IPMC의 구동에 있어서 백금전극, 금속이온, 극성용매의 영향에 대한 연구 = Study on Bending Behavior of Ionic Polymer Metal Composites using Different Platinum Electrodes, Counter-Cations and Solvents

국문 초록 (Abstract)

영문초록: Ionic polymer-metal composite(IPMC) is very effective material which show large bending deformation in the presence of low applied voltage. It consists of ion-exchange membrane sandwiched between two novel metal plates. The ion-exchange membrane is neutralized with an amount of metal ions, balancing the charge of anions covalently fixed to the membrane. When a small potential is applied to an IPMC in the hydrated state, the mobile metal cations are subjected to diffuse toward the cathode. As a result, the composite undergoes bending deformation toward the anode. The overall performance of an IPMC is dependent upon many parameters including electrical properties of material. Experimental studies were conducted on the performance of NafionTM-based IPMCs using different platinum electrodes, counter-cations and solvents. In the first experiments, the reduction temperature was treated as a major process parameter. IPMCs were prepared at various reduction temperature; 5℃, 25℃, 45℃. The reduction process creates platinum particle between 4 and 20 nm in mean particle size. The platinum penetration is measured by SEM cross-sectioning and surface resistivities of the samples were measured by Jandel Multiposition probe. Overall, it should be noted that the samples having low surface resistivities tend to produce larger deformations. Counter cationic species of IPMC also strongly affect the performance of deformation. The mechanism of the bending motion is due to unidirectional electro-osmosis by cations. Water enrichment at the cathode and depletion at the anode causes bending due to differential swelling and shrinkage. The purpose of second experiment is to investigate the relationship between the deformations of IPMCs having different counter cations and water states in their membranes. Each IPMC sample was treated to contain different counter-caions; H+, Li+, Na+, Co2+, Cu2+. When exchanged with H+, Li+ and Na+ ions as counter ions, the displacement is rapid. The fast response is thought to be linked with the small radius of the hydrated ion compared to the hydrophilic channel size in the membrane. In contrast, the displacement with Co2+and Cu2+ ions increases, while the rate decreases, systematically with molecular size. The transduction in the material is caused by redistribution of the mobile cations in the material, which is made possible because the material is saturated with a solvent. Typically, the solvent used is water, although its use limits the performance of these materials. With water as the solvent, the applied electric potential must be limited less than 1.3V at room temperature, to avoid electrolysis. Moreover, water evaporation in open air presents additional problems. These limit the application of IPMCs with water as the solvent. The main focus in the third experiments are the behavior of IPMCs with heavy water, DMSO, NMP, DMF and PEG 200 as the solvents. IPMCs solvated with these solvents have improved staility when operated in air as compared to the same materials solvated with water, although the magnitude of the response decreased as compared to the water samples. The use of D2O to replace water as the solvent in IPMC shows promise for improving the stability of IPMC when operated in air