Search

Oxidative polymerization of pyrrole directly on preformed bucky gel slurry was carried out in order to combine the remarkable properties of ionic actuators based on carbon nanotubes and polypyrrole. Bimorph solid state ionic actuators were prepared with this novel hybrid material and compared with classical bucky gel actuators. A small amount of polypyrrole is sufficient to dramatically improve the overall actuator performance. The maximum strain is five times larger than the one of actuators prepared only with carbon nanotubes. Moreover, for the same applied charge, the strain generated increases up to twenty-five times.

Bucky gels are considered novel electro active polymers based on carbon nanotubes (CNTs). They are used to make electrochemical actuators that operate with a solid polymer electrolyte and so can work in air at low voltage (2–4 V) for long time with a maximum strain of approximately 1% and operating frequencies of a few tens of Hertz. It is reported in literature that the use of super-growth carbon nanotubes (SG-CNTs) affords the preparation of a composite with increased actuation performance that may considered the ‘benchmark’ material. We have recently shown a chemical route to modify single walled carbon nanotubes (SW-CNTs) with aromatic diamines (SW-amide) that significantly enhances the performance of bucky gel actuators through increasing the binding between CNTs. In this paper we compare the actuation performance of bucky gels made using chemically modified SW-CNTs with the one achieved using pristine SG-CNTs. The unique properties of SG-CNTs allow the preparation of actuators that outperform the ones made from pristine commercial CNTs in strain-charge and strain-frequency response but when SW-amide based actuators are compared with those made from SG-CNTs they show similar performances that stem from the increased binding between CNTs induced by the chemical modification.

doi: 10.1016/j.jowsour.2008.09.016 Safety is the main concern for energy storage-system application in hybrid-electrical vehicles (HEVs) and ionic liquids (ILs) of low vapour pressure and high thermal stability represent a strategy to meet this key requisite. The use of solvent-free ILs in supercapacitors enables the high cell voltages required for increasing supercapacitor energy up to the values for power-assist application in HEVs. In order to exploit the wide electrochemical stability window of ILs, tailored electrode materials and cell configurations have to be used. The performance of asymmetric double-layer carbon supercapacitors (AEDLCs) and carbon/poly(3-methylthiophene) hybrid supercapacitors operating with different pyrrolidinium-based ILs are reported and compared. This study demonstrates that a design-optimized AEDLC operating with safe, solvent-free IL electrolyte meets cycling stability and the energy and power requisites for power-assisted HEVs at the investigated temperatures.

The ionic liquids (ILs) N-butyl-N-methyl-pyrrolidinium trifluoromethanesulfonate (PYR14Tf) and N-methyl-N-propyl-pyrrolidinium bis(fluorosulfonyl)imide (PYR13FSI) are investigated as electropolymerization media for poly(3-methylthiophene) (pMeT) in view of their use in carbon/IL/pMeT hybrid supercapacitors. Data on the viscosity, solvent polarity, conductivity and electrochemical stability of PYR14Tf and PYR13FSI as well as the effect of their properties on the electropolymerization and electrochemical performance of pMeT, which features >200 Fg−1 at 60 °C when prepared and tested in such ILs, are reported and discussed; the results of the electrochemical characterization in N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide of the so-obtained pMeT are also given, for comparison.

Object grasping and manipulation in humanoid robots depend, for advanced and long lasting performance, on the development of reliable tactile sensors. Materials used for sensor implementation have to be chosen accurately and optimized in order to endow the device with sufficient resilience to endure long lasting grasping tasks. In particular care has to be taken when trying to enhance durability by the use of materials with high shore hardness as this choice can noticeably reduce pressure sensitivity. In this paper, a comparison between two implementations of the fingertip sensor of the humanoid robot iCub is presented by using a raw characterization of the response along a straight line. Prototypes differ in the materials used for the dielectric and protective layers, while maintaining the same capacitive architecture. The relevant result that emerges from the characterization is that the prototype with Soma Foama presents a higher sensitivity compared to the prototype in PDMS, while the second has a higher mechanical strength.