离子聚合物金属复合材料(Ionic Polymer Metal Composite)作为新型的电致动材料具有巨大的应用潜力。但就目前国内外研究结果显示,现有的IPMC电致动材料仍具有一个显著的的缺点:非水工作时间短。本文通过用离子液体1-乙基-3-甲基咪唑硫氰酸盐(EMImSCN)替代水作为IPMC中的溶剂,以此来提高IPMC的非水工作时间。实验结果表明:在4V正弦交流电压下,当IPMC在空气中作用时间延长至320s时,以水为介质的IPMC位移减小了93%,位移大小几乎为0,而以[EMIm]SCN为介质的IPMC位移减小了63%,并长期处于一个稳定的位移值不变。
Ionic Polymer Metal Composite （IPMC） can be used as an electrically activated actuator, which has been widely used in artificial muscles, bionic robotic actuators, and dynamic sensors since it has the advantages of large deformation, light weight, flexibility, and low driving voltage, etc. To further improve the mechanical properties of IPMC, this paper reports a new method for preparing organic-inorganic hybrid Nafion/SiO2 membranes. Beginning from cast Nation membranes, IPMCs with various tetraethyl orthosilicate （TEOS） contents were fabricated by electroless plating. The elastic moduli of cast Nation membranes were measured with nano indenters, the water contents were calculated, and the cross sections of Nation membranes were observed by scanning electron microscopy. The blocking force, the displacement, and the electric current of IPMCs were then measured on a test apparatus. The results show that the blocking force increases as the TEOS content gradually increases, and that both the displacement and the electric current initially decrease, then increase. When the TEOS content is 1.5%, the IPMC shows the best improved mechanical properties. Finally, the IPMC with the best improved performance was used to successfully actuate the artificial eye and tested.
Qingsong HeMin YuYuxiu LiYan DingDongjie GuoZhendong Dai
The motion of an Ionic Polymer Metal Composite （IPMC） cantilever under a periodic voltage control is modeled. In our finite element 3D model, we follow both the free tip displacements and the blocking forces for various thicknesses and elastic constants of the ionomer membrane. It turns out that the maximum displacement of the free tip strongly depends on the value of the Young＇s modulus of the electrodes. Furthermore, the maximum blocking force, Fmax, increases with the thickness of the ionomer membrane. At constant values of Young＇s moduli of the electrodes and ionomer membrane thickness, if the Young＇s modulus of the ionomer membrane varies within the range from 0.2 MPa to 1 GPa, the change of Fmax is less than 10 %. The simulated maximal displacements, blocking forces and electrical currents are compared with the corresponding sets of ex- perimental data, respectively. Qualitative agreement between the simulated and the respective measured data profiles is ob- tained. Furthermore, it is found that the assumption of electrostatic interactions in the cation depleted region of the ionomer membrane has a negligible effect. The advantage of the model consists in its simplicity.
David VokounQingsong HeLudek HellerMin YuZhendong Dai
离子聚合物金属复合材料(ionic polymer metal composite,IPMC)是一种离子型电活性聚合物,具有驱动电压低、位移变形量大、反应迅速和质量轻等优点,作为新型的电致动材料具有广阔的应用前景。但是现有的IPMC电致动材料存在输出力小和非水工作时间短的缺点。通过制备厚度上具有梯度变化的三维IPMC来提高IPMC的驱动性能;采用不易电解挥发、稳定性较好的乙二醇作为IPMC的工作介质,延长IPMC的非水工作时间。研究结果表明,在相同幅值的正弦交流电压下,具有一定梯度结构的IPMC能够显著提高其形变位移和输出力,幅值为3.5V时,形变位移和输出力较相同质量厚度的平面型IPMC分别提升了7.0%和47.9%;用乙二醇置换水作为工作介质的平面型IPMC,其非水工作时间得到大幅提升,从150s延长至300s。IPMC电机械输出性能的提升和非水工作时间的延长对于IPMC在驱动领域的进一步应用开发具有重要意义。
The performance of Ionic Polymer Metal Composite （IPMC） actuator was significantly enhanced by incorporating surfactant-assisted processable Multi-Walled Carbon Nanotubes （MWCNTs） into a Nation solution. Cationic surfactant Cetyl Trimethyl Ammonium Bromide （CTAB） was employed to disperse MWCNTs in the Nation matriX, forming a homogeneous and stable dispersion ofnanotubes. The processing did not involve any strong acid treatment and thus effectively preserved the excellent electronic properties associated with MWCNT. The as-obtained MWCNT/Nafion-IPMC actuator was tested in terms of conductivity, bulk and surface morphology, blocking force and electric current. It was shown that the blocking force and the current of the new IPMC are 2.4 times and 1.67 times higher compared with a pure Nation-based IPMC. Moreover, the MWCNT/IPMC performance is much better than previously reported Nafion-IPMC doped by acid-treated MWCNT. Such significantly improved performance should be attributed to the improvement of electrical property associated with the addition of MWCNTs without acid treatment.
Materials with appropriate adhesive properties are suitable for the fabrication of bionic adhesive pads. In this study, a novel polydimethylsiloxane （PDMS） material enhanced with two types of crosslinkers, carbon nanotubes and graphene sheets, was fabricated. The Contact Angle （CA） and cross-sectional morphology of the new material were investigated and observed using a CA meter and Scanning Electron Microscopy （SEM）, respectively. CA measurements indicate that the surface energy of the novel material is twice that of the common PDMS material. SEM observations show that carbon nanotubes and graphene sheets are well dispersed in the polymer, a feature that improves the mechanical properties of the new material. The adhesive performance of this novel composite was tested on an in-house fabricated friction machine. Results show that at a preload of only 50 mN, the adhesion of the novel PDMS material is up to -3.7 times that of common PDMS. The maximum macroscale shear strength and normal adhesion reach 4 N·cm^-2 and 1 N·cm^-2, respectively. The adhesive capability of the material is maintained even after hundreds of times of repeated use. This novel material exhibits excellent adhesion, sufficiently high elastic modulus and high repeatability at low preloads.
Qingsong HeMin YuYang LiXinlong ChenHao ZhangLing GongZhendong Dai
