys. 181 (2012) 70–76. doi:http://dx.doi.org/10.1016/j.sna.2012.05.002.
[153] Y. Liu, M. Ghaffari, R. Zhao, J.-H. Lin, M. Lin, Q.M. Zhang, Enhanced Electromechanical Response of Ionic Polymer Actuators by Improving Mechanical Coupling between Ions and Polymer Matrix, Macromolecules. 45 (2012) 5128–5133. doi:10.1021/ma300591a.
[154] V. Panwar, S.Y. Ko, J.-O. Park, S. Park, Enhanced and fast actuation of fullerenol/PVDF/PVP/PSSA based ionic polymer metal composite actuators, Sensors Actuators B Chem. 183 (2013) 504–517. doi:http://dx.doi.org/10.1016/j.snb.2013.04.037.
[155] S. Kim, S. Hong, Y.-Y. Choi, H. Song, K. No, Effect of nucleation time on bending response of ionic polymer–metal composite actuators, Electrochim. Acta. 108 (2013) 547–553. doi:http://dx.doi.org/10.1016/j.electacta.2013.06.092.
[156] N. Terasawa, I. Takeuchi, Electrochemical and electromechanical properties of high-performance polymer actuators containing vapor grown carbon nanofiber and metal oxide, Sensors Actuators B Chem. 176 (2013) 1065–1073. doi:http://dx.doi.org/10.1016/j.snb.2012.10.043.
[157] J.-W. Lee, Y.-T. Yoo, J.Y. Lee, Ionic Polymer–Metal Composite Actuators Based on Triple-Layered Polyelectrolytes Composed of Individually Functionalized Layers, ACS Appl. Mater. Interfaces. 6 (2014) 1266–1271. doi:10.1021/am405090d.
[158] M. Itik, Repetitive control of a trilayer conjugated polymer actuator, Sensors Actuators A Phys. 194 (2013) 149–159. doi:http://dx.doi.org/10.1016/j.sna.2013.01.052.
[159] J. Kim, J.-H. Jeon, H.-J. Kim, H. Lim, I.-K. Oh, Durable and Water-Floatable Ionic Polymer Actuator with Hydrophobic and Asymmetrically Laser-Scribed Reduced Graphene Oxide Paper Electrodes, ACS Nano. 8 (2014) 2986–2997. doi:10.1021/nn500283q.
[160] Y. Wang, H. Chen, Y. Wang, Z. Zhu, D. Li, Effect of Dehydration on the Mechanical and Physicochemical Properties of Gold- and Palladium -Ionomeric Polymer-Metal Composite (IPMC) Actuators, Electrochim. Acta. 129 (2014) 450–458. doi:http://dx.doi.org/10.1016/j.electacta.2014.02.114.
[161] P.M. Welch, A Tunable Dendritic Molecular Actuator, Nano Lett. 5 (2005) 1279–1283. doi:10.1021/nl050422c.
[162] J. Shi, Z.-X. Guo, B. Zhan, H. Luo, Y. Li, D. Zhu, Actuator Based on MWNT/PVA Hydrogels, J. Phys. Chem. B. 109 (2005) 14789–14791. doi:10.1021/jp052677k.
[163] K.Y. Cho, H.G. Lim, S.R. Yun, J. Kim, K.S. Kang, Electric Field Frequency and Strength Effects on Au-Electrode Damage for an Electroactive Paper Actuator Coated with Polypyrrole, J. Phys. Chem. C. 112 (2008) 7001–7004. doi:10.1021/jp067012c.
[164] L. Zhao, L. Tong, C. Li, Z. Gu, G. Shi, Polypyrrole actuators with inverse opal structures, J. Mater. Chem. 19 (2009) 1653. doi:10.1039/b819831d.
[165] B.K. Juluri, A.S. Kumar, Y. Liu, T. Ye, Y.-W. Yang, A.H. Flood, L. Fang, J.F. Stoddart, P.S. Weiss, T.J. Huang, A Mechanical Actuator Driven Electrochemically by Artificial Molecular Muscles, ACS Nano. 3 (2009) 291–300. doi:10.1021/nn8002373.
[166] C.-A. Dai, C.-J. Chang, A.-C. Kao, W.-B. Tsai, W.-S. Chen, W.-M. Liu, W.-P. Shih, C.-C. Ma, Polymer actuator based on PVA/PAMPS ionic membrane: Optimization of ionic transport properties, Sensors Actuators A Phys. 155 (2009) 152–162. doi:http://dx.doi.org/10.1016/j.sna.2009.08.002.
[167] A. Liu, L. Zhao, H. Bai, H. Zhao, X. Xing, G. Shi, Polypyrrole Actuator with a Bioadhesive Surface for Accumulating Bacteria from Physiological Media, ACS Appl. Mater. Interfaces. 1 (2009) 951–955. doi:10.1021/am9000387.
[168] D. Brandell, H. Kasemägi, A. Aabloo, Poly(ethylene oxide)–poly(butadiene) interpenetrated networks as electroactive polymers for actuators: A molecular dynamics study, Electrochim. Acta. 55 (2010) 1333–1337. doi:http://dx.doi.org/10.1016/j.electacta.2009.04.070.
[169] X.-L. Wang, I.-K. Oh, S. Lee, Electroactive artificial muscle based on crosslinked PVA/SPTES, Sensors Actuators B Chem. 150 (2010) 57–64. doi:http://dx.doi.org/10.1016/j.snb.2010.07.042.
[170] M. Rajagopalan, J.-H. Jeon, I.-K. Oh, Electric-stimuli-responsive bending actuator based on sulfonated polyetherimide, Sensors Actuators B Chem. 151 (2010) 198–204. doi:http://dx.doi.org/10.1016/j.snb.2010.09.021.
[171] V. Palmre, E. Lust, A. Jänes, M. Koel, A.-L. Peikolainen, J. Torop, U. Johanson, A. Aabloo, Electroactive polymer actuators with carbon aerogel electrodes, J. Mater. Chem. 21 (2011) 2577. doi:10.1039/c0jm01729a.
[172] L. Chen, C. Liu, K. Liu, C. Meng, C. Hu, J. Wang, S. Fan, High-Performance, Low-Voltage, and Easy-Operable Bending Actuator Based on Aligned Carbon Nanotube/Polymer Composites, ACS Nano. 5 (2011) 1588–1593. doi:10.1021/nn102251a.
[173] M. Luqman, J.-W. Lee, K.-K. Moon, Y.-T. Yoo, Sulfonated polystyrene-based ionic polymer–metal composite (IPMC) actuator, J. Ind. Eng. Chem. 17 (2011) 49–55. doi:http://dx.doi.org/10.1016/j.jiec.2010.10.008.
[174] J. Torop, T. Sugino, K. Asaka, A. Jänes, E. Lust, A. Aabloo, Nanoporous carbide-derived carbon based actuators modified with gold foil: Prospect for fast response and low voltage applications, Sensors Actuators B Chem. 161 (2012) 629–634. doi:http://dx.doi.org/10.1016/j.snb.2011.10.079.
[175] J.-W. Lee, S.M. Hong, J. Kim, C.M. Koo, Novel sulfonated styrenic pentablock copolymer/silicate nanocomposite membranes with controlled ion channels and their {IPMC} transducers, Sensors Actuators B Chem. 162 (2012) 369–376. doi:http://dx.doi.org/10.1016/j.snb.2011.12.105.
[176] J. Tang, B. Yang, J. Liu, Y. Wang, L. Huang, Z. Huang, Y. Wang, Q. Zhu, L.A. Belfiore, Electric-field-actuation of in situ composites that contain silver-coated carbon fibers in sodium sulfonate ionomers, RSC Adv. 2 (2012) 8813–8820. doi:10.1039/C2RA20766D.
[177] R. Gao, D. Wang, J.R. Heflin, T.E. Long, Imidazolium sulfonate-containing pentablock copolymer–ionic liquid membranes for electroactive actuators, J. Mater. Chem. 22 (2012) 13473. doi:10.1039/c2jm16117f.
[178] B. Gaihre, S. Ashraf, G.M. Spinks, P.C. Innis, G.G. Wallace, Comparative displacement study of bilayer actuators comprising of conducting polymers, fabricated from polypyrrole, poly(3,4-ethylenedioxythiophene) or poly(3,4-propylenedioxythiophene), Sensors Actuators A Phys. 193 (2013) 48–53. doi:http://dx.doi.org/10.1016/j.sna.2012.12.007.
[179] G. Alici, A. Punning, H.R. Shea, Enhancement of actuation ability of ionic-type conducting polymer actuators using metal ion implantation, Sensors Actuators B Chem. 157 (2011) 72–84. doi:http://dx.doi.org/10.1016/j.snb.2011.03.028.
[180] B.-K. Lee, S.J. Park, D.S. Kim, Fabrication of ionic polymer actuator with graphene nanocomposite electrodes and its characterization, Curr. Appl. Phys. 13 (2013) 1520–1524. doi:http://dx.doi.org/10.1016/j.cap.2013.05.011.
[181] Y. Tang, Z. Xue, X. Zhou, X. Xie, C.-Y. Tang, Novel sulfonated polysulfone ion exchange membranes for ionic polymer–metal composite actuators, Sensors Actuators B Chem. 202 (2014) 1164–1174. doi:http://dx.doi.org/10.1016/j.snb.2014.06.071.
[182] Z. Zeng, H. Jin, L. Zhang, H. Zhang, Z. Chen, F. Gao, Z. Zhang, Low-voltage and high-performance electrothermal actuator based on multi-walled carbon nanotube/polymer composites, Carbon N. Y. 84 (2015) 327–334. doi:http://dx.doi.org/10.1016/j.carbon.2014.12.012.