Sang-Mun Kim

Palladium buffer-layered high performance ionic polymer-metal composites

A new IPMC fabrication method—that is not a repetitive reduction processes—and a new supporting electrode material that is responsible for this procedure are described in this paper. A palladium metal, acting as a buffer layer, was deposited before plating the platinum electrode in order to articulate the surface morphology and the interfacial effect between the electrode and the membrane. The platinum layer was sequentially grown using an electroless chemical deposition on a palladium buffer layer on the polymer membrane. The surface morphology and conductivity of the electrode were enhanced by depositing a buffer layer. Under the same applied voltage, when compared to IPMCs without a buffer layer, the IPMCs with a palladium buffer layer showed a greater bending tendency and had a higher blocking force. The results also indicated that such IPMCs do not exhibit the back relaxation phenomenon under a sustained DC voltage. The amplitude of the transduction signal produced by the Pt/Pd IPMC shows much larger amplitude of the signal produced by the Pt IPMC. Thus, the IPMC with a palladium buffer layer has the potential for future applications as an actuator and transducer.

Mechanical and thermal behavior of ionic polymer?metal composites: effects of electroded metals

In this study, we investigated the mechanical properties of various types of ionic polymer–metal composites (IPMCs) and Pt, Au, Pd, and Pt electroded ionic liquid (IL-Pt) IPMCs, by testing tensile modulus and dynamic mechanical behavior. The SEM was utilized to investigate the characteristics of the doped electroding layer, and the DSC was probed in order to look into the thermal behavior of various types of IPMCs. Au IPMCs, having a 5–7 µm-doped layer and nanosized Au particles (ca. 10 nm), showed the highest tensile strength (56 MPa) and modulus (602 MPa) in dried conditions. With regards to thermal behavior, Au IPMC had the highest Tg (153 °C) and Tm (263 °C) in both the DMA and DSC results. The fracture behavior of various types of IPMCs followed the behavior of the base material, Nafion™, which is represented as the semicrystalline polymer characteristic.Corrections were made to the caption of figure 6 on 18 June 2007. The corrected electronic version is identical to the print version.

Visualization of the cation migration in ionic polymer-metal composite under an electric field

Ionic polymer-metal composites (IPMCs) exhibit a large dynamic bending deformation due to the redistribution of counter-ions inside the polymer. It has not been possible to get the high resolution data of the cation migration. The images obtained so far have only validated the versatile actuation model. The actuation model states that the electrically induced cation movement contributes to the volumetric stress change in the membrane. In this work, a visualization of the cation migration using the fluorescent microscopy is created. The results demonstrated in this letter help to understand the underlying mechanism of the IPMC transduction.

An electrode model for ionic polymer?metal composites

In this study, we geometrically modeled an electroless-plated platinum electrode of the IPMC and performed parametric studies to estimate the electrical properties (resistance and capacitance) of the electrode. We conducted experiments to control the change of the electrode characteristics (electrode thickness, particle size, particle gap, etc.). We measured the electrical properties of the electrodes in an aqueous environment and compared these findings with the modeling results to verify the model. The models estimations of the effects of the parameters were well conceived; however, it was also found that there were limits of the estimations of the curved electrodes properties.

A Novel Ionic Polymer Metal ZnO Composite (IPMZC)

The presented research introduces a new Ionic Polymer-Metal-ZnO Composite (IPMZC) demonstrating photoluminescence (PL)-quenching on mechanical bending or application of an electric field. The newly fabricated IPMZC integrates the optical properties of ZnO and the electroactive nature of Ionic Polymer Metal Composites (IPMC) to enable a non-contact read-out of IPMC response. The electro-mechano-optical response of the IPMZC was measured by observing the PL spectra under mechanical bending and electrical regimes. The working range was measured to be 375–475 nm. It was noted that the PL-quenching increased proportionally with the increase in curvature and applied field at 384 and 468 nm. The maximum quenching of 53.4% was achieved with the membrane curvature of 78.74/m and 3.01% when electric field (12.5 × 103 V/m) is applied. Coating IPMC with crystalline ZnO was observed to improve IPMC transduction.

The mechanical properties of ionic polymer-metal composites

In this study, we investigated the mechanical properties of various type ionic polymer-metal composites (IPMCs) and Pt, Au, Pd, and Pt electroded ionic liquid (IL-Pt) IPMCs, by testing tensile modulus and dynamic mechanical behavior. The SEM was utilized to investigate the characteristics of the doped electroding layer, and the DSC was probed in order to look into the thermal behavior of various types of IPMCs. Au IPMCs, having a 5~7 &mgr;m doped layer and nano-sized Au particles (ca. 10 nm), showed the highest tensile strength (56 MPa) and modulus (602 MPa) in a dried condition. In a thermal behavior, Au IPMC has the highest Tg (153°C) and Tm (263°C) in both the DMA and DSC results. The fracture behavior of various types IPMCs followed base materials behavior, NafionTM, which is represented as the semicrystalline polymer characteristic.

IPMC-assisted miniature disposable infusion pumps with embedded computer control

For military applications, the availability of safe, disposable, and robust infusion pumps for intravenous fluid and drug delivery would provide a significant improvement in combat healthcare. To meet these needs, we have developed a miniature infusion prototype pump for safe and accurate fluid and drug delivery that is programmable, lightweight, and disposable. In this paper we present techniques regarding inter-digitated IPMCs and a scaleable IPMC that exhibits significantly improved force performance over the conventional IPMCs. The results of this project will be a low cost accurate infusion device that can be scaled from a disposable small volume liquid drug delivery patch to disposable large volume fluid resuscitation infusion pumps for trauma victims in both the government and private sectors of the health industry.

Ionic polymer-metal composites (IPMCs) with bimetallic Pt-Pd electrode

The characteristics of Ionic polymer metal-composites, containing bimetallic Pt-Pd electrodes which had been prepared by an electroless chemical reduction method on a polymer membrane, were investigated. Bimetallic Pt-Pd electrodes with various compositions (Pt:Pd weight ratios) were compared with those of monometallic Pt and Pd electrodes that had been prepared under similar conditions. The surface compositions of the Pt and Pd on the electrodes were compared using an energy dispersive X-ray spectroscopy (EDS). The crystal structures of the electrodes were investigated by an X-ray diffraction (XRD); surface morphologies were also compared by scanning electron microscopy (SEM) which depends on the palladium amounts. The optimal composition of the Pt and Pd affects not only surface morphology, but also the improvement of the actuation and associated relaxation phenomena of IPMCs.

A novel ionic polymer-metal composites incorporating ZnO thin film

This paper aims to introduce newly developed Ionic Polymer-metal Composites (opto-IPMCs) targeting optical applications. The thin optical film of ZnO was deposited on IPMC by an electroless deposition method. This ZnO/Pt IPMC demonstrates photoluminescence (PL) quenching phenomenon, which is reduction in PL intensity (PLI) with an increase in applied electric fields. The crystal structure, morphology and atomic compositions of the resulting ZnO incorporated IPMCs were proved by X-ray diffraction, scanning electron microscopy, and the energy dispersive X-ray spectroscopy, respectively. We observed that ZnO incorporated IPMCs show stable and large displacement under a square current pulse. Also, the electro-optical responses of the manufactured opto-IPMCs were characterized by the PL spectra. The working range of the newly developed electro-optical system was measured to be within the 375-475 nm wavelength.

Sulfonated Polyamide Based IPMCs

In this study, we introduce a newly developed Ionic Polymer-Metal Composite (IPMC) family that is manufactured using a novel ionic exchange membrane-a randomly sulfonated fluoropoly(ether amide) (TFIPA-90)-as the base material. The thermal behavior and mechanical properties of the ionic polymer were probed by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Electrochemical properties and the actuation performance of the TFIPA-90 based IPMCs were also investigated in this study. The stiffness of the TFIPA polymer was significantly higher than that of Nafion® and much noted at high temperatures (>100 oC). The thermal behavior of the TFIPA polymer also showed better stability than Nafion(R) at high temperatures due to the more rigid chemical structure of the ionomer. As an actuator, a new IPMC prepared from TFIPA-90 showed improved performance with rapid response time to the electric field and a large bending displacement. The TFIPA-based IPMC may be useful for microwave-driven robotic applications.