An investigation is reported into the electrochemomechanical deformation (ECMD) of polypyrrole (PPy) doped with
dodecylbenzenesulfonate (DBS) in the form of freestanding films and deposited onto conductive substrates (chemically
fixed poly-3,4-(ethylenedioxythiophene, PEDOT) based on PVdF (poly(vinylidenefluoride)). Linear actuation has been
achieved starting from a trilayer bending actuator design with a stretchable middle layer. To allow evaluation of the
proposed design, commercially available PVdF membranes were chosen as model material. For bending trilayer
functionality, electronic separation of both electrode layers is essential, but in order to obtain linear actuation, the CP
layers on either side are connected to form a single working electrode. The PPyDBS free standing films and PPyDBS
deposited on PEDOT-PVdF-PEDOT were investigated by electrochemical methods (cyclic voltammetry, square wave
potentials) in a 4-methyl-1,3-dioxolan-2-one (propylene carbonate, PC) solution of tetrabutylammonium
trifluoromethanesulfonate (TBACF3SO3). This study also presents a novel method of utilizing scanning ion-conductance
microscopy (SICM) to accurately examine the electrochemical redox behavior of the surface layer of the linear actuator
using a micropipette tip.
Carbide–derived Carbon (CDC) material is applied for super capacitors due to their nanoporous structure and their high
charging/discharging capability. In this work we report for the first time CDC linear actuators and CDC combined with
polypyrrole (CDC-PPy) in ECMD (Electrochemomechanical deformation) under isotonic (constant force) and isometric
(constant length) measurements in aqueous electrolyte. CDC-PPy actuators showing nearly double strain under cyclic
voltammetric and square wave potential measurements in comparison to CDC linear actuators. The new material is
investigated by SEM (scanning electron microscopy) and EDX (energy dispersive X-ray analysis) to reveal how the
conducting polymer layer and the CDC layer interfere together.
Novel bending actuators were made solely from electrochemically polymerized conducting polymer materials. The working principle for these free-standing conducting polymer (CP) films is based on different anion- and cation-dominated actuation for the two layers. Synthesis conditions for the two layers of the same polymer film have been chosen such that the mobility of cations and anions in the considered potential window is different. Polymerization of CP layers of this nature on top of each other results in a sandwich structure with bilayer functionality in a properly chosen electrolyte. The results of a comparative study of various combinations of sandwiched PEDOT films in terms of actuation properties are presented in this study. Free-standing films of PEDOT linear actuators electrodeposited in the same electrolyte at different polymerization potentials were investigated by means of electro-chemo-mechanical deformation measurements. PEDOT-PEDOT bilayer functionality is studied in this work with a view to their bending actuation properties.
Trilayer actuators were constructed using polypyrrole (PPy) films doped with dodecylbenzene sulfonate (DBS). Identical
5-20 μm PPy/DBS films were grown on either side of a 110 μm poly(vinylidene fluoride) (PVDF) membrane to serve as
working and counter electrodes with respect to each other. The performance of the trilayer actuator was tested using
potential step experiments between -0.8 and +0.8 V at different frequencies (0.03 to 10 Hz) and trilayer lengths (1 to 2.5
cm), and the extent of deflection was measured using a CCD camera. Satisfactory deflections in the range of 1-3 mm
were observed for 10 μm thick PPy layers on trilayers 1.5 to 2.5 cm in length when operated at 1-5 Hz for over 40,000
cycles. The trilayer actuators were examined in a fluidics channels, and mathematical modelling using finite element
analysis was used to predict overall fluid movement and flow rates. The trilayers were also used to construct a 'fish-tail'
positioned at the back of a self-driven robotic fish.
The actuation properties of free standing films of poly-3,4-ethylenedioxythiophene (PEDOT) prepared from propylene
carbonate (PC) solutions of tetrabutylammonium trifluromethanesulfonate have been studied in a range of aqueous and
organic (PC) solvent electrolytes. The following electrolyte salts were investigated: TBACF3SO3, LiCF3SO3, TBAPF6,
NaPF6, NaDBS and TMACl. The best actuation performance was achieved in TMACl (aq.) with >4 % strain, 0.18 % s-1
strain rate and a low creep of 2.3 % after 50 cycles using potential step experiments. The PEDOT film morphology was
significantly changed from an open sub-micron pore polymer network to a morphology with fewer and less open pores when the solvent was changed from PC to water.
Investigations of the actuation properties of free standing PPy and PEDOT films in a propylene carbonate-triflate electrolyte (PC/TBACF3SO3) under isotonic (constant load)
conditions are presented in this work. The PPy film showed mixed ion movement during charging and discharging in cyclic voltammetric and chronoamperometric experiments. At a potential of -1.0 V the maximum strain was in the range of 1-2 % whereas at the anodic potential of +1.0 V strains in the range of 3-4 % were observed. Cyclic voltammetry experiments at higher scan rates to 10 mV/s led to a decrease in the anodic strain and an increase in the cathodic strain before it declined at higher scan rates. The free-standing PEDOT films showed mainly cathodic actuation at the potential -1.0 V and the size of actuation was again dependent upon the scan rate. Cation movement is discussed in terms of
the immobilisation of CF3SO3- anions during polymerisation. Extended potential step experiments showed good actuation and low creep in the potential range between 0.0 and
+1.0 V. The surface morphology (SEM) showed an open porous structure for PEDOT in contrast to the smooth morphology of PPy.
To construct practical devices based on the actuating properties of conducting polymers we need to understand the underlying mechanism of the reversible length change and the effect of numerous synthetic and processing parameters on the extent of actuation, reversibility and durability. Here, we have investigated the out-of-plane actuation of polypyrrole (PPy) doped with dodecylbenzenesulfonate (DBS) in an aqueous electrolyte, and the linear actuation of PPy/DBS (aq.) and PPy/ hexafluorophosphate (PF6) in a propylene carbonate (PC) based electrolyte. The out-of-plane actuation was examined by means of AFM, and linear actuation was evaluated by a combination of electrochemomechanical deformation (ECMD) measurements, cycling voltammetry, chronoamperometry and conductivity measurements. The results revealed a very large actuation for PPy/DBS (aq.) in the out- of-plane mode, but a very limited actuation in the linear direction with low reversibility. PPy/PF6 (PC) showed much higher linear actuation than PPy/DBS, with reversible ECMD characteristics.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.