Structural Electrochemistry from Freestanding Polypyrrole Films: Full Hydrogen Inhibition from Aqueous Solutions

Free-standing polypyrrole films, being the metal–polymer contact located several millimeters outside the electrolyte, give stationary closed coulovoltammetric (charge/potential) loop responses to consecutive potential sweeps from –2.50 V to 0.65 V in aqueous solutions. The continuous and closed charge evolution corroborates the presence of reversible film reactions (electroactivity), together high electronic and ionic conductivities in the full potential range. The closed charge loop demonstrates that the irreversible hydrogen evolution is fully inhibited from aqueous solutions of different salts up to –2.5 V vs Ag/AgCl. The morphology of the closed charge loops shows abrupt slope changes corresponding to the four basic components of the structural electrochemistry for a 3D electroactive gel: reduction-shrinking, reduction-compaction, oxidation-relaxation, and oxidation-swelling. Freestanding films of conducting polymers behave as 3D gel electrodes (reactors) at the chain level, where reversible electrochemical reactions drive structural conformational and macroscopic (volume variation) changes. Very slow hydrogen evolution is revealed by coulovoltammetric responses at more cathodic potentials than –1.1 V from strong acid solutions, or in neutral salts self-supported blend films of polypyrrole with large organic acids. Conducting polymers overcome graphite, mercury, lead, diamond, or carbon electrodes as hydrogen inhibitors, and can compete with them for some electro-analytical and electrochemical applications in aqueous solutions

Planate conducting polymer actuator based on polypyrrole and its application

In this study, we propose a planate actuator which can transform only its central part locally. We have developed a planate conducting polymer actuator based on polypyrrole (PPy) and two types of acids, such as p-phenol sulfonic acid and dodecylbenzene sulfonic acid, by electrodeposition. Its structure was patterned bimorph structure with anion-driven, cation-driven and bimorph layers. The planate conducting polymer actuator could deform only its central part locally. Moreover, we introduce a micro-pump that operates by planate conducting polymer actuator as the drive source. The water level in the flow channel of micro-pump shows the reciprocating motion measuring ±2 mm in accordance with the oscillation of the bimorph conducting polymer actuator which was approximately 28 μl/min. The oscillating volume can be controlled by the application of electrochemical potential and its scan rate applied to the actuator

Investigations of Effects of Intermetallic Compound on the Mechanical Properties and Shape Memory Effect of Ti–Au–Ta Biomaterials

Owing to the world population aging, biomedical materials, such as shape memory alloys (SMAs) have attracted much attention. The biocompatible Ti–Au–Ta SMAs, which also possess high X–ray contrast for the applications like guidewire utilized in surgery, were studied in this work. The alloys were successfully prepared by physical metallurgy techniques and the phase constituents, microstructures, chemical compositions, shape memory effect (SME), and superelasticity (SE) of the Ti–Au–Ta SMAs were also examined. The functionalities, such as SME, were revealed by the introduction of the third element Ta; in addition, obvious improvements of the alloy performances of the ternary Ti–Au–Ta alloys were confirmed while compared with that of the binary Ti–Au alloy. The Ti3Au intermetallic compound was both found crystallographically and metallographically in the Ti–4 at.% Au–30 at.% Ta alloy. The strength of the alloy was promoted by the precipitates of the Ti3Au intermetallic compound. The effects of the Ti3Au precipitates on the mechanical properties, SME, and SE were also investigated in this work. Slight shape recovery was found in the Ti–4 at.% Au–20 at.% Ta alloy during unloading of an externally applied stress

Planate conducting polymer actuator based on polypyrrole and its application

In this study, we propose a planate actuator which can transform only its central part locally. We have developed a planate conducting polymer actuator based on polypyrrole (PPy) and two types of acids, such as p-phenol sulfonic acid and dodecylbenzene sulfonic acid, by electrodeposition. Its structure was patterned bimorph structure with anion-driven, cation-driven and bimorph layers. The planate conducting polymer actuator could deform only its central part locally. Moreover, we introduce a micro-pump that operates by planate conducting polymer actuator as the drive source. The water level in the flow channel of micro-pump shows the reciprocating motion measuring ±2 mm in accordance with the oscillation of the bimorph conducting polymer actuator which was approximately 28 μl/min. The oscillating volume can be controlled by the application of electrochemical potential and its scan rate applied to the actuator

ヒービング運動翼に働く非定常流体力

It is known that an oscillating airfoil can produce a driving force through the generation of a reversed Karman vortex street, and this can be expected to be a new highly effective propulsion system. A heaving airfoil model was made and it was operated within a water channel at low Reynolds number. The dynamic thrust and lift acting on heaving airfoil were measured simultaneously using a 6-axis force sensor based on force and moment detectors. We have been examined various conditions such as heaving frequency and amplitude in NACA 0010 profile. The results showed that thrust coefficient increased with reduced frequency. We also presented the experimental results on the unsteady fluid forces of heaving airfoil at various parameters.(流体工学,流体機械