Polypyrrole with Phosphor Tungsten Acid and Carbide-Derived Carbon: Change of Solvent in Electropolymerization and Linear Actuation

Abstract

Linear actuators based on polypyrrole (PPy) are envisaged to have only one ion that triggers the actuation direction, either at oxidation (anion-driven) or at reduction (cation-driven). PPy doped with dodecylbenzenesulfonate (PPy/DBS) is the most common applied conducting polymer having cation-driven actuation in aqueous solvent and mainly anion-driven actuation in an organic electrolyte. It is somehow desired to have an actuator that is independent of the applied solvent in the same actuation direction. In this research we made PPy/DBS with the addition of phosphorus tungsten acid, forming PPyPT films, as well with included carbide derived carbon (CDC) resulting in PPyCDC films. The solvent in electropolymerization was changed from an aqueous ethylene glycol mixture to pure EG forming PPyPT-EG and PPyCDC-EG composites. Our goal in this study was to investigate the linear actuation properties of PPy composites applying sodium perchlorate in aqueous (NaClO4-aq) and propylene carbonate (NaClO4-PC) electrolytes. Cyclic voltammetry and square potential steps in combination with electro-chemo-mechanical-deformation (ECMD) measurements of PPy composite films were performed. The PPyPT and PPyCDC had mixed ion-actuation in NaClO4-PC while in NaClO4-aq expansion at reduction (cation-driven) was observed. Those novel PPy composites electropolymerized in EG solvent showed independently which solvent applied mainly expansion at reduction (cation-driven actuator). Chronopotentiometric measurements were performed on all composites, revealing excellent specific capacitance up to 190 F g−1 for PPyCDC-EG (best capacitance retention of 90% after 1000 cycles) and 130 F g−1 for PPyPT-EG in aqueous electrolyte. The films were characterized by scanning electron microscopy (SEM), Raman, Fourier-transform infrared (FTIR) and energy dispersive X-ray spectroscopy (EDX).

Role of Polyoxometalate Contents in Polypyrrole: Linear Actuation and Energy Storage

“…Here, we show the effect of PPy/DBS-PT films in an organic electrolyte while keeping in mind that pristine PPy/DBS changed the actuation direction from cation-driven in the aqueous electrolyte to anion-driven in an organic electrolyte [ 18 , 24 ]. Besides the applied solvent in electropolymerization [ 20 ], the potential window also plays a role in the actuation direction [ 25 ]. Here, we have chosen the potential window of 1.0 to −0.55 V, which shows, in most cases of pristine PPy/DBS films, the main expansion upon oxidation, while small expansion upon reduction was also observed depending on the applied electrolytes [ 26 ].…”

“…The application of PPy/DBS-PT films in organic electrolytes has, in general, a lower capacitance than those in aqueous solution [ 6 ]. PPy combined with POM (Lindqvist-type anions, V n M 6-n O 19 (2+n)− ) showed specific capacitance in an organic electrolyte (acetonitrile) in the range of 25–36 F g −1 [ 7 ], and research on PPy/DBS-PT (0.01 M) in a NaClO 4 -PC electrolyte had specific capacitance in the range of 34 F g −1 (0.05 A g −1 ) [ 20 ]. In summary, the inclusion of PTA in PPy/DBS films led to enhanced specific capacitance, with an optimum found for 0.01 M PTA, which enables the use of these composites in flexible fabrics where energy storage is required.…”

“…If those PPy/DBS are applied in the organic electrolyte, the immobile DBS − –cation + pairs cannot dissociate, and the formerly cation-driven PPy/DBS becomes anion-driven [ 18 , 19 ], with new places of PPy charged upon oxidation, followed by anion ingress. It was found from recent research [ 20 ] that PPy/DBS-PT films have also shown expansion upon oxidation with a similar solvent effect, whereby PT 4− cation complexes cannot dissociate in organic electrolytes. The mixed actuation revealed in former research was the reason that some anions that were incorporated at charging of PPy/DBS-PT films became immobile, and upon reduction, they were compensated with cations of the surrounding electrolytes.…”

Conducting polymers as bio-mimetic multistep macromolecular sensors of working conditions: polyindole/polyvinyl alcohol hybrid film senses electrical and chemical working ambient

“…Reports in the literature show that the reactive sensing capability and simultaneous sensing actuator property has only been studied in detail with polypyrrole [60][61][62][63] and only a single paper has been found for polyaniline (PANI). 64 We suggest that it is a general property of all conducting polymers and here we are presenting the evidence for our claim that all CPs can act as bio-mimetic multistep macromolecular sensors of the working conditions by taking, for the first time, PIN and its electrochemical reaction as the model material and process, respectively, for mimicking the related biological process occurring in natural muscles.…”

Polypyrrole Polyethylene Composite for Controllable Linear Actuators in Different Organic Electrolytes

“…Nevertheless, the effects of different electrolytes in propylene carbonate solvent have not been shown for PPy-PEO films. Electrolytes such as EDMICF 3 SO 3 , NaClO 4 and TBAPF 6 which have the tendencies of mixed-ion actuation shown in PPy films [24,25] are designated. The linear actuation response of PPy-PEO is compared to pristine PPy/DBS films.…”