Study of Polyelectrolyte/Carbon Nanotubes Composite Film for Application in Actuators
|關鍵字:||離子型電致動聚合物;聚乙烯醇;聚(2-丙烯酰胺-2-甲基-1-丙磺酸);多層奈米碳管;人工肌肉;電致動高分子;離子交換膜;IPMC;PVA;PAMPS;MWNTs;Artificial muscle;Electroactive polymer;Ion exchange membrane||公開日期:||2008||摘要:||在感應器、致動器和生醫應用的領域中，離子型電致動聚合物(IPMC)是一種相當有潛力的材料。典型的IPMC由離子交換膜、電極以及可移動的陽離子所構成，¬而一般常用的離子交換膜為杜邦所生產具有碳氟鍵的Nafion薄膜。在本研究中，我們則是利用poly (vinyl alcohol) (PVA) /poly (2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS)膜作為IPMC的離子交換膜，並利用連續吸附/還原化學反應在膜兩邊鍍上白金電極。在施加電壓下，此IPMC可產生較大的bending angle且產生最佳的tip force約0.65 gf 。而薄膜厚度、施加電壓大小與PAMPS添加量也都會影響著IPMC的bending angle和tip force。由實驗結果顯示，PVA/PAMPS薄膜隨著PAMPS添加量愈多，IEC、離子導電度愈高，IPMC所表現出的電致動效果也愈好。離子交換膜本身性質影響著IPMC的致動效果。 為了增強IPMC的機械與電性質，我們添加了多層奈米碳管到PVA/PAMPS薄膜中。多層奈米碳管的分散性藉由TEM來鑑定。而為了避免短路的情形發生，多層奈米碳管的添加量在0.1到3 wt%之間。藉由bending angle和tip force的量側，可知微量添加多層奈米碳管有利於IPMC的電致動性質。此外，在本研究中應用IPMC所製成人工肌肉於尿失禁的治療上，展現了IPMC應用於生物醫學的可能性。
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.
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