Ionic Polymer-Polymer Composites Research Articles

Investigation of Ionic EAP Actuators with Metal and Polymer Electrodes in Aqueous Medium

Electroactive polymers (EAP) are promising materials for creating electromechanical transducers. Among ionic EAP, ionic polymer-metal composites (IPMC), which are an ion-exchange membrane with metal electrodes on both sides, have been widely spread and well studied. The evolutionary development of IPMC results in ionic polymer-polymer composites (IP2C), in which polymer electrodes are used. To obtain IPMC actuators with platinum electrodes, the method of chemical reduction from the salt solution was chosen, and to obtain IP2C actuators with PEDOT electrodes, the method of in situ polymerization of the monomer on the membrane surface was chosen. Samples of 2x0.5 cm in size based on the MF-4SK membrane with a thickness of 290 μm were preliminarily kept in deionized water (H+ form) and in 0.1 M CuSO4 aqueous solution (Cu2+ form), after which their performance was studied in air, in deionized water, as well as in aqueous solutions of CuSO4 and NaCl. When applying a DC voltage and a sine wave AC voltage, a decrease in the maximum displacement and peak-to-peak displacement of the IPMC actuators and IP2C actuators with an increase in the ionic strength of the liquid was observed, except for the case of the IPMC actuator operation in CuSO4 aqueous solutions. In all considered media, the IPMC actuators and IP2C actuators in Cu2+ form displaced more strongly than the corresponding samples in H+ form, except for the IP2C actuators in deionized water. The largest peak-to-peak displacement was demonstrated by the IPMC actuators in Cu2+form when operating in air (5 mm) and the IP2С actuators in H+ form when operating in deionized water (8.4 mm).

Electromechanical Transducers Based on Ionic Polymer-Polymer Composites

Electromechanical Transducers Based on Ionic Polymer-Polymer Composites

Ionic polymer-metal composites (IPMCs) and ionic polymer-polymer composites (IP<sup>2</sup>Cs): Effects of electrode on mechanical, thermal and electromechanical behaviour

Electro-active polymers (EAPs) are soft polymers that develop mechanical strain if subjected to electrical stimuli or, on the contrary, produce voltages if mechanically deformed. Their discovery has led to take into account their possible use as sensor-actuator for both bio-mimetic applications and traditional robotics. Ionic polymer-metal composites (IPMCs) and ionic polymer-polymer composites (IP 2 Cs) belong to EAPs. Both of them are fabricated starting from an ionic polymer (typically Nafion ® 117) but while in IPMCs the electrode is based on a metal (Ag, Au or Pt), IP 2 Cs are all-organic devices: in fact a conducting polymer (e.g., poly(3,4-ethylendioxytiophene)-polystyrenesulfonate, PEDOT/PSS) is used as the electrode. In this work, a comparison has been done among the fabrication processes and the mechanical, thermal and electromechanical behaviour of IPMCs and IP 2 Cs. The objective is to investigate the influence of the kind of electrode on the final properties of the devices, taking, also, into account the effect of different solvents, used for realizing the actuation process (H 2 O or Ethylene Glycol). Reported results show that the performance of the obtained devices are function of manufacture parameters, the kind of electrode and solvent; consequently, taking into account the possible application, it is possible to choose the device that better meets specific requirements.

A Multiphysics Frequency-Dependent Model of an ${\rm IP}^{2}{\rm C}$ Actuator

Ionic polymer-polymer composites (IP2Cs) are electroactive polymers which can be used both as sensors and as actuators. In this paper, a new multiphysics model of IP2Cs working as an actuator is presented and implemented using a finite element methods solver (COMSOL Multiphysics). The model involves electrical, mechanical, chemical, and thermal effects and yields a unique solution. Knowledge acquired by measuring campaigns has been included in the model. More specifically the frequency dependence of Young's modulus was experimentally determined and introduced in such a model. A frequency-domain investigation is performed and a model optimization procedure that integrates the Nelder-Mead simplex method with the COMSOL Multiphysics models is exploited to identify IP2C model parameter by fitting experimental data. A fractional order dynamics has been identified in the model, confirming previous studies on IPMC gray box modeling and on electroactive polymeric devices.

Neural Modeling of Relative Humidity on IP2C Vibrating Transducer

Abstract IP2Cs (Ionic Polymer-Polymer Composites) are electro-active polymers which can be used both as sensors and as actuators. In this work Neural Network models of IP2Cs working as actuators and with water as the solvent are developed using experimental data. Moreover, models proposed here take into account the humidity dependence of the device as modifying input. Three different Neural Network models, i.e. Feed-forward neural network, Radial-basis neural network and recurrent neural network based models are developed and a comparison of proposed model is reported.

All-Organic Motion Sensors: Electromechanical Modeling

A new class of materials called ionic polymer-polymer composites has been investigated to demonstrate the sensing and acting capabilities of these all-organic structures. Samples have been realized by covering Nafion membranes, with Orgacon 3040 conducting polymer as electrode material. Membranes whose electrodes were manufactured using the drop-casting technique exhibited the best electromechanical performances. Sensors have been tested in a dedicated experimental setup to model their electromechanical transduction behavior. Thus, the obtained model has been validated.