Study of Polyelectrolyte/Carbon Nanotubes Composite Film for Application in Actuators
Date Issued
2008
Date
2008
Author(s)
Kao, An-Cheng
Abstract
Ionic polymer-metal composite (IPMC) is a promising material in the field of sensors, actuators, and biomedical applications. Typically, IPMC consists of the ion exchange membrane, electrodes on both sides of the membrane, and mobile cations. Nafion (perfluorosulfonate, made by DuPont) membrane is the widely used in this technique due to its fast ion exchange and chemical stability. In this study, a novel ion exchange membrane has been developed by blending a polymer gel network, poly (vinyl alcohol) (PVA) and a polyelectrolyte with high ion conduction sulfonic acid groups, poly (2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS). The membranes were characterized by measuring water uptake, ion exchange capacity, and ionic conductivity. We employed PVA/PAMPS membranes in IPMC construction and platinum electrodes were plated by sequential adsorption/reduction plating cycles. IPMC based on PVA/PAMPS membranes showed large bending angle under an applied voltage without relaxation and generated the optimal tip force about 0.65gf. To test IPMC, we also measured bending angle and tip force for several parameters such as the thickness of the membrane, applied voltage, and the PAMPS content. With increasing the amount of PAMPS content, IPMC showed the larger bending angel and bending rate. These experimental data presents that the property of the ionic membrane greatly affects the actuation performance of IPMC. In order to improve the mechanical and electrical properties, multi-walled carbon nanotubes (MWNTs) were added into PVA/PAMPS membranes. The properties of PVA/PAMPS/CNT membranes were also characterized by measuring water uptake, ion exchange capacity (IEC), and ionic conductivity. With an increase of MWNTs content, these properties were changed due to two competitive factors: (1) the carboxylic acid groups (2) the inorganic filler. The well dispersion of MWNTs was investigated by TEM, and the addition of MWNTs into PVA/PAMPS membrane was in the range of 0.1 to 3 wt% in order to avoid the risk of short circuit. Bending angle and tip force tests were performed in this section. Under an applied voltage, IPMC with 1 wt% MWNTs showed larger deflection and generated the optimal tip force about 0.72gf. These results showed that the slight addition of MWNTs (<1 wt%) is a benefit to the actuation performance of IPMC. The result presents that IPMC shows a possibility and a usability of the bio-mimetic artificial muscles.
Subjects
IPMC
PVA
PAMPS
MWNTs
Artificial muscle
Electroactive polymer
Ion exchange membrane
Type
thesis
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